of different pathways, either resulting in or resulting from diffeent pathological features of the tumor. An inverse relation between PD-ECGF/TP and VEGF has been described for cervical cancers, and there was no correlation between MVD and PD-ECGF/TP (Tokumo et al, 1998). It was described by O’Brien et al that PD-ECGF/TP expression in invasive bladder tumors was 260 fold higher than in normal mucosa, and 33-fold higher than in superficial tumors (O'Brien et al, 1995). The reverse was true for VEGF, which was lower in invasive compared to superficial tumors (O'Brien et al, 1995). In a study in pancreatic cancer it was found that both VEGF and PD-ECGF/TP were correlated to MVD; VEGF and MVD were not predictive for overall survival, but elevated PD-ECGF/TP was correlated with poor a survival (Fujimoto et al, 1998). Van Triest et al also found co-expression of VEGF and PD-ECGF/TP in colorectal cancer and correlation with MVD. High PD-ECGF/TP also proved to be an independent prognostic factor (van Triest et al, 2000). Co-expression of PD-ECGF/TP and VEGF was found in breast cancer (Toi et al, 1995b).

The co-expression of PD-ECGF/TP and VEGF is not uniform and varies per tumor type and study. VEGF is generally correlated with MVD and can be considered as the major pro-angiogenic factor. However, PD-ECGF/TP only seems to play an additional role in certain circumstances and tumor types.

Tumors are heterogeneous tissues consisting of unknown variable contributions of tumor, stromal and infiltrating cells all may express PD-ECGF/TP (Takahashi et al, 1996; Giatromanolaki et al, 1998b; Matsumura et al, 1998; van Triest et al, 2000). It has been shown that TP can be increased in malignant cells rather than in the tumor stroma (Maeda et al, 1996). In some tumors PD-ECGF/TP seems to be present both in malignant and stromal cells (Takebayashi et al, 1996a). Koukourakis et al reported TP expression of cancer cells, stromal cells (stroma associated fibroblasts) and infiltrating cells like macrophages (Koukourakis et al, 1998). In this study it was shown that PD-ECGF/TP expression in various cells might have different effects and different associations withprognosis. PD-ECGF/TP over-expression in cancer cells was related with poor prognosis, while PD-ECGF/TP expression of the stroma was related to a better survival in a subset of the patients. It was hypothesized that PD-ECGF/TP in the stroma was a marker of infiltrating macrophages, cells that are evidently involved in tumor biology. Infiltrating macrophages have been identified as producers of pro- and anti-angiogenic factors promoting or inhibiting tumor growth, however, overall they appear to be promoting tumor growth, contributing to the pathology (Bingle et al, 2002). Co-localization of macrophages and PD-ECGF/TP, alone or with other angiogenic factors, e.g. VEGF, interleukin 8 (IL-8) has been studied extensively by immunohistochemsitry. In most of these studies co-expression of PD-ECGF/TP and macrophages was observed in melanoma (Torisu-Itakura et al, 2000), glioblastoma multiforme (Hirano et al, 2001), breast (Toi et al, 1999; Ueno et al, 2000), cervical (Fujimoto et al, 2002), colon (Takahashi et al, 1996; Zhang et al, 2004), and prostate cancer (Sivridis et al, 2002).

The expression of PD-ECGF/TP is often both cytoplasmic and nuclear (Fox et al, 1996; Yang et al, 2000). In a study on gallbladder adenocarcinomas only nuclear PD-ECGF/TP staining correlated with increased angiogenic activity (Giatromanolaki et al, 2002).

In summary, PD-ECGF/TP has been found to have higher expression in tumor tissue compared to normal tissues in a variety of human malignancies, and its expression is not only found in cancer cells but also in the stromal macrophages, lymphocytes and fibroblasts. Overall a high level of PD-ECGF/TP expression is correlated with a higher MVD, more metastases and it appears to be a poor prognostic factor. Two other examples of these particular diseases are osteoarthritis and inflammatory bowel disease (Giatromanolaki et al 2003).

C. Other diseases expressing PD-ECGF/TP

Increased PD-ECGF/TP mRNA and immunoreactivity were found in lesional psoriasis compared to non-lesional skin (Creamer et al, 1997). In another study it was shown that the thymidine phosphorylase activity was twenty-fold higher in psoriatic lesions than in normal skin (Hammerberg et al, 1991). There is one study, which examined the activity and distribution of PD-ECGF/TP in the nasal mucosa of people with nasal allergy, and observed that the mucosal TP-activity of patients was higher than that of the normal controls. Strong staining of eosinophils was observed, indicating that the enhanced activity might be due to an increased number of PD-ECGF/TP expressing infiltrating cells (Nishimoto et al, 2000). Elevated levels of (circulating) PD-ECGF/TP were found in rheumatoid arthritis patients (Asai et al, 1993; Giatromanolaki et al 2003). The diseases in which an elevation of PD-ECGF/TP has been described thus far are immune system related and have features of chronic inflammation.

D. Circulating PD-ECGF/TP

Pauly et al identified and compared TP activity in the plasma of healthy subjects and cancer patients (Pauly et al, 1977) and found that TP activity was higher in the plasma of cancer patients. This finding was confirmed in the ascites and plasma of tumor bearing animals in which TP activity was elevated compared to healthy animals (Pauly et al, 1978). Although this discovery was disputed by Woodman (Woodman, 1979), it has been found again in later studies (Poon et al, 2001; Shimada et al, 2002; Brostjan et al, 2003). In patients with uterine cervical cancer it was shown that serum PD-ECGF/TP levels had a positive correlation with clinical stage and tumor size (Fujimoto et al, 2000). The prognosis of the patients with high serum PD-ECGF/TP levels was extremely poor (Fujimoto et al, 2000). In a group of gastric adenocarcinoma patients the serum level was higher than those of healthy controls (Katayanagi et al, 2003). This seemed to reflect that the tumor-tissue levels showed an elevated PD-ECGF/TP expression compared to the healthy tissue (Katayanagi et al, 2003). In hepatocellular carcinoma patients serum PD-ECGF/TP was increased in late stage compared to early stage disease, reflecting immunohistochemical stainings showing that PD-ECGF/TP was increased in tumor compared to normal tissue (Jin-no et al, 1998).

In the sera and synovial fluids of patients suffering from rheumatoid arthritis PD-ECGF/TP could be detected at high levels, (Asai et al, 1993). In addition, there was a significant positive correlation between PD-ECGF/TP levels in synovial fluid and in serum (Asai et al, 1993). Other findings suggested that serum PD-ECGF/TP levels could be used as indicator for synovitis and the efficacy of surgical treatment (Muro et al, 2001). The elevated PD-ECGF/TP levels presumably arise through induction of PD-ECGF/TP in synoviocytes, resulting from aberrant production of cytokines like TNFa and IL1 (Waguri et al, 1997).

In conclusion, in both cancer and RA tissues elevated levels of PD-ECGF/TP have been found. This indicates active angiogenesis, known to play an important role in the pathology of both diseases (Folkman, 1995; Koch, 2000). The origin of PD-ECGF/TP in the circulation remains ground for speculation. There are several possibilities such as shedding from tumor cells and synoviocytes or active excretion from the producing cells. Although PD-ECGF/TP lacks a hydrophobic leader (Ishikawa et al, 1989), other pathways might be in place to excrete PD-ECGF/TP. These pathways might be similar to those described for acidic and basic fibroblast growth factor (Powers et al, 2000). The serine residues of PD-ECGF/TP can be covalently linked to phosphate groups of nucleotides, leading to a nucleotidylated protein, a post-translational process possibly playing a role in the excretion process (Usuki et al, 1991). There are at least two tumor cell lines, A341 and MKN74 and cytokine treated fibroblast-like-synoviocytes that appear to actively excrete PD-ECGF/TP in the medium (Matsukawa et al, 1996; Waguri et al, 1997). Another less explored possibility to explain the increased PD-ECGF/TP in sera and plasma of cancer and RA patients might be the release of platelet content. It is known that activated platelets deposit the content of their a-granules on (activated) endothelium, thereby releasing several angiogenic and coagulation factors. This can lead to a rise of angiogenic factors at the site of deposition and subsequently in the circulation of patients with active angiogenesis (as in cancer and rheuma patients) (Pinedo et al, 1998). One of the proteins present in a granules is PD-ECGF/TP. It can be speculated that the level of PD-ECGF/TP in peripheral blood mononuclear cells and platelets can be further elevated through PD-ECGF/TP inducing cytokines.

E. MNGIE

Mitochondrial neurogastrointestinal encephalo myopathy (MNGIE) is an autosomal, recessive disorder involving mitochondrial DNA alterations (Bardosi et al, 1987; Hirano et al, 1994). The onset of the disease is between the first and fifth decades and is characterized by ptosis, progressive external opthalmoparesis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and leukoencephalopahty. Further analysis of muscle biopsies showed mitochondrial abnormalities such as ragged-red fibers and focal cytochrome c oxidase deficiency sometimes in association with multiple respiratory chain enzyme defects. The mitochondrial DNA in the skeletal muscle is partially depleted, has multiple deletions or both (Nishino et al, 2001). The gene responsible for the disease proved to be PD-ECGF/TP (Nishino et al, 1999). Potential gene mutations in PD-ECGF/TP exons were screened in 35 patients from 21 distinct families, which resulted in the finding of 16 mutations such as missense, splice site, microdeletions and single nucleotide insertions (Hirano et al, 1998; Nishino et al, 1999). As a result, these mutations in PD-ECGF/TP are associated with a severe reduction of the enzyme activity (Nishino et al, 1999). Heterozygotic activity is between the normal and the impaired activity, which might be a reflection of the heterodimer structure of the protein (Spinazzola et al, 2002). The impairment of the TP-enzyme activity leads to increased thymidine plasma levels, up to 60-fold and increased deoxyuridine levels which is also a substrate for PD-ECGF/TP (Marti et al, 2003). Mitochondrial dNTP pools are more dependent on the thymidine salvage pathway than de novo synthesis, and constitutively expressed, mitochondrial thymidine kinase 2 (TK2), converting thymidine to thymidine-monophosphate (TMP), is a result of this dependency. The conversion to TMP, TDP and TTP is the only metabolic pathway for TdR in MNGIE patients. It is hypothesized that due to the high levels of thymidine, the mitochondrial dNTP pools are altered and lead to mtDNA depletions and multiple deletions in these patients (Spinazzola et al, 2002). The impact of PD-ECGF/TP deficiency on the mitochondrial dNTP pool and mtDNA is more severe than on the nuclear pools because: 1) TK2 is constitutively expressed and cytosolic TK1 is not, 2) mitochondria have physically separate nucleotide pools and 3) mtDNA constantly replicates, even in post-mitotic cells.

One important fact is that in MNGIE patients so far no vascular abnormalities have been identified, suggesting that absence of TP-activity does not interfere with normal angiogenesis (Nishino et al, 1999).

II. Experimental proof of angiogenesis and possible mechanisms

A. Basic observations and transfected models

After the original discovery of PD-ECGF, the initial identification of the angiogenic effect was based upon the incorporation of (³H)-thymidine into endothelial cells (Miyazono et al, 1987). Subsequently it was discovered that PD-ECGF was identical to the well known enzyme from pyrimidine metabolism, TP (Furukawa et al, 1992). Due to this fact the (³H)-thymidine incorporation studies need to be viewed in a different light, since the PD-ECGF/TP converts TdR into thymine (Usuki et al, 1992), which would prevent its incorporation into DNA. When PD-ECGF/TP was added to endothelial cells, it increased the uptake of (³H)-thymidine when added as a pulse. An explanation for this might be that PD-ECGF/TP depletes TdR in the medium thereby indirectly decreasing the TdR concentration in the cells; a subsequent pulse would then replenish the intracellular pool of TdR with (³H)-thymidine. Increasing concentrations of PD-ECGF/TP led to a bell shaped curve, TdR depletion is replenished to a maximum after PD-ECGF/TP breakdown. In the declining part of the curve the amount of PD-ECGF/TP starts to breakdown the (³H)-thymidine pulse leaving less for replenishment and apparent incorporation (Usuki et al, 1992). When PD-ECGF/TP and (³H)-thymidine were added simultaneously, there was a decrease of (³H)-thymidine incorporation, due to direct breakdown of (³H)-thymidine by PD-ECGF/TP (Usuki et al, 1992). This phenomenon of increasing (³H)-thymidine apparent incorporation, could be found in both dividing human umbilical cord endothelial cells (HUVECs) and quiescent, non dividing bovine adrenal capillary endothelial (BACE) cells, (Moghaddam and Bicknell, 1992). PD-ECGF/TP might have mediated TdR uptake as a result of the protein’s intrinsic thymidine phosphorylase activity. It appears therefore that the original identification of PD-ECGF/TP as a mitogenic activator of endothelial cell growth has been based on an erroneous assay since (³H)-thymidine incorporation into DNA does not always reflect cellular proliferation. There is however one paper which debates these findings, stating that PD-ECGF/TP reduces the amount of TdR in the surroundings of endothelial cells, thereby reducing the inhibitory effect of TdR on EC growth, thus giving rise to cell growth and to the bell shaped curve (Finnis et al, 1993). In our experiments using human umbilical vascular endothelial cells (HUVEC) in growth assays we found no growth promoting activity of PD-ECGF/TP, using the MTT assay (Figure 2). Parallel to the experiments showing possible mitogenic effects of PD-ECGF/TP other experiments were undertaken to further clarify the angiogenic effect of PD-ECGF/TP. It was shown that PD-ECGF/TP had a chemotactic effect on endothelial cells in vitro, had angiogenic capacity in the CAM assay and induced more vascularized tumors formed by NIH3T3 cells in nude mice, compared to its mock-transfected counterparts (Ishikawa et al, 1989). Another approach taken to show the angiogenic effect of PD-ECGF/TP was the use of (gelatine) sponge assays, whereby the sponges with potential angiogenic compounds are implanted in a subcutaneous pouch in mice or rats. After removal the hemoglobin content extracted from the sponge is a measure of the vascularization. It was shown that PD-ECGF/TP indeed increased the hemoglobin content in this assay (Haraguchi et al, 1994; Moghaddam et al, 1995)which could be inhibited by a competitive inhibitor, once again indicating the importance of the enzymatic reaction (Moghaddam et al, 1995). Therefore, despite the fact that the original assay of (³H)-thymidine incorporation might not have been interpreted correctly, there is still ample evidence for angiogenic properties of PD-ECGF/TP.

Many cell lines have been transfected with PD-ECGF/TP, either to study the angiogenic effect or to study its role in fluoropyrimidine sensitivity. The first example comes from Ishikawa et al, (1989) PD-ECGF/TP provided NIH3T3 transfected cells with a growth advantage, resulting in more vascularized tumors. Interestingly, we observed that wild-type NIH3T3 cells, which have no PD-ECGF/TP did not form tumors in our experiments. However, the ras- and trk- transfected variants had high PD-ECGF/TP and formed well vascularized tumors (Peters et al, 1993). MCF7, breast cancer cells transfected with PD-ECGF/TP, also resulted in tumors with enhanced tumor growth in vivo (Moghaddam et al, 1995).

PD-ECGF/TP transfected human epidermoid cells grew more rapidly in xenograft experiments than the parental line which was associated with an elevated MVD. This effect was not observed when cells were transfected with mutant PD-ECGF/TP rendering enzymatic inactive proteins (Nishimoto et al, 1997). Later this model has been used to study the impact of PD-ECGF/TP on apoptosis (Matsushita et al, 1999) and suppression of PD-ECGF/TP mediated growth and angiogenesis by L-deoxyribose (L-dR) (Kitazono et al, 1998; Uchimiya et al, 2002). RT112 bladder cells transfected with PD-ECGF/TP, showed an increased invasion capacity in an in vitro bladder invasion assay (Jones et al, 2002). Further testing of these cells in xenograft transplants showed that the RT112-TP cells grew significantly faster than the mock transfected RT112-EV (Jones et al, 2002). In order to study the impact on fluoropyrimidine sensitivity, Marchetti et al transfected a rat colon carcinoma cell line, PROb with PD-ECGF/TP, which increased its sensitivity to several fluoropyrimidines. However the effect on tumor growth in vivo was relatively low and appeared to be confined to the initial stages of tumor development; staining for the endothelial cell marker factor VIII was always higher in transfected cells compared to control cells (Marchetti et al, 2001). Ciccolini et al also reported that LST174 PD-ECGF/TP transfected cells did not grow faster than the wild-type cells, furthermore there was no increase in endothelial markers (Ciccolini et al, 2001). This lack of growth advantage in PD-ECGF/TP transfected mice and human cells has been reported in previous studies from the same group (Evrard et al, 1999b; Ciccolini et al, 2000).

In conclusion, in several of the transfected model systems PD-ECGF/TP does increase tumor growth and sometimes MVD and the malignant phenotype. However studies have been published in which the transfer of the PD-ECGF/TP gene did not have an impact on tumor growth. Possibly other angiogenic factors or conditions, not influenced by transfection of PD-ECGF/TP determined the angiogenic potential and tumor growth in these model systems.

B. Mechanistic background of the angiogenic and tumor promoting effect of PD-ECGF/TP

Most research on PD-ECGF/TP was performed to show its presence with immunohistochemical stainings; but there are very few studies on the mechanistic background. The enzymatic activity seems indispensable for the angiogenic effect of PD-ECGF/TP. The lack of a hydrophobic leader sequence and a receptor, makes that it is not a classical angiogenic factor. Since enzymatic activity is of importance for the angiogenic activity of PD-ECGF/TP, the focus of research has been on the products produced in the enzymatic reaction: thymine, dR-1-P and deoxyribose (dR), the dephosphorylated product of dR-1-P (Brown and Bicknell, 1998) and to a lesser extent the decrease of TdR. Sengupta et al observed that dR and dR-1-P promoted endothelial tube formation and the regeneration of an endothelial monolayer in the wound assay in vitro without stimulating mitogenesis. In vivo, TP and dR increased vascularization in the sponge assay, in which the clearance of a radiolabel (¹³³Xe) was a measure for the extent of vascularization of the sponge (Sengupta et al, 2003). It was shown that PD-ECGF/TP had chemotactic activity in vitro (Ishikawa et al, 1989). dR was able to induce migration of bovine aortic endothelial (BAE) cells similar to PD-ECGF/TP. The results were repeated in the CAM assay, in which dR and PD-ECGF/TP could induce development of the vascular system. Hotchkiss et al, (2003a) found that the production of dR-1-P and dR explained how PD-ECGF/TP, expressed by either tumor cells or monocytes mediates endothelial cell migration. Tumor cells, transfected with PD-ECGF/TP or monocyte-like cell lines THP1 and U937 naturally expressing PD-ECGF/TP were used. Purified PD-ECGF/TP can mediate a chemotactic effect in the endothelial migration assay, for which TdR is required. This confirmed the necessity of enzymatic activity, since the effect was abrogated in the absence of substrate. The importance of enzymatic activity was further strengthened by inhibition of migration in the presence of an inhibitor of PD-ECGF/TP. In contrast to Sengupta et al, (2003), Hotchkiss et al found no effect of PD-ECGF/TP in a wound assay (Hotchkiss et al, 2003a), in their view confirming the need of a gradient of dR. It was shown that dR was 10 times more potent in inducing migration than dR-1-P, while the combined effect of PD-ECGF/TP plus TdR was comparable to dR alone. The hypothesis that dR-1-P needs to be converted to dR before inducing maximal chemotactic effects, was tested and confirmed by the addition of an inhibitor of alkaline phosphatase (API), which attenuated not only the migration induced by dR-1-P but also by PD-ECGF/TP. The inhibition of PD-ECGF/TP induced migration by API, while blocking the dephosphorylation of dR-1-P confirmed that this conversion to dR was part of the mechanism. Altogether, the data using cell lines, naturally expressing high PD-ECGF/TP or by transfection, underlined that migration was dependent on dR produced by PD-ECGF/TP. These cell lines released more dR than dR-1-P. dR-1-P is formed intracellularly and is not able to diffuse to the extracellular space. Its conversion to dR is likely due to an intracellular phosphatase resulting in a chemotactic dR concentration gradient after subsequent extracellular release (Hotchkiss et al, 2003a). These authors provided the first substantial evidence that dR-1-P is converted to dR.

The exact mechanism by which dR might exert chemotactic effects on the endothelial cells is largely unknown. It has been proposed that a chemotactic gradient is detected at opposite sides of the cell, followed by migration through pseudopodal processes. However these actions are usually mediated through specific receptors, which have so far not been identified for dR on endothelial cells (Brown and Bicknell, 1998). Corneal endothelial cells indeed migrate in the direction of simple sugars which could be utilized as an energy source(Vogel et al, 1993).

Hotchkiss et al, (2003b) identified the formation of focal adhesions and the phosphorylation of focal adhesion kinase (FAK) in HUVECs after both PD-ECGF/TP or dR stimulation. FAK is a non-receptor protein kinase that is recruited to focal adhesions by integrin engagement with the extracellular matrix and plays a central role in mediating cell attachment and migration. It was observed that VEGF, PD-ECGF/TP and dR similarly stimulated the formation of these focal adhesions and phosphorylation of FAK in HUVECs. There was however a difference in the involvement of specific integrins. PD-ECGF/TP migration was blocked by antibodies against a₅b₁ and a_Vb₃, whereas VEGF induced migration seemed to involve only a_Vb₃ (Hotchkiss et al, 2003b). Seeliger et al describe that dR activates p70/S6 kinase, this activation could be blocked with rapamycin, an inhibitor of the molecular target of rapamycin (mTOR), thereby explaining the blockage of the pro-angiogenic effect of dR in an endothelial migration assay and in the rat aortic ring assay (Seeliger et al, 2004). Malik and Parsons investigated the interaction of integrin receptors with ECM proteins resulting in the activation of p70/S6 kinase, it was shown that for this activation there is at least a partial requirement for FAK (Malik and Parsons, 1996). These two observations together with the finding of Hotchkiss et al (Hotchkiss et al, 2003b) all implicate that dR induced signaling is through FAK and p70/S6 kinase. Furthermore, p70/S6 kinase has been shown to signal survival and inhibits the pro-apoptotic molecule BAD (Harada et al, 2001).

At high non-physiological concentrations the reducing sugar dR can induce apoptosis in peripheral blood mononuclear cells (Barbieri et al, 1994) and fibroblasts (Kletsas et al, 1998). This cytotoxic effect was observed in cycling and in G₀ arrested cells and could be reversed by the antioxidant N-acetyl cysteine (NAC) indicating a role for oxidative stress induced by dR (Kletsas et al, 1998). One process, which might be responsible for the induction of cell death, involves the high reducing capability of dR and dR-1-P. Reducing sugars are involved in non-enzymatic glycosylation of proteins: the so called Maillard reaction (Monnier, 1990). The Maillard reaction leads to the formation of specific protein adducts, known as advanced glycosylation end products (AGEs). The reaction is initiated by non-enzymatic condensation of a reducing sugar with an amine, occurring preferentially on lysine and arginine groups or N-terminal groups. The reactivity of the sugars is a function of the anomerization rate of the sugar, meaning the larger the percentage of a given sugar in the open chain form, the more reactive (Bunn and Higgins, 1981). The reaction rate is inversely proportional to the number of carbon atoms in the sugar, being lowest for hexoses and highest for trioses, like glyceraldehyde. Furthermore phosphorylated sugars are much more reactive than their non-phosphorylated counterparts (Monnier, 1990) After the condensation Schiff base adducts and Amadori products are formed. These unstable intermediates react via a series of non-enzymatic reactions to form AGEs. During these reactions, specifically in the transition metal-catalyzed autooxidation, free radicals are produced (Monnier, 1990) (Bierhaus et al, 1998). AGE formation plays a role in aging processes and diabetes related pathologies; this role appears to have two aspects: alterations of proteins due to glycosylation and induction of reactive oxygen species (ROS) (Baynes, 2001).

Brown et al, (2000) postulated that the Maillard reaction could be the biological activity which might underlie the angiogenic effect of PD-ECGF/TP. They also suggested that the angiogenic effect of PD-ECGF/TP, which was increased in a PD-ECGF/TP overexpressing bladder tumor cell line RT112, might be related to an increase of interleukin-8 (IL-8), vascular endothelial growth factor (VEGF) and matrix metalloproteinase 1 (MMP1) production after addition of TdR. A specific thymidine phosphorylase inhibitor (TPI) (Fukushima et al, 2000) and thymine inhibited this effect, both through abrogation of the enzymatic reaction (thymine by shifting the balance of the reaction). PD-ECGF/TP mediated TdR breakdown was associated with induction of ROS, since the expression of the oxidative stress marker heme oxygenase-I (HO-I) increased in transfected cells after incubation with TdR. This induction could be inhibited by N-acetyl cysteine (NAC), substantiating the evidence for ROS formation (Brown et al, 2000). It was hypothesized that dR, dR-1-P and dR-5-P, which potentially can be formed from dR-1-P through the action of phosphoribomutase (E.C. 5.4.2.7) react in the Maillard reaction (Monnier, 1990), thereby inducing ROS, leading to the upregulation of the described angiogenic factors (Brown et al, 2000). This is a novel finding that PD-ECGF/TP indirectly induces angiogenesis, without a direct interaction between products or substrates of the enzymatic reaction and endothelial cells. Nakajima et al found similar results showing that PD-ECGF/TP transfected KB epidermoid tumor cells, excreted IL-8 and VEGF in higher quantities (Nakajima et al, 2004). In human malignant melanoma it was found that there was an apparent co-expression of PD-ECGF/TP and HO-I in infiltrating macrophages (Torisu-Itakura et al, 2000), supporting the ROS hypothesis.

These hypotheses on the link between TP-activity and angiogenesis are based on the formation of dR-1-P and further metabolism, in most cases to dR. Although all papers concerning the angiogenic effect of PD-ECGF/TP mention the formation of dR from dR-1-P as a fact, evidence offering proof for this is scarce, and needs more exploration. Little is known of the cellular metabolism of dR-1-P. It can either be dephosphorylated to dR and leave the cell, or isomerized by phosphoribomutase to dR-5-P which can enter glycolytic metabolism. Anand and Anand question the fate of dR-1-P, mentioning the lack of knowledge about the metabolic pathways responsible for dR-1-P breakdown and conversion(Anand and Anand, 2000).

Previous studies did not actually evaluate dR-1-P accumulation and disappearance after TdR exposure. De Bruin et al, (2003) studied the generation of dR-1-P and its accumulation after incubation with TdR in an intact colon cancer cell line and its PD-ECGF/TP transfected variant. Thymine production was measured in the medium providing an accurate estimate of the minimal amount of dR-1-P produced inside the cells. Subsequent analysis of cellular dR-1-P content showed that less than 1% of the estimated dR-1-P was detected, indicating that there was a very rapid disappearance of dR-1-P. This was confirmed in cellular extracts when dR-1-P was added directly and incubated and the majority of dR-1-P disappeared within 10 minutes (De Bruin et al, 2003a). In order to obtain insight to where the dR-1-P is disappearing deoxyribose or dR-5-P were added to influence the dephosphorylation or conversion into dR-5-P, respectively. Deoxyribose did not influence the disappearance whereas dR-5-P resulted in an initial increase followed by a decrease (Figure 3) (De Bruin et al, 2004). This disappearance could be decrease by dR-5-P and not by deoxyribose indicating that dR-1-P is converted to dR-5-P and is then on route to be metabolised in the glycolysis or pentose phosphate pathway.

Summarized, PD-ECGF/TP can have a dual role in the tumor. Its angiogenic activity promotes tumor growth and progression providing a target for intervention via inhibition of PD-ECGF/TP, e.g. by TPI. The other role is the utilization of the overexpression of PD-ECGF/TP in order to activate fluoropyrimidine prodrugs (Focher and Spadari, 2001; Marchetti et al, 2001).

IV. Pyrimidine phosphorylases; Thymidine phosphorylase and Uridine phosphorylase

Of note, besides PD-ECGF/TP there is a closely related pyrimidine phosphorylase active in human tumors: uridine phosphorylase (UP, EC 2.4.2.3) (Pizzorno et al, 2002). Since both TP and UP have broad and sometimes overlapping substrate specificity depending on the tissue in which they are measured, it can be difficult to distinguish between them. Two specific inhibitors TPI for PD-ECGF/TP and 5-benzylacyclouridine (BAU) (Niedzwicki et al, 1982) for UP, can be used as tools when the phosphorylase activity in cells or tissues is measured. Furthermore there are also interspecies differences, which might limit the use of certain model systems. El-Kouni et al, (1993) described that specificity of TP and UP for substrates varied between two different organs and cancers from mouse and humans. Using UP knockout embryonic stem (ES) cells, Cao et al found a 10-fold increase in IC₅₀ for 5FU compared to normal ES cells. Furthermore there was a 16-fold increase in the IC50s for 5’DFUR (Cao et al, 2002). This is indicative for a role for UP in (oral) fluoropyrimidines and is in contrast to the finding that transfection of MCF7 cells with the UP gene did not influence the effect of 5FU or 5'DFUR (Cuq et al, 2001).

V. Regulation of PD-ECGF/TP expression and (Bio)modulation of fluoropyrimidines

The PD-ECGF/TP promoter does not contain ‘TATA’ or ‘CCAAT’ boxes, sequences recognized by RNA polymerase II, prevalent in most eukaryotic genes (Hagiwara et al, 1991). The exact mechanism of regulation of PD-ECGF/TP gene expression is yet unknown, however the promoter contains six to nine Sp1 transcription factor binding sites (i.e. GC-box) postulated to contribute to both basal and inducible expression (Hagiwara et al, 1991; Zhu et al, 2002).

PD-ECGF/TP can be upregulated by cytokines such as tumor necrosis factor-a (TNF-a), IL-1, interferon-g (IFN-g) (Eda et al, 1993) and IFN-a (Schwartz et al, 1992; Tevaearai et al, 1992; Makower and Wadler, 1999; Morita and Tokue, 1999). Other identified transcription binding sites in the PD-ECGF/TP promoter are an interferon stimulated response element (ISRE) (Schwartz et al, 1998) and a g activated sequence (GAS) (Goto et al, 2001). The ISRE and GAS are sequences through which interferon (IFN)-mediated signaling acts. IFN-a, b and g act via the signal transducer and activator of transcription (STAT) family of transcription factors. IFN-a and b phosphorylate STAT1 and 3, which with a third cytoplasmic protein forms an activated transcription complex. IFN g results in STAT 1 phosphorylation and homodimerization (Borden, 1998). The activated STAT transcription factors can then bind to their consensus sequences in the DNA to activate transcription.

Furthermore, various chemotherapeutic agents including taxanes, cyclophosphamide and mitomycin C (Sawada et al, 1998), and X-ray radiation (Sawada et al, 1999) can upregulate PD-ECGF/TP. The latter two may induce PD-ECGF/TP indirectly via upregulation of TNF-a or IFN-g (Blanquicett et al, 2002). Fukushima et al investigated PD-ECGF/TP upregulation due to IFN-a and paclitaxel in vitro and in vivo. Cell lines with high PD-ECGF/TP mostly had high STAT1 levels and PD-ECGF/TP and could no longer be induced by IFN-a, whereas low PD-ECGF/TP expressing cell lines in which expression could be induced, had low inducible STAT1. Furthermore in clinically resected tumors PD-ECGF/TP and STAT1 were measured simultaneously and almost all tumors had high expression of both PD-ECGF/TP and STAT1 (Fukushima et al, 2002).

There is also a role for NFkB. Although, no direct involvement of NFkB has been shown in relation to PD-ECGF/TP expression, Zhu and Schwartz, (2003) recently suggested that NFkB and TNFRII may be involved in the regulation of PD-ECGF/TP gene expression. We found that monocytic cells exposed to a NFkB inhibitor, sulfasalazine, had an altered pathway and a marked downregulation of TNFRII, confirming the finding of Zhu et al in a different system.

Microenvironmental conditions, such as hypoxia and low pH can also upregulate PD-ECGF/TP expression possibly explaining the preferential presence around necrotic areas (Griffiths et al, 1997; Griffiths and Stratford, 1998). Others have shown increased PD-ECGF/TP expression at the infiltrating tumor edge (Maeda et al, 1996).

Since it has been shown, in numerous transfection studies, that PD-ECGF/TP enhanced the efficacy of at least 5’DFUR (and thus of capecitabine), PD-ECGF/TP is used as a target to modulate fluoropyrimidine sensitivity (Morita et al, 2001). Xenograft models of human breast and colon cancers exposed to paclitaxel, docetaxel, mitomycin C or cyclophosphamide showed increased PD-ECGF/TP concentrations. In combination therapy, taxol, docetaxel and X-ray radiation with capecitabine or 5’DFUR were more effective than either alone (Sawada et al, 1998, 1999). Similar results were found by Endo et al, (1999) who found that cyclophosphamide preferentially upregulated pyrimidine phosphorylase activity (PyNPase) in the human tumor, whereas no change was detected in several other tissues of the tumor bearing and treated mouse. This upregulation of pyrimidine phosphorylase (PyNPase) resulted in a synergistic effect between cyclophosphamide and 5’DFUR or capecitabine, without enhancement of toxicity (Endo et al, 1999). Attempts to enhance the effects of 5’DFUR and capecitabine by specifically upregulating PD-ECGF/TP is a straightforward approach. However the results of the attempts to influence 5FU are less clear. 5FU has been combined with IFNs in order to increase its efficacy, resulting in abrogation of 5FU associated TS increase, augmentation of 5FU plasma levels and increased 5FU induced DNA damage (Schwartz et al, 1992;Makower and Wadler, 1999;van der Wilt et al, 1997;Horowitz et al, 1995). Although initially the response rates appeared to be higher when 5FU was combined with IFN-a, randomized trials showed that the survival was equivalent, with in some instances an increased toxicity when IFN was added (Kemeny and Younes, 1992; Atzpodien et al, 1994; Greco et al, 1996; Labianca et al, 1996; Makower and Wadler, 1999).

VI. Conclusion

There are many data indicating a role for PD-ECGF/TP in (tumor) angiogenesis. Numerous immunohistological studies showed correlation between MVD and PD-ECGF/TP expression. Furthermore PD-ECGF/TP is often an independent marker for poor prognosis. The investigations focusing on the mechanism of the angiogenic effect of PD-ECGF/TP are far less in number. The main focus of research has been the enzymatic reaction catalyzed by PD-ECGF/TP and more specifically the products from the reaction. dR appears to play a key role in the pro-angiogenic and anti-apoptotic effects. However, the route and mechanism of this metabolite remain partly unknown. So far Induction of endothelial cell migration, enhanced metastasis and migration of cancer cells and induction of other angiogenic factors appears to play a role. The fact that L-dR can counteract most effects of dR and PD-ECGF/TP is reasonable proof that dR is responsible for the effects. Although PD-ECGF/TP cleaves TdR to thymine and dR-1-P, not much is known of the elimination of dR-1-P or generation of dR from dR-1-P. So further research upstream of dR is warranted.

Besides this apparent role in tumor progression PD-ECGF/TP is also a key player in fluoropyrimidine sensitivity. It proved to be able to generate 5FU from 5’DFUR, a feature used as strategy in the development of capecitabine. The application of capecitabine has proven that specific activation by PD-ECGF/TP is feasible and effective. Furthermore, it is capable of breaking down TFT into an inactive form. In the drug combination TAS-102 (TFT plus TPI), TFT is protected from breakdown by the inhibitor. A combination with a PD-ECGF/TP inhibitor is very appealing. TPI has been shown to inhibit some of the pro-angiogenic and anti-apoptotic features of PD-ECGF/TP.

Other articles describe L-dR as good candidate for combination with fluoropyrimidines, still being able to take advantage of the high PD-ECGF/TP levels in tumors but inhibiting the pro-tumor effects down-stream of the PD-ECGF/TP reaction.

PD-ECGF/TP is an enzyme with two faces in tumor development and treatment. It promotes tumor growth in various manners, but due to its up-regulation, it can also be utilized as a target for drug modulation.

References

Ackland SP, Peters GJ (1999) Thymidine phosphorylase: its role in sensitivity and resistance to anticancer drugs. Drug Resist Updat 2, 205-214.

Alcalde RE, Terakado N, Otsuki K, Matsumura T (1997) Angiogenesis and expression of platelet-derived endothelial cell growth factor in oral squamous cell carcinoma. Oncology 54, 324-328.

Anand U, Anand CV (2000) What is the fate of deoxyribose-1-phosphate? Biochemical Education 28, 113-114.

Ansfield FJ, Ramirez G (1971) Phase I and II studies of 2'-deoxy-5-trifluoromethyl-uridine NSC-75520. Cancer Chemother Rep 55, 205-208.

Arima J, Imazono Y, Takebayashi Y, Nishiyama K, Shirahama T, Akiba S, Furukawa T, Akiyama S, Ohi Y (2000) Expression of thymidine phosphorylase as an indicator of poor prognosis for patients with transitional cell carcinoma of the bladder. Cancer 88, 1131-1138.

Asai K, Hirano T, Kaneko S, Moriyama A, Nakanishi K, Isobe I, Eksioglu YZ, Kato T (1992a) A novel glial growth inhibitory factor, gliostatin, derived from neurofibroma. J Neurochem 59, 307-317.

Asai K, Hirano T, Matsukawa K, Kusada J, Takeuchi M, Otsuka T, Matsui N, Kato T (1993) High concentrations of immunoreactive gliostatin/platelet-derived endothelial cell growth factor in synovial fluid and serum of rheumatoid arthritis. Clin Chim Acta 218, 1-4.

Asai K, Nakanishi K, Isobe I, Eksioglu YZ, Hirano A, Hama K, Miyamoto T, Kato T (1992b) Neurotrophic action of gliostatin on cortical neurons. Identity of gliostatin and platelet-derived endothelial cell growth factor. J Biol Chem 267, 20311-20316.

Atzpodien J, Kirchner H, Hanninen EL, Menzel T, Deckert M, Franzke A, Schomburg A, Poliwoda H (1994) Treatment of metastatic colorectal cancer patients with 5-fluorouracil in combination with recombinant subcutaneous human interleukin-2 and a-interferon. Oncology 51, 273-275.

Barbieri D, Grassilli E, Monti D, Salvioli S, Franceschini MG, Franchini A, Bellesia E, Salomoni P, Negro P, Capri M, Troiano L, Cossarizza A, Franceschi C (1994) D-ribose and deoxy-D-ribose induce apoptosis in human quiescent peripheral blood mononuclear cells. Biochem Biophys Res Commun 201, 1109-1116.

Bardosi A, Creutzfeldt W, DiMauro S, Felgenhauer K, Friede RL, Goebel HH, Kohlschutter A, Mayer G, Rahlf G, Servidei S, (1987) Myo-, neuro-, gastrointestinal encephalopathy MNGIE syndrome due to partial deficiency of cytochrome-c-oxidase. A new mitochondrial multisystem disorder. Acta Neuropathol Berl 74, 248-258.

Baynes JW (2001) The role of AGEs in aging: causation or correlation. Exp Gerontol 36, 1527-1537.

Bierhaus A, Hofmann MA, Ziegler R, Nawroth PP (1998) AGEs and their interaction with AGE-receptors in vascular disease and diabetes mellitus. I. The AGE concept. Cardiovasc Res 37, 586-600.

Bingle L, Brown NJ, Lewis CE (2002) The role of tumour-associated macrophages in tumour progression: implications for new anticancer therapies. J Pathol 196, 254-265.

Blanquicett C, Gillespie GY, Nabors LB, Miller CR, Bharara S, Buchsbaum DJ, Diasio RB, Johnson MR (2002) Induction of thymidine phosphorylase in both irradiated and shielded, contralateral human U87MG glioma xenografts: implications for a dual modality treatment using capecitabine and irradiation. Mol Cancer Ther 1, 1139-1145.

Borden EC (1998) Gene Regulation and Clinical Roles for Interferons in Neoplastic Diseases. Oncologist 3, 198-203.

Borner MM, Schoffski P, de Wit R, Caponigro F, Comella G, Sulkes A, Greim G, Peters GJ, Van Der Born K, Wanders J, de Boer RF, Martin C, Fumoleau P (2002) Patient preference and pharmacokinetics of oral modulated UFT versus intravenous fluorouracil and leucovorin: a randomised crossover trial in advanced colorectal cancer. Eur J Cancer 38, 349-358.

Brostjan C, Bayer A, Zommer A, Gornikiewicz A, Roka S, Benko T, Yaghubian R, Jakesz R, Steger G, Gnant M, Friedl J, Stift A (2003) Monitoring of circulating angiogenic factors in dendritic cell-based cancer immunotherapy. Cancer 98, 2291-2301.

Brown NS, Bicknell R (1998) Thymidine phosphorylase, 2-deoxy-D-ribose and angiogenesis. Biochem J 334, 1-8.

Brown NS, Jones A, Fujiyama C, Harris AL, Bicknell R (2000) Thymidine phosphorylase induces carcinoma cell oxidative stress and promotes secretion of angiogenic factors. Cancer Res 60, 6298-6302.

Bunn HF, Higgins PJ (1981) Reaction of monosaccharides with proteins: possible evolutionary significance. Science 213, 222-224.

Cao D, Russell RL, Zhang D, Leffert JJ, Pizzorno G (2002) Uridine phosphorylase -/- murine embryonic stem cells clarify the key role of this enzyme in the regulation of the pyrimidine salvage pathway and in the activation of fluoropyrimidines. Cancer Res 62, 2313-2317.

Carta MC, Mattana A, Camici M, Allegrini S, Tozzi MG, Sgarrella F (2001) Catabolism of exogenous deoxyinosine in cultured epithelial amniotic cells. Biochim Biophys Acta 1528, 74-80.

Ciccolini J, Cuq P, Evrard A, Giacometti S, Pelegrin A, Aubert C, Cano JP, Milano G, Iliadis A (2001) Combination of thymidine phosphorylase gene transfer and deoxinosine treatment greatly enhances 5-fluorouracil antitumor activity in vitro and in vivo. Molecular Cancer Therapeutics 1, 133-139.

Ciccolini J, Peillard L, Evrard A, Cuq P, Aubert C, Pelegrin A, Formento P, Milano G, Catalin J (2000) Enhanced antitumor activity of 5-fluorouracil in combination with 2'-deoxyinosine in human colorectal cell lines and human colon tumor xenografts. Clin Cancer Res 6, 1529-1535.

Creamer D, Jaggar R, Allen M, Bicknell R, Barker J (1997) Overexpression of the angiogenic factor platelet-derived endothelial cell growth factor/thymidine phosphorylase in psoriatic epidermis. Br J Dermatol 137, 851-855.

Cuq P, Rouquet C, Evrard A, Ciccolini J, Vian L, Cano JP (2001) Fluoropyrimidine sensitivity of human MCF-7 breast cancer cells stably transfected with human uridine phosphorylase. Br J Cancer 84, 1677-1680.

De Bruin M, Smid K, Laan AC, Noordhuis P, Fukushima M, Hoekman K, Pinedo HM, Peters GJ (2003a) Rapid disappearance of deoxyribose-1-phosphate in platelet derived endothelial cell growth factor/thymidine phosphorylase overexpressing cells. Biochem Biophys Res Commun 301, 675-679.

De Bruin M, Van Capel T, Smid K, Van der Born K, Fukushima M, Hoekman K, Pinedo HM, Peters GJ (2004) Role of platelet derived endothelial cell growth factor/thymidine phosphorylase in fluoropyrimidine sensitivity and potential role of deoxyribose-1-phosphate. Nucleosides Nucleotides Nucleic Acids 23, 1485-1490.

De Bruin M, Van Capel T, Van der Born K, Kruyt FA, Fukushima M, Hoekman K, Pinedo HM, Peters GJ (2003b) Role of platelet-derived endothelial cell growth factor/thymidine phosphorylase in fluoropyrimidine sensitivity. Br J Cancer 88, 957-964.

Dexter DL, Wolberg WH, Ansfield FJ, Helson L, Heidelberger C (1972) The clinical pharmacology of 5-trifluoromethyl-2'-deoxyuridine. Cancer Res 32, 247-253.

Eckstein JW, Foster PG, Finer-Moore J, Wataya Y, Santi DV (1994) Mechanism-based inhibition of thymidylate synthase by 5- trifluoromethyl -2'-deoxyuridine 5'-monophosphate. Biochemistry 33, 15086-15094.

Eda H, Fujimoto K, Watanabe S, Ura M, Hino A, Tanaka Y, Wada K, Ishitsuka H (1993) Cytokines induce thymidine phosphorylase expression in tumor cells and make them more susceptible to 5'-deoxy-5-fluorouridine. Cancer Chemother Pharmacol 32, 333-338.

el Kouni MH, el Kouni MM, Naguib FN (1993) Differences in activities and substrate specificity of human and murine pyrimidine nucleoside phosphorylases: implications for chemotherapy with 5-fluoropyrimidines (published erratum in Cancer Res 1993 ;53:4738). Cancer Res 53, 3687-3693.

Emura T, Nakagawa F, Fujioka A, Ohshimo H, Kitazato K (2004a) Thymidine kinase and thymidine phosphorylase level as the main predictive parameter for sensitivity to TAS-102 in a mouse model. Oncol Rep 11, 381-387.

Emura T, Nakagawa F, Fujioka A, Ohshimo H, Yokogawa T, Okabe H, Kitazato K (2004b) An optimal dosing schedule for a novel combination antimetabolite, TAS-102, based on its intracellular metabolism and its incorporation into DNA. Int J Mol Med 13, 249-255.

Endo M, Shinbori N, Fukase Y, Sawada N, Ishikawa T, Ishitsuka H, Tanaka Y (1999) Induction of thymidine phosphorylase expression and enhancement of efficacy of capecitabine or 5'-deoxy-5-fluorouridine by cyclophosphamide in mammary tumor models. Int J Cancer 83, 127-134.

Engels K, Fox SB, Whitehouse RM, Gatter KC, Harris AL (1997) Up-regulation of thymidine phosphorylase expression is associated with a discrete pattern of angiogenesis in ductal carcinomas in situ of the breast. J Pathol 182, 414-420.

Evrard A, Cuq P, Ciccolini J, Vian L, Cano JP (1999a) Increased cytotoxicity and bystander effect of 5-fluorouracil and 5'-deoxy-5-fluorouridine in human colorectal cancer cells transfected with thymidine phosphorylase. Br J Cancer 80, 1726-1733.

Evrard A, Cuq P, Robert B, Vian L, Pelegrin A, Cano JP (1999b) Enhancement of 5-fluorouracil cytotoxicity by human thymidine-phosphorylase expression in cancer cells: in vitro and in vivo study. Int J Cancer 80, 465-470.

Finnis C, Dodsworth N, Pollitt CE, Carr G, Sleep D (1993) Thymidine phosphorylase activity of platelet-derived endothelial cell growth factor is responsible for endothelial cell mitogenicity. Eur J Biochem 212, 201-210.

Focher F, Spadari S (2001) Thymidine phosphorylase: a two-face Janus in anticancer chemotherapy. Curr Cancer Drug Targets 1, 141-153.

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

Fox SB, Engels K, Comley M, Whitehouse RM, Turley H, Gatter KC, Harris AL (1997) Relationship of elevated tumour thymidine phosphorylase in node-positive breast carcinomas to the effects of adjuvant CMF. Ann Oncol 8, 271-275.

Fox SB, Moghaddam A, Westwood M, Turley H, Bicknell R, Gatter KC, Harris AL (1995) Platelet-derived endothelial cell growth factor/thymidine phosphorylase expression in normal tissues: an immunohistochemical study. J Pathol 176, 183-190.

Fox SB, Westwood M, Moghaddam A, Comley M, Turley H, Whitehouse RM, Bicknell R, Gatter KC, Harris AL (1996) The angiogenic factor platelet-derived endothelial cell growth factor/thymidine phosphorylase is up-regulated in breast cancer epithelium and endothelium. Br J Cancer 73, 275-280.

Fujii S, Kitano S, Ikenaka K, Shirasaka T (1979) Effect of coadministration of uracil or cytosine on the anti-tumor activity of clinical doses of 1- 2-tetrahydrofuryl -5-fluorouracil and level of 5-fluorouracil in rodents. Gann 70, 209-214.

Fujimoto J, Aoki I, Toyoki H, Khatun S, Tamaya T (2002) Clinical implications of expression of ETS-1 related to angiogenesis in uterine cervical cancers. Ann Oncol 13, 1598-1604.

Fujimoto J, Sakaguchi H, Aoki I, Tamaya T (2000) The value of platelet-derived endothelial cell growth factor as a novel predictor of advancement of uterine cervical cancers. Cancer Res 60, 3662-3665.

Fujimoto J, Sakaguchi H, Hirose R, Ichigo S, Tamaya T (1999) Expression of platelet-derived endothelial cell growth factor PD-ECGF and its mRNA in uterine cervical cancers. Br J Cancer 79, 1249-1254.

Fujimoto K, Hosotani R, Wada M, Lee JU, Koshiba T, Miyamoto Y, Tsuji S, Nakajima S, Doi R, Imamura M (1998) Expression of two angiogenic factors, vascular endothelial growth factor and platelet-derived endothelial cell growth factor in human pancreatic cancer, and its relationship to angiogenesis. Eur J Cancer 34, 1439-1447.

Fujiwaki R, Hata K, Iida K, Koike M, Miyazaki K (1998) Immunohistochemical expression of thymidine phosphorylase in human endometrial cancer. Gynecol Oncol 68, 247-252.

Fujiwaki R, Hata K, Iida K, Maede Y, Koike M, Miyazaki K (1999a) Thymidine phosphorylase expression in progression of cervical cancer: correlation with microvessel count, proliferating cell nuclear antigen, and apoptosis. J Clin Pathol 52, 598-603.

Fujiwaki R, Hata K, Iida K, Maede Y, Watanabe Y, Koike M, Miyazaki K (1999b) Co-expression of vascular endothelial growth factor and thymidine phosphorylase in endometrial cancer. Acta Obstet Gynecol Scand 78, 728-734.

Fujiwara Y, Oki T, Heidelberger C (1970) Fluorinated pyrimidines. XXXVII. Effects of 5-trifluoromethyl-2'-deoxyuridine on the synthesis of deoxyribonucleic acid of mammalian cells in culture. Mol Pharmacol 6, 273-280.

Fukuiwa T, Takebayashi Y, Akiba S, Matsuzaki T, Hanamure Y, Miyadera K, Yamada Y, Akiyama S (1999) Expression of thymidine phosphorylase and vascular endothelial cell growth factor in human head and neck squamous cell carcinoma and their different characteristics. Cancer 85, 960-969.

Fukushima M, Okabe H, Takechi T, Ichikawa W, Hirayama R (2002) Induction of thymidine phosphorylase by interferon and taxanes occurs only in human cancer cells with low thymidine phosphorylase activity. Cancer Lett 187, 103-110.

Fukushima M, Suzuki N, Emura T, Yano S, Kazuno H, Tada Y, Yamada Y, Asao T (2000) Structure and activity of specific inhibitors of thymidine phosphorylase to potentiate the function of antitumor 2'-deoxyribonucleosides. Biochem Pharmacol 59, 1227-1236.

Furukawa T, Yoshimura A, Sumizawa T, Haraguchi M, Akiyama S, Fukui K, Ishizawa M, Yamada Y (1992) Angiogenic factor letter. Nature 356, 668.

Gasparini G, Toi M, Miceli R, Vermeulen PB, Dittadi R, Biganzoli E, Morabito A, Fanelli M, Gatti C, Suzuki H, Tominaga T, Dirix LY, Gion M (1999) Clinical relevance of vascular endothelial growth factor and thymidine phosphorylase in patients with node-positive breast cancer treated with either adjuvant chemotherapy or hormone therapy. Cancer J Sci Am 5, 101-111.

Giatromanolaki A, Fountzilas G, Koukourakis MI, Arapandoni P, Theologi V, Kakolyris S, Georgoulias V, Harris AL, Gatter KC (1998a) Neo-angiogenesis in locally advanced squamous cell head and neck cancer correlates with thymidine phosphorylase expression and p53 nuclear oncoprotein accumulation. Clin Exp Metastasis 16, 665-672.

Giatromanolaki A, Koukourakis MI, Kakolyris S, Kaklamanis L, Barbatis K, O'Byrne KJ, Theodosssiou D, Harris AL, Gatter KC (1998b) Focal expression of thymidine phosphorylase associates with CD31 positive lymphocytic aggregation and local neo-angiogenesis in non-small cell lung cancer. Anticancer Res 18, 71-76.

Giatromanolaki A, Sivridis E, Maltezos E, Athanassou N, Papazoglou D, Gatter KC, Harris AL, Koukourakis MI (2003a) Upregulated hypoxia inducible factor-1a and -2a pathway in rheumatoid arthritis and osteoarthritis. Arthritis Res Ther 5, R193-R201.

Giatromanolaki A, Sivridis E, Maltezos E, Papazoglou D, Simopoulos C, Gatter KC, Harris AL, Koukourakis MI (2003b) Hypoxia inducible factor 1alpha and 2a overexpression in inflammatory bowel disease. J Clin Pathol 56, 209-213.

Giatromanolaki A, Sivridis E, Simopoulos C, Polychronidis A, Gatter KC, Harris AL, Koukourakis MI (2002) Thymidine phosphorylase expression in gallbladder adenocarcinomas. Int J Surg Pathol 10, 181-188.

Goto H, Kohno K, Sone S, Akiyama S, Kuwano M, Ono M (2001) Interferon gamma-dependent induction of thymidine phosphorylase/platelet-derived endothelial growth factor through gamma-activated sequence-like element in human macrophages. Cancer Res 61, 469-473.

Greco FA, Figlin R, York M, Einhorn L, Schilsky R, Marshall EM, Buys SS, Froimtchuk MJ, Schuller J, Schuchter L, Buyse M, Ritter L, Man A, Yap AK (1996) Phase III randomized study to compare interferon alfa-2a in combination with fluorouracil versus fluorouracil alone in patients with advanced colorectal cancer. J Clin Oncol 14, 2674-2681.

Griffiths L, Dachs GU, Bicknell R, Harris AL, Stratford IJ (1997) The influence of oxygen tension and pH on the expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase in human breast tumor cells grown in vitro and in vivo. Cancer Res 57, 570-572.

Griffiths L, Stratford IJ (1998) The influence of elevated levels of platelet-derived endothelial cell growth factor/thymidine phosphorylase on tumourigenicity, tumour growth, and oxygenation. Int J Radiat Oncol Biol Phys 42, 877-883.

Hagiwara K, Stenman G, Honda H, Sahlin P, Andersson A, Miyazono K, Heldin CH, Ishikawa F, Takaku F (1991) Organization and chromosomal localization of the human platelet-derived endothelial cell growth factor gene. Mol Cell Biol 11, 2125-2132.

Hammerberg C, Fisher GJ, Voorhees JJ, Cooper KD (1991) Elevated thymidine phosphorylase activity in psoriatic lesions accounts for the apparent presence of an epidermal "growth inhibitor," but is not in itself growth inhibitory. J Invest Dermatol 97, 286-290.

Harada H, Andersen JS, Mann M, Terada N, Korsmeyer SJ (2001) p70S6 kinase signals cell survival as well as growth, inactivating the pro-apoptotic molecule BAD. Proc Natl Acad Sci U S A 98, 9666-9670.

Haraguchi M, Miyadera K, Uemura K, Sumizawa T, Furukawa T, Yamada K, Akiyama S, Yamada Y (1994) Angiogenic activity of enzymes letter. Nature 368, 198.

Hata K, Kamikawa T, Arao S, Tashiro H, Katabuchi H, Okamura H, Fujiwaki R, Miyazaki K, Fukumoto M (1999a) Expression of the thymidine phosphorylase gene in epithelial ovarian cancer. Br J Cancer 79, 1848-1854.

Hata K, Nagami H, Iida K, Miyazaki K, Collins WP (1998) Expression of thymidine phosphorylase in malignant ovarian tumors: correlation with microvessel density and an ultrasound-derived index of angiogenesis. Ultrasound Obstet Gynecol 12, 201-206.

Hata K, Takebayashi Y, Iida K, Fujiwaki R, Fukumoto M, Miyazaki K (1999b) Expression of thymidine phosphorylase in human cervical cancer. Anticancer Res 19, 709-716.

Heidelberger C, Anderson SW (1964) Fluorinated pyrimidines. XXI. The tumor-inhibitory activity of 5-trifluoromethyl-2'-deoxyuridine. Cancer Res 24, 1979-1985.

Heidelberger C, Chaudhuri N, Danneberg P, Mooren D, Griesbach L, Duschinsky R, Schnitzer R, Pleven E, Scheiner J (1957) Fluorinated pyrimidines, a new class of tumour-inhibitory compounds. Nature 179, 663-666.

Heidelberger C, Parsons D, Remy D (1964) Syntheses of 5-trifluoromethyluracil and 5-trifluoromethyl-2'-deoxyuridine. J Med Chem 55, 1-5.

Hirano H, Tanioka K, Yokoyama S, Akiyama S, Kuratsu J (2001) Angiogenic effect of thymidine phosphorylase on macrophages in glioblastoma multiforme. J Neurosurg 95, 89-95.

Hirano M, Garcia-de-Yebenes J, Jones AC, Nishino I, DiMauro S, Carlo JR, Bender AN, Hahn AF, Salberg LM, Weeks DE, Nygaard TG (1998) Mitochondrial neurogastrointestinal encephalomyopathy syndrome maps to chromosome 22q13.32-qter. Am J Hum Genet 63, 526-533.

Hirano M, Silvestri G, Blake DM, Lombes A, Minetti C, Bonilla E, Hays AP, Lovelace RE, Butler I, Bertorini TE, (1994) Mitochondrial neurogastrointestinal encephalomyopathy MNGIE : clinical, biochemical, and genetic features of an autosomal recessive mitochondrial disorder. Neurology 44, 721-727.

Hoff PM (2000) The tegafur-based dihydropyrimidine dehydrogenase inhibitory fluoropyrimidines, UFT/leucovorin ORZEL and S-1: a review of their clinical development and therapeutic potential. Invest New Drugs 18, 331-342.

Hoff PM, Cassidy J, Schmoll HJ (2001) The evolution of fluoropyrimidine therapy: from intravenous to oral. Oncologist 6 Suppl, 4, 3-11.

Horowitz R, Schwartz EL, Wadler S (1995) Modulation of 5-fluorouracil by interferon: a review of potential cellular targets. Med Oncol 12, 3-8.

Hotchkiss KA, Ashton AW, Klein RS, Lenzi ML, Zhu GH, Schwartz EL (2003a) Mechanisms by which tumor cells and monocytes expressing the angiogenic factor thymidine phosphorylase mediate human endothelial cell migration. Cancer Res 63, 527-533.

Hotchkiss KA, Ashton AW, Schwartz EL (2003b) Thymidine phosphorylase and 2-deoxyribose stimulate human endothelial cell migration by specific activation of the integrins a5b1 and aVb3. J Biol Chem 278, 19272-19279.

Igarashi M, Dhar DK, Kubota H, Yamamoto A, El Assal O, Nagasue N (1998) The prognostic significance of microvessel density and thymidine phosphorylase expression in squamous cell carcinoma of the esophagus. Cancer 82, 1225-1232.

Ikeda R, Furukawa T, Kitazono M, Ishitsuka K, Okumura H, Tani A, Sumizawa T, Haraguchi M, Komatsu M, Uchimiya H, Ren XQ, Motoya T, Yamada K, Akiyama SS (2002) Molecular Basis for the Inhibition of Hypoxia-Induced Apoptosis by 2- Deoxy-d-ribose. Biochem Biophys Res Commun 291, 806-812.

Ikeda R, Furukawa T, Mitsuo R, Noguchi T, Kitazono M, Okumura H, Sumizawa T, Haraguchi M, Che XF, Uchimiya H, Nakajima Y, Ren XQ, Oiso S, Inoue I, Yamada K, Akiyama S (2003) Thymidine phosphorylase inhibits apoptosis induced by cisplatin. Biochem Biophys Res Commun 301, 358-363.

Ikeguchi M, Cai J, Fukuda K, Oka S, Katano K, Tsujitani S, Maeta M, Kaibara N (2001a) Correlation between spontaneous apoptosis and the expression of angiogenic factors in advanced gastric adenocarcinoma. J Exp Clin Cancer Res 20, 257-263.

Ikeguchi M, Oka S, Saito H, Kondo A, Tsujitani S, Maeta M, Kaibara N (1999) Clinical significance of the detection of thymidine phosphorylase activity in esophageal squamous cell carcinomas. Eur Surg Res 31, 357-363.

Ikeguchi M, Sakatani T, Ueta T, Fukuda K, Yamaguchi K, Tsujitani S, Kaibara N (2001b) The expression of thymidine phosphorylase suppresses spontaneous apoptosis of cancer cells in esophageal squamous cell carcinoma. Pathobiology 69, 36-43.

Imazano Y, Takebayashi Y, Nishiyama K, Akiba S, Miyadera K, Yamada Y, Akiyama S, Ohi Y (1997) Correlation between thymidine phosphorylase expression and prognosis in human renal cell carcinoma. J Clin Oncol 15, 2570-2578.

Ishikawa F, Miyazono K, Hellman U, Drexler H, Wernstedt C, Hagiwara K, Usuki K, Takaku F, Risau W, Heldin CH (1989) Identification of angiogenic activity and the cloning and expression of platelet-derived endothelial cell growth factor. Nature 338, 557-562.

Ishikawa T, Sekiguchi F, Fukase Y, Sawada N, Ishitsuka H (1998a) Positive correlation between the efficacy of capecitabine and doxifluridine and the ratio of thymidine phosphorylase to dihydropyrimidine dehydrogenase activities in tumors in human cancer xenografts. Cancer Res 58, 685-690.

Ishikawa T, Utoh M, Sawada N, Nishida M, Fukase Y, Sekiguchi F, Ishitsuka H (1998b) Tumor selective delivery of 5-fluorouracil by capecitabine, a new oral fluoropyrimidine carbamate, in human cancer xenografts. Biochem Pharmacol 55, 1091-1097.

Jackson MR, Carney EW, Lye SJ, Ritchie JW (1994) Localization of two angiogenic growth factors PDECGF and VEGF in human placentae throughout gestation. Placenta 15, 341-353.

Jin-no K, Tanimizu M, Hyodo I, Nishikawa Y, Hosokawa Y, Endo H, Doi T, Mandai K, Ishitsuka H (1998) Circulating platelet-derived endothelial cell growth factor increases in hepatocellular carcinoma patients. Cancer 82, 1260-1267.

Jones A, Fujiyama C, Turner K, Cranston D, Williams K, Stratford I, Bicknell R, Harris AL (2002) Role of thymidine phosphorylase in an in vitro model of human bladder cancer invasion. J Urol 167, 1482-1486.

Katayanagi S, Aoki T, Takagi Y, Ito K, Sudo H, Tsuchida A, Koyanagi Y (2003) Measurement of serum thymidine phosphorylase levels by highly sensitive enzyme-linked immunosorbent assay in gastric cancer. Oncol Rep 10, 115-119.

Kato Y, Matsukawa S, Muraoka R, Tanigawa N (1997) Enhancement of drug sensitivity and a bystander effect in PC-9 cells transfected with a platelet-derived endothelial cell growth factor thymidine phosphorylase cDNA. Br J Cancer 75, 506-511.

Kemeny N, Younes A (1992) Alfa-2A interferon and 5-fluorouracil for advanced colorectal carcinoma: the Memorial Sloan-Kettering experience. Semin Oncol 19, 171-175.

Kitazono M, Takebayashi Y, Ishitsuka K, Takao S, Tani A, Furukawa T, Miyadera K, Yamada Y, Aikou T, Akiyama S (1998) Prevention of hypoxia-induced apoptosis by the angiogenic factor thymidine phosphorylase. Biochem Biophys Res Commun 253, 797-803.

Kletsas D, Barbieri D, Stathakos D, Botti B, Bergamini S, Tomasi A, Monti D, Malorni W, Franceschi C (1998) The highly reducing sugar 2-deoxy-D-ribose induces apoptosis in human fibroblasts by reduced glutathione depletion and cytoskeletal disruption. Biochem Biophys Res Commun 243, 416-425.

Koch AE (2000) The role of angiogenesis in rheumatoid arthritis: recent developments. Ann Rheum Dis 59 Suppl, 1, i65-i71.

Kodama J, Seki N, Tokumo K, Hongo A, Miyagi Y, Yoshinouchi M, Okuda H, Kudo T (1999) Platelet-derived endothelial cell growth factor is not implicated in progression of cervical cancer. Oncol Rep 6, 617-620.

Kohne CH, Peters GJ (2000) UFT: mechanism of drug action. Oncology Huntingt 14, 13-18.

Koide N, Watanabe H, Yazawa K, Adachi W, Amano J (1999) Immunohistochemical expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor in squamous cell carcinoma of the esophagus. Hepatogastroenterology 46, 944-951.

Komatsu T, Yamazaki H, Shimada N, Nakajima M, Yokoi T (2000) Roles of cytochromes P450 1A2, 2A6, and 2C8 in 5-fluorouracil formation from tegafur, an anticancer prodrug, in human liver microsomes. Drug Metab Dispos 28, 1457-1463.

Koukourakis MI, Giatromanolaki A, Fountzilas G, Sivridis E, Gatter KC, Harris AL (2000) Angiogenesis, thymidine phosphorylase, and resistance of squamous cell head and neck cancer to cytotoxic and radiation therapy. Clin Cancer Res 6, 381-389.

Koukourakis MI, Giatromanolaki A, Kakolyris S, O'Byrne KJ, Apostolikas N, Skarlatos J, Gatter KC, Harris AL (1998) Different patterns of stromal and cancer cell thymidine phosphorylase reactivity in non-small-cell lung cancer: impact on tumour neoangiogenesis and survival. Br J Cancer 77, 1696-1703.

Koukourakis MI, Giatromanolaki A, O'Byrne KJ, Comley M, Whitehouse RM, Talbot DC, Gatter KC, Harris AL (1997) Platelet-derived endothelial cell growth factor expression correlates with tumour angiogenesis and prognosis in non-small-cell lung cancer. Br J Cancer 75, 477-481.

Kubota Y, Miura T, Moriyama M, Noguchi S, Matsuzaki J, Takebayashi S, Hosaka M (1997) Thymidine phosphorylase activity in human bladder cancer: difference between superficial and invasive cancer. Clin Cancer Res 3, 973-976.

Labianca R, Pessi A, Facendola G, Pirovano M, Luporini G (1996) Modulated 5-fluorouracil 5-FU regimens in advanced colorectal cancer: a critical review of comparative studies. Eur J Cancer 32A Suppl, 5, S7-12.

Leek RD, Landers R, Fox SB, Ng F, Harris AL, Lewis CE (1998) Association of tumour necrosis factor a and its receptors with thymidine phosphorylase expression in invasive breast carcinoma. Br J Cancer 77, 2246-2251.

Liu G, Franssen E, Fitch MI, Warner E (1997) Patient preferences for oral versus intravenous palliative chemotherapy. J Clin Oncol 15, 110-115.

Maeda K, Chung YS, Ogawa Y, Takatsuka S, Kang SM, Ogawa M, Sawada T, Onoda N, Kato Y, Sowa M (1996) Thymidine phosphorylase/platelet-derived endothelial cell growth factor expression associated with hepatic metastasis in gastric carcinoma. Br J Cancer 73, 884-888.

Makower D, Wadler S (1999) Interferons as biomodulators of fluoropyrimidines in the treatment of colorectal cancer. Semin Oncol 26, 663-671.

Malet-Martino M, Martino R (2002) Clinical studies of three oral prodrugs of 5-fluorouracil capecitabine, UFT, S-1 : a review. Oncologist 7, 288-323.

Malik RK, Parsons JT (1996) Integrin-dependent activation of the p70 ribosomal S6 kinase signaling pathway. J Biol Chem 271, 29785-29791.

Marchetti S, Chazal M, Dubreuil A, Fischel JL, Etienne MC, Milano G (2001) Impact of thymidine phosphorylase surexpression on fluoropyrimidine activity and on tumour angiogenesis. Br J Cancer 85, 439-445.

Marti R, Nishigaki Y, Hirano M (2003) Elevated plasma deoxyuridine in patients with thymidine phosphorylase deficiency. Biochem Biophys Res Commun 303, 14-18.

Matsukawa K, Moriyama A, Kawai Y, Asai K, Kato T (1996) Tissue distribution of human gliostatin/platelet-derived endothelial cell growth factor PD-ECGF and its drug-induced expression. Biochim Biophys Acta 1314, 71-82.

Matsumura M, Chiba Y, Lu C, Amaya H, Shimomatsuya T, Horiuchi T, Muraoka R, Tanigawa N (1998) Platelet-derived endothelial cell growth factor/thymidine phosphorylase expression correlated with tumor angiogenesis and macrophage infiltration in colorectal cancer. Cancer Lett 128, 55-63.

Matsushita S, Nitanda T, Furukawa T, Sumizawa T, Tani A, Nishimoto K, Akiba S, Miyadera K, Fukushima M, Yamada Y, Yoshida H, Kanzaki T, Akiyama S (1999) The effect of a thymidine phosphorylase inhibitor on angiogenesis and apoptosis in tumors. Cancer Res 59, 1911-1916.

Matsuura T, Kuratate I, Teramachi K, Osaki M, Fukuda Y, Ito H (1999) Thymidine phosphorylase expression is associated with both increase of intratumoral microvessels and decrease of apoptosis in human colorectal carcinomas. Cancer Res 59, 5037-5040.

Metzger R, Danenberg K, Leichman CG, Salonga D, Schwartz EL, Wadler S, Lenz HJ, Groshen S, Leichman L, Danenberg PV (1998) High basal level gene expression of thymidine phosphorylase platelet-derived endothelial cell growth factor in colorectal tumors is associated with nonresponse to 5-fluorouracil. Clin Cancer Res 4, 2371-2376.

Mimori K, Ueo H, Shirasaka C, Shiraishi T, Yamagata M, Haraguchi M, Mori M (1999) Up-regulated pyrimidine nucleoside phosphorylase in breast carcinoma correlates with lymph node metastasis. Ann Oncol 10, 111-113.

Miwa M, Ura M, Nishida M, Sawada N, Ishikawa T, Mori K, Shimma N, Umeda I, Ishitsuka H (1998) Design of a novel oral fluoropyrimidine carbamate, capecitabine, which generates 5-fluorouracil selectively in tumours by enzymes concentrated in human liver and cancer tissue. Eur J Cancer 34, 1274-1281.

Miyadera K, Sumizawa T, Haraguchi M, Yoshida H, Konstanty W, Yamada Y, Akiyama S (1995) Role of thymidine phosphorylase activity in the angiogenic effect of platelet derived endothelial cell growth factor/thymidine phosphorylase. Cancer Res 55, 1687-1690.

Miyazono K, Okabe T, Urabe A, Takaku F, Heldin CH (1987) Purification and properties of an endothelial cell growth factor from human platelets. J Biol Chem 262, 4098-4103.

Mizutani Y, Okada Y, Yoshida O (1997) Expression of platelet-derived endothelial cell growth factor in bladder carcinoma. Cancer 79, 1190-1194.

Moghaddam A, Bicknell R (1992) Expression of platelet-derived endothelial cell growth factor in Escherichia coli and confirmation of its thymidine phosphorylase activity. Biochemistry 31, 12141-12146.

Moghaddam A, Zhang HT, Fan TP, Hu DE, Lees VC, Turley H, Fox SB, Gatter KC, Harris AL, Bicknell R (1995) Thymidine phosphorylase is angiogenic and promotes tumor growth. Proc Natl Acad Sci U S A 92, 998-1002.

Monnier VM (1990) Nonenzymatic glycosylation, the Maillard reaction and the aging process. J Gerontol 45, B105-B111.

Mori S, Takao S, Ikeda R, Noma H, Mataki Y, Wang X, Akiyama S, Aikou T (2002) Thymidine phosphorylase suppresses Fas-induced apoptotic signal transduction independent of its enzymatic activity. Biochem Biophys Res Commun 295, 300-305.

Morita T, Matsuzaki A, Suzuki K, Tokue A (2001) Role of thymidine phosphorylase in biomodulation of fluoropyrimidines. Curr Pharm Biotechnol 2, 257-267.

Morita T, Tokue A (1999) Biomodulation of 5-fluorouracil by interferon-a in human renal carcinoma cells: relationship to the expression of thymidine phosphorylase. Cancer Chemother Pharmacol 44, 91-96.

Murakami Y, Kazuno H, Emura T, Tsujimoto H, Suzuki N, Fukushima M (2000) Different mechanisms of acquired resistance to fluorinated pyrimidines in human colorectal cancer cells. Int J Oncol 17, 277-283.

Muro H, Waguri-Nagaya Y, Otsuka T, Matsui N, Asai K, Kato T (2001) Serum gliostatin levels in patients with rheumatoid factor-negative and -positive rheumatoid arthritis and changes of these levels after surgical treatments. Clin Rheumatol 20, 331-336.

Nakajima Y, Gotanda T, Uchimiya H, Furukawa T, Haraguchi M, Ikeda R, Sumizawa T, Yoshida H, Akiyama S (2004) Inhibition of metastasis of tumor cells overexpressing thymidine phosphorylase by 2-deoxy-L-ribose. Cancer Res 64, 1794-1801.

Nakayama Y, Sueishi K, Oka K, Kono S, Tomonaga M (1998) Stromal angiogenesis in human glioma: a role of platelet-derived endothelial cell growth factor. Surg Neurol 49, 181-187.

Niedzwicki JG, Chu SH, el Kouni MH, Rowe EC, Cha S (1982) 5-benzylacyclouridine and 5-benzyloxybenzylacyclouridine, potent inhibitors of uridine phosphorylase. Biochem Pharmacol 31, 1857-1861.

Nishimoto K, Matsune S, Miyadera K, Takebayashi Y, Furukawa T, Sumizawa T, Akiyama SI, Kurono Y (2000) The role of thymidine phosphorylase in the pathogenesis of allergic rhinitis. Acta Otolaryngol 120, 644-648.

Nishimoto K, Miyadera K, Takebayashi Y, Fukuda K, Haraguchi M, Furukawa T, Yamada Y, Akiyama S (1997) Thymidine phosphorylase activity required for tumor angiogenesis and growth. Oncol Rep 4, 55-58.

Nishino I, Spinazzola A, Hirano M (1999) Thymidine phosphorylase gene mutations in MNGIE, a human mitochondrial disorder. Science 283, 689-692.

Nishino I, Spinazzola A, Hirano M (2001) MNGIE: from nuclear DNA to mitochondrial DNA. Neuromuscul Disord 11, 7-10.

O'Brien T, Cranston D, Fuggle S, Bicknell R, Harris AL (1995) Different angiogenic pathways characterize superficial and invasive bladder cancer. Cancer Res 55, 510-513.

O'Brien TS, Fox SB, Dickinson AJ, Turley H, Westwood M, Moghaddam A, Gatter KC, Bicknell R, Harris AL (1996) Expression of the angiogenic factor thymidine phosphorylase/platelet-derived endothelial cell growth factor in primary bladder cancers. Cancer Res 56, 4799-4804.

O'Byrne KJ, Koukourakis MI, Giatromanolaki A, Cox G, Turley H, Steward WP, Gatter K, Harris AL (2000) Vascular endothelial growth factor, platelet-derived endothelial cell growth factor and angiogenesis in non-small-cell lung cancer. Br J Cancer 82, 1427-1432.

Okamoto E, Osaki M, Kase S, Adachi H, Kaibara N, Ito H (2001) Thymidine phosphorylase expression causes both the increase of intratumoral microvessels and decrease of apoptosis in human esophageal carcinomas. Pathol Int 51, 158-164.

Osaki M, Sakatani T, Okamoto E, Goto E, Adachi H, Ito H (2000) Thymidine phosphorylase expression results in a decrease in apoptosis and increase in intratumoral microvessel density in human gastric carcinomas. Virchows Arch 437, 31-36.

Patterson AV, Talbot DC, Stratford IJ, Harris AL (1998) Thymidine phosphorylase moderates thymidine-dependent rescue after exposure to the thymidylate synthase inhibitor ZD1694 Tomudex in vitro. Cancer Res 58, 2737-2740.

Patterson AV, Zhang H, Moghaddam A, Bicknell R, Talbot DC, Stratford IJ, Harris AL (1995) Increased sensitivity to the prodrug 5'-deoxy-5-fluorouridine and modulation of 5-fluoro-2'-deoxyuridine sensitivity in MCF-7 cells transfected with thymidine phosphorylase. Br J Cancer 72, 669-675.

Pauly JL, Paolini NS, Ebarb RL, Germain MJ (1978) Elevated thymidine phosphorylase activity in the plasma and ascitis fluids of tumor-bearing animals. Proc Soc Exp Biol Med 157, 262-267.

Pauly JL, Schuller MG, Zelcer AA, Kirss TA, Gore SS, Germain MJ (1977) Identification and comparative analysis of thymidine phosphorylase in the plasma of healthy subjects and cancer patients. J Natl Cancer Inst 58, 1587-1590.

Peters GJ, Braakhuis BJ, de Bruijn EA, Laurensse EJ, van Walsum M, Pinedo HM (1989) Enhanced therapeutic efficacy of 5'deoxy-5-fluorouridine in 5- fluorouracil resistant head and neck tumours in relation to 5- fluorouracil metabolising enzymes. Br J Cancer 59, 327-334.

Peters GJ, Laurensse E, Leyva A, Pinedo HM (1987) Purine nucleosides as cell-specific modulators of 5-fluorouracil metabolism and cytotoxicity. Eur J Cancer Clin Oncol 23, 1869-1881.

Peters GJ, van Groeningen CJ, Laurensse EJ, Pinedo HM (1991) A comparison of 5-fluorouracil metabolism in human colorectal cancer and colon mucosa. Cancer 68, 1903-1909.

Peters GJ, Wets M, Keepers YP, Oskam R, Ark-Otte J, Noordhuis P, Smid K, Pinedo HM (1993) Transformation of mouse fibroblasts with the oncogenes H-ras OR trk is associated with pronounced changes in drug sensitivity and metabolism. Int J Cancer 54, 450-455.

Pinedo HM, Peters GJ (1988) Fluorouracil: biochemistry and pharmacology. J Clin Oncol 6, 1653-1664.

Pinedo HM, Verheul HM, D'Amato RJ, Folkman J (1998) Involvement of platelets in tumour angiogenesis? Lancet 352, 1775-1777.

Pizzorno G, Cao D, Leffert JJ, Russell RL, Zhang D, Handschumacher RE (2002) Homeostatic control of uridine and the role of uridine phosphorylase: a biological and clinical update. Biochim Biophys Acta 1587, 133-144.

Poon RT, Fan ST, Wong J (2001) Clinical implications of circulating angiogenic factors in cancer patients. J Clin Oncol 19, 1207-1225.

Powers CJ, McLeskey SW, Wellstein A (2000) Fibroblast growth factors, their receptors and signaling. Endocr Relat Cancer 7, 165-197.

Reynolds K, Farzaneh F, Collins WP, Campbell S, Bourne TH, Lawton F, Moghaddam A, Harris AL, Bicknell R (1994) Association of ovarian malignancy with expression of platelet-derived endothelial cell growth factor. J Natl Cancer Inst 86, 1234-1238.

Saeki T, Tanada M, Takashima S, Saeki H, Takiyama W, Nishimoto N, Moriwaki S (1997) Correlation between expression of platelet-derived endothelial cell growth factor thymidine phosphorylase and microvessel density in early-stage human colon carcinomas. Jpn J Clin Oncol 27, 227-230.

Saito H, Tsujitani S, Oka S, Kondo A, Ikeguchi M, Maeta M, Kaibara N (1999) The expression of thymidine phosphorylase correlates with angiogenesis and the efficacy of chemotherapy using fluorouracil derivatives in advanced gastric carcinoma. Br J Cancer 81, 484-489.

Sakamoto H, Shirakawa T, Izuka S, Igarashi T, Kinoshita K, Ohtani K, Takami T, Nakayama Y, Teramoto K, Satoh K (1999) Thymidine phosphorylase expression is predominantly observed in stroma of well-differentiated adenocarcinoma of endometrium and correlates with a frequency of vascular involvement. Gynecol Oncol 72, 298-305.

Salonga D, Danenberg KD, Johnson M, Metzger R, Groshen S, Tsao-Wei DD, Lenz HJ, Leichman CG, Leichman L, Diasio RB, Danenberg PV (2000) Colorectal tumors responding to 5-fluorouracil have low gene expression levels of dihydropyrimidine dehydrogenase, thymidylate synthase, and thymidine phosphorylase. Clin Cancer Res 6, 1322-1327.

Santi DV, Sakai TT (1971) Thymidylate synthetase. Model studies of inhibition by 5-trifluoromethyl-2'-deoxyuridylic acid. Biochemistry 10, 3598-3607.

Sawada N, Ishikawa T, Fukase Y, Nishida M, Yoshikubo T, Ishitsuka H (1998) Induction of thymidine phosphorylase activity and enhancement of capecitabine efficacy by taxol/taxotere in human cancer xenografts. Clin Cancer Res 4, 1013-1019.

Sawada N, Ishikawa T, Sekiguchi F, Tanaka Y, Ishitsuka H (1999) X-ray irradiation induces thymidine phosphorylase and enhances the efficacy of capecitabine Xeloda in human cancer xenografts. Clin Cancer Res 5, 2948-2953.

Sawase K, Nomata K, Kanetake H, Saito Y (1998) The expression of platelet-derived endothelial cell growth factor in human bladder cancer. Cancer Lett 130, 35-41.

Schuller J, Cassidy J, Dumont E, Roos B, Durston S, Banken L, Utoh M, Mori K, Weidekamm E, Reigner B (2000) Preferential activation of capecitabine in tumor following oral administration to colorectal cancer patients. Cancer Chemother Pharmacol 45, 291-297.

Schwartz EL, Baptiste N, O'Connor CJ, Wadler S, Otter BA (1994) Potentiation of the antitumor activity of 5-fluorouracil in colon carcinoma cells by the combination of interferon and deoxyribonucleosides results from complementary effects on thymidine phosphorylase. Cancer Res 54, 1472-1478.

Schwartz EL, Hoffman M, O'Connor CJ, Wadler S (1992) Stimulation of 5-fluorouracil metabolic activation by interferon-a in human colon carcinoma cells. Biochem Biophys Res Commun 182, 1232-1239.

Schwartz EL, Wan E, Wang FS, Baptiste N (1998) Regulation of expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor in human colon carcinoma cells. Cancer Res 58, 1551-1557.

Seeliger H, Guba M, Koehl GE, Doenecke A, Steinbauer M, Bruns CJ, Wagner C, Frank E, Jauch KW, Geissler EK (2004) Blockage of 2-deoxy-D-ribose-induced angiogenesis with rapamycin counteracts a thymidine phosphorylase-based escape mechanism available for colon cancer under 5-fluorouracil therapy. Clin Cancer Res 10, 1843-1852.

Sengupta S, Sellers LA, Matheson HB, Fan TP (2003) Thymidine phosphorylase induces angiogenesis in vivo and in vitro: an evaluation of possible mechanisms. Br J Pharmacol 139, 219-231.

Sgarrella F, Del Corso A, Tozzi MG, Camici M (1992) Deoxyribose 5-phosphate aldolase of Bacillus cereus: purification and properties. Biochim Biophys Acta 1118, 130-133.

Sgarrella F, Poddie FP, Meloni MA, Sciola L, Pippia P, Tozzi MG (1997) Channelling of deoxyribose moiety of exogenous DNA into carbohydrate metabolism: role of deoxyriboaldolase. Comp Biochem Physiol B Biochem Mol Biol 117, 253-257.

Shaw T, Smillie RH, MacPhee DG (1988) The role of blood platelets in nucleoside metabolism: assay, cellular location and significance of thymidine phosphorylase in human blood. Mutat Res 200, 99-116.

Shimada H, Takeda A, Shiratori T, Nabeya Y, Okazumi S, Matsubara H, Funami Y, Hayashi H, Gunji Y, Kobayashi S, Suzuki T, Ochiai T (2002) Prognostic significance of serum thymidine phosphorylase concentration in esophageal squamous cell carcinoma. Cancer 94, 1947-1954.

Shirasaka T, Shimamato Y, Ohshimo H, Yamaguchi M, Kato T, Yonekura K, Fukushima M (1996) Development of a novel form of an oral 5-fluorouracil derivative S-1 directed to the potentiation of the tumor selective cytotoxicity of 5-fluorouracil by two biochemical modulators. Anticancer Drugs 7, 548-557.

Shirasaka T, Shimamoto Y, Fukushima M (1993) Inhibition by oxonic acid of gastrointestinal toxicity of 5-fluorouracil without loss of its antitumor activity in rats. Cancer Res 53, 4004-4009.

Shomori K, Sakatani T, Goto A, Matsuura T, Kiyonari H, Ito H (1999) Thymidine phosphorylase expression in human colorectal mucosa, adenoma and carcinoma: role of p53 expression. Pathol Int 49, 491-499.

Sivridis E, Giatromanolaki A, Anastasiadis P, Georgiou L, Gatter KC, Harris AL, Bicknell R, Koukourakis MI (2002a) Angiogenic co-operation of VEGF and stromal cell TP in endometrial carcinomas. J Pathol 196, 416-422.

Sivridis E, Giatromanolaki A, Papadopoulos I, Gatter KC, Harris AL, Koukourakis MI (2002b) Thymidine phosphorylase expression in normal, hyperplastic and neoplastic prostates: correlation with tumour associated macrophages, infiltrating lymphocytes, and angiogenesis. Br J Cancer 86, 1465-1471.

Spinazzola A, Marti R, Nishino I, Andreu AL, Naini A, Tadesse S, Pela I, Zammarchi E, Donati MA, Oliver JA, Hirano M (2002) Altered thymidine metabolism due to defects of thymidine phosphorylase. J Biol Chem 277, 4128-4133.

Stenman G, Sahlin P, Dumanski JP, Hagiwara K, Ishikawa F, Miyazono K, Collins VP, Heldin CH (1992) Regional localization of the human platelet-derived endothelial cell growth factor ECGF1 gene to chromosome 22q13. Cytogenet Cell Genet 59, 22-23.

Sugamoto T, Tanji N, Nishio S, Yokoyama M (1999) Expression of platelet-derived endothelial cell growth factor in prostatic adenocarcinoma. Oncol Rep 6, 519-522.

Sugata S, Kono A, Hara Y, Karube Y, Matsushima Y (1986) Partial purification of a thymidine phosphorylase from human gastric cancer. Chem Pharm Bull Tokyo 34, 1219-1222.

Sumizawa T, Furukawa T, Haraguchi M, Yoshimura A, Takeyasu A, Ishizawa M, Yamada Y, Akiyama S (1993) Thymidine phosphorylase activity associated with platelet-derived endothelial cell growth factor. J Biochem Tokyo 114, 9-14.

Suzuki K, Morita T, Hashimoto S, Tokue A (2001) Thymidine phosphorylase/platelet-derived endothelial cell growth factor PD-ECGF associated with prognosis in renal cell carcinoma. Urol Res 29, 7-12.

Takahashi Y, Bucana CD, Akagi Y, Liu W, Cleary KR, Mai M, Ellis LM (1998) Significance of platelet-derived endothelial cell growth factor in the angiogenesis of human gastric cancer. Clin Cancer Res 4, 429-434.

Takahashi Y, Bucana CD, Liu W, Yoneda J, Kitadai Y, Cleary KR, Ellis LM (1996) Platelet-derived endothelial cell growth factor in human colon cancer angiogenesis: role of infiltrating cells. J Natl Cancer Inst 88, 1146-1151.

Takao S, Akiyama SI, Nakajo A, Yoh H, Kitazono M, Natsugoe S, Miyadera K, Fukushima M, Yamada Y, Aikou T (2000) Suppression of metastasis by thymidine phosphorylase inhibitor. Cancer Res 60, 5345-5348.

Takao S, Takebayashi Y, Che X, Shinchi H, Natsugoe S, Miyadera K, Yamada Y, Akiyama S, Aikou T (1998) Expression of thymidine phosphorylase is associated with a poor prognosis in patients with ductal adenocarcinoma of the pancreas. Clin Cancer Res 4, 1619-1624.

Takebayashi Y, Akiyama S, Akiba S, Yamada K, Miyadera K, Sumizawa T, Yamada Y, Murata F, Aikou T (1996a) Clinicopathologic and prognostic significance of an angiogenic factor, thymidine phosphorylase, in human colorectal carcinoma see comments. J Natl Cancer Inst 88, 1110-1117.

Takebayashi Y, Miyadera K, Akiyama S, Hokita S, Yamada K, Akiba S, Yamada Y, Sumizawa T, Aikou T (1996b) Expression of thymidine phosphorylase in human gastric carcinoma. Jpn J Cancer Res 87, 288-295.

Takebayashi Y, Natsugoe S, Baba M, Akiba S, Fukumoto T, Miyadera K, Yamada Y, Takao S, Akiyama S, Aikou T (1999) Thymidine phosphorylase in human esophageal squamous cell carcinoma. Cancer 85, 282-289.

Tanaka T, Yoshiki T, Arai Y, Higuchi K, Kageyama S, Ogawa Y, Isono T, Okada Y (1999) Expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase in human bladder cancer. Jpn J Cancer Res 90, 1344-1350.

Tatsumi K, Fukushima M, Shirasaka T, Fujii S (1987) Inhibitory effects of pyrimidine, barbituric acid and pyridine derivatives on 5-fluorouracil degradation in rat liver extracts. Jpn J Cancer Res 78, 748-755.

Temmink OH, De Bruin M, Comijn EM, Fukushima M, Peters GJ (2005) Determinants of trifluorothymidine sensitivity and metabolism in colon and lung cancer cells. Anticancer Drugs 16, 285-292.

Tevaearai HT, Laurent PL, Suardet L, Eliason JF, Givel JC, Odartchenko N (1992) Interactions of interferon-a 2a with 5'-deoxy-5-fluorouridine in colorectal cancer cells in vitro. Eur J Cancer 28, 368-372.

Thomas MB, Hoff PM, Carter S, Bland G, Lassere Y, Wolff R, Xiong H, Hayakawa T, Abbruzzese J (2002) A dose-finding, safety and pharmacokinetics study of TAS-102, an antitumor / antiangiogenic agent given orally on a once -daily schedule for five days every three weeks in patients with solid tumor. Proc Amer Assoc Cancer Res 43, 554.

Toi M, Hoshina S, Taniguchi T, Yamamoto Y, Ishitsuka H, Tominaga T (1995a) Expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase in human breast cancer. Int J Cancer 64, 79-82.

Toi M, Inada K, Hoshina S, Suzuki H, Kondo S, Tominaga T (1995b) Vascular endothelial growth factor and platelet-derived endothelial cell growth factor are frequently coexpressed in highly vascularized human breast cancer. Clin Cancer Res 1, 961-964.

Toi M, Ion M, Biganzoli E, Dittadi R, Boracchi P, Miceli R, Mori K, Tominaga T, Gasparini G (1997) Co-determination of the angiogenic factors thymidine phosphorylase and vascular endothelial growth factor in node-negative breast cancer: prognostic implications. Angiogenesis 1, 71-83.

Toi M, Ueno T, Matsumoto H, Saji H, Funata N, Koike M, Tominaga T (1999) Significance of thymidine phosphorylase as a marker of protumor monocytes in breast cancer. Clin Cancer Res 5, 1131-1137.

Tokumo K, Kodama J, Seki N, Nakanishi Y, Miyagi Y, Kamimura S, Yoshinouchi M, Okuda H, Kudo T (1998) Different angiogenic pathways in human cervical cancers. Gynecol Oncol 68, 38-44.

Torisu-Itakura H, Furue M, Kuwano M, Ono M (2000) Co-expression of Thymidine Phosphorylase and Heme Oxygenase-1 in Macrophages in Human Malignant Vertical Growth Melanomas. Jpn J Cancer Res 91, 906-910.

Uchimiya H, Furukawa T, Okamoto M, Nakajima Y, Matsushita S, Ikeda R, Gotanda T, Haraguchi M, Sumizawa T, Ono M, Kuwano M, Kanzaki T, Akiyama S (2002) Suppression of thymidine phosphorylase-mediated angiogenesis and tumor growth by 2-deoxy-L-ribose. Cancer Res 62, 2834-2839.

Ueda M, Terai Y, Kumagai K, Ueki K, Okamoto Y, Ueki M (1999) Correlation between tumor angiogenesis and expression of thymidine phosphorylase, and patient outcome in uterine cervical carcinoma. Hum Pathol 30, 1389-1394.

Ueki T, Nakanishi K, Asai K, Okouchi Y, Isobe I, Eksioglu YZ, Kato T, Kohno K (1993) Neurotrophic action of gliostatin on cocultured neurons with glial cells. Brain Res 622, 299-302.

Ueno T, Toi M, Saji H, Muta M, Bando H, Kuroi K, Koike M, Inadera H, Matsushima K (2000) Significance of macrophage chemoattractant protein-1 in macrophage recruitment, angiogenesis, and survival in human breast cancer. Clin Cancer Res 6, 3282-3289.

Usuki K, Miyazono K, Heldin CH (1991) Covalent linkage between nucleotides and platelet-derived endothelial cell growth factor. J Biol Chem 266, 20525-20531.

Usuki K, Norberg L, Larsson E, Miyazono K, Hellman U, Wernstedt C, Rubin K, Heldin CH (1990) Localization of platelet-derived endothelial cell growth factor in human placenta and purification of an alternatively processed form. Cell Regul 1, 577-584.

Usuki K, Saras J, Waltenberger J, Miyazono K, Pierce G, Thomason A, Heldin CH (1992) Platelet-derived endothelial cell growth factor has thymidine phosphorylase activity. Biochem Biophys Res Commun 184, 1311-1316.

Van Cutsem E, Findlay M, Osterwalder B, Kocha W, Dalley D, Pazdur R, Cassidy J, Dirix L, Twelves C, Allman D, Seitz JF, Scholmerich J, Burger HU, Verweij J (2000) Capecitabine, an oral fluoropyrimidine carbamate with substantial activity in advanced colorectal cancer: results of a randomized phase II study. J Clin Oncol 18, 1337-1345.

Van Cutsem E, Twelves C, Cassidy J, Allman D, Bajetta E, Boyer M, Bugat R, Findlay M, Frings S, Jahn M, McKendrick J, Osterwalder B, Perez-Manga G, Rosso R, Rougier P, Schmiegel WH, Seitz JF, Thompson P, Vieitez JM, Weitzel C, Harper P (2001) Oral capecitabine compared with intravenous fluorouracil plus leucovorin in patients with metastatic colorectal cancer: results of a large phase III study. J Clin Oncol 19, 4097-4106.

van der Wilt CL, Smid K, Aherne GW, Noordhuis P, Peters GJ (1997) Biochemical mechanisms of interferon modulation of 5-fluorouracil activity in colon cancer cells. Eur J Cancer 33, 471-478.

van Triest B, Pinedo HM, Blaauwgeers JL, van Diest PJ, Schoenmakers PS, Voorn DA, Smid K, Hoekman K, Hoitsma HF, Peters GJ (2000) Prognostic role of thymidylate synthase, thymidine phosphorylase/platelet-derived endothelial cell growth factor, and proliferation markers in colorectal cancer. Clin Cancer Res 6, 1063-1072.

Venturini M (2002) Rational development of capecitabine. Eur J Cancer 38 Suppl, 2, 3-9.

Vogel T, Blake DA, Whikehart DR, Guo NH, Zabrenetzky VS, Roberts DD (1993) Specific simple sugars promote chemotaxis and chemokinesis of corneal endothelial cells. J Cell Physiol 157, 359-366.

Volm M, Koomagi R, Mattern J (1999) PD-ECGF, bFGF, and VEGF expression in non-small cell lung carcinomas and their association with lymph node metastasis. Anticancer Res 19, 651-655.

Volm M, Mattern J, Koomagi R (1998) Expression of platelet-derived endothelial cell growth factor in non-small cell lung carcinomas: relationship to various biological factors. Int J Oncol 13, 975-979.

Waguri Y, Otsuka T, Sugimura I, Matsui N, Asai K, Moriyama A, Kato T (1997) Gliostatin/platelet-derived endothelial cell growth factor as a clinical marker of rheumatoid arthritis and its regulation in fibroblast-like synoviocytes. Br J Rheumatol 36, 315-321.

Warrell RP, Jr, Currie V, Kempin S, Young C (1979) Phase II trial of pyrazofurin, alone and in combination with trifluorothymidine, in non-Hodgkin's lymphoma. Cancer Treat Rep 63, 1423-1425.

Woodman PW (1979) Thymidine phosphorylase activity in plasma: a cancer marker or an artifact of ultrafiltration? Proc Soc Exp Biol Med 162, 175-178.

Yamagata M, Mori M, Mimori K, Mafune KI, Tanaka Y, Ueo H, Akiyoshi T (1999) Expression of pyrimidine nucleoside phosphorylase mRNA plays an important role in the prognosis of patients with oesophageal cancer. Br J Cancer 79, 565-569.

Yamamoto A, Dhar DK, El Assal ON, Igarashi M, Tabara H, Nagasue N (1998) Thymidine phosphorylase platelet-derived endothelial cell growth factor, microvessel density and clinical outcome in hepatocellular carcinoma. J Hepatol 29, 290-299.

Yamashita J, Ogawa M, Abe M, Nishida M (1999) Platelet-derived endothelial cell growth factor/thymidine phosphorylase concentrations differ in small cell and non-small cell lung cancer. Chest 116, 206-211.

Yang Q, Sakurai T, Shan L, Yoshimura G, Yu Z, Suzuma T, Tamaki T, Umemura T, Nakamura Y, Nakamura M, Utsunomiya H, Mori I, Kakudo K (2000) Thymidine Phosphorylase Expression Correlates with Tumor Differentiation and Bcl-2 in Invasive Breast Cancer. Breast Cancer 7, 210-214.

Yang Q, Yoshimura G, Mori I, Sakurai T, Kakudo K (2002) Thymidine phosphorylase and breast carcinoma. Anticancer Res 22, 2355-2360.

Yoshikawa T, Suzuki K, Kobayashi O, Sairenji M, Motohashi H, Tsuburaya A, Nakamura Y, Shimizu A, Yanoma S, Noguchi Y (1999) Thymidine phosphorylase/platelet-derived endothelial cell growth factor is upregulated in advanced solid types of gastric cancer. Br J Cancer 79, 1145-1150.

Yoshimura A, Kuwazuru Y, Furukawa T, Yoshida H, Yamada K, Akiyama S (1990) Purification and tissue distribution of human thymidine phosphorylase; high expression in lymphocytes, reticulocytes and tumors. Biochim Biophys Acta 1034, 107-113.

Yoshisue K, Masuda H, Matsushima E, Ikeda K, Nagayama S, Kawaguchi Y (2000) Tissue distribution and biotransformation of potassium oxonate after oral administration of a novel antitumor agent drug combination of tegafur, 5-chloro-2,4-dihydroxypyridine, and potassium oxonate to rats. Drug Metab Dispos 28, 1162-1167.

Yu LJ, Matias J, Scudiero DA, Hite KM, Monks A, Sausville EA, Waxman DJ (2001) P450 enzyme expression patterns in the NCI human tumor cell line panel. Drug Metab Dispos 29, 304-312.

Zhang JM, Mizoi T, Shiiba K, Sasaki I, Matsuno S (2004) Expression of thymidine phosphorylase by macrophages in colorectal cancer tissues. World J Gastroenterol 10, 545-549.

Zhu GH, Lenzi M, Schwartz EL (2002) The Sp1 transcription factor contributes to the tumor necrosis factor-induced expression of the angiogenic factor thymidine phosphorylase in human colon carcinoma cells. Oncogene 21, 8477-8485.

Zhu GH, Schwartz EL (2003) Expression of the angiogenic factor thymidine phosphorylase in THP-1 monocytes: induction by autocrine tumor necrosis factor-a and inhibition by aspirin. Mol Pharmacol 64, 1251-1258.

	PD-ECGF/TP correlation with:
Disease	Angiogenesis	Prognosis	References
	Yes / No / ND	Yes / No / ND
Uterine cervical cancer	3 / 2 / 0	3 / 0 / 2	Tokumo et al, 1998; Fujimoto et al, 1999; Hata et al, 1999b; Kodama et al, 1999; Ueda et al, 1999
Endometrial cancer	2 / 1 / 1	0 / 3 / 1	Fujiwaki et al, 1998, 1999b; Sakamoto et al, 1999; Sivridis et al, 2002a
Ovarian cancer	1 / 0 / 2	1 / 0 / 2	Reynolds et al, 1994; Hata et al, 1998; Hata et al, 1999a
Non small cell lung cancer	2 / 0 / 3	1 / 1 / 3	Koukourakis et al, 1997; Giatromanolaki et al, 1998b; Volm et al, 1998; Volm et al, 1999; Yamashita et al, 1999
Esophageal cancer	3 / 0 / 2	3 / 2 / 0	Igarashi et al, 1998; Takebayashi et al, 1999; Ikeguchi et al, 1999; Koide et al, 1999; Yamagata et al, 1999
Gastric cancer	4 / 0 / 1	3 / 0 / 2	Maeda et al, 1996; Takebayashi et al, 1996b; Takahashi et al, 1998; Yoshikawa et al, 1999; Saito et al, 1999
Colon cancer	5 / 0 / 0	2 / 0 / 3	Takahashi et al, 1996; Takebayashi et al, 1996a; Saeki et al, 1997; Matsumura et al, 1998; Shomori et al, 1999
Breast cancer	3 / 3 / 2	1 / 5 / 2	Toi et al, 1995a, 1997, 1999; Fox et al, 1996, 1997; Engels et al, 1997; Leek et al, 1998; Mimori et al, 1999
Pancreatic cancer	2 / 0 / 0	2 / 0 / 0	Fujimoto et al, 1998; Takao et al, 1998
Bladder cancer	0 / 1 / 5	1 / 2 / 3	O'Brien et al, 1996; Kubota et al, 1997; Mizutani et al, 1997; Sawase et al, 1998; Tanaka et al, 1999; Arima et al, 2000
Renal cell carcinoma	1 / 1 / 0	2 / 0 / 0	Imazano et al, 1997; Suzuki et al, 2001
Head and neck cancer	2 / 1 / 0	1 / 0 / 2	Giatromanolaki et al, 1998a; Fukuiwa et al, 1999; Koukourakis et al, 2000
Prostate	1 / 1 / 0	0 / 0 / 2	Sugamoto et al, 1999; Sivridis et al, 2002b
Glioma	1 / 0 / 0	0 / 0 / 1	Nakayama et al, 1998
Hepatocellular carcinoma	0 / 1 / 0	0 / 0 / 1	Yamamoto et al, 1998
Oral squamous cell carcinoma	1 / 0 / 0	0 / 0 / 1	Alcalde et al, 1997
Overall # studies	31 / 11 / 16	20 / 13 / 25

Review Article

Received: 28 September 2005; Accepted: 08 November 2005; electronically published: March 2006

I. Introduction

A. PD-ECGF/TP

B. PD-ECGF/TP expression in health and disease

References

C. Other diseases expressing PD-ECGF/TP

E. MNGIE

C. The Influence of PD-ECGF/TP on apoptosis and the effect of L-deoxyribose on angiogenesis and apoptosis

A. Oral fluoropyrimidines: UFT, S1 and capecitabine

B. Trifluorothymidine plus thymidine phosphorylase inhibitor; TAS-102

IV. Pyrimidine phosphorylases; Thymidine phosphorylase and Uridine phosphorylase

V. Regulation of PD-ECGF/TP expression and (Bio)modulation of fluoropyrimidines

References