Cancer Therapy Vol 2, 131-148, 2004

TNF and cancer: good or bad?

Review Article

Ashita Waterston and Mark Bower*

Department of Oncology, The Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK

__________________________________________________________________________________

*Correspondence: Dr Mark Bower PhD FRCP, Department of Oncology, The Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, United Kingdom; Tel 011 44 208 237 5054; Fax 011 44 208 746 8863; E mail m.bower@imperial.ac.uk

Key Words: TNF, cancer, Apoptosis, Activation, anti-cancer therapy, gene polymorphism, carcinogenesis, neovascularisation, angiogenesis, extra cellular matrix, vasculature, lymphatics

Abbreviations: bacillus Calmette-Guérin, (BCG); basal cell carcinoma, (BCC); cervical intraepithelial neoplasia, (CIN); containing recombinant human TNF, (rhTNF); Death receptor 3, (DR3); epidermal growth factor, (EGF); germinal centres kinase, (GCK); IkB kinase, (IKK); inducible nitric oxide synthase, (iNOS); MAPK activate protein kinase, (MAPKAP); MAPK kinases, (MKK); matrix metalloproteinases, (MMP); monoclonal antibody, (mAb); TNF converting enzyme, (TACE); natural killer, (NK); osteoprotegerin, (OPG); reactive oxygen species, (ROS); Tissue inhibitors of MMP, (TIMP); TNF receptor associated Death domain protein,, (TRADD)

Received: 27 April 2004; Accepted: 4 May 2004; electronically published: May 2004

Summary

Tumour necrosis factor (TNF) is a pro inflammatory cytokine whose role is established in the pathogenesis of chronic inflammatory diseases such as rheumatoid arthritis and Crohn’s disease. It is a 17KD molecule that exists as a trimer, dimer and monomer in equilibrium and as a membrane bound 26KD molecule. It binds to two receptors the 55KD and 75KD proteins. These receptors on binding aggregate and set up a number of signal transducing mechanisms that lead to cell apoptosis or gene upregulation. The latter often occurs via the MAPKinase and NFkB pathways. TNF in large amounts can induce haemorraghic necrosis of tumours. This anti-cancer effect is multi-factorial as TNF can cause vascular necrosis, a direct apoptotic effect on the cells and also free radical induced cell death. A number of studies have examined the anticancer effects of TNF in combination with other cytokines or chemotherapy agents. However the only use of TNF alone in clinical trials has been in limb perfusion studies for sarcoma and melanoma. More recently, TNF has been found to have a pro-cancerous effect. In a mouse skin model TNF induces carcinogenesis. Furthermore, gene polymorphisms that increase or decrease TNF production confer either an increased risk or protective effect on a number of different cancers and precancerous diseases including gastric cancer, lymphoma and cervical cancer as well as cervical intraepithelial neoplasia. Moreover, in murine models TNF promotes metastasis, tumour angiogenesis and cachexia. Trials with anti-TNF therapies are awaited to see the effects of blocking this cytokine in patients with cancer.

I. Introduction

TNF was initially identified in two laboratories and alternatively named cachectin, for the wasting effect induced in mice (Beutler et al, 1985), and tumour necrosis factor, because it caused haemorrhagic necrosis of various murine tumours in vivo (Carswell et al, 1975). TNF has been identified as a key mediator in the pathogenesis of both acute and chronic diseases. Successful strategies have been developed to block its action in animal models of shock (Beutler et al, 1985; Tracey et al, 1987), collagen induced arthritis (Thorbecke et al, 1992; Williams et al, 1992) and experimental autoimmune encephalomyelitis (Baker et al, 1994). Anti-TNF monoclonal antibody (mAb) therapy in human clinical trials has had success in some but not all diseases. (Elliot et al, 1994, Abraham et al, 1995, D'Haens et al, 1999, 2001; Lipsky et al, 2000). Anti-TNF mAbs are licensed in the USA and Europe for the treatment of rheumatoid arthritis and Crohn's disease. However the role of TNF in cancer is less clear with both anti-cancer and pro-cancerous effects.

A. TNF structure

TNF is found as a 26kd membrane bound molecule which, when cleaved by the TNF converting enzyme (TACE), forms soluble TNF consisting of the 76 amino-terminal residues with a molecular weight of 17kd (Black et al, 1997). Under native conditions bound and soluble TNF exist as a monomer, dimer and trimer in equilibrium, with the trimer being the biologically active form. TNF belongs to the TNF superfamily, which includes Lymphotoxin a and b, Fas ligand, CD40 ligand, and two apoptosis inducing ligands, TRAIL/Apo-2 ligand (Wiley et al, 1995; Pitti et al, 1996) and Light, which is also involved in T cell activation (Mauri et al, 1998; Zhai et al, 1998). These proteins are all ligands for the TNF receptor superfamily.

B. TNF receptors

TNF binds with high affinity to two cell surface receptors, a 55kd protein (p55TNF-R) and a 75kd protein (p75TNF-R), both are expressed by most cell lines and primary tissues. However, the level of receptor expression varies with cell type. The p55TNF-R expression is dominant on most cells, except for haemopoetic cells, and is relatively constant, while the p75TNF-R expression fluctuates. The binding of trimeric TNF to membrane anchored receptors causes cross-linking and aggregation of the homologous receptors. The cytoplasmic portion of the receptors interacts with signal transducing molecules initiating down stream intracellular signalling events. It is thought that p55TNF-R is the major signal transducer of soluble TNF responses, due to the abundance and binding avidity of this receptor; while p75TNF-R is preferentially activated by membrane bound TNF (Grell et al, 1995). Both receptors belong to the TNF receptor superfamily, which include among others Fas, CD40, (Smith et al, 1994), the Death receptor 3 (DR3) (Chinnaiyan et al, 1996), the Trail receptors DR4 (Pan et al, 1997b), DR5 (Pan et al, 1997a), TRID (Sheridan et al, 1997), the Light receptor TR2/HVEM (Kwon et al, 1997; Montgomery et al, 1996) and osteoprotegerin (OPG) which inhibits osteoclastic bone resorption (Simonet et al, 1997). All these receptors are membrane glycoproteins with sequence homology in the extra-cellular cysteine rich region. The p75TNF-R expression is controlled by extra cellular stimuli acting at the transcriptional and post-transcriptional level (Brockhaus et al, 1990; Thoma et al, 1990), and by receptor shedding. The extra cellular portion of both the p55 and p75 TNF receptors can be cleaved and released into serum as soluble forms. Soluble TNF receptors bind to soluble TNF, inhibiting systemic effects of TNF and enhancing clearance by the kidneys (Olsson et al, 1989; Porteu and Nathan, 1990; Bemelmans et al, 1993).

C. TNF function

The major sources of TNF are macrophages and to a lesser extent T lymphocytes, proliferating B cells, natural killer (NK) cells, mast cells and stimulated neutrophils (Gemlo et al, 1988; Sung et al, 1988; Djeu et al, 1990; Dubravec et al, 1990; Gordon and Gallis, 1990; Kinkhabwala et al, 1990; English et al, 1991; Stein and Gordan, 1991). Non-immune cells such as keratinocytes, smooth muscle cells, astrocytes and microglial cells have all been shown to produce TNF upon LPS stimulation in vitro (Sawada et al, 1989; Warner and Libby, 1989; Kock et al, 1990). TNF is a pleiotropic cytokine, which acts on a large variety of cells with wide ranging effects on individual cells (Table 1). Amongst the haemopoetic actions of TNF, are the activation of macrophages/monocytes (Trinchieri et al, 1986; Drapier et al, 1987; Kirchheimaer et al, 1988; Wang et al, 1990), lymphocytes (Jerlinek and Lipsky, 1987; Scheurich et al, 1987; Yokota et al, 1988), neutrophils (Schleiffenbaum and Fehr, 1990) and the promotion of coagulation (Lentz et al, 1991). It has a dual role in NK cells depending on the target cell. A subset of NK cells, lacking CD16, undergo TNF-induced apoptosis (Jewett et al, 1997), while IL-2 with TNF causes activation and increases NK cytolytic function (Ostensen et al, 1987). TNF induces bone resorption, important in bone metastasis formation (Bertolini et al, 1986; Johnson et al, 1989) and inhibits adipocyte proliferation which may contribute to cachexia (Kawakami et al, 1989).

Table 1. A list of TNF target cells

Target Cell	Action	Reference
Macrophages/ Monocytes	Activation, differentiation, chemotaxis	(Trinchieri et al, 1986; Drapier et al, 1987; Kirchheimaer et al, 1988; Wang et al, 1990)
Neutrophils	Activation, chemotaxis	(Schleiffenbaum and Fehr, 1990)
T lymphocytes	Proliferation, activation	(Scheurich et al, 1987; Yokota et al, 1988)
B Lymphocytes	Proliferation, differentiation, activation	(Jerlinek and Lipsky, 1987)
NK and LAK lymphocytes	Proliferation, activation, apoptosis	(Ostensen et al, 1987, Jewett et al, 1997)
Endothelial cells	Promotes clotting, haemopoetic growth factors and cytokine production	(Seelentag et al, 1987; Gimbrone et al, 1989; Osborn, 1990)
Adipocytes	Inhibition	(Kawakami et al, 1989)
Myocytes	Inhibition	(Miller et al, 1988)
Fibroblasts	Proliferation, cytokine production	(Butler et al, 1988)
Cartilage	Inhibits proteoglycan synthesis, resorption	(Saklatvala et al, 1985; Saklatvala, 1986;)
Osteoclasts	Activation	(Bertolini et al, 1986; Johnson et al, 1989)
Oligodendrocytes	Cytotoxic	(Selmaj et al, 1990)
Astrocytes	Proliferation	(Selmaj et al, 1990)
Keratinocytes	Differentiation, inhibits proliferation, cytokine production	(Nickoloff et al, 1991)

TNF has multiple effects on endothelial cells in vitro, such as promoting cytokine production that increases angiogenesis in vivo (Yoshida et al, 1997). TNF promotes the pro-inflammatory cascade, by inducing the release of pro-inflammatory cytokines such as the chemokine IL-8 (Gimbrone et al, 1989; Schroder et al, 1990; Nickoloff et al, 1991), IL-6 (Jirik et al, 1989), Groa (Dong et al, 1999), haemopoetic growth factors including G-CSF (Seelentag et al, 1987) and adhesion molecules such as VCAM important in metastasis (Osborn, 1990).

TNF also induces increased matrix metalloproteinase expression in a number of cell types and integrin expression. As shown by TNF knockout mice studies, this cytokine is necessary for normal splenic organisation in foetal growth (Keffer et al, 1991). In general, TNF exerts a similar range of effects as IL-1, except that it is able to induce apoptosis (Wallach et al, 1998) and is less efficient in inducing cartilage resorption (Saklatvala, 1986; Saklatvala et al, 1985). The cellular effects of TNF occur through binding to its receptor, which leads to secondary signalling events. These signalling events cause either apoptosis or gene regulation.

D. TNF receptor signalling

1. Apoptosis

In recent years, there has been significant progress in unravelling the TNF cell signalling pathways following receptor ligation, although this complex area is still under investigation (Figure 1). Upon TNF binding and aggregation of p55TNF-R, a portion of the intracellular domain of the receptor, known as the death domain, binds to an intracellular signalling moiety TRADD (TNF receptor associated Death domain protein) (Hsu et al, 1995). The death domains consist of six-amphipathic a-helices, in an anti-parallel arrangement that can interact with other death domains. TRADD, in turn, through its own death domain-like region interacts with MORT 1/Fadd (Varfolomeev et al, 1997), RIP and RAIDD, sequentially. This complex then recruits caspases 8 and 10, which belong to a family of enzymes essential in apoptosis (Boldin et al, 1996; Muzio et al, 1996). Caspase 2 is also recruited by the p55TNF-R via its N-terminal recruitment domain CARD that interacts with the CARD domain on RAIDD/CRADD using the RIP-RAIDD axis instead of MORT-1/FADD, to induce apoptosis (Ahmad et al, 1997; Duan and Dixit, 1997). The caspase cascade leads to the cleavage and disruption of proteins such as I-CAD, which acts as an inhibitor of CAD, a DNAse that degrades nuclear DNA into fragments characteristic of apoptosis (Enari et al, 1998). Apoptosis, however, only occurs when a cell is stressed, for example, by exposure to UV radiation or a protein /RNAse synthesis inhibitor, such as actinomycin D. Normally apoptosis is prevented from occurring through the recruitment of TRAF molecules (TNF receptor associated factor) (Rothe et al, 1995; Kelliher et al, 1998). The recruitment of TRAF molecules by TNF leads to up-regulation of genes and cellular activation.

2. Activation

TNF proliferative and stimulatory responses occur by induction of a number of genes such as other cytokines as well as cell cycling mechanisms. For this to occur the ligation and aggregation of p55TNF-R recruits TRADD and RIP, as previously described. However, TRADD and RIP can also act via alternative signalling pathways by recruiting TRAFs. To date six TRAF molecules have been identified that all have a conserved C terminal protein-protein interacting domain known as the TRAF domain, which interacts with members of the TNF-R superfamily (Hu et al, 1994; Rothe et al, 1994; Cheng et al, 1995; Mosialos et al, 1995; Regnier et al, 1995; Sato et al, 1995; Cao et al, 1996; Ishida et al, 1996; Nakano et al, 1996). TRAF 1, 2, 5 and 6 activate the NF-kB and JNK pathways, and TRAF 1 and 2 are associated with TNF signalling (Rothe et al, 1995; Song et al, 1997). TRAF 2 recruits TRAF 1, which then interacts with MAPK (Mitogen Activated Phosphorylation Kinase) pathways, proteins belonging to the MAPKKK superfamily that phosphorylates IkB kinase (IKK). This kinase then degrades cytoplasmic I-kB (Regnier et al, 1997), which releases NF-kB to translocate into the nucleus. This prevents apoptosis and activates other cellular responses. TRAF 2 is recruited directly via the p75TNF-R to activate the NF-kB and JNK pathways, explaining the overlapping actions of both receptors (Natoli et al, 1998). The best studied of the signalling pathways is the MAPKinase pathway (Figure 2). It involves a signalling cascade, which upon TRAF 2 recruitment, leads to phosphorylation of a serine/threonine kinase known as MAPK kinase kinase (MKKK). The process by which TRAF 2 leads to activation of MKKKs remains unclear but may involve small G–proteins and further MKKKs. The MKKKs in turn phosphorylate other serine/threonine kinases known as MAPK kinases (MKK). There are a number of MKKs activated by cytokines and other environmental factors. The TNF receptor is thought to activate MKK3 leading to p38 MAPK phosphorylation (Winston et al, 1997). Other kinases such as ASK 1 and MEKK, a MKKK, may also phophorylate MKK3, although they have been implicated to have a major role in the phosphorylation of p54 MAPK (JNK/SAPK) (Nishitoh et al, 1998; Yujiri et al, 1998). p38 MAPK phosphorylates targets downstream that affect the transcription factor ATF2 and cytosolic proteins cPLA₂ and Hsp27. cPLA₂ and MAPK activate protein kinase (MAPKAP), another cytosolic protein, along with the transcription factor Elk1 can also be activated by TNF via p42/44 MAPK (ERK). In murine macrophages this involves phosphorylation of MEKK (Winston et al, 1997) and in HL-60 and Cos cells this involves cRaf1 (Berra et al, 1995; Yao et al, 1995). Upon TNF receptor ligation, TRAF2 can also activate p54 MAPK, via a number of pathways involving ASK1, that in turn activates MKK7 (Ichijo et al, 1997) or MEKK-1 that interacts with germinal centres kinase (GCK), a MAP4K (Shi and Kehrl, 1997). p54 MAPK activation can also occur via the tyrosine protein kinase Pyk2 and the small G proteins PAK, Rac and cdc42 (Tokiwa et al, 1996).

Figure 1. TNF signalling through the p75 and p55 TNF receptor. This is a simplified diagram to show the main components of TNF signalling through its aggregated receptors. This process can either lead to apoptosis via the death effecter molecules, such as TRADD, and the caspases or cell activation via the TRAF molecules to protein kinases such as MAPK and NF-kB..

Figure 2. Schematic diagram to show the anti-cancer effects of TNF. TNF causes haemorrhagic necrosis in vivo with destruction of tumour vasculature and ischaemia. It also promotes tumour lysis by activating the anti-tumour immune response and can lead to direct tumour lysis via hydroxyl radicals and lysosomal enzymes. TNF can act synergistically with variety of other agents such as cytokines, chemotherapy and hyperthermia to induce tumour killing.

In summary, TNF on receptor ligation leads to activation of TRAF molecules which causes phosphorylation of a cascade of serine threonine kinases known as the MAP kinases pathway leading to activation of a number of cytosolic proteins which eventually lead to activation of transcription molecules and gene regulation.

II. TNF as an anti-cancer agent

Initially TNF was isolated from the serum of mice infected with bacillus Calmette-Guérin (BCG) treated with endotoxin. It was found to mimic the action of endotoxin by inducing tumour necrosis in vivo when given directly to a range of transplanted tumours including Meth A sarcoma (Carswell et al, 1975). Furthermore, in vitro it was cytotoxic to L293 cells and cytostatic to Meth A sarcoma cells (Carswell et al, 1975). A number of studies using syngeneic cancer models, particularly the transplantable methylcholanthrene induced sarcoma model, have shown tumour regression with either direct intra-tumoural TNF injection or systemic intravenous TNF injections (Creasey et al, 1986; Watanabe et al, 1988). Animal xenograft models have also shown that intra-tumoural injection of recombinant TNF can lead to tumour regression (Balkwill et al, 1986; Creasey et al, 1986).

A. Mechanisms of anti-cancer action

There appear to be a number of mechanisms by which TNF induces an anti-cancer effect (Figure 3). In vivo recombinant TNF directly injected into tumours destroys the tumour vasculature. It blocks blood flow, inducing congestion and haemorrhage of tumour vasculature (Watanabe et al, 1988a). On close examination of the tumours there are multiple petechial haemorrhages in the tumour-vascular bed causing ischaemia to the centre of the tumours due to the loss of blood supply (Havell et al, 1988). This however, only leads to 75% destruction of the tumour with a small rim of viable tissue remaining (Havell et al, 1988). TNF has also been shown to cause haemorrhagic necrosis in conjunction with IFNg, inducing vascular engorgement by erythrocytes and adhesion of platelets to tumour vascular endothelium. This then leads to destruction of the tumour vasculature with necrosis and apoptosis of tumour cells (de Kossodo et al, 1995). In isolated limb perfusion studies with TNF, within hours of TNF perfusion, the tumour endothelial cells appear swollen with increased VCAM and ELAM I adhesion molecules and tumour destruction due to a coagulative necrosis. Within 3 days there was significant polymorphonuclear cell colonisation of tumours, followed by T cells and macrophages 4 days later and B cells in the second week (Renard et al, 1994).

TNF may induce killing of tumours by immune cells. Genetically engineered tumour cells producing high levels of TNF have been implanted into tumours and, although they do not kill the tumours, they inhibit growth through the activation of macrophages and NK cells (Blankenstein et al, 1991). Using TNF knockout mice the ability of NK and LAK cells to induce cytotoxicity in a variety of tumour cell targets were found to be impaired. This cytotoxicity in the knockout mice required Fas-ligand and perforin, while the infusion of recombinant TNF in the knockout mice restored TNF induced cytotoxicity by these cells, similar to wild type mice. In vivo the TNF knockout mice were unable to reject MC57X syngeneic fibrosarcomas but did so if injected with recombinant TNF. Clearly, this shows, both in vitro and in vivo, TNF is required for NK and LAK induced tumour killing and tumour rejection in vivo (Baxevanis et al, 2000). It is likely that the NK cells themselves produce TNF along with FasL and other cytokines to induce apoptosis of tumours (Kashii et al, 1999). CTL tumour elimination and immunity also appears to be TNF dependant. In a Lewis lung carcinoma model (A9) injection of tumour cells containing a CD8 T cell epitope transgene GP33 leads to tumour elimination. This immunity was also perforin, IFNg and TNF dependant, providing evidence for the crucial role of TNF in CD8 directed tumour elimination in vivo (Prevost-Blondel et al, 2000). Conversely, tumours grown in T cell deficient mice had impaired tumour eradication, therefore, to achieve complete TNF-induced intra tumoural haemorrhagic necrosis an adequate host T cell immunity is required (Havell et al, 1988). Dendritic cells also have a potent anti-tumour effect against breast cancer cells in vitro, which is mediated by TNF and blocked by the addition of anti-TNF monoclonal antibodies (Manna and Mohanakumar, 2002). Furthermore, immature dendritic cells induced apoptosis of tumour cells by TNF, FasL, lymphotoxin b and TRAIL through the corresponding death receptors in a range of cancer cells (Lu et al, 2002).

Finally, TNF can have a direct effect on the tumour cells. Using inhibitors to lysozymal enzymes, hydroxyl radicals and mitochondrial respiratory inhibitors Watanabe et al found that there was a reduction in TNF induced tumour death. This study indicates that for TNF induced cell destruction, lysozymal enzymes, hydroxyl radicals and ATP may be needed (Watanabe et al, 1988b). TNF also leads to tumour cell death by inducing cytochrome c release from mitochondria and mitochondrial membrane permeabilisation leading to apoptosis (Partheniou et al, 2001). One of the mechanisms tumours use to generate a growth advantage is reducing TNF induced apoptosis through mutations in p53. Mutations in p53 were found to reduce caspase 8 activation and mitochondrial membrane permeabilisation and infection with adenovirus containing wildtype p53 restored caspase cleavage and mitochondrial permeabilisation and apoptosis due to TNF (Ameyar-Zazoua et al, 2002). TNF induced apoptosis may not always be p53 dependant. In a non-small cell lung cancer cell line the combination of TNF and IFNg induced apoptosis, without altering the expression levels of p53, indicating this was p53 independent. However, the addition of c-myc anti-sense oligonucleotides did reduce the combined TNF/IFNg induced apoptosis indicating that c-myc may contribute to TNF induced apoptosis of this lung cancer cell. Another mechanism by which TNF induces tumour cell apoptosis or resistance to apoptosis, is via the inhibition or activation of NF-kB. In lung adenocarcinoma cells the constitutive activation of NF-kB leads to resistance to apoptosis, however, in the presence

Figure 3. Schematic diagram to show the role of TNF in the up-regulation of Cancer. TNF can induce cancer by affecting tumour proliferation, altering the cell structure and appears to act early to promote carcinogenesis. Furthermore, TNF also helps tumours to metastasise by inducing extracellular matrix (ECM) adhesion and degradation as well as promoting adhesion of tumour cells to endothelial cells and neovascularisation. TNF also contributes to cancer cachexia by increasing proteolysis and lipid metabolism. Polymorphisms in the TNF promoter region regulate TNF production and may affect prognosis.

of TNF the blocking of NF-kB by proteosome inhibitors induces apoptosis (Milligan and Nopajaroonsri, 2001). Therefore, TNF induced apoptosis of tumour cells is very much dependant on which cell signalling pathways are constitutively active in tumour cells. IFN g leads to sensitisation of ovarian tumour cells to TNF induced apoptosis by down regulating NF-kB. This occurs by IFN g inducing inducible nitric oxide synthase (iNOS), which generates nitric oxide. The nitric oxide can then react with oxygen reducing the production of hydrogen peroxide an activator of NF-kB (Garban and Bonavida, 2001). Studies with MCF 7 breast cancer cells have shown that TNF alone also up-regulates iNOS, thereby leading to cell apoptosis (Binder et al, 1999). In Erlich ascitic tumours, TNF increased reactive oxygen species (ROS), which led to a reduction in mitochondrial glutathione and caused apoptosis in mice already depleted of glutathione by eating a glutamate-enriched diet. Glutamate is an inhibitor of glutathione (Obrador et al, 2001). A recent study has shown a direct link between increased ROS due to TNF and the reduction in mitochondrial ATPase protein subunits, cytochrome c oxidase subunit II and increased protein levels of phosphofructokinase; these changes were associated with an increase in L929 cell apoptosis (Sanchez-Alcazar et al, 2002). TNF induces tumour cell apoptosis by generating ROS at the mitochondrial membrane. Oxidative substrates, electron-transport inhibitors, caspase inhibitors, glutathione and thiol-reactive agents modulate the ROS production induced by TNF (Goossens et al, 1999).

B. TNF in combination with other anti-cancer therapies

To enhance the ability of TNF to kill tumours, a number of studies have examined the synergistic effects of TNF in combination with chemotherapy agents. Using L-M cells the addition of a number of commonly used chemotherapy agents to cultures containing recombinant human TNF (rhTNF) produced a 4-347-fold decrease in the IC50 (the concentration required for 50% inhibition of cell growth) compared to rhTNF alone (Watanabe et al, 1988c). A similar study examined the cytotoxicity of TNF with hyperthermia in L-M cells and found a 500-fold increase in toxicity at 40ΦC compared to 37ΦC. The combination of TNF and hyperthermia in vivo with transplantation of Meth A fibrosarcoma cells in mice also produced cures in 5 mice compared to a partial response with TNF alone (Watanabe et al, 1988c). However, due to the high toxicity profile of TNF, its systemic use is limited. To circumvent this problem Curnis et al have coupled TNF to CNGRC, a peptide that targets tumour neovasculature. This allows a 10-fold decrease in the dose of TNF required. They have used TNF to alter the endothelial barrier within tumour vasculature and thereby increase the efficacy of doxorubicin by 8-10 fold without increasing toxicity (Curnis et al, 2002). The other way to reduce systemic toxicity of TNF has been by isolated limb perfusion of TNF; this has been used in rat models and patients (Eggermont et al, 1996; de Wilt et al, 1999).

C. Clinical trials of recombinant TNF

TNF has been administered intravenously to a wide range of tumours in Phase I and II clinical trials with none or limited tumour responses and was associated with severe toxicity particularly hypotension, rigors, fever and hepatotoxicity (Selby et al, 1987; Creagan et al, 1988; Brown et al, 1991; Furman et al, 1993). The use of TNF and IFNg, which had been shown in vitro to act synergistically, has also been evaluated in clinical trials, again the toxicity produced was unacceptable and the tumour responses disappointing (Abbruzzese et al, 1990; Fiedler et al, 1991). TNF however, has been shown to be useful in limb perfusion studies for patients with melanoma and soft tissue sarcomas. In these studies, the limb vasculature was isolated from the body and large amounts of systemically toxic TNF were infused into these tumour-bearing limbs to necrose the tumour (Eggermont et al, 1996). This strategy is licensed in Europe in combination with melphalan, since the addition of TNF to melphalan increased the response rates considerably.

The use of TNF as an anti-cancer agent has clear limitations due to its toxicity and may even be deleterious in the long term, as it can lead to re-growth of resistant tumours and, in the case of melanoma, more aggressive strains (Zouboulis et al, 1990). There is significant evidence pointing to TNF as an agent promoting different aspects of cancer (Figure 3).

III. TNF as a carcinogen

A. TNF in human tumours

TNF has been detected in a number of different tumour types such as ovarian and breast tissue as well as haematological malignancies (Naylor et al, 1993; Miles et al, 1994; Sati et al, 1999; Warzocha et al, 2000). Both mRNA expression and TNF protein has been found in human epithelial ovarian tumour cells as well as within the infiltrating macrophages. The p55 TNFR has also been detected within ovarian tumour cells and infiltrating macrophages but not stromal macrophages whilst the p75 TNFR has only been found within the infiltrating macrophages (Naylor et al, 1993). In 49 biopsies taken from patients with breast cancer, 43 expressed TNF mRNA and protein compared to 4/11 biopsies from patients with benign breast disease. The TNF was localised to tumour stroma and infiltrating macrophages. Furthermore, though the number of macrophages did not increase with tumour grade, the expression of TNF within the macrophages increased with tumour grade (Miles et al, 1994). A similar picture of increased production of TNF correlating with worse prognosis has been identified in patients with prostrate cancer (Nakashima et al, 1998). In these patients, raised serum TNF levels were associated with a reduction in body mass index and other factors associated with cachexia as well as a significantly increased mortality (Nakishima et al, 1998). In keeping with this, TNF has been shown to inhibit androgen receptor sensitivity, a poor prognostic indicator, and hence induce androgen independent proliferation in the LNCaP cell line (Mizokami et al, 2000). In chronic B cell lymphocytic leukaemia, increased TNF levels were found at all stages with a progressive increase in serum TNF levels in relation to the disease (Adami et al, 1994). Patients with other haematological malignancies such as lymphoma have also been examined: correlating the production of TNF with histology revealed higher levels of TNF, p55TNFR, Lymphotoxin (LT)a and LTb-R mRNA in follicular NHL than other histological entities (Warzocha et al, 2000).

B. TNF gene polymorphism and cancer

A single gene polymorphism within the TNF locus (-308) has been identified using an allele-specific polymerase chain reaction. This together with a polymorphism on the LTa locus has been measured in 273 lymphoma patients (Warzocha et al, 1997). The presence of the TNF allele involved in gene transcription was associated with higher plasma levels of TNF at the time of tumour diagnosis. Expression of the two alleles associated with increased TNF production were found to be a risk factor for failure of first-line chemotherapy, a shorter progression-free survival and a reduction in overall survival (Warzocha et al, 1997). A similar increase in risk of developing MGUS and myeloma has also been associated with high TNF producers (Davies et al, 2000).

TNF microsatellite polymorphisms have also been examined in gastrointestinal cancer. In 47 patients with gastric cancer there was an increase in frequency of TNFa3 allele and a decrease in frequency of TNFa10 allele compared to normal controls. In 77 patients with colorectal cancers there was an increase in frequency of TNFd7 allele compared to normal controls. No correlation with expression of the allele and TNF production were discussed in the paper (Saito et al 2001). Other studies have shown that the expression of the TNF-308A allele, which is known to up-regulate TNF did not increase the risk of gastric cancer but the expression of TNF–238A allele, which is known to down-regulate TNF transcription could be protective against gastric cancer, although the sample size was small (Gonzalez et al 2002).

Single nucleotide polymorphisms of the promoter region of TNF were examined in prostrate cancer. The 488 locus was associated with a 17 fold increased incidence of prostrate cancer and an increase in tumour staging was related to polymorphisms at the–308 locus (Oh et al, 2000). However, a more recent larger study looking at single nucleotide polymorphisms at the TNF-308 locus found no difference between patients and controls (MacCarron et al, 2000).

In two other cancers, microsatellite polymorphism studies have found a correlation with TNF polymorphism and the risk of cancer. In a study of Swedish women with the HLA DR15-DQ6-haplotype there was an increased frequency of TNFa-11 polymorphism and an increase in HPV16 positivity. The TNF polymorphism was not associated with the pre-cancerous lesion cervical intraepithelial neoplasia (CIN) alone, however the relative risk of CIN conferred by the combination of TNFa-11, HLA-DQ6 and HPV 16 positivity was 15 (Ghaderi et al, 2001). In the same population, the risk of cervical cancer associated with the TNFa-11 polymorphism was also examined. The increased frequency of TNFa-11 was associated with HPV18 positivity but not HPV16 and TNFa-11 increased the risk of cancer in patients with the HLA DQ6 haplotype (Ghaderi et al, 2001). A further study in patients with cervical cancer has also shown under representation of the TNF-238 polymorphism, which is associated with a down regulation of TNF transcription (Calhoun et al, 2002). In cutaneous basal cell carcinoma (BCC), there was difference in the frequency of a1 and a7 polymorphisms in patients with BCC compared to controls. There was also an increase in the number of BCC in patients with alleles d4 and d6 alone or TNFa2-b4-d5 haplotype (Hajeer et al, 2000).

C. The role of TNF in carcinogenesis

A number of studies attempted to establish a link between inflammation and carcinogenesis; including experiment to assess the ability of pro-inflammatory cytokines such as TNF, to induce tumours. TNF is a cytokine that is produced early in the inflammatory cascade and has been shown to promote carcinogenesis in murine skin tumours. Using TNF knockout mice the development of skin carcinomas by chemical carcinogen DMBA (7.12-dimethylbanz[a]-antracene) and tumour promoter TPA (12-0-tetradecanoyl-phorbol-13-acetate) were decreased compared to wildtype mice (Moore et al, 1999, Suganuma et al, 1999). Using pentoxifylline, which was shown to inhibit TNF and IL-1a gene expression, the growth of DMBA/TPA induced papillomas were inhibited (Robertson et al, 1996). Pentoxifylline was also able to inhibit the inflammatory response and TNF production induced by cutaneous UV-B light exposure. Indicating that TNF may be involved in the mechanism by which long-term UV-B light exposure, can contribute to skin cancer (Oberyszyn et al, 1998). Earlier studies have shown that TNF is able to induce growth of v-Ha-ras transfected BALB/3T3 cells though not the non-transfected BalB3/T3 cells and that the chemical carcinogen okadaic acid induces mouse TNF-a in the transfected and non-transfected tumours. These results suggest that a chemical tumour promoter can induce the secretion of TNF-a from various cells and that TNF can then act as an endogenous tumour promoter in vivo (Komori et al, 1993). The mechanism and signalling events associated with this carcinogenesis are still being elucidated. In basal cell keratinocytes, the chemical promoter TPA induces PKC a a process down-regulated in TNF knockout mice, as is the transcription factor AP-1. AP-1 induces GM-CSF, MMP 9 and MMP 3 proteins that are important in tumour development (Arnott et al, 2002). Using the epidermal JB6 murine model, AP-1, NF-kB and nitric oxide synthetase have all been implicated in tumour promotion by TPA, epidermal growth factor, TNF and oxidative stress. In this particular model, the effect of TNF was primarily in up-regulating NF-kB (Dhar et al, 2002). Other groups, however, have shown that TNF, along with other pro-inflammatory cytokines, induces nitric oxide synthetase in a cholangiocarcinoma cell line (Jaiswal et al, 2000). This enzyme produces nitric oxide, which can increase DNA damage by inhibiting sensitive DNA repair enzymes, and thereby contributes to an increase in genetic mutations (Jaiswal et al 2000). Other studies have shown that the presence of iNOS in gynaecological tumours correlates with dedifferentiation (Thomsen et al, 1994). Therefore, the production of nitric oxide through TNF induction of iNOS may not only lead to tumour cell apoptosis, as described previously, but may also promote carcinogenesis. In a gastric carcinoma cell line the up-regulation of WNT10A and WNT10B by TNF and Helicobacter pylori may be an important pathway in carcinogenesis (Kirikoshi et al, 2001). The WNT 10A and 10B genes are human orthologues of the mouse proto-oncogene Wnt-10b, which activates the b catenin-TCF signalling pathway. Deregulation of this pathway has been implicated in several forms of cancer such as colon cancer and melanoma (Brantjes et al, 2002). In liver tumour formation, Knight et al found that TNF was up-regulated by hepatic stem cells (oval cells) and contributed to their proliferation via p55 TNFR, as there was a reduction in proliferation and liver tumour formation in p55TNFR but not p75 TNFR knockout mice (Knight et al, 2000). TNF however, is not the only important cytokine in liver tumour formation, hepatocellular proliferation and tumour formation in rats exposed to a peroxisome proliferator can be induced via IL-1 and IL-6 (Anderson et al, 2001). It may be that different carcinogens require different cytokines to aid carcinogenesis. The signalling pathways induced by TNF have also been examined in rat mammary cells. TNF stimulated growth and morphogenesis of normal rat mammary epithelial cells as well as transformed mammary epithelial tumours. NF-kB/p50 DNA binding was present in the tumour cells but absent in normal mammary epithelium, however, TNF stimulation of normal epithelia leads to an induction of NF-kB/p50 DNA binding (Varela et al, 2001). Therefore, TNF may induce carcinogenesis by up-regulating NF-kB leading to the up-regulation of other proteins that cause cell proliferation and morphogenesis.

D. The role of TNF in metastasis

During inflammation, a number of proteins can be up-regulated to allow immune cells to migrate to sites of inflammation. Tumours use these same processes to invade adjacent structures. TNF is a potent pro-inflammatory cytokine that can be utilised by tumours to induce other downstream molecules involved in the metastatic process. Recombinant TNF injected into mice inoculated with a methylcholanthrene-induced fibrosarcoma increased the number of lung metastases (Orosz et al, 1993). Cells transfected with the TNF gene were also found to increase metastatic potential. In Chinese hamster ovarian cells transfected with TNF there was increased intraperitoneal invasion, compared to cells infected with vector alone, and furthermore, antibodies to TNF abrogated this ability. (Malik et al, 1990). Similarly, ESB tumour cells infected with a retrovirus carrying the TNF gene were found to have augmented metastatic tumour activity and this metastatic process could be reversed with anti-TNF mAbs (Quin et al, 1993). Blocking TNF using the human p55-IgG fusion protein in a murine B16-BL6 melanoma model reduced the number of metastatic lung tumours indicating that some tumours may intrinsically use TNF within their microenvironment to aid metastasis (Cubillos et al, 1997). The administration of intraperitoneal TNF in human ovarian xenograft models had a paradoxical effect on the tumours. The intraperitoneal administration of rhTNF had anti-tumour activity in two out of three xenografts with tumour clumps in the peritoneum being surrounded by host inflammatory cells and necrosis of the tumours in 4-7 days. The third xenograft however, continued to grow and rhTNF promoted adhesion of the tumour cells to the peritoneum and the establishment of tumour nodules on the mesothelial surface, phenomena noted in the other two xenografts as well (Malik et al, 1989). This suggests that human TNF may also promote metastasis in human tissue. Metastasis can be divided into a series of biological processes described below. TNF appears to be involved in the up-regulation of these pro-metastatic factors and hence contributes to the completion of each of these processes.

1. Neovascularisation, angiogenesis and the role of TNF

In order for a primary tumour to expand, it requires nutrition and oxygen. When tumours are less than 200mm in diameter this occurs by diffusion, however larger tumours require vasculature. Chemokines such as IL-8 and Groa as well as other growth factors e.g. FGF, PDGF and thymidine phosphorylase are important in neovascularisation (Folkman, 1986, 1995; Folkman and Klagsbrun, 1987; Auerbach and Auerbach, 1994; Fidler and Ellis, 1994; Nagy et al, 1995; Leek et al, 1998). They attract endothelial cells and cause the migration of capillaries into the tumours. The endothelial cells proliferate and form vascular loops with new basement membranes with different cellular composition, permeability and stability as well as growth regulation compared to the host capillaries. TNF has been found to increase the expression of IL-8 and Groa in a number of different cell types (Strieter et al, 1995). In histological samples of malignant breast cancer, increased TNF staining correlated with increased thymidine phosphorylase an important enzyme in angiogenesis (Leek et al, 1998).

There also needs to be down-regulation of various inhibitors in order for angiogenesis to occur. These include inhibitors of matrix metalloproteinases (MMP), as they prevent migratory endothelial cells degrading basement membrane. A number of artificial MMP inhibitors are being used in anti-angiogenic trials to inhibit endothelial invasion (Nemunaitis et al, 1998; Shalinsky et al, 1999). TNF has been found to up-regulate MMP 9 and thereby may contribute to angiogenesis (Shin et al, 2000). Therefore, inhibition of TNF may have a role in preventing angiogenesis by inhibiting MMPs. It is thought that the anti-angiogenic mechanism of thalidomide is in part due to the inhibition of pro-inflammatory cytokines such as TNF. Thalidomide is in Phase II trials for a number of tumours including renal cancer and melanoma (Stebbing et al, 2001).

2. TNF increases detachment from the primary site

Cells within a tissue are retained within the structure by their adhesion to neighbouring cells and by the extra cellular matrix. Therefore, in order for invasion to occur tumour cells need to detach and become mobile. There are four groups of adhesion molecules important in this process. The first are the cadherins, which interact with other cadherins to form cell-to-cell attachments. The down-regulation of E-Cadherin in particular has been implicated in cancer invasion in a number of human malignancies (Shiozaki et al, 1991; Tohma et al, 1992; Dorudi et al, 1993). Stimulation of intestinal cells with TNF reduced E-Cadherin levels enhanced invasion, via a Src kinase dependant mechanism (Kawai et al, 2002).

The second group of important adhesion molecules are the integrins, which are made up of differing combinations of a and b subunits. These molecules enable cells to adhere to components of the basement membrane and stroma such as collagen, vitronectin, laminin and fibronectin during migration (Hynes, 1992). In OST osteosarcoma cells, stimulation with TNF causes up-regulation of a2b1 and a5b1 with increased adhesion and migration through the extra cellular matrix (Kawashima et al, 2001).

The third group of adhesion molecules are members of the immunoglobulin superfamily including ICAM 1, 2 and 3, and other immunoglobulin superfamily members such as VCAM, which bind integrins and are important in cell-to-cell interactions. These molecules are up-regulated by pro-inflammatory cytokines such as TNF, IFNg, and IL-1 and they have a major role in T cell and NK cells adhesion and migration. In a cancer setting, TNF appears to attenuate the basal expression of ICAM-1 in the presence of the extra cellular matrix in a thyroid cancer cell line (Miller et al, 2000).

The fourth major group of adhesion molecules are the selectins, which bind to carbohydrate groups on glycoproteins. E-selectin found on endothelial cells binds sialyl-Lewis X and G found on epithelial cells in colon and gastric carcinomas. TNF appeared to stimulate E-selectin expression on cultured human vascular endothelial cells to increase their adhesion to Sialyl-Lewis (a) on pancreatic cancer cells and thereby aid tumour entry into the vasculature (Nozawa et al, 2000).

3. Increased motility and the possible role of TNF

Tumour invasion requires the cells to be motile. Autocrine motility factors and those due to stromal cytokine production are associated with changes in the tumour cell cytoskeleton. TNF has been found to increase the motility of a number of cancer cells (Rosen et al, 1991; Dekker et al, 1994; Carpenter et al, 1997). In order for cells to move they undergo distinct events that are regulated by separate signalling pathways (Condeelis et al, 2001; Kassis et al, 2001; Price and Collard, 2001). Dividing the process into separate entities, the initial event is the extension of the lamellipodia, which is then stabilised by adhesion to the substratum. This is followed by the generation of contractile forces causing translocation of the body of the cell and finally the detachment of the trailing edge. To produce the lamellipodia there needs to be reorganisation of the cytoskeleton and the cyclic polymerisation and de-polymerisation of actin. The Rho family of GTPases affects these processes. Cdc42, Rho and Rac1 have all been shown in vitro to lead to the formation of actin stress fibres, lamellipodia and filopodia respectively, which are all involved in motility. In fibroblasts, TNF and IL-1 stimulate CdC42 causing filopodia formation (Puls et al, 1999) and via ceramide, increase stress fibre formation (Hanna et al, 2001). The effects of TNF on motility does, however, appear to be cell-dependant. In macrophages for example, TNF inhibits filopodia and reduces F-actin via the p55 TNFR death domain. Inhibition of the death domain by the synthetic compound D609 or TNFR mutants increases F actin with accumulation at the cell cortex and involves the FAN binding site of the receptor (Peppelenbosch et al, 1999). Therefore, the effect of TNF on cytoskeletal reorganisation may depend on the region of the TNFR that is activated. In tumour cells epidermal growth factor (EGF) has been shown to activate Rho-GTPases and induce cytoskeletal reorganisation and tumour invasion in vitro. The effect of TNF on cytoskeletal reorganisation in tumour cells remains to be elucidated. The adhesion of the lamellipodia and de-adhesion of the trailing edge involves the regulation of adhesion factors such as integrins. TNF has been shown to up-regulate integrins and aid invasion in vitro in specific tumour cells (Kawashima et al, 2001).

4. TNF increases invasion of the extra cellular matrix

In order for cells to migrate they need to degrade the basement membrane. The membrane primarily consists of type IV collagen and stroma, the latter is composed of types I, II, III collagen, proteoglycan and glycoprotein. To degrade the membrane the cancer cells produce matrix-degrading enzymes. The major family of degrading enzymes are the MMP, which contain a zinc-binding domain at their catalytic site. They are secreted in their inactive form and are activated by other proteases. The MMP can be divided into different groups based on their properties and substrates. MMP 2 and 9 are up-regulated in breast (Davies et al, 1993b), prostate (Stearns and Wang, 1993) ovarian (Davis et al, 1993a) and bladder cancer (Davies et al, 1993c). TNF appears to up-regulate MMP 2 and 9 in some bladder cancer cell lines (Shin et al, 2000). Host stromal cells also produce MMP and cancer cells may utilise them to facilitate invasion. TNF production by stromal cells induces MMP 9 production in human giant cell tumours of bone (Rao et al, 1999). MMP have natural inhibitors known as TIMP (Tissue inhibitors of MMP), which control their activity. Tumour invasion depends in part on the balance of MMP with TIMP and pro inflammatory cytokines such as TNF can tip the balance in favour of MMP (Hajitou et al, 2001).

Other proteases that degrade the extra cellular matrix include serine proteases, which have a serine in their active site. An example of this is urokinase-plasminogen activator that catalyses the conversion of plasminogen to plasmin, which degrades components of the extra cellular matrix. TNF has been found to up regulate urokinase-plasminogen and thereby increase invasiveness of tumours (Wu et al, 1999).

5. Entry into vasculature and lymphatics

Once the tumour cells invade through the basement membrane they enter the lymphatic or vascular system and disseminate to the rest of the body. The lymphatics and blood stream are interlinked, so that tumours that pass into one system can readily pass into the other system. Due to the processes of neovascularisation the capillary vasculature lies close to the basement membrane, so that tumour cells, once they have invaded the basement membrane, are able to adhere to the endothelial cells and pass into the vasculature easily. The adhesion of tumour cells to endothelial cells occurs via endothelial adhesion molecules such as E-selectin and VCAM (Nozawa et al, 2000; Flugy et al, 2002; Simiantonaki et al, 2002) that bind to glycoproteins and integrins on the tumour cells (Voura et al, 2001). The capillaries tend to be more permeable than the normal physiological capillary vasculature, enabling tumour cells to squeeze between endothelial cells into the blood vessels.

6. Extravasation

The circulating tumours are able to adhere to the endothelium and using pseudopodial projections invade the surrounding tissue (Morris et al, 1997). The tumours adhere to components of the extra cellular matrix using integrins in a similar process to invasion from the primary site (Renkonen et al, 1999; Tanaka, 1999). Once they have penetrated the organ parenchyma, their proliferation depends on the environment.

7. Proliferation of metastases

Once tumours arrive at their sites of metastasis, they can manipulate the host environment to develop the tumour architecture. TNF may help in this by stimulating the proliferation of fibroblasts and collagen (Mauviel et al 1991, Battegay et al 1995). Tumours also use the host environment to aid proliferation by binding to growth factors released from the stroma. For example, in multiple myeloma, TNF induces bone marrow stromal cells to produce IL-6, a myeloma growth factor (Hideshima et al, 2001). Once metastatic tumours grow, they again need to develop a vasculature to increase beyond a certain size and do so in a similar way to the primary tumours. This in turn aids metastasis, as they are then able to metastasise to other organs.

Since tumours are genetically unstable, often the metastatic tumours may have developed an advantage compared to the primary tumour aiding their survival. Parratto et al, (1989) found an inverse correlation between a strong antibody response and metastatic ability, so that the host’s immune response may be selecting out the poorly metastatic clones and allowing the highly metastatic clones to proliferate. The production of TNF by the host immune cells may thereby contribute to the development of metastatic clones.

IV. Conclusion

TNF has a wide range of activities in cancer including cancer related cachexia that has not been covered in this review. It was initially thought that the majority of the effects of TNF on cancers were beneficial enhancing immunological rejection of cancers via NK and CTL responses. However, the clinical trials using TNF to treat cancer were disappointing due to the high toxicity caused by large amounts of cytokine. Indeed now the only therapeutic role that remains is for the treatment of melanoma in isolated limb perfusion. More recently, as is often seen with TNF, it has converse actions that induce a number of pro-inflammatory genes, which the tumours utilise to promote cancer such as cytokines, angiogenic factors and MMPs. These factors contribute to tumour formation, growth, invasion and metastasis to other sites. Many of the actions of TNF may occur by the stimulation of stromal tissue, tumour-associated macrophages and fibroblasts. These cells may then produce inflammatory cytokines including TNF itself, as well as some of the angiogenic factors described above, contributing to tumour proliferation and invasion. Anti-TNF mAbs have now been licensed in the USA and Europe and are widely used for the treatment of rheumatoid arthritis and Crohn's disease. We await with interest the long term follow up of these clinical trials which have specifically blocked to TNF as they may provide an indication of the role of this cytokine in promoting cancer.

Acknowledgements

This work was supported in part by a Vaekstfond grant from the Danish Government. The authors thank Prof. R. Kohnen, IMEREM GmbH for professional monitoring of this clinical trial.

References

Abbruzzese JL, Levin B, Ajani JA, Faintuch JS, Pazdur R, Saks S, Edwards C, and Gutterman JU (1990) A phase II trial of recombinant human interferon-g and recombinant tumor necrosis factor in patients with advanced gastrointestinal malignancies: results of a trial terminated by excessive toxicity. J Biol Response Mod 9, 522-7.

Abraham E, Wunderink R, Silverman H, Perl TM, Nasraway S, Levy H, Bone R, Wenzel RP, Balk R, Allred R et al, (1995) Efficacy and safty of monoclonal antibody to human tumor necrosis factor a in patients with sepsis syndrome. A randomized, controlled, double-blind, multicenter clinical trial. TNF-a Mab Sepsis Study Group. JAMA 273, 934-941.

Adami F, Guarini A, Pini M, Siviero F, Sancetta R, Massaia M, Trentin L, Foa R, and Semenzato G (1994) Serum levels of tumour necrosis factor-a in patients with B-cell chronic lymphocytic leukaemia. Eur J Cancer 30A, 1259-63.

Ahmad M, Srinivasula SM, Wang L, Talanian RV, Litwack G, Fernandes-Alnemri T, and Alnemri ES (1997) CRADD, a novel human apoptotic adaptor molecule for caspase-2, and FasL/tumor necrosis factor receptor-interacting protein RIP. Cancer Res 57, 615-9.

Ameyar-Zazoua M, Larochette N, Dorothee G, Daugas E, Haddad H, Gouloumet V, Metivier D, Stancou R, Mami-Chouaib F, Kroemer G, and Chouaib S (2002) Wild-type p53 induced sensitization of mutant p53 TNF-resistant cells: role of caspase-8 and mitochondria. Cancer Gene Ther 9, 219-27.

Anderson SP, Dunn CS, Cattley RC, and Corton JC (2001) Hepatocellular proliferation in response to a peroxisome proliferator does not require TNFa signaling. Carcinogenesis 22, 1843-51.

Arnott CH, Scott KA, Moore RJ, Hewer A, Phillips DH, Parker P, Balkwill FR, and Owens DM (2002) Tumour necrosis factor-a mediates tumour promotion via a PKC a- and AP-1-dependent pathway. Oncogene 21, 4728-38.

Auerbach W, and Auerbach R (1994) Angiogenesis inhibition: a review. Pharmacol Ther 63, 265-311.

Baker D, Butler D, Scallon BJ, JK ON, Turk JL, and Feldmann M (1994) Control of established experimental allergic encephalomyelitis by inhibition of tumor necrosis factor (TNF) activity within the central nervous system using monoclonal antibodies and TNF receptor-immunoglobulin fusion proteins. Eur J Immunol 24, 2040-8.

Balkwill FR, Lee A, Aldam G, Moodie E, Thomas JA, Tavernier J, and Fiers W (1986) Human tumor xenografts treated with recombinant human tumor necrosis factor alone or in combination with interferons. Cancer Res 46, 3990-3.

Battegay EJ, Raines EW, Colbert T, and Ross R (1995) TNF-a stimulation of fibroblast proliferation. Dependence on platelet-derived growth factor (PDGF) secretion and alteration of PDGF receptor expression. J Immunol 154, 6040-7.

Bemelmans MH, Gouma DJ, and Buurman WA (1993) Influence of nephrectomy on tumor necrosis factor clearance in a murine model. J Immunol 150, 2007-17.

Berra E, Diaz-Meco MT, Lozano J, Frutos S, Municio MM, Sanchez P, Sanz L, and Moscat J (1995) Evidence for a role of MEK and MAPK during signal transduction by protein kinase C zeta. Embo J 14, 6157-63.

Bertolini DR, Nedwin GE, Bringman TS, Smith DD, and Mundy GR (1986) Stimulation of bone resorption and inhibition of bone formation in vitro by human tumour necrosis factors. Nature 319, 516-8.

Beutler B, Mahoney J, Le Trang N, Pekela P, and Cerami A (1985a) Purification of cachectin, a lipoprotein lipase-suppressing hormone secreted by endotoxin induced RAW 264.7 cells. J Exp Med 161, 984-995.

Beutler B, Milsark BIW, and Cerami A (1985b) Passive immunisation against cachectin/tumor necrosis factor (TNF) protects mice from the lethatl effects of endotoxin. Science 229, 869-71.

Binder, C, Schulz, M, Hiddemann, W, and Oellerich, M (1999) Induction of inducible nitric oxide synthase is an essential part of tumor necrosis factor-a-induced apoptosis in MCF-7 and other epithelial tumor cells. Lab Invest, 79, 1703-12.

Black RA, Rauch CT, Kozlosky CJ, Peschon JJ, Slack JL, Wolfson MF, Castner BJ, Stocking KL, Reddy P, Srinivasan S, Nelson, N Boiani N, Schooley KA, Gerhart M, Davi R, Fitzner JN, Johnson RS, Paxton RJ, March CJ, and Cerretti DP (1997) A metalloproteinase disintegrin that releases tumour-necrosis factor-a from cells. Nature 385, 729-33.

Blankenstein T, Qin ZH, Uberla K, Muller W, Rosen H, Volk HD, and Diamantstein T (1991) Tumor suppression after tumor cell-targeted tumor necrosis factor a gene transfer. J Exp Med 173, 1047-52.

Boldin M, Goncharov T, Goltsev Y, and Wallach D (1996) Involvement of MACH, a novel MORT/FADD-interacting protease, in Fas/APO-1 and TNF receptor-induced cell death. Cell 85, 803-815.

Brantjes H, Barker N, van EJ, and Clevers H (2002) TCF: Lady Justice casting the final verdict on the outcome of Wnt signalling. Biol Chem 383, 255-61.

Brockhaus M, Schoenfeld HJ, Schlaeger EJ, Hunziker W, Lesslauer W, and Loetscher H (1990) Identification of two types of tumor necrosis factor receptors on human cell lines by monoclonal antibodies. Proc Natl Acad Sci USA 87, 3127-3131.

Brown TD, Goodman P, Fleming T, Macdonald JS, Hersh EM, and Braun TJ, (1991) A, phase II trial of recombinant tumor necrosis factor in patients with adenocarcinoma of the pancreas: A, Southwest Oncology Group study. J Immunother 10, 376-8.

Butler DM, Piccoli DS, Hart PH, and Hamilton JA, (1988) Stimulation of human synovial fibroblast DNA synthesis by recombinant human cytokines. J Rheumatol 15, 1463-70.

Calhoun ES, McGovern RM, Janney CA, Cerhan JR, Iturria SJ, Smith DI, Gostout BS, and Persing DH (2002) Host genetic polymorphism analysis in cervical cancer. Clin Chem 48, 1218-24.

Cao Z, Xiong J, Takeuchi M, Kurama T, and Goeddel DV, (1996) TRAF6, is A, signal transducer for interleukin-1. Nature 383, 443-6.

Carpenter PM, Gatanaga T, Nguyen HP, and Hiserodt JC, (1997) Lymphocyte and monocyte-induced motility of MCF-7, cells by tumor necrosis factor-a. Int J Cancer 71, 64-70.

Carswell EA, Old LJ, Kassel RL, Green S, Fiore N, and Williamson B, (1975) An endotoxin-induced serum factor that causes necrosis of tumors. Proc Natl Acad Sci U S A, 72, 3666-70.

Cheng G, Cleary AM, Ye ZS, Hong DI, Lederman S, and Baltimore D, (1995) Involvement of CRAF1, A, relative of TRAF in CD40, signaling. Science 267, 1494-8.

Chinnaiyan AM, K OR, Yu GL, Lyons RH, Garg M, Duan DR, Xing L, Gentz R, Ni J, and Dixit VM, (1996) Signal transduction by DR3 A, death domain-containing receptor related to TNFR-1, and CD95. Science 274, 990-2.

Condeelis JS Wyckoff JB, Bailly M Pestell R, Lawrence D, Backer J, and Segall JE, (2001) Lamellipodia in invasion. Semin Cancer Biol 11, 119-28.

Creagan ET, Kovach JS, Moertel CG, Frytak S, and Kvols LK, (1988) A, phase I clinical trial of recombinant human tumor necrosis factor. Cancer 62, 2467-71.

Creasey AA, Reynolds MT, and Laird W, (1986) Cures and partial regression of murine and human tumors by recombinant human tumor necrosis factor. Cancer Res 46, 5687-90.

Cubillos S, Scallon B, Feldmann M, and Taylor P, (1997) Effect of blocking TNF on IL-6, levels and Metastasis in A, B16-BL6, melanoma mouse model. Anticancer Research 17, 2207-2212.

Curnis F, Sacchi A, and Corti A, (2002) Improving chemotherapeutic drug penetration in tumors by vascular targeting and barrier alteration. J Clin Invest 110, 475-82.

Davies B, Miles DW, Happerfield LC, Naylor MS, Bobrow LG, Rubens RD, and Balkwill FR, (1993a) Activity of type IV collagenases in benign and malignant breast disease. Br J Cancer 67, 1126-31.

Davies B, Waxman J, Wasan H, Abel P, Williams G, Krausz T, Neal D, Thomas D, Hanby A, and Balkwill F, (1993b) Levels of matrix metalloproteases in bladder cancer correlate with tumor grade and invasion. Cancer Res 53 5365-9.

Davies FE, Rollinson SJ, Rawstron AC, Roman E, Richards S, Drayson M, Child JA, and Morgan GJ, (2000) High-producer haplotypes of tumor necrosis factor a and lymphotoxin a are associated with an increased risk of myeloma and have an improved progression-free survival after treatment. J Clin Oncol 18, 2843-51.

de Kossodo S, Moore R, Gschmeissner S, East N, Upton C, and Balkwill FR, (1995) Changes in endogenous cytokines adhesion molecules and platelets during cytokine-induced tumour necrosis. Br J Cancer 72, 1165-72.

de Wilt JH, Manusama ER, van Tiel ST, van Ijken MG, ten Hagen TL, and Eggermont AM, (1999) Prerequisites for effective isolated limb perfusion using tumour necrosis factor a and melphalan in rats. Br J Cancer 80, 161-6.

Dekker SK, Vink J, Vermeer BJ, Bruijn JA, Mihm MC Jr, and Byers HR, (1994) Differential effects of interleukin 1-a (IL-1a) or tumor necrosis factor-a (TNF-a) on motility of human melanoma cell lines on fibronectin. J Invest Dermatol 102, 898-905.

D'Haens G, Swijsen C, Noman M, Lemmens L, Ceuppens J, Agbahiwe H, Geboes K, and Rutgeerts P, (2001) Etanercept in the treatment of active refractory Crohn's disease: A, single-center pilot trial. Am J Gastroenterol 96, 2564-8.

D'Haens G, Van Deventer S, Van Hogezand R, Chalmers D, Kothe C, Baert F, Braakman T, Schaible T, Geboes K, and Rutgeerts P, (1999) Endoscopic and histological healing with infliximab anti-tumor necrosis factor antibodies in Crohn's disease: A, European multicenter trial. Gastroenterology 116, 1029-34.

Dhar A, Young MR, and Colburn NH, (2002) The role of AP-1, NF-kB and ROS/NOS in skin carcinogenesis: the JB6, model is predictive. Mol Cell Biochem 234-235, 185-93.

Djeu JY, Serbousek D, and Blanchard DK, (1990) Release of tumor necrosis factor by human polymorphonuclear leukocytes. Blood 76, 1405-9.

Dorudi S, Sheffield JP, Poulsom R, Northover JM, and Hart IR (1993) E-cadherin expression in colorectal cancer. An immunocytochemical and in situ hybridization study. Am J Pathol 142, 981-6.

Drapier JC, Wietzerbin J, and Hibbs JB, (1987) Interferon-g and tumour necrosis factor induce the L-arginine-dependent cytotoxic effector mechanism in murine macrophages. Eur J Immunol 18, 1587-92.

Duan H, and Dixit v (1997) RAIDD is A, new 'death' adaptor molecule. Nature 385, 86-89.

Dubravec DB, Spriggs DR, Mannick JA, and Rodrick ML, (1990) Circulatinghuman peripheral blood granulocytes synthesize and secrete tumor necrosis factor a. Proc Natl Acad Sci 87, 6758-61.

Eggermont AM, (1996) The success of TNF a in isolated limb perfusion for irresectable extremity soft tissue sarcomas melanoma and carcinomas: observations in patients and preclinical perfusion models. Gan To Kagaku Ryoho 23 1357-70.

Eggermont AM Schraffordt Koops H Klausner JM Lienard D, Kroon BB Schlag PM Ben-Ari G and Lejeune FJ (1997) Isolation limb perfusion with tumor necrosis factor a and chemotherapy for advanced extremity soft tissue sarcomas. Semin Oncol 24, 547-55.

Elliot MJ, Maini RN, Feldmann M, Kalden JR, Antoni C, Smolen JS, Leeb B, Breedveld FC, Macfarlane JD, Bijl H, and Woody JN, (1994) Randomised double-blind comparison of chimeric monoclonal antibody to tumour necrosis factor a versus placebo in rheumatoid arthritis. Lancet 344, 1105-10.

Enari M, Sakahira H, Yokoyama H, Okawa K, Iwamatsu A, and Nagata S, (1998) A, caspase-activated DNase that degrades DNA during apoptosis and its inhibitor ICAD [see comments] [published erratum appears in Nature 1998, May 28;393(6683):396]. Nature 391, 43-50.

English BK Weaver WM, and Wilson CB, (1991) Differential regulation of lymphotoxin and tumor necrosis factor genes in human T lymphocytes. J Biol Chem 266, 7108-13.

Fidler IJ, and Ellis LM, (1994) The implications of angiogenesis for the biology and therapy of cancer metastasis. Cell 79, 185-8.

Fiedler W Zeller W, Peimann CJ, Weh HJ, and Hossfeld DK, (1991) A, phase II combination trial with recombinant human tumor necrosis factor and g interferon in patients with colorectal cancer. Klin Wochenschr 69, 261-8.

Flugy AM, D'Amato M, Russo D, Di Bella MA, Alaimo G, Kohn EC, De Leo G, and Alessandro R, (2002) E-selectin modulates the malignant properties of T84, colon carcinoma cells. Biochem Biophys Res Commun 293 1099-106.

Folkman J, (1986) How is blood vessel growth regulated in normal and neoplastic tissue? GHA. Clowes memorial Award lecture. Cancer Res 46, 467-73.

Folkman J, (1995) Angiogenesis in Cancer vascular rheumatoid and other disease. Nat Med 1, 27-31.

Folkman J, and Klagsbrun M, (1987) Angiogenic factors. Science 235, 442-7.

Furman WL, Strother D, McClain K, Bell B, Leventhal B, and Pratt CB, (1993) Phase I clinical trial of recombinant human tumor necrosis factor in children with refractory solid tumors: A, Pediatric Oncology Group study. J Clin Oncol 11, 2205-10.

Garban HJ, and Bonavida B, (2001) Nitric oxide disrupts H2O2-dependent activation of nuclear factor kB. Role in sensitization of human tumor cells to tumor necrosis factor-a -induced cytotoxicity. J Biol Chem 276, 8918-23.

Gemlo BT, Palladino MAJ, Jaffe HS, Espevik TP, and Rayner AA, (1988) Circulating cytokines in patients with metastatic cancer trated with recombinant interleukin 2, and lymphokine-activated killer cells. Cancer Res 48, 5864-67.

Ghaderi M, Nikitina Zake L, Wallin K, Wiklund F, Hallmans G, Lenner P, Dillner J, and Sanjeevi CB (2001) Tumor necrosis factor a and MHC class I chain related gene A, (MIC-A) polymorphisms in Swedish patients with cervical cancer. Hum Immunol 62, 1153-8.

Gimbrone M, Obin M, Brock A, Luis E, Hass P, Hebert C, Yip Y, Leung D, Lowe D, Kohr W Darbonne W Bechtol K and Baker J, (1989) Endothelial interleukin-8: A, novel inhibitor of leukocyte-endothelial interactions. Science 246, 1601-03.

Gonzalez CA, Sala N, and Capella G, (2002) Genetic susceptibility and gastric cancer risk. Int J Cancer 100, 249-60.

Goossens V, De Vos K, Vercammen D, Steemans M, Vancompernolle K, Fiers W Vandenabeele P and Grooten J (1999) Redox regulation of TNF signaling. Biofactors 10, 145-56.

Gordon JR and Gallis SJ, (1990) Mast cells as A, source of both preformed and immunologically inducible TNF-a/cachectin. Nature 346, 274-76.

Grell M Douni E Wajant H Lohden M Clauss M Maxeiner B Georgopoulos S Lesslauer W Kollias G Pfizenmaier K and et al (1995) The transmembrane form of tumor necrosis factor is the prime activating ligand of the 80, kDa tumor necrosis factor receptor. Cell 83 793-802.

Hajeer AH Lear JT Ollier WE Naves M Worthington J Bell DA Smith AG Bowers WP Jones PW Strange RC and Fryer AA (2000) Preliminary evidence of an association of tumour necrosis factor microsatellites with increased risk of multiple basal cell carcinomas. Br J Dermatol 142, 441-5.

Hajitou A, Sounni NE, Devy L, Grignet-Debrus C, Lewalle JM, Li H, Deroanne CF, Lu H Colige A, Nusgens BV Frankenne F, Maron A, Yeh P, Perricaudet M, Chang Y, Soria C, Calberg-Bacq CM, Foidart JM and Noel A, (2001) Down-regulation of vascular endothelial growth factor by tissue inhibitor of metalloproteinase-2: effect on in vivo mammary tumor growth and angiogenesis. Cancer Res 61, 3450-7.

Hanna AN, Berthiaume LG, Kikuchi Y, Begg D, Bourgoin S, and Brindley DN (2001) Tumor necrosis factor-a induces stress fiber formation through ceramide production: role of sphingosine kinase. Mol Biol Cell 12, 3618-30.

Havell EA, Fiers W, and North RJ, (1988) The antitumor function of tumor necrosis factor (TNF) I. Therapeutic action of TNF against an established murine sarcoma is indirect immunologically dependent and limited by severe toxicity. J Exp Med 167, 1067-85.

Hideshima T, Nakamura N, Chauhan D, and Anderson KC, (2001) Biologic sequelae of interleukin-6, induced PI3-K/Akt signaling in multiple myeloma. Oncogene 20, 5991-6000.

Hu HM, K OR, Boguski MS, and Dixit VM, (1994) A novel RING finger protein interacts with the cytoplasmic domain of CD40. J Biol Chem 269, 30069-72.

Hynes RO, (1992) Integrins: versatility modulation and signaling in cell adhesion. Cell 69, 11-25.

Ichijo H, Nishida E, Irie K, ten Dijke P, Saitoh M, Moriguchi T, Takagi M, Matsumoto K, Miyazono K, and Gotoh Y, (1997) Induction of apoptosis by ASK1, A mammalian MAPKKK that activates SAPK/JNK and p38, signaling pathways. Science 275, 90-4.

Ishida TK, Tojo T, Aoki T, Kobayashi N, Ohishi T, Watanabe T, Yamamoto T, and Inoue J, (1996) TRAF5, A novel tumor necrosis factor receptor-associated factor family protein mediates CD40, signaling. Proc Natl Acad Sci U S A, 93 9437-42.

Jaiswal M, LaRusso NF, Burgart LJ, and Gores GJ, (2000) Inflammatory cytokines induce DNA damage and inhibit DNA repair in cholangiocarcinoma cells by A, nitric oxide-dependent mechanism. Cancer Res 60, 184-90.

Jerlinek D, and Lipsky P, (1987) Enhancement of human B cell proliferation and differentiation by tumor necrosis factor-a and interleukin 1. J Immunol 139, 2970-76.

Jewett A, Cavalcanti M, and Bonavida B, (1997) Pivotal role of endogenous TNF-a in the induction of functional inactivation and apoptosis in NK cells. J Immunol 159, 4815-22.

Jirik FR, Podor TJ, Hirano T, Carson DA, and Lotz M, (1989) Bacterial lipopolysaccaride and inflammatory mediators augment IL-6, secretion by human endothelial cells. J Immunol 142, 144-47.

Johnson RA, Boyce BF, Mundy GR, and Roodman GD, (1989) Tumors producing human tumor necrosis factor induced hypercalcemia and osteoclastic bone resorption in nude mice. Endocrinology 124, 1424-7.

Kashii Y, Giorda R, Herberman RB, Whiteside TL, and Vujanovic NL, (1999) Constitutive expression and role of the TNF family ligands in apoptotic killing of tumor cells by human NK cells. J Immunol 163 5358-66.

Kassis J, Lauffenburger DA, Turner T, and Wells A, (2001) Tumor invasion as dysregulated cell motility. Semin Cancer Biol 11, 105-17.

Kawai N, Tsuji S Tsujii M, Ito T, Yasumaru M, Kakiuchi Y, Kimura A, Komori M Sasaki Y Hayashi N Kawano S Dubois R, and Hori M, (2002) Tumor necrosis factor a stimulates invasion of Src-activated intestinal cells. Gastroenterology 122, 331-9.

Kawakami M, Watanabe N, Ogawa H, Kato A, Sando H, Yamada N, Murase T, Takaku F, Shibata S, and Oda T, (1989) Cachectin/TNF kills or inhibits the differentiation of 3T3-L1, cells according to developmental stage. J Cell Physiol 138, 1-7.

Kawashima A, Kawahara E, Tokuda R, and Nakanishi I, (2001) Tumour necrosis factor-a provokes upregulation of a2b1, and a5b1, integrins and cell migration in OST osteosarcoma cells. Cell Biol Int 25, 319-29.

Keffer J, Probert L, Cazlaris H, Georgopoulos S, Kaslaris E, Kioussis D, and Kollias G, (1991) Transgenic mice expressing human tumour necrosis factor: A, predictive genetic model of arthritis. Embo J 10, 4025-31.

Kelliher MA, Grimm S, Ishida Y, Kuo F, Stanger BZ, and Leder P, (1998) The death domain kinase RIP mediates the TNF-induced NF-kB signal. Immunity 8, 297-303.

Kinkhabwala M, Sehajpal P, Skolnik E, Sharma V, Vlassara H, Cerami A, and Suthanthiran M, (1990) A, novel addition to the T cell repertory Cell surface expression of tumor necrosis factor/cachectin by activated normal human T cells. J Exp Med 171, 941-46.

Kirchheimaer J, Nong Y, and Remold H, (1988) IFN-g tumor necrosis factor-a and urokinase regulate the expresssion of urokinase receptors on human monocytes. J Immunol 141, 4229-34.

Kirikoshi H, Sekihara H, and Katoh M, (2001) Up-regulation of WNT10A by tumor necrosis factor a and Helicobacter pylori in gastric cancer. Int J Oncol 19, 533-6.

Knight B, Yeoh GC, Husk KL, Ly T, Abraham LJ, Yu C, Rhim JA and Fausto N, (2000) Impaired preneoplastic changes and liver tumor formation in tumor necrosis factor receptor type 1, knockout mice. J Exp Med 192, 1809-18.

Kock A, Schwarz T, Kirnbauer R, Urbanski A, Perry P, Ansel JC, and Luger TA, (1990) Human keratinocytes are A, source of tumor necrosis factor a evidence for synthesis and release upon stimulation with endotoxin or ultraviolet light. J Exp Med 172, 1609-14.

Komori A, Yatsunami J, Suganuma M, Okabe S, Abe S, Sakai A, Sasaki K, and Fujiki H (1993) Tumor necrosis factor acts as A, tumor promoter in BALB/3T3 cell transformation. Cancer Res 53 1982-5.

Kwon BS, Tan KB, Ni J, Oh KO, Lee ZH, Kim KK, Kim YJ, Wang S, Gentz R, Yu GL, Harrop J, Lyn SD, Silverman C, Porter TG, Truneh A, and Young PR, (1997) A, newly identified member of the tumor necrosis factor receptor superfamily with A, wide tissue distribution and involvement in lymphocyte activation. J Biol Chem 272, 14272-6.

Lentz SR, Tsiang M, and Sadler JE, (1991) Regulation of thrombomodulin by tumor necrosis factor-a: comparison of transcriptional and posttranscriptional mechanisms. Blood 77, 542-50.

Lipsky PE, van der Heijde DM, St Clair EW, Furst DE, Breedveld FC, Kalden JR, Smolen JS, Weisman M, Emery P, Feldmann M, Harriman GR, and Maini RN, (2000) Infliximab and methotrexate in the treatment of rheumatoid arthritis. Anti-Tumor Necrosis Factor Trial in Rheumatoid Arthritis with Concomitant Therapy Study Group. N Engl J Med 343 1594-602.

Lu G, Janjic BM, Janjic J, Whiteside TL, Storkus WJ, and Vujanovic NL, (2002) Innate direct anticancer effector function of human immature dendritic cells. II. Role of TNF lymphotoxin-a(1)b(2) Fas ligand and TNF-related apoptosis-inducing ligand. J Immunol 168, 1831-9.

Malik ST, Naylor MS, East N, Oliff A, and Balkwill FR, (1990) Cells secreting tumour necrosis factor show enhanced metastasis in nude mice. Eur J Cancer 26, 1031-4.

Malik STA, Griffin DB, Fiers A, and Ballwill FR, (1989) Paradoxical effects of tumour necrosis factor in experimental ovarian cancer. Int J Cancer 44, 918.

Manna PP, and Mohanakumar T, (2002) Human dendritic cell mediated cytotoxicity against breast carcinoma cells in vitro. J Leukoc Biol 72, 312-20.

Mauri DN, Ebner R, Montgomery RI, Kochel KD, Cheung TC, Yu GL, Ruben S, Murphy M, Eisenberg RJ, Cohen GH, Spear PG, and Ware CF, (1998) LIGHT A, new member of the TNF superfamily and lymphotoxin a are ligands for herpesvirus entry mediator. Immunity 8, 21-30.

Mauviel A, Heino J, Kahari VM, Hartmann DJ, Loyau G, Pujol JP, and Vuorio E, (1991) Comparative effects of interleukin-1, and tumor necrosis factor-a on collagen production and corresponding procollagen mRNA levels in human dermal fibroblasts. J Invest Dermatol 96, 243-9.

McCarron SL, Edwards S, Evans PR, Gibbs R, Dearnaley DP, Dowe A, Southgate C, Easton DF, Eeles RA, and Howell WM, (2002) Influence of cytokine gene polymorphisms on the development of prostate cancer. Cancer Res 62, 3369-72.

Miles DW, Happerfield LC, Naylor MS, Bobrow LG, Rubens RD, and Balkwill FR, (1994) Expression of tumour necrosis factor (TNFa) and its receptors in benign and malignant breast tissue. Int J Cancer 56, 777-82.

Miller A, Kraiem Z, Sobel E, Lider O, and Lahat N, (2000) Modulation of human leukocyte antigen and intracellular adhesion molecule-1, surface expression in malignant and nonmalignant human thyroid cells by cytokines in the context of extracellular matrix. Thyroid 10, 945-50.

Milligan SA, and Nopajaroonsri C, (2001) Inhibition of NF-kB with proteasome inhibitors enhances apoptosis in human lung adenocarcinoma cells in vitro. Anticancer Res 21, 39-44.

Mizokami A, Gotoh A, Yamada H, Keller ET, and Matsumoto T, (2000) Tumor necrosis factor-a represses androgen sensitivity in the LNCaP prostate cancer cell line. J Urol 164, 800-5.

Montgomery RI, Warner MS, Lum BJ, and Spear PG, (1996) Herpes simplex virus-1, entry into cells mediated by A, novel member of the TNF/NGF receptor family. Cell 87, 427-36.

Moore RJ, Owens DM, Stamp G, Arnott C, Burke F, East N, Holdsworth H, Turner L, Rollins B, Pasparakis M, Kollias G, and Balkwill F, (1999) Mice deficient in tumor necrosis factor-a are resistant to skin carcinogenesis. Nat Med 5, 828-31.

Morris VL, Schmidt EE, MacDonald IC, Groom AC, and Chambers AF, (1997) Sequential steps in hematogenous metastasis of cancer cells studied by in vivo videomicroscopy. Invasion Metastasis 17, 281-96.

Mosialos G, Birkenbach M, Yalamanchili R, VanArsdale T, Ware C, and Kieff E, (1995) The Epstein-Barr virus transforming protein LMP1, engages signaling proteins for the tumor necrosis factor receptor family. Cell 80, 389-99.

Muzio M, Chinnaiyan A, Kischkel K, O'Rourke K, Shevchenko A, and Ni J, (1996) FLICE A, novel FADD homologous ICE/CED-3-like protease is recruited to the CD95, (Fas/APO-1) death-inducing signal complex. Cell 85, 817-827.

Nagy JA, Masse EM, Herzberg KT, Meyers MS, Yeo KT, Yeo TK, Sioussat TM, and Dvorak HF, (1995) Pathogenesis of ascites tumor growth: vascular permeability factor vascular hyperpermeability and ascites fluid accumulation. Cancer Res 55, 360-8.

Nakano H, Oshima H, Chung W, Williams-Abbott L, Ware CF, Yagita H, and Okumura K, (1996) TRAF5, an activator of NF-kB and putative signal transducer for the lymphotoxin-b receptor. J Biol Chem 271, 14661-4.

Nakashima J, Tachibana M, Ueno M, Miyajima A, Baba S, and Murai M, (1998) Association between tumor necrosis factor in serum and cachexia in patients with prostate cancer. Clin Cancer Res 4, 1743-8.

Natoli G, Costanzo A, Guido F, Moretti F, and Levrero M, (1998) Apoptotic non-apoptotic and anti-apoptotic pathways of tumor necrosis factor signalling. [49, refs]. Biochem Pharmacol 56, 915-20.

Naylor MS, Stamp GW, Foulkes WD, Eccles D, and Balkwill FR, (1993) Tumor necrosis factor and its receptors in human ovarian cancer. Potential role in disease progression. J Clin Invest 91, 2194-206.

Nickoloff BJ, Karabin GD, Barker JN, Griffiths CE, Sarma V, Mitra RS, Elder JT, Kunkel SL, and Dixit VM, (1991) Cellular localization of interleukin-8, and its inducer tumor necrosis factor-a in psoriasis. Am J Pathol 138, 129-40.

Nishitoh H, Saitoh M, Mochida Y, Takeda K, Nakano H, Rothe M, Miyazono K, and Ichijo H, (1998) ASK1, is essential for JNK/SAPK activation by TRAF2. Mol Cell 2, 389-95.

Nozawa F, Hirota M, Okabe A, Shibata M, Iwamura T, Haga Y, and Ogawa M, (2000) Tumor necrosis factor a acts on cultured human vascular endothelial cells to increase the adhesion of pancreatic cancer cells. Pancreas 21, 392-8.

Oberyszyn TM, Tober KL, Ross MS, and Robertson FM, (1998) Inhibitory effects of pentoxifylline on ultraviolet B light-induced cutaneous inflammation. Mol Carcinog 22, 16-25.

Obrador E, Carretero J, Pellicer JA, and Estrela JM, (2001) Possible mechanisms for tumour cell sensitivity to TNF-a and potential therapeutic applications. Curr Pharm Biotechnol 2, 119-30.

Oh BR, Sasaki M, Perinchery G, Ryu SB, Park YI, Carroll P, and Dahiya R, (2000) Frequent genotype changes at -308, and 488, regions of the tumor necrosis factor-a (TNF-a) gene in patients with prostate cancer. J Urol 163 1584-7.

Olsson I, Lantz M, Nilsson E, Peetrie C, Thysell H, Grubb A, and Adolf G, (1989) Isolation and Characterisation of A, TNF binding protein from Urine. Eur J Haematol 42, 270-275.

Orosz P, Echtenacher B, Werner F, Ruschoff J, Weber D, and Mannel DN, (1993) Enhancement of experimental metastasis by tumor necrosis factor. J. Exp. Med 177, 1391-1398.

Osborn L, (1990) Leukocyte adhesion to endothelium in inflammation. Cell 62, 3-6.

Ostensen M, Thiele D, and Lipsky P, (1987) Tumor necrosis factor-a enhances cytolytic activity of human natural killer cells. J Immunol 138, 4185-91.

Pan G, K OR, Chinnaiyan AM, Gentz R, Ebner R, Ni J, and Dixit VM, (1997a) The receptor for the cytotoxic ligand TRAIL. Science 276, 111-3.

Pan G, Ni J, Wei YF, Yu G, Gentz R, and Dixit VM, (1997b) An antagonist decoy receptor and A, death domain-containing receptor for TRAIL [see comments]. Science 277, 815-8.

Parratto NP, Odebralski JM, and Kimura AK, (1989) Poorly metastatic tumor cell variants as primary targets of syngeneic antibody responses against murine melanoma. Cancer Res 49, 3722-8.

Partheniou F, Kelsey SM, Srinivasula SM, Newland AC, Alnemri ES, and Jia L, (2001) c-IAP1, blocks TNFa-mediated cytotoxicity upstream of caspase-dependent and -independent mitochondrial events in human leukemic cells. Biochem Biophys Res Commun 287, 181-9.

Peppelenbosch M, Boone E, Jones GE, van Deventer S, Haegeman G, Fiers W, Grooten J, and Ridley AJ, (1999) Multiple signal transduction pathways regulate TNF-induced actin reorganization in macrophages: inhibition of Cdc42-mediated filopodium formation by TNF. J Immunol 162, 837-45.

Pitti RM, Marsters SA, Ruppert S, Donahue CJ, Moore A, and Ashkenazi A, (1996) Induction of apoptosis by Apo-2, ligand A, new member of the tumor necrosis factor cytokine family. J Biol Chem 271, 12687-90.

Porteu F, and Nathan CF, (1990) Shedding of tumor necrosis factor receptors by activated human neutrophils. J. Exp. Med 172, 599-607.

Prevost-Blondel A, Roth E, Rosenthal FM, and Pircher H (2000) Crucial role of TNF-a in CD8, T cell-mediated elimination of 3LL-A9, Lewis lung carcinoma cells in vivo. J Immunol 164, 3645-51.

Price LS, and Collard JG, (2001) Regulation of the cytoskeleton by Rho-family GTPases: implications for tumour cell invasion. Semin Cancer Biol 11, 167-73.

Puls A, Eliopoulos AG, Nobes CD, Bridges T, Young LS, and Hall A, (1999) Activation of the small GTPase Cdc42, by the inflammatory cytokines TNF(a) and IL-1, and by the Epstein-Barr virus transforming protein LMP1. J Cell Sci 112, 2983-92.

Quin Z, Kruger-Krasagakes S, Kunzendorf U, Hock H, Diamantstein T, and Blankenstein T, (1993) Expression of tumor necrosis factor by different tumor cell lines fesults either in tumor suppressoion or augmented metastasis. J Exp Med 178, 355-360.

Rao VH, Singh RK, Delimont DC, Finnell RH, Bridge JA, Neff JR, Garvin BP, Pickering DL, Sanger WG, Buehler BA, and Schaefer GB, (1999) Transcriptional regulation of MMP-9, expression in stromal cells of human giant cell tumor of bone by tumor necrosis factor-a. Int J Oncol 14, 291-300.

Regnier CH, Song HY, Gao X, Goeddel DV, Cao Z, and Rothe M, (1997) Identification and characterization of an IkB kinase. Cell 90, 373-83.

Regnier CH, Tomasetto C, Moog-Lutz C, Chenard MP, Wendling C, Basset P, and Rio MC, (1995) Presence of A, new conserved domain in CART1, A, novel member of the tumor necrosis factor receptor-associated protein family which is expressed in breast carcinoma. J Biol Chem 270, 25715-21.

Renard N, Lienard D, Lespagnard L, Eggermont A, Heimann R, and Lejeune F, (1994) Early endothelium activation and polymorphonuclear cell invasion precede specific necrosis of human melanoma and sarcoma treated by intravascular high-dose tumour necrosis factor a (rTNF a) Int J Cancer 57, 656-63.

Renkonen R, Mattila P, Majuri ML, Rabina J, Toppila S, Renkonen J, Hirvas L, Niittymaki J, Turunen JP, Renkonen O, and Paavonen T, (1997) In vitro experimental studies of sialyl Lewis x and sialyl Lewis A, on endothelial and carcinoma cells: crucial glycans on selectin ligands. Glycoconj J 14, 593-600.

Robertson FM, Ross MS, Tober KL, Long BW, and Oberyszyn TM, (1996) Inhibition of pro-inflammatory cytokine gene expression and papilloma growth during murine multistage carcinogenesis by pentoxifylline. Carcinogenesis 17, 1719-28.

Rosen EM, Goldberg ID, Liu D, Setter E, Donovan MA, Bhargava M, Reiss M, and Kacinski BM, (1991) Tumor necrosis factor stimulates epithelial tumor cell motility. Cancer Res 51, 5315-21.

Rothe M, Sarma V, Dixit VM, and Goeddel DV, (1995) TRAF2-mediated activation of NF-kB by TNF receptor 2, and CD40. Science 269, 1424-7.

Rothe M, Wong SC, Henzel WJ, and Goeddel DV, (1994) A, novel family of putative signal transducers associated with the cytoplasmic domain of the 75, kDa tumor necrosis factor receptor. Cell 78, 681-92.

Saito S, Kasai Y, Nomoto S, Fujiwara M, Akiyama S, Ito K, and Nakao A, (2001) Polymorphism of tumor necrosis factor in esophageal gastric or colorectal carcinoma. Hepatogastroenterology 48, 468-70.

Saklatvala J, (1986) Tumour necrosis factor a stimulates resorption and inhibits synthesis of proteoglycan in cartilage. Nature 322, 547-9.

Saklatvala J, Sarsfield SJ, and Townsend Y, (1985) Pig interleukin 1. Purification of two immunologically different leukocyte proteins that cause cartilage resorption lymphocyte activation and fever. J Exp Med 162, 1208-22.

Sanchez-Alcazar JA, Schneider E, Hernandez-Munozz I, Ruiz-Cabello J, Siles-Rivas E, Borstein B, Brea G, Arenas J, Garesse R, Solis-Herruzo JA, Knox A, and Navas P, (2002) Reactive oxygen species mediate the down-regulation of mitochondrial transcripts and proteins by Tumor Necrosis Factor-a in L929, cells. Biochem J 6.

Sati HI, Greaves M, Apperley JF, Russell RG, and Croucher PI, (1999) Expression of interleukin-1b and tumour necrosis factor-a in plasma cells from patients with multiple myeloma. Br J Haematol 104, 350-7.

Sato T, Irie S, and Reed JC, (1995) A, novel member of the TRAF family of putative signal transducing proteins binds to the cytosolic domain of CD40. FEBS Lett 358, 113-8.

Sawada M, Kondo N, Suzumura A, and Marunouchi T, (1989) Production of tumor necrosis factor-a by microgle and astrocytes in culture. Brain Res 491, 394-97.

Scheurich P, Thoma B, Ucer U, and Pfizenmaier K, (1987) Immunoregulatory activity of recombinant human tumor necrosis factor (TNF)-a: induction of TNF receptors on human Tcells and TNF-a-mediated enhancement of Tcell responses. J Immunol 138, 1786-90.

Schleiffenbaum B, and Fehr J, (1990) The tumor necrosis factor receptor and human neutrophil function. Deactrivation and cross-deactivation of tumor necrosis factor-induced neutrophil responses by receptor down-regulation. J Clin Invest 86, 184-95.

Schroder JM, Sticherling M, Heinneicke HH, Preissner WC, and Christophers E, (1990) IL-1a or tumor necrosis factor-a stimulate release of three NAP- 1/IL-8-related neutrophil chemotactic protiens in human dermal fibroblasts. J Immunol 144, 2223-32.

Seelentag WK, Mermod JJ, Montesano R, and Vassalli P, (1987) Additive effects of interleukin-1, and tumor necrosis factor-a on the accumulation of the three granulocyte and macrophage colony stimulating factor mRNA in human endothelial cells. EMBO J 6, 2261-65.

Selby P, Hobbs S, Viner C, Jackson E, Jones A, Newell D, Calvert AH, McElwain T, Fearon K, Humphreys J, and et al (1987) Tumour necrosis factor in man: clinical and biological observations. Br J Cancer 56, 803-8.

Selmaj KW, Farooq M, Norton WT, Raine CS, and Brosnan CF, (1990) Proliferation of astrocytes in vitro in response to cytokines. A, primary role for tumor necrosis factor. J Immunol 144, 129-35.

Shalinsky DR, Brekken J, Zou H, McDermott CD, Forsyth P, Edwards D, Margosiak S, Bender S, Truitt G, Wood A, Varki NM, and Appelt K, (1999) Broad antitumor and antiangiogenic activities of AG3340, A, potent and selective MMP inhibitor undergoing advanced oncology clinical trials. Ann N Y Acad Sci 878, 236-70.

Sheridan JP, Marsters SA, Pitti RM, Gurney A, Skubatch M, Baldwin D, Ramakrishnan L, Gray CL, Baker K, Wood WI, Goddard AD, Godowski P, and Ashkenazi A, (1997) Control of TRAIL-induced apoptosis by A, family of signaling and decoy receptors [see comments]. Science 277, 818-21.

Shi CS, and Kehrl JH, (1997) Activation of stress-activated protein kinase/c-Jun N-terminal kinase but not NF-kB by the tumor necrosis factor (TNF) receptor 1, through A, TNF receptor-associated factor 2- and germinal center kinase related-dependent pathway. J Biol Chem 272, 32102-7.

Shin KY, Moon HS, Park HY, Lee TY, Woo YN, Kim HJ, Lee SJ, and Kong G, (2000) Effects of tumor necrosis factor-a and interferon-g on expressions of matrix metalloproteinase-2, and -9, in human bladder cancer cells. Cancer Lett 159, 127-34.

Shiozaki H, Tahara H, Oka H, Miyata M, Kobayashi K, Tamura S, Iihara K, Doki Y, Hirano S, Takeichi M, and et al, (1991) Expression of immunoreactive E-cadherin adhesion molecules in human cancers. Am J Pathol 139, 17-23.

Simiantonaki N, Jayasinghe C, and Kirkpatrick CJ, (2002) Effect of pro-inflammatory stimuli on tumor cell-mediated induction of endothelial cell adhesion molecules in vitro. Exp Mol Pathol 73 46-53.

Simonet WS, Lacey DL, Dunstan CR, Kelley M, Chang MS, Luthy R, Nguyen HQ, Wooden S, Bennett L, Boone T, Shimamoto G, DeRose M, Elliott R, Colombero A, Tan HL, Trail G, Sullivan J, Davy E, Bucay N, Renshaw-Gegg L Hughes TM, Hill D, Pattison W, Campbell P, Boyle WJ, and et al, (1997) Osteoprotegerin: A, novel secreted protein involved in the regulation of bone density [see comments]. Cell 89, 309-19.

Smith CA, Farrah T, and Goodwin RG, (1994) The TNF receptor superfamily of cellular and viral proteins: activation costimulation and death. [26, refs]. Cell 76, 959-62.

Song HY, Regnier CH, Kirschning CJ, Goeddel DV, and Rothe M, (1997) Tumor necrosis factor (TNF)-mediated kinase cascades: bifurcation of nuclear factor-kB and c-jun N-terminal kinase (JNK/SAPK) pathways at TNF receptor-associated factor 2. Proc Natl Acad Sci U S A, 94, 9792-6.

Stearns ME, and Wang M, (1993) Type IV collagenase (M(r) 72000) expression in human prostate: benign and malignant tissue. Cancer Res 53 878-83.

Stebbing J, Benson C, Eisen T, Pyle L, Smalley K, Bridle H, Mak I, Sapunar F, Ahern R, and Gore ME, (2001) The treatment of advanced renal cell cancer with high-dose oral thalidomide. Br J Cancer 85, 953-8.

Stein M, and Gordan S, (1991) Regulation of tumor necrosis factor (TNF) release by murine macrophages: role of cell stimulation and specific phagocytic plasma membrane receptors. Eur J Immunol 21, 431-37.

Strieter RM, Polverini PJ, Kunkel SL, Arenberg DA, Burdick MD, Kasper J, Dzuiba J, Van Damme J, Walz A, Marriott D, and et al, (1995) The functional role of the ELR motif in CXC chemokine-mediated angiogenesis. J Biol Chem 270, 27348-57.

Suganuma M, Okabe S, Marino MW, Sakai A, Sueoka E, and Fujiki H, (1999) Essential role of tumor necrosis factor a (TNF-a) in tumor promotion as revealed by TNF-a-deficient mice. Cancer Res 59, 4516-8.

Sung S, Jung L, Walters J, Chen W, Wang C, and Fu S, (1988) Production of tumor necrosis factor/cachectin by human Bcell lines and tonsillar B cells. J Exp Med 168, 1539-51.

Tanaka M, Fuentes ME, Yamaguchi K, Durnin MH, Dalrymple SA, Hardy KL, and Goeddel DV, (1999) Embryonic lethality liver degeneration and impaired NF-kB activation in IKK-b-deficient mice. Immunity 10, 421-9.

Thoma B, Grell M, Pfizenmaier K, and Scheurich P, (1990) Identification of A, 60-kD tumor necrosis factor (TNF) receptor as the major signal transducing component in TNF responses. J Exp Med 172, 1019-23.

Thomsen LL, Lawton FG, Knowles RG, Beesley JE, Riveros-Moreno V, and Moncada S, (1994) Nitric oxide synthase activity in human gynecological cancer. Cancer Res 54, 1352-4.

Thorbecke GJ, Shah R, Leu CH, Kuruvilla AP, Hardison AM, and Palladino MA, (1992) Involvement of endogenous tumor necrosis factor a and transforming growth factor b during induction of collagen type II arthritis in mice. Proc Natl Acad Sci U S A, 89, 7375-9.

Tohma Y, Yamashima T, and Yamashita J, (1992) Immunohistochemical localization of cell adhesion molecule epithelial cadherin in human arachnoid villi and meningiomas. Cancer Res 52, 1981-7.

Tokiwa G, Dikic I, Lev S, and Schlessinger J, (1996) Activation of Pyk2, by stress signals and coupling with JNK signaling pathway. Science 273 792-4.

Tracey KJ, Fong Y, Hesse DG, Manogue KR, Lee AT, Kuo GC, Lowry SF, and Cerami A, (1987) Anti-cachectin/TNF monoclonal antibodies prevent septic shock during lethal bacteraemia. Nature 330, 662-4.

Trinchieri G, Kobayashi M, Rosen M, Loudon R, Murphy M, and Perussia B, (1986) Tumor necrosis factor and lymphotoxin induce differentiation of human myeloid cell lines in synergy with immune interferon. J Exp Med 164, 1206-25.

Varela LM, Stangle-Castor NC, Shoemaker SF, Shea-Eaton WK and Ip MM, (2001) TNFa induces NFkB/p50, in association with the growth and morphogenesis of normal and transformed rat mammary epithelial cells. J Cell Physiol 188, 120-31.

Varfolomeev E, Boldin M, Goncharov T, and Wallach D, (1996) A, Potential Mechanism of "Cross-Talking" between the p55, Tumor Necrosis Factor Receptor and Fas/APO1:Protein Binding to the Death Domains of the Two Receptors Also Bind Each Other. J. Exp. Med 183 1271-1275.

Voura EB, Ramjeesingh RA, Montgomery AM, and Siu CH, (2001) Involvement of integrin a(v)b(3) and cell adhesion molecule L1, in transendothelial migration of melanoma cells. Mol Biol Cell 12, 2699-710.

Wallach D, Kovalenko AV, Varfolomeev EE, and Mark PB, (1998) Death-inducing functions of lignads of the tumor necrosis factor faily: A, Sanhedrin verdict. Current opinion in Immunology 10, 279-288.

Wang JM, Walter S, and Mantovani A, (1990) Re-evaluation of the chemotactic activity of tumour necrosis factor for monocytes. Immunology 71, 364-7.

Warner SJC, and Libby P, (1989) Human vascular smooth muscle cells. Target for and source of tumor necrosis factor. J Immunol 142, 100-9.

Warzocha K, Ribeiro P, Renard N, Bienvenu J, Charlot C, Coiffier B, and Salles G, (2000) Expression of genes coding for the tumor necrosis factor and lymphotoxin ligand-receptor system in non-Hodgkin's lymphomas. Cancer Immunol Immunother 49, 469-75.

Warzocha K, Salles G, Bienvenu J, Bastion Y, Dumontet C, Renard N, Neidhardt-Berard EM, and Coiffier B, (1997) Tumor necrosis factor ligand-receptor system can predict treatment outcome in lymphoma patients. J Clin Oncol 15, 499-508.

Watanabe N, Niitsu Y, Neda H, Sone H, Yamauchi N, Maeda M, and Urushizaki I, (1988a) Cytocidal mechanism of TNF: effects of lysosomal enzyme and hydroxyl radical inhibitors on cytotoxicity. Immunopharmacol Immunotoxicol 10, 109-16.

Watanabe N, Niitsu Y, Umeno H, Kuriyama H, Neda H, Yamauchi N, Maeda M, and Urushizaki I, (1988b) Toxic effect of tumor necrosis factor on tumor vasculature in mice. Cancer Res 48, 2179-83.

Watanabe N, Niitsu Y, Umeno H, Kuriyama H, Neda H, Yamauchi N, Maeda M, and Urushizaki I (1988c) Synergistic cytotoxic and antitumor effects of recombinant human tumor necrosis factor and hyperthermia. Cancer Res 48, 650-3.

Watanabe N, Niitsu Y, Umeno H, Kuriyama H, Neda H, Yamauchi N, Maeda M, and Urushizaki I (1988d) Synergistic cytotoxicity of recombinant human TNF and various anti-cancer drugs. Immunopharmacol Immunotoxicol 10, 117-27.

Wiley SR, Schooley K, Smolak PJ, Din WS, Huang CP, Nicholl JK, Sutherland GR, Smith TD, Rauch C, Smith CA, and et al, (1995) Identification and characterization of A, new member of the TNF family that induces apoptosis. Immunity 3 673-82.

Williams RO, Feldmann M, and Maini RN, (1992) Anti-tumor necrosis factor ameliorates joint disease in murine collagen-induced arthritis. Proc Natl Acad Sci U S A, 89, 9784-8.

Winston BW Chan ED Johnson GL and Riches DW (1997) Activation of p38mapk MKK3 and MKK4, by TNF-a in mouse bone marrow-derived macrophages. J Immunol 159, 4491-7.

Wu W, Yamaura T, Murakami K, Ogasawara M, Hayashi K, Murata J, and Saiki I, (1999) Involvement of TNF-a in enhancement of invasion and metastasis of colon 26-L5, carcinoma cells in mice by social isolation stress. Oncol Res 11, 461-9.

Yao B, Zhang Y, Delikat S, Mathias S, Basu S, and Kolesnick R, (1995) Phosphorylation of Raf by ceramide-activated protein kinase. Nature 378, 307-10.

Yokota S, Geppert T, and Lipsky P, (1988) Enhancement of antigen- and mitogen-induced human T lymphocyte proliferation by tumor necrosis factor-a. J Immunol 140, 531-36.

Yoshida S, Ono M, Shono T, Izumi H, Ishibashi T, Suzuki H, and Kuwano M ,(1997) Involvement of interleukin-8, vascular endothelial growth factor and basic fibroblast growth factor in tumor necrosis factor a-dependent angiogenesis. Mol Cell Biol 17, 4015-23.

Yujiri T, Sather S, Fanger GR, and Johnson GL, (1998) Role of MEKK1, in cell survival and activation of JNK and ERK pathways defined by targeted gene disruption. Science 282, 1911-4.

Zhai Y, Guo R, Hsu TL, Yu GL, Ni J, Kwon BS, Jiang GW, Lu J, Tan J, Ugustus M, Carter K, Rojas L, Zhu F, Lincoln C, Endress G, Xing L, Wang S, Oh KO, Gentz R, Ruben S, Lippman ME, Hsieh SL, and Yang D, (1998) LIGHT A, novel ligand for lymphotoxin b receptor and TR2/HVEM induces apoptosis and suppresses in vivo tumor formation via gene transfer. J Clin Invest 102, 1142-51.

Zouboulis CC, Schroder K, Garbe C, Krasagakis K, Kruger S, and Orfanos CE, (1990) Cytostatic and cytotoxic effects of recombinant tumor necrosis factor-a on sensitive human melanoma cells in vitro may result in selection of cells with enhanced markers of malignancy. J Invest Dermatol 95, 223S-230S.