Inhibition of thymidine phosphorylase expression by Hsp90 inhibitor potentiates the cytotoxic effect of salinomycin in human non-small-cell lung cancer cells

Salinomycin is a polyether ionophore antibiotic having anti-tumorigenic property in various types of cancer. Elevated thymidine phosphorylase (TP) levels, a key enzyme in the pyrimidine nucleoside salvage pathway, are associated with an aggressive disease phenotype and poor prognoses. Heat shock protein 90 (Hsp90) is a ubiquitous molecular chaperone that is responsible for the stabilization and maturation of many oncogenic proteins. In this study, we report whether Hsp90 inhibitor 17-AAG could enhance salinomycin-induced cytotoxicity in NSCLC cells through modulating TP expression in two non-small-cell lung cancer (NSCLC) cell lines, A549 and H1975. We found that salinomycin increased TP expression in a MKK3/6-p38 MAPK activation manner. Knockdown of TP using siRNA or inactivation of p38 MAPK by pharmacological inhibitor SB203580 enhanced the cytotoxic and growth inhibition effects of salinomycin. In contrast, enforced expression of MKK6E (a constitutively active form of MKK6) reduced the cytotoxicity and cell growth inhibition of salinomycin. Moreover, Hsp90 inhibitor 17-AAG enhanced cytotoxicity and cell growth inhibition of salinomycin in NSCLC cells, which were associated with down-regulation of TP expression and inactivation of p38 MAPK. Together, the Hsp90 inhibition induced TP down-regulation involved in enhancing the salinomycin-induced cytotoxicity in A549 and H1975 cells.

Radiation recall gastritis secondary to erlotinib in a patient with pancreatic cancer

BACKGROUND

Radiation recall refers to chemotherapy-triggered inflammation in healthy areas previously exposed to irradiation. Chemotherapeutics known to be associated with radiation recall phenomenon include anthracyclines, taxanes and antimetabolites, such as gemcitabine and capecitabine. Case reports detailing radiation recall dermatitis and pneumonitis associated with erlotinib have been previously described in the literature, however, there are no reported cases describing radiation gastritis associated with erlotinib. We report a patient with pancreatic cancer who developed gastrointestinal bleeding secondary to radiation recall gastritis related to erlotinib exposure.

CASE REPORT

A 57-year-old Hispanic male with pancreatic cancer initially received 7 cycles of FOLFIRINOX followed by capecitabine with radiation therapy for 28 fractions for a total of 5,040 cGy. Re-staging with computed tomography demonstrated stable disease. The patient was then treated with erlotinib and capecitabine for approximately two months before restaging demonstrated progressive disease. Shortly after discontinuing erlotinib and capecitabine, the patient reported maroon colored stools. Laboratory studies demonstrated a precipitous drop in hemoglobin and hematocrit from pre-treatment baseline, ultimately requiring transfusion with packed red blood cells. Subsequent esophagogastroduodenoscopy demonstrated findings consistent with radiation gastritis, with oozing in the gastric body and antrum, which was treated therapeutically with argon plasma coagulation. The patient's gastrointestinal bleed was difficult to control. Over the course of a two-month period - the patient required multiple admissions, repeat therapeutic esophagogastroduodenoscopies and transfusions.

DISCUSSION

Radiation recall from erlotinib is rare but can potentially arise in any site that has been previously irradiated. There may be an association between the pathogenesis of radiation recall and erlotinib's up-regulation of the angiogenic growth factor thymidine phosphorylase. Treating physicians are reminded of the potential toxicity from erlotinib either given concomitantly or followed by radiation. We suggest discontinuing erlotinib if radiation gastritis is observed. We encourage physicians with similar experiences with erlotinib to report their findings. Further studies are warranted to investigate the pathogenesis of this unique phenomenon and its association with erlotinib.

Enzymatic synthesis of 2'-deoxyuridine by whole cell catalyst co-expressing uridine phosphorylase and thymidine phosphorylase through auto-induction system

Genes encoding uridine phosphorylase (UP) and thymidine phosphorylase (TP) from Escherichia coli K12 were cloned and recombined respectively into plasmids pET-21a(+) and pET-28a(+). The recombinant plasmids BL21/pET21a-UP and BL21/pET28a-TP were co-transformed into E. coli BL21(DE3) to construct highly effective BTU strain (BL21/pET28a-TP, pET21a-UP) overexpressing both of UP and TP. BTU was cultivated in ZYM-Fe-5052 medium for 10 h and used as catalyst to synthesize 2'-deoxyuridine (dUR). It was found to increase the productivity of dUR by 8-9 fold when compared to wild E. coli K12 and E. coli BL21(DE3) strains. A series of experiments were carried out to find out the optimal conditions for synthesis of dUR. At 50°C, with 0.25‰ dry wt./v to catalyze the reaction of 2:1 β-thymidine: uracil (60 mM β-thymidine, 30 mM uracil), the conversion rate of dUR would reach 61.6% at 1 h, which was much higher than the rates obtained by BTU strain cultured in LB medium and induced by IPTG. This result proved co-expression and auto-induction were efficient methods in enhancing the expression quantity and activity of nucleoside phosphorylases, and they also had significant implications for large-scale industrial production of dUR and synthesis of other nucleoside derivatives.

Gene therapy using a liver-targeted AAV vector restores nucleoside and nucleotide homeostasis in a murine model of MNGIE

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in TYMP, enconding thymidine phosphorylase (TP). TP deficiency results in systemic accumulation of thymidine and deoxyuridine, which interferes with mitochondrial DNA (mtDNA) replication and leads to mitochondrial dysfunction. To date, the only treatment available for MNGIE patients is allogeneic hematopoietic stem cell transplantation, which is associated with high morbidity and mortality. Here, we report that AAV2/8-mediated transfer of the human TYMP coding sequence (hcTYMP) under the control of a liver-specific promoter prevents the biochemical imbalances in a murine model of MNGIE. hcTYMP expression was restricted to liver, and a dose as low as 2 × 10(11) genome copies/kg led to a permanent reduction in systemic nucleoside levels to normal values in about 50% of treated mice. Higher doses resulted in reductions to normal or slightly below normal levels in virtually all mice treated. The nucleoside reduction achieved by this treatment prevented deoxycytidine triphosphate (dCTP) depletion, which is the limiting factor affecting mtDNA replication in this disease. These results demonstrate that the use of AAV to direct TYMP expression in liver is feasible as a potentially safe gene therapy strategy for MNGIE.

Thymidine phosphorylase expression in B-cell lymphomas and its significance: a new prognostic marker?

OBJECTIVE

To explore thymidine phosphorylase (TP) expression in B-cell lymphomas (BCLs). TP is expressed by tumor and stromal cells in a variety of cancers.

STUDY DESIGN

Paraffin-embedded tissues from follicular lymphomas, diffuse large BCLs (DLBCLs), and benign lymph nodes were studied using immunohistochemical staining with antibodies for TP and CD68. Prognostic markers were used to stain DLBCLs. We correlated TP expression in DLBCL indirectly with prognostic immunomarkers and directly with survival data.

RESULTS

TP expression in BCLs was noted in a subset of malignant B cells. TP expression in higher-grade lymphoma was identified in 66% of cases and 11% of lower-grade lymphomas. Macrophages/stromal cells demonstrated an intense cytoplasmic and/or nuclear staining pattern in both lymphoma and benign lymph nodes, confirmed by CD68 coexpression. Increased macrophage/ stromal cells in higher-grade lymphomas are associated with enhanced TP expression in neoplastic B cells (observation only). Sixty-eight percent of TP-positive DLBCLs were of nongerminal center origin, indicating poorer prognosis.

CONCLUSION

TP is more likely expressed by malignant B cells in higher-grade lymphomas, and expression of TP possibly results from changes intrinsic to the tumor cells or interactions between microenvironment and tumor. TP positivity in DLBCL correlates with nongerminal center origin and worse outcome.

Thymidine phosphorylase inhibits vascular smooth muscle cell proliferation via upregulation of STAT3

Dysregulated growth and motility of vascular smooth muscle cells (VSMC) play important role in obstructive vascular diseases. We previously reported that gene transfer of thymidine phosphorylase (TP) into rat VSMC inhibits cell proliferation and attenuates balloon injury induced neointimal hyperplasia; however, the mechanism remains unclear. The current study identified a signaling pathway that mediates effect of TP inhibited VSMC proliferation with a TP activity-dependent manner. Rat VSMC overexpressing human TP gene (C2) or control empty vector (PC) were used. Serum stimulation induced constitutive STAT3 phosphorylation at tyrosine705 in C2 cell but not in PC, which was independent of JAK2 signaling pathway. Inhibition of Src family kinases activity inhibited STAT3 phosphorylation in C2 cells. Lyn activity was higher in C2 cell than in PC. SiRNA based gene knockdown of Lyn significantly decreased serum induced STAT3 phosphorylation in C2 and dramatically increased proliferation of this cell, suggesting that Lyn plays a pivotal role in TP inhibited VSMC proliferation. Unphosphorylated STAT3 (U-STAT3) expression was significantly increased in C2 cells, which may be due to the increased STAT3 transcription. Gene transfection of mouse wild-type or Y705F mutant STAT3 into PC cell or mouse primary cultured VSMC significantly reduced proliferation of these cells, suggesting that overexpression of U-STAT3 inhibits VSMC proliferation. We conclude that Lyn mediates TP induced STAT3 activation, which subsequently contributes to upregulate expression of U-STAT3. The U-STAT3 plays a critical role in inhibiting VSMC proliferation.

[Improved sensitivity of gastric carcinoma cells to fluorouracil-related drugs by transfection of thymidine phosphorylase gene]

OBJECTIVE

To investigate the relationship between the expression of thymidine phosphorylase (TP) and the sensitivity of gastric carcinoma to 5-fluorouracil (5-FU) and its prodrugs.

METHODS

Gastric carcinoma cell line AGS was transfected with recombinant plasmid pEGFP-N1-TP or control plasmid pEGFP-N1 by lipofectamin 2000. The expression of green fluorescence labeled protein was observed under fluorescence microscope. Positive clones AGS-p and AGS-pTP were selected by G418 treatment. Expression of TP protein and mRNA was detected by immunocytochemistry and RT-PCR, respectively. Drug sensitivity to 5-FU and its prodrugs was assessed by MTT assay.

RESULTS

Cell clones with the expression of green fluorescent protein (AGS-p) and a clone with TP and green fluorescent fusion protein (AGS-pTP) were established. Immunostaining of TP protein was strongly positive in AGS-pTP and negative in AGS-p and AGS. The expression of TP mRNA was significantly higher in AGS-pTP (0.8090 ± 0.0450) than that in AGS (0.0490 ± 0.0046) and AGS-p (0.0610 ± 0.0069; P < 0.01). The sensitivity to doxifluridine and capecitabine in AGS-pTP was significantly increased, as compared with that in AGS-p. IC50 values of AGS-pTP to doxifluridine and capecitabine were estimated 1.7 folds and 2.2 folds as much as that of AGS-p, respectively. The sensitivity to 5-FU was not different between AGS-pTP and AGS-p.

CONCLUSIONS

Enhancement of TP expression improves the sensitivity of gastric carcinoma cells to doxifluridine and capecitabine. But it does not affect the sensitivity to 5-FU.

[The thymidine phosphorylase as the platelet-derived endothelial cell growth factor of endometrial cancer]

OBJECTIVES

The aim of the study was to assess the correlation between the activity of thymidine phosphorylase (TP) and the platelet derived-endothelial cell growth factor (PD-ECGF) expression in endometrial carcinoma.

METHODS

The study group consisted of 40 tissue samples taken from patients with endometrial carcinoma, who underwent surgery in First Clinic of Gynecology and Oncologic Gynecology of Medical University in Lodz. The control tissue samples were taken from patients who were operated on for non-oncologic reason. The activity of TP was measured by the spectrophotometric method in the cytosol of tumor cells, and the immunohistochemical staining of PD-ECGF was performed in the same tumors. The results of TP activity were compared with the microvessel density (MD) assessed by immunohistochemical analysis and with clinico-pathological features like tumor grade and FIGO stage.

RESULT

A positive correlation between the enzyme activity and expression of TP/PD-ECGF protein was found. Moreover a significantly higher TP activity was confirmed in malignant tumors from endometrial cancer patients when compared to the controls. A positive correlation between the enzyme activity and MD was also stated, but there was no connection to the grade of tumors and FIGO stage. Since the TP activity proved to be related to PD-ECGF expression and angiogenesis, we can state that TP seems to be an active form of PD-ECGF growth factor in endometrial carcinoma. This is in agreement with the results of many publications on other malignancies. The proper modulation of this activity may be useful in adjuvant therapies.

Micro-vessel density and the expression of vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PdEGF) in classical Hodgkin lymphoma (HL)

There is little information to date regarding the role of angiogenesis in Hodgkin lymphoma (HL). The present study examines micro-vessel density and the expression of vascular endothelial growth factor (VEGF) and platelet-derived endothelial growth factor (PdEGF) in lymph node biopsies of patients with HL at presentation and relapse. Using immunohistochemistry, the degree of new blood vessel formation and the expression of VEGF and PdEGF was assessed in Hodgkin-rich tissue. The micro-vessel density (MVD) increased with disease progression in seven out of 11 cases. Expression of VEGF was observed in endothelial cells (EC) of some micro-vessels and also in follicular dendritic cells. The Hodgkin/Reed-Sternberg (H-RS) cells as well as the inflammatory lymphocytes were negative for VEGF. Cytoplasmic or cytoplasmic and nuclear expression of PdEGF by the H-RS cells was observed in five of the 11 presentation cases. The expression of PdEGF increased with disease progression in seven cases. In conclusion, Hodgkin tissue shows prominent vascularization. The increased MVD and PdEGF expression with disease progression merits further investigation.

Significance of thymidine phosphorylase expression in stromal cells around invasive front of rectal cancer

BACKGROUND/AIMS

Thymidine Phosphorylase (TP) expression in the tumor cells correlates with postoperative recurrence, but the significance of its expression in the stromal cells around the invasive front of the tumor is not clarified.

METHODOLOGY

This study was conducted on 95 patients with T2 (n=34) or T3 (n=61) rectal cancer for whom curative surgical resection was performed between 1998 and 2002. As a control, appendix vermiform of twenty patients excised for acute appendicitis during the same period was analyzed. Paraffin-embedded sections of their surgical specimens were immunostained for TP and Vascular Endothelial Growth Factor (VEGF). Relationship between expression level of the binary angiogenic factors and malignant potential were evaluated.

RESULTS

There was a strong relationship between TP expression in the malignant cells at the invasive front of the tumor and depth of tumor invasion. TP expression in the stromal cells was very high regardless of the status of the depth of tumor invasion. TP expressions in the stromal cells in the appendix with inflammation were also very high, which was detectable both in the nucleus as well as in the cytoplasm.

CONCLUSION

TP expression in the stromal cells may seem to reflect local immunoreactions, rather than tumor anginogenesis.

[Interferon-alpha upregulates thymidine phosphorylase expression via JAK-STAT transcriptional activation and mRNA stabilization in human hepatocellular carcinoma SMMC-7721 cells]

OBJECTIVE

To examine how the thymidine phosphorylase (TP) gene expression is upregulated by interferon-alpha (IFN-alpha) in human hepatocellular carcinoma SMMC-7721 cells.

METHODS

TP mRNA levels were determined by RT-PCR. Whether the JAK-STAT cascade mediates IFN-alpha-induced TP mRNA expression was studied by pretreatment with Janus Kinase (JAK) inhibitor, AG-490. Effects of IFN-alpha on TP mRNA stability were detected with additional actinomycin D.

RESULTS

The expression of TP mRNA was induced by IFN-alpha in a dose- and time-dependent manner in SMMC-7721 (human hepatocellular carcinoma) cells. TP mRNA levels rose at 8 h, reached the peak value at 12 h, and remained at a high level up to 72 h in SMMC-7721 cells treated with IFN-alpha 10000 U/ml. IFN-alpha at a dose of 5000 or 10000 U/ml up-regulated TP expression about 3 fold compared with that of non-treated cells (P < 0.05). Induction of TP mRNA expression by IFN-alpha was significantly inhibited in SMMC-7721 cells by pretreatment with AG-490, in comparison with that treated with IFN-alpha alone. Pretreatment of SMMC-7721 cells with IFN-alpha 10000 U/ml for 24 h caused a substantial stabilization of TP mRNA, with a half-live of 35.8 h, compared with 8.5 hr in the control SMMC-7721 cells.

CONCLUSION

IFN-alpha at certain doses upregulates TP mRNA expression via both JAK-STAT transcriptional activation and post-transcriptional mRNA stabilization in human hepatocellular carcinoma SMMC-7721 cells.

Changes of gene expression of thymidine phosphorylase, thymidylate synthase, dihydropyrimidine dehydrogenase after the administration of 5'-deoxy-5-fluorouridine, paclitaxel and its combination in human gastric cancer xenografts

BACKGROUND

Although a variety of combination chemotherapies has been tested in gastric carcinoma, the most effective chemotherapeutic regimen and the precise mechanisms underlying anticancer agent combination have not yet been sufficiently elucidated.

MATERIALS AND METHODS

Experimental chemotherapy was performed using human gastric carcinoma xenografts, MKN-45 and TMK-1, to examine the anticancer effects and gene expressions of the enzymes involved in 5-fluorouracil metabolism, thymidine phosphorylase (dThdPase), thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD). Nude mice were treated with 5'-deoxy-5-fluorouridine (5'-dFUrd), or paclitaxel alone or in combination. The in vivo antitumor effects on gene expressions of the enzymes were examined using the quantitative real-time RT-PCR method.

RESULTS

The combined use of 5'-dFUrd and paclitaxel showed additive to synergistic antitumor effects on both gastric cancer xenografts. There were significant differences of the gene expressions of dThdPase, TS, and DPD between the xenografts. The expression of dThdPase mRNA was consistently up-regulated by the administration of paclitaxel, while no constant direction of TS mRNA and DPD mRNA change was found in the xenografts.

CONCLUSION

A synergistic antitumor effect of the combined administration of 5'-dFUrd and paclitaxel was found in gastric cancer xenografts and up-regulation of dThdPase mRNA may be an important underlying mechanism especially in tumors with high gene expression of this enzyme.

5-Fluorouracil-related gene expression in primary sites and hepatic metastases of colorectal carcinomas

The aim of this study was to investigate the correlation of the mRNA expressions of 5-fluorouracil (5FU)-related genes in the primary sites and liver metastases of colorectal carcinomas.

PATIENTS AND METHODS

Patients with liver metastases from colorectal carcinomas were included (n = 43). The expression ratios to beta-actin of mRNA of thymidine synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP) and oroteta phosphoribosyl transferase (OPRT) were measured in primary and liver metastases of colorectal carcinomas by laser-captured microdissection and real time PCR.

RESULTS

The ratios for the expression of TS, DPD, TP and OPRT mRNAs were significantly correlated between paired primary sites and liver metastases. The mRNA expression ratios of DPD and TP showed a significant correlation both in primary sites and in liver metastases.

CONCLUSION

Enzymes of the primary colorectal carcinomas can be used in predicting the therapeutic efficacy of 5FU against liver metastases.

Importance of thymidine phosphorylase, dihydropyrimidine dehydrogenase and thymidylate synthase expression at the invasive front of T3 rectal cancer as prognostic factors

BACKGROUND/AIMS

We evaluated a relationship between postoperative recurrence and thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) expression at the invasive front of T3 rectal cancer.

METHODOLOGY

This study was conducted on 61 patients with T3 rectal cancer who underwent surgically curative resection between 1998 and 2002. Paraffin-embedded sections of these patients were immunostained for TP, DPD and TS. Relationship between expression level of the three factors and postoperative recurrence were evaluated.

RESULTS

There was no relationship between expression of DPD or TS in the tumor cells and recurrences. Although no relationship was present between expression of TP in the stromal cells around the invasive front of the tumor and postoperative recurrences, there was a strong correlation between expression of TP in the invasive front of the tumor and postoperative recurrence. Moreover, by multivariate logistic regression analysis, TP expression in the tumor cells was the only independent contributory factor for postoperative recurrences (p = 0.021) with an odds ratio of 8.27.

CONCLUSIONS

TP expression at the invasive front of the tumor may be an important prognostic factor for T3 rectal cancer, and patients with such a condition may benefit from intensive chemotherapy.

5-Fluorouracil-related gene expression in hepatic artery infusion-treated patients with hepatic metastases from colorectal carcinomas

AIM

To predict the therapeutic efficacy of hepatic arterial infusion (HAI) with 5-fluorouracil (5FU) for patients with liver metastases from colorectal carcinomas, 5FU-related gene expressions were examined in primary colorectal carcinomas.

PATIENTS AND METHODS

Thirty-eight patients with liver metastases from colorectal carcinoma received HAI of 5FU. The expressions of the mRNAs for thymidine synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), and oroteta phophoribosyl transferase (OPRT) in primary colorectal carcinomas were measured by RT-PCR.

RESULTS

The response rate was 52.6% (20/38). The overall median survival time was 29.1 months. DPD and TP expression was significantly higher in the progressive disease (PD) group than in the complete response (CR) or partial response (PR) group (p = 0.032, p = 0.014), respectively. The levels of DPD and TP mRNAs showed a significant correlation (r = 0.76, p = 0.0001).

CONCLUSION

The expression of DPD and TP mRNAs in primary colorectal carcinomas was significantly predictive of the therapeutic response to 5FU HAI.

Prognostic role of angiogenesis and its correlations with thymidine phosphorylase and p53 expression in ductal adenocarcinoma of the pancreas

BACKGROUND/AIMS

Currently, little information is available regarding the prognostic role of angiogenesis and its correlation with Thymidine phosphorylase (dThdPase) in ductal adenocarcinoma of the pancreas. In the present study, we aimed to evaluate whether tumor angiogenesis, dThdPase expression correlates with prognosis in patients after radical surgical treatment for ductal adenocarcinoma of the pancreas and to investigate the correlation between tumor angiogenesis and dThdPase expression. Furthermore, the role of p53 expression in tumor neovascularization was also examined in this study.

METHODOLOGY

Tissue samples were taken from 32 patients with ductal adenocarcinoma of the pancreas after radical surgical treatment. Intratumoral microvessel density (IMVD) and dThdPase, p53 expression were examined immunohistochemically.

RESULTS

Increased IMVD significantly correlated with the tumor size, lymph node metastasis and advanced TNM stage (p < 0.05, respectively). Furthermore, increased IMVD correlated withpoorer survival curve (p < 0.05). A significant correlation was present between IMVD and dThdPase expression (p < 0.001), while dThdPase expression did not correlate with prognosis. p53 expression correlated with prognosis, whereas no significant correlation was shown between p53 expression and IMVD in ductal adenocarcinoma of the pancreas.

CONCLUSIONS

Tumor angiogenesis is associated with clinicopathological factors regarding tumor progression and may be an important prognostic factor in ductal adenocarcinoma of the pancreas. dThdPase plays an important role in tumor angiogenesis in ductal adenocarcinoma of the pancreas. Mutant p53 expression may not involve in tumor angiogenesis in ductal adenocarcinoma of the pancreas.

Suppression of thymidine phosphorylase expression by promoter methylation in human cancer cells lacking enzyme activity

PURPOSE

Thymidine phosphorylase (TP, EC 2.4.2.4) activity varies in different human cancer cell lines. Nevertheless, little is known about the regulatory mechanisms of TP expression in such cancers. Promoter methylation of dinucleotide cytosine-guanine (CpG) sites is a known mechanism of reversible gene expression silencing.

METHODS

TP promoter methylation was investigated in five cancer cell lines (SKBR-3, 786-O, HT-29, MDA-231, DLD-1). TP mRNA levels were determined by real-time quantitative PCR. The degree of methylation was identified by bisulfite sequencing. Minimal TP promoter activity was determined by Luciferase reporter assays. DNA-protein interactions were evaluated by electrophoretic mobility shift assays.

RESULTS

SKBR-3 cells exhibited the highest TP expression, 786-O, HT-29, and MDA-231 cells exhibited intermediate TP expression, while DLD-1 cells did not express TP as demonstrated by TP mRNA, protein, and enzyme activity levels. SKBR-3 lacked methylation in the TP promoter, intron 1 and exon 1 regions, while DLD-1 showed extensive methylation. Treatment of DLD-1 and SKBR-3 with the methylation-inhibitor, 5-aza-2'-deoxycytidine (5-aza-2dC), resulted in a concentration-dependent increase in TP mRNA and protein levels in DLD-1 but not SKBR-3 cells. Trichostatin-A treatment, a histone deacetylase inhibitor, improved the 5-aza-2dC-induced TP re-activation. Electrophoretic mobility shift assays demonstrated that methylation significantly inhibits transcription factor binding. Supershift analyses suggest that the Sp1 and Sp3 (to a lesser degree) transcription factors have a role in the regulation of TP expression.

CONCLUSIONS

These findings suggest that TP promoter methylation is a mechanism for down-regulation of TP expression in cancer cells and may have implications in modulating prognosis of cancer patients.

Anthracyclines and taxanes induce the upregulation of thymidine phosphorylase in breast cancer cells

We have investigated the immunohistochemical expression of thymidine phosphorylase before and after the administration of anthracycline, and/or anthracycline/taxane-based preoperative chemotherapy in a consecutive series of 55 patients with primary operable breast cancer. Pretreatment, large core breast biopsies and the corresponding surgical samples were retrospectively evaluated for thymidine phosphorylase immunoreactivity. Immunohistochemical expression was evaluated on tumor cells (nuclear and cytoplasmic staining) and on stromal cells (cytoplasmic staining). The cytoplasmic expression of thymidine phosphorylase was enhanced in the tumor cells after treatment (P=0.04). An increase in thymidine phosphorylase cytoplasmic tumor expression was observed in 33% (95% confidence interval: 19-50%) of patients after preoperative chemotherapy (P=0.01). No statistically significant nuclear staining changes were observed in response to treatment. Similarly, no significant changes of the enzyme expression were seen in stromal cells. This study provides further evidence that, at least in breast cancer, thymidine phosphorylase is upregulated after anthracycline and/or taxane-containing chemotherapy. Accordingly, it supports the hypothesis of a synergistic effect between thymidine phosphorylase-modulating and thymidine phosphorylase-targeting anticancer agents. Translational studies, specifically designed on the basis of this rationale, are eagerly waited.

Expression of thymidine phosphorylase in peripheral blood cells of breast cancer patients is not increased by paclitaxel

Background

A synergistic cytotoxic effect has been hypothesized for taxanes and capecitabine, a prodrug of 5-fluorouracil. Based on preclinical studies, this synergism has been attributed to an up-regulation of the enzyme thymidine phosphorylase (TP). Beside tumour tissue, TP is highly expressed in white blood cells, possibly causing increased hematotoxicity, when taxanes are combined with capecitabine. So far, this hypothesis has not been investigated in humans.

Methods

A total of 128 consecutive blood samples were collected from eight patients with advanced breast cancer receiving paclitaxel weekly at a dose of 80 mg/m². To assess the expression of TP in blood cells, samples were collected prior to first therapy, at the end of infusion, and up to 15 days thereafter. This procedure was repeated during the sixth application of paclitaxel. After isolation of the peripheral mononuclear blood cells, the expression of TP was assessed by ELISA. In parallel, paclitaxel level in plasma was evaluated at three selected time points as pharmacokinetic control parameter.

Results

Paclitaxel concentrations at the end of infusion did not change significantly from week 1 to week 6. The expression of TP in peripheral mononuclear blood cells decreased significantly after infusion below pretherapeutic values (p = 0.023; n = 8). After the nadir on day 3, the expression of TP increased moderately returning to baseline levels within one week. The overall picture in week 6 was similar to week 1. Using a trend analysis, neither a short-term nor a long-term induction of TP was observed.

Conclusion

TP in peripheral mononuclear blood cells was hardly regulated under therapy with paclitaxel. Therefore, no increased haematotoxicity due to TP upregulation is expected from the combination of taxanes and capecitabine.

Gene expression profile of 5-fluorouracil metabolic enzymes in primary colorectal cancer: potential as predictive parameters for response to fluorouracil-based chemotherapy

BACKGROUND

Thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP) and orotate phosphoribosyltransferase (OPRT) have been reported to be predictive parameters for the efficacy of fluoropyrimidine-based chemotherapy. Therapy guided by chemotherapy sensitivity and resistance assays may lead to rational treatment decisions.

MATERIALS AND METHODS

mRNA expression of TS, DPD, TP, and OPRT were quantified by reverse-transcriptase polymerase chain reaction (RT-PCR) after harvesting from paraffin embedded specimens through microdissection. In vitro chemosensitivity testing by histoculture drug response assay (HDRA) was performed with fresh specimens of the primary tumor from 49 patients with colorectal cancer. Correlations between the results of a chemosensitivity test (the T/C ratio; the percentage of optical density of a tumor treated with anticancer drugs in relation to the optical density of the tumor cultured in RPMI 1640 medium only) and the gene expression were assessed.

RESULTS

The gene expression of TS, TP, and OPRT had no correlation with clinicopathological factors, survival, and T/C ratio. The DPD mRNA levels (0.295 vs. 0.381, p = 0.2460) and OPRT/DPD ratio (5.535 vs. 4.394. p = 0.226) had a weak correlation with the T/C ratio. Of the eleven patients who were actually treated with chemotherapy, the responders had higher OPRT/DPD ratios (8.065 vs. 4.081, p = 0.090).

CONCLUSION

The DPD mRNA level and OPRT/DPD ratio evaluated from paraffin embedded specimens are candidates for further evaluation as predictors of response against 5-fluorouracil-based chemotherapy in colorectal cancer.

Angiogenesis in gastric cancer: importance of the thymidine phosphorylase expression of cancer cells as an angiogenic factor

Thymidine phosphorylase (TP) has been reported to stimulate angiogenesis in a variety of human malignancies. We investigated TP expression and its association with angiogenesis in 73 cases of resected gastric cancer. In addition, we compared the expression of the other angiogenesis related factors (VEGF, eNOS and p53) with that of TP with respect to angiogenesis. TP expression was not detected in most of the non-tumoral glandular epithelial cells except for 5 cases. TP expression of the cancer cells and the stroma was assessed separately. The stromal TP expression was not associated with the TP expression of the cancer cells. The mean percent of TP reactive cancer cells was 18.36+/-2.61 (median, 10.00; range, 0-90) and cases showing a percentage higher than the mean were considered as bearing high reactivity. The mean microvessel score assessed was 90.44+/-3.69 (median, 86; range, 31-174). The TP expression of cancer cells was strongly associated with microvessel density (p=0.030), but the stromal TP expression was not. The microvessel density of the tumor showed strong correlation with VEGF expression (p<0.001), but a marginally significant association with eNOS (p=0.055). On the contrary, there was no association with p53 expression and microvessel density of the tumor. No significant correlation was detected between lymph node metastasis and tumoral or stromal TP expression or VEGF/TP coexpression. In gastric cancer, TP expression of the cancer cells, not stromal cells may play an important role in tumor growth by microvessel formation.

Platelet-derived endothelial cell growth factor gene therapy for limb ischemia

OBJECTIVES

Platelet-derived endothelial cell growth factor (PD-ECGF) is identical to thymidine phosphorylase (TP), and it can induce angiogenesis, including arteriogenesis, in chronically ischemic canine myocardium. Because its effect on peripheral arterial disease has not been elucidated, we investigated whether overexpression of PD-ECGF/TP could ameliorate chronic limb ischemia in rabbits.

METHODS

Left femoral arteries were resected from 24 male rabbits. After 10 days, a plasmid vector containing human PD-ECGF/TP complimentary DNA was injected into 10 sites in the adductor muscles. Control groups received either the LacZ plasmid vector or saline vehicle only (n = 8 per group). Blood pressure was measured in the calf before surgery, at the onset of ischemia, 10 days later, and 20 and 30 days after gene transfer. Collateral vessel development and limb perfusion were assessed by angiography, and resected tissues underwent molecular and histologic examination.

RESULTS

In the PD-ECGF/TP group, human PD-ECGF/TP messenger RNA and protein were still detected at 30 days after treatment. Calf blood pressure decreased significantly after femoral artery resection in all three groups. It subsequently showed a greater increase in the PD-ECGF/TP group than in either control group, and the difference was significant at 20 days after treatment (PD-ECGF/TP, 97.4 +/- 7.4; LacZ, 58.6 +/- 6.9; saline, 41.3 +/- 3.6). Immunohistochemical staining demonstrated an increased ratio of capillaries and arterioles to muscle fibers in the PD-ECGF/TP group (2.14 +/- 0.13 and 1.51 +/- 0.06), but not in the LacZ group (1.39 +/- 0.04 and 0.71 +/- 0.05) or the saline group (1.34 +/- 0.05 and 0.71 +/- 0.04, P < .01). The angiographic score was higher in the PD-ECGF/TP group (0.96 +/- 0.08) than in the LacZ group (0.50 +/- 0.02) or saline group (0.51 +/- 0.03) at 30 days after gene transfer (P < .01).

CONCLUSIONS

This study demonstrated that PD-ECGF/TP gene transfer induced angiogenesis and decreased ischemia in a rabbit hindlimb model by promoting arteriogenesis, suggesting that targeting this gene may be a promising therapeutic strategy for peripheral vascular disease.

Expression of genes for 5-FU-metabolizing enzymes and response to irinotecan plus 5-FU-leucovorin in colorectal cancer

BACKGROUND

5-Fluorouracil (5-FU) is initially catabolized by dihydropyrimidine dehydrogenase. Thymidylate synthase (TS) is the target enzyme of 5-FU. In addition, activation of 5-FU to form various nucleotides via three pathways requires phosphorylation by orotate phosphoribosyltransferase, thymidine phosphorylase and uridine phosphorylase, respectively. The aim of this study was to assess the predictive value of the expression of these genes in patients receiving irinotecan plus 5-FU/leucovorin therapy (IFL) for colorectal cancer.

PATIENTS AND METHODS

Twenty-seven patients with metastatic, or recurrent colorectal cancer were studied. Enzyme gene expression was measured in primary tumors by the real-time reverse transcription PCR method.

RESULTS

The TS mRNA level was significantly higher in the responders than in the non-responders (p=0.0409).

CONCLUSION

The effect of IFL therapy may be determined by the extent of TS mRNA expression. It is suggested that assay of TS mRNA may be useful for predicting the effect of intravenous regimens such as FOLFIRI.

Phase II clinical trial of capecitabine in the treatment of advanced, persistent or recurrent squamous cell carcinoma of the cervix with translational research: a gynecologic oncology group study

PURPOSE

To evaluate the anti-tumor activity and adverse events of capecitabine in advanced, persistent or recurrent squamous cell carcinoma of the cervix, and to explore biomarkers with the potential to predict capecitabine response and toxicity.

EXPERIMENTAL DESIGN

Eligible, consenting patients were treated with a starting dose of 2500 mg/m(2)/day or 1800 mg/m(2)/day (divided into two doses given every 12 h) for 14 days of each 21-day cycle. Prior chemotherapy was allowed only in the context of radiation "sensitization". Genotyping in the 5' and 3' ends of thymidylate synthase (TS) was performed in DNA from pretreatment blood. Relative gene expression of TS, dihydropyrimidine dehydrogenase (DPD) and thymidine phosphorylase (TP) was quantified in RNA extracted from paraffin-embedded tumor.

RESULTS

All patients had prior radiotherapy and 22 received a radiation sensitizer. A partial response was observed in 4 of 26 (15%) evaluable patients. An additional 35% of patients achieved stable disease while 42% experienced increasing disease. The most common serious non-hematological toxicities were gastrointestinal and dermatologic. Exploratory analyses suggested that: a germline polymorphism in the 3' or the 5' end of TS was not associated with TS gene expression, relative tumor expression of TS, DPD and TP were not correlated, and relative tumor expression of TP may predict severe anemia.

CONCLUSIONS

Based on the modest response rate, this trial was closed without a second stage of accrual; single agent capecitabine was not selected for further study in advanced persistent or recurrent squamous cell carcinoma of the cervix previously treated with radiation or chemoradiation.

Thymidine phosphorylase levels and dihydropyrimidine dehydrogenase levels in non-small cell lung cancer tissues

Thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) are the major catabolic enzymes of 5-FU. In this study, we analyzed the concentration of TP and DPD in non-small cell lung cancer tissue by enzyme-linked immunosorbent assay. We measured the TP and DPD levels in 25 adenocarcinoma tissues and 25 squamous cell carcinoma tissues. The mean TP concentration in non-small cell lung cancer tissue was statistically higher than that of normal lung tissue as was the mean DPD concentration. The ratio of the TP level to DPD level in tumor tissue was higher in squamous cell carcinoma than in adenocarcinoma. No significant difference could be detected between the TP level, DPD level, or TP/DPD level and the tumor size or lymph node metastasis. In conclusion, chemotherapy with 5-FU may be more effective in squamous cell lung cancer patients than lung adenocarcinoma patients from the result of the ratio of TP to DPD.

Expression of chemoresistance-related proteins in alpha-fetoprotein-producing adenocarcinoma of the digestive organs

alpha-fetoprotein-producing adenocarcinoma of the digestive organs (APAD) is known to show a poor prognosis. To clarify the characteristics of chemoresistance in APAD, three proteins of fluoropyrimidine chemotherapy association [dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP) and thymidylate synthase (TS)] and one protein of cisplatin association [metallothionein (MT)] were immunohistochemically evaluated. Tissue samples were taken from 12 AFP-positive gastric cancers and 94 AFP-negative gastric cancers. Four AFP-positive cancer xenografts (one colonic, two pancreatic, and one biliary tract) and 17 AFP-negative cancer xenografts were also examined. In gastric cancers, high expression of TP was observed in 30% of AFP-negative tumors but in none of AFP-positive tumors (p=0.03). High expression of MT was found in 30% of AFP-negative tumors but in only one of the AFP-positive tumors. The TP-low and MT-low phenotype was noted in 92% of AFP-positive tumors and in 46% of AFP-negative tumors (p=0.004). None of the AFP-positive cancer xenografts revealed high TP expression and only one showed high MT expression. In the cellular level, TP and MT were scarcely co-expressed with AFP in either gastric cancer or xenograft series, using double immunostaining and serial sectioning techniques. There were no significant differences in the expression of DPD and TS between AFP-positive group and -negative group. However, DPD was frequently co-expressed with AFP in poorly differentiated medullary areas of the AFP-positive gastric cancers. The data presented herein suggest that APAD should be sensitive to cisplatin, but resistant to capecitabine and 5'-deoxyfluorouridine, fluoropyrimidines which are converted to 5-fluorouracil by TP. S-1, a fluoropyrimidine containing a strong DPD inhibitor, may be effective for AFP-positive gastric cancers with poorly differentiated medullary growth pattern.

Plausible linkage of hypoxia inducible factor-1α in uterine cervical cancer

Angiogenesis is essential for the development, growth and advancement of solid tumors. Angiogenesis is induced by hypoxia with angiogenic transcription factor hypoxia inducible factors (HIF). This prompted us to study the clinical implications of HIF relative to angiogenesis in uterine cervical cancers. Although there was no significant difference in HIF-1alpha histoscores and mRNA levels according to histopathological type or lymph node metastasis, HIF-1alpha histoscores and mRNA levels increased significantly with advancing cancer stages. The prognosis of 30 patients with high HIF-1alpha in uterine cervical cancers was poor (73% survival), whereas the 24-month survival rate of the other 30 patients with low HIF-1alpha was 93%. HIF-1alpha histoscores and mRNA levels were correlated with the levels of the angiogenic factors thymidine phosphorylase and interleukin-8, and HIF-1alpha might be linked with these factors in cervical cancer tissue. HIF-1alpha is a candidate for prognostic indicator as an angiogenic mediator in uterine cervical cancer.

[Relationships among the expression of thymidylate synthase, thymidine phosphorylase, and dihydropyrimidine dehydrogenase and the prognosis of breast cancer]

OBJECTIVE

To investigate the relationships among the expression of thymidylate synthase (TS), thymidine phosphorylase (TP), and dihydropyrimidine dehydrogenase (DPD) and the prognosis of breast cancer.

METHODS

Immunochemistry (ABC method) was used to detect the expression of TS, TP, and DPD in the samples of breast cancer resected during operation from 28 female patients. The microvessel density (MVD) in the cancer tissue was measured by immunochemistry (LSAB method).

RESULTS

The TS positive rate was 30.26% and the TP positive rate was 21%, and the DPD positive rate was 30.03%. The expression levels of TS and TP were both correlated with the tumor size, lymph node status, histological grading of tumor, and microvessel count (MVC) (all P < 0.01), and was not correlated with age, status of estrogen receptors, status of prasterone receptors (all P > 0.05). The DPD expression was not correlated with the age, tumor size, lymph node status, histological grading of tumor, status of estrogen receptors, status of prasterone receptors, and MVC. The ten-year disease-free survival rate of the TS-positive patients was 0, significantly lower than that of the TS-negative patients (25%, P < 0.01). The ten-year overall survival rate of the TS-positive patients was 3.9%, significantly lower than that of the TS-negative patients (58.8%, P < 0.01). The ten-year disease-free survival rate of the TP-positive patients was 0, significantly lower than the TP-negative patients (25.4%, P < 0.01). The ten-year overall survival rate of the TP-positive patients was 0.9%, significantly lower than that of the TP-negative patients (61.8%, P < 0.01). The ten-year disease-free survival rate and ten-year overall survival rate of the DPD positive patients were not significantly different from those of the DPD negative patients (both P > 0.05). MCV and TS expression were strong protective factors of disease-free survival rate and overall survival rate.

CONCLUSION

The levels of TS and TP are both prognostic indicis of breast cancer.

Expression of thymidine phosphorylase and VEGF in esophageal squamous cell carcinoma

The purpose of this study was to determine the role of TP and VEGF in angiogenesis and its clinical significance in prognosis of patients with esophageal carcinoma. Expressions of TP and VEGF, microvascular density and cell proliferation activity were evaluated by using 40 immunohistochemically stained resected esophageal carcinoma tissues, and the survival rate of the patients was analyzed. Significant positive correlation and regression were found between the VEGF expression level of tumor and microvascular density (r=0.73, p<0.0001). Not statistically strong but significant positive correlation and regression were found between the TP expression level of tumor and microvascular density (r=0.32, p=0.046). No significant relationships were found between TP and VEGF expressions. Pathological T-factor and pathological N-factor were significant prognostic factors. Tumor length, site of lesion, gender, age, and Ki67 labeling index were not significant prognostic factors. The VEGF expression level was one of the unfavorable prognostic factors (risk ratio =1.035, 95% CI=1.007-1.065, p=0.01). The patients with high TP expression showed a tendency for unfavorable prognosis, but it was not statistically significant (RR=1.017, 95% CI=0.996-1.042, p=0.1). The prognosis of patients in the TP/VEGF[+/+] group was significantly poorer than that of the patients in the TP/VEGF[-/-] group and TP/VEGF[+/- or -/+] group (RR=0.488 for TP/VEGF[-/-] group, =0.717 for TP/VEGF[+/- or -/+] group, p=0.005). In conclusion, VEGF and TP expression seems to have a relationship with tumor angiogenesis, and co-expression of TP and VEGF seemed to be one of the unfavorable prognostic factors.

Thymidylate synthase expression in oral squamous cell carcinoma predicts response to S-1

The purpose of this research was to evaluate the predictive value of expression of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), or orotate phosphoribosyltransferase (OPRT) genes for response to S-1. Twenty-five patients with oral squamous cell carcinoma (OSCC) received S-1 80 mg/m2/day. Pretreatment tumor biopsies were analyzed for TS, DPD, TP or OPRT mRNA expression by real-time reverse transcription-PCR. TS protein expression was evaluated by immunohistochemistry using a polyclonal TS antibody. Twenty-five patients were evaluable for response and gene expression. Six of the 25 (24%) achieved complete remission and 4 of the 25 (16%) had a partial response. Median TS/beta-actin was 2.51 (range 0.98-7.07). Median TS/beta-actin was 1.26 in responding patients and 3.43 in non-responders (P=0.0001). Ten of 11 patients with TS/beta-actin <1.80 and 0 of 15 with higher values responded (P<0.0001). Overall survival was 29.7 months in patients with TS/beta-actin <1.80 and 41.7 months in patients with higher values (P=0.0013). No correlations were seen between expression of DPD, TP or OPRT mRNA and response or survival. Weak TS staining was seen in 6 of 25 tumors evaluable for immunohistochemistry, including 5 responders. All 4 of the patients with both weak staining and TS/beta-actin <1.80 responded. High TS mRNA expression predicts non-response to S-1. On the other hand, high levels of DPD or TP mRNA and low levels of OPRT mRNA are not associated with S-1 resistance. TS mRNA expression is considered to be a useful prognostic factor in OSCC patients with S-1 single-agent therapy.

No relationship between thymidine phosphorylase (TP, PD-ECGF) expression and hypoxia in carcinoma of the cervix

The expression of hypoxia-regulated genes promotes an aggressive tumour phenotype and is associated with an adverse cancer treatment outcome. Thymidine phosphorylase (TP) levels increase under hypoxia, but the protein has not been studied in association with hypoxia in human tumours. An investigation was made, therefore, of the relationship of tumour TP with hypoxia, the expression of other hypoxia-associated markers and clinical outcome. This retrospective study was carried out in patients with locally advanced cervical carcinoma who underwent radiotherapy. Protein expression was evaluated with immunohistochemistry. Hypoxia was measured using microelectrodes and the level of pimonidazole binding. There was no relationship of TP expression with tumour pO₂ (r=−0.091, P=0.59, n=87) or pimonidazole binding (r=0.13, P=0.45, n=38). There was no relationship between TP and HIF-1α, but there was a weak borderline significant relationship with HIF-2α expression. There were weak but significant correlations of TP with the expression of VEGF, CA IX and Glut-1. In 119 patients, the presence of TP expression predicted for disease-specific (P=0.032) and metastasis-free (P=0.050) survival. The results suggest that TP is not a surrogate marker of hypoxia, but is linked to the expression of hypoxia-associated genes and has weak prognostic power.

Expression of thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase, and orotate phosphoribosyl transferase in prostate cancer

The enzymes thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), thymidine phosphorylase (TP), and orotate phosphoribosyl transferase (OPRT) are involved in the metabolism of the anticancer drug 5-fluorouracil. No reports have examined the expression of these enzymes in prostate cancer (CaP). A total of 25 previously untreated, hormone-sensitive CaP tissue samples and 11 benign prostatic hyperplasia (BPH) specimens were examined. Tissue of CaP and BPH tissue samples were obtained from formalin-fixed, paraffin-embedded sections by laser-captured microdissection, and then RNA was extracted. mRNA expression of TS, DPD, TP, and OPRT was analyzed by quantitative reverse transcriptase-polymerase chain reaction. TS and OPRT expression levels were significantly higher in CaP samples than in BPH. DPD expression level in poorly differentiated CaP was significantly lower than that in CaP with more favorable--well or moderately differentiated--histopathology.

Immunohistochemical analysis of thymidylate synthase, thymidine phosphorylase, and dihydropyrimidine dehydrogenase in rectal cancer (cUICC II/III): correlation with histopathologic tumor regression after 5-fluorouracil-based long-term neoadjuvant chemoradiotherapy

In locally advanced rectal cancer, neoadjuvant 5-fluorouracil (5-FU)-based long-term chemoradiotherapy leads to marked tumor reduction and decrease of local recurrence rate. Thymidylate synthase (TS), thymidine phosphorylase (TP), and dihydropyrimidine dehydrogenase (DPD) are known to be important biomarkers to predict tumor response to 5-FU-based therapy. The aim of this study was to examine the correlation between TS, TP, and DPD protein expression and histopathologic tumor regression after neoadjuvant chemoradiotherapy. The results were compared with the recently published mRNA data. Preoperative biopsies (n = 25) and resection specimens (n = 40) from patients with rectal carcinoma (clinical UICC stage II/III) receiving neoadjuvant 5-FU-based chemoradiotherapy were studied for TS, TP, and DPD protein expression by immunohistochemistry using three different scoring systems (intensity, pattern, intensity + pattern). Results were compared with histopathologic tumor regression. A significant correlation between protein expression and tumor response was only seen when both staining intensity and staining pattern were considered. With this method, a significant association was seen between high TS expression in tumor biopsies as well as resection specimens and nonresponse of the tumor to therapy (P = 0.04). Furthermore, low TP expression in the resection specimens was significantly associated with lack of response (P = 0.02). For DPD no significant correlations were found at all. In conclusion, these results suggest that immunohistochemistry like RT-PCR is a suitable method to determine the correlation between TS, TP, and DPD expression and histopathologic tumor regression. However, precise results can only be achieved if staining intensity as well as staining pattern within the tumors are evaluated.

Upregulation of thymidine phosphorylase in chronic glomerulonephritis and its role in tubulointerstitial injury

Chronic tubulointerstitial injury (CTI), commonly a sequel to chronic glomerulonephritis (CGN), is associated with the proliferation of new blood vessels. Angiogenesis is an essential process in chronic inflammation, and is controlled by a number of angiogenic factors including thymidine phosphorylase (TP). Knowledge of TP in renal disease is still rudimentary, and its role in CGN has not been explored. We analyzed the expression of TP by RTPCR, immunohistology and in situ hybridization in 20 human kidneys with CGN. To evaluate the degree of angiogenesis, we counted the microvessel density (MVD). MVD was significantly higher in all categories of CGN, between 19.7 +/- 7.7 and 58.9 +/- 7.5, compared to control value, 12.7 +/- 5.0 (p < 0.05). MVD was increased in areas of abundant mononuclear cell infiltration with minimal interstitial fibrosis, and decreased or absent in areas of marked fibrosis. There was a significant correlation between MVD and interstitial fibrosis (p < 0.0001). TP mRNA was upregulated for all categories of CGN. TP was strongly expressed by mononuclear inflammatory cells and in most atrophic tubules. Each MVD and interstitial volume was significantly correlated with both the number of TP+ mononuclear cells and TP+ tubular cells, respectively (p < 0.0001). We have demonstrated an upregulation of TP and increase in MVD in areas of CTI in a variety of CGN. The up-regulation of TP may contribute to angiogenesis, which may play a critical role in the progression of interstitial fibrosis in CGN.

Expression levels of thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) in patients with gastrointestinal cancer

BACKGROUND

Thymidine phosphorylase (TP) is a key enzyme involved in pyrimidine nucleoside metabolism. Dihydropyrimidine dehydrogenase (DPD) is the major catabolic enzyme of 5-fluorouracil (5-FU). These are important enzymes in the pyrimidine salvage pathway and are considered to be key enzymes for determining the prognosis of patients with gastrointestinal cancer. In the present study, TP and DPD were quantified and evaluated in gastric and colorectal cancer.

PATIENTS AND METHODS

In 111 cases of malignancy, including 30 gastric cancers and 81 colorectal cancers, the expression levels of both TP and DPD in fresh-frozen samples from either tumor or adjacent normal tissue were quantified using enzyme-linked immunosorbent assay (ELISA). The relationships between TP or DPD expression levels in tumor tissues or adjacent normal tissues and clinicopathological factors were evaluated.

RESULTS

The TP expression levels in gastric or colorectal tumor tissues were found to be significantly higher than those in the adjacent normal tissue. Although the DPD expression levels in gastric tumor tissue were significantly higher than those in adjacent normal tissue, the DPD expression levels in colorectal tumor tissue were nearly identical to those in the adjacent normal tissue. The DPD expression levels in gastric tumor tissues were significantly higher than those in colorectal tumor tissues. The TP expression levels correlated significantly with the DPD expression levels in tumor or adjacent normal tissues. The DPD expression levels in tumor tissues significantly correlated with those in adjacent normal tissue.

CONCLUSION

The difference in DPD expressions between gastric and colorectal cancer tissues may reflect the organ specificity of the carcinomas and a difference in chemotherapeutic sensitivity to 5-FU or its analogs. The correlation between TP and DPD expression levels suggests the existence of a common regulatory pathway.

Combination of oral fluoropyrimidine and docetaxel: reappraisal of synergistic effect against gastric carcinoma xenografts

BACKGROUND

The synergistic antitumor effect of a combination of docetaxel and capecitabine is reported to be attributable to docetaxel-mediated up-regulation of thymidine phosphorylase (dThdPase).

MATERIALS AND METHODS

Intravenous docetaxel (15 mg/kg) was given to nude mice bearing xenografts of the gastric cancer cell lines MKN45 and MKN28. Mice were sacrificed on days 7, 10 and 22 and tumor samples were taken to measure the activities of thymidylate synthase, dihydropyrimidine dehydrogenase, dThdPase and orotate phosphoribosyltransferase. The efficacy of capecitabine or S-1, alone and in combination with docetaxel, was then evaluated in vivo. Docetaxel was administered intravenously on days 8 and 22 at 15 mg/kg, while capecitabine (269 mg/kg) or S-1 (7.5 mg/kg) were administered orally 5 times a week for 4 weeks.

RESULTS

Tumor regression was observed only for a combination of capecitabine and docetaxel against MKN28, while additive growth inhibition was obtained by the combination of docetaxel and both S-1 and capecitabine on MKN45 tumor xenografts. Induction of dThdPase activity was observed only for MKN45. The activity of no other enzyme was significantly affected following administration of docetaxel.

CONCLUSION

The combination of oral fluoropyrimidine and docetaxel showed augmented antitumor activity, but this may be attributed to mechanisms other than changes in 5-fluorouracil-metabolizing enzymes.

Interferons upregulate thymidine phosphorylase expression via JAK-STAT-dependent transcriptional activation and mRNA stabilization in human glioblastoma cells

Overexpression of the angiogenic enzyme thymidine phosphorylase (TP) in tumor cells and/or infiltrating macrophages correlates with increased microvessel density and poor prognosis in various tumor types including glioma. The present study examined how the TP gene expression is regulated by different types of interferons (IFNs) in human T98G and A172 glioblastoma cells. Both type I (alpha, beta) and type II (gamma) IFNs upregulated TP mRNA and protein expression while inhibiting cell proliferation. IFN-induced TP mRNA accumulation was not inhibited by the protein synthesis inhibitor cycloheximide, but was strongly blocked by the transcription inhibitor actinomycin D, as well as by transcription factor decoy oligodeoxynucleotides containing the putative IFN response element or the gamma-activated sequence in the TP promoter. The Janus kinase (JAK) inhibitor AG-490 blocked both IFN-induced STAT1 (signal transducers and activators of transcription 1) phosphorylation and TP expression. All IFNs increased the stability of TP mRNA as well. In addition, IFN-evoked TP enzyme activity enhanced the cytotoxicity of 5-fluorouracil (5-FU). These findings indicate that TP expression may be upregulated by IFNs via the JAK-STAT signaling pathway and both transcriptional and posttranscriptional mechanisms. Combined treatment with IFN and 5-fluorouracil may be a useful therapeutic strategy for malignant gliomas.

Thymidine phosphorylase profiles in nonmalignant and malignant pancreatic tissue. Potential therapeutic role of capecitabine on tumoral and endothelial cells and tumor-infiltrating macrophages

The drug capecitabine (CAP) is a thymidine Pi-deoxyribosyltransferase (TP) activated oral fluorpyrimidine that generates 5-fluorouracil (5-FU), preferentially, within tumors. Here, in 38 patients with pancreatic cancer we analyzed immunohistochemical TP expression in pancreatic cancer tissue (PCT) and adjacent nonmalignant pancreatic tissue (ANMPT). In addition, a correlation with the main clinical pathological features was made. Furthermore, TP-positive macrophages (MO) isolated from neoplastic tissue were determined. The mean of TP-positive epithelial cells and endothelial cells in terms of microvessel density was significantly higher in PCT than in ANMPT. Because pancreatic cancer is sensitive to 5-FU, TP-activated oral CAP in tumoral and endothelial cells and tumor infiltrating MO could increase the concentration of 5-FU at tumor site, thus resulting in an enhanced antitumor activity.

The inhibitory effect of disease-modifying anti-rheumatic drugs and steroids on gliostatin/platelet-derived endothelial cell growth factor production in human fibroblast-like synoviocytes

Gliostatin/platelet-derived endothelial cell growth factor (GLS/PD-ECGF) is known to have both angiogenic and arthritogenic activities. The purpose of this study was to investigate whether disease-modifying anti-rheumatic drugs (DMARDs) and steroids are involved in the regulation of GLS expression. Fibroblast-like synoviocytes (FLSs) obtained from patients with rheumatoid arthritis (RA) were cultured and stimulated by interleukin (IL)-1beta with or without DMARDs and steroids. The expression levels of GLS were determined using the reverse transcription-polymerase chain reaction and an ELISA. In cultured rheumatoid FLSs, the expression of GLS mRNA was significantly increased by stimulation with IL-1beta. By contrast, GLS mRNA levels in IL-1beta-stimulated FLSs were reduced by treatment with aurothioglucose (AuTG) and dexamethasone (DEX). These findings indicate that AuTG and DEX have anti-rheumatic activity, which is mediated via the suppression of GLS production. Neither methotrexate (MTX) nor sulfasalazine (SSZ) had a significant influence on GLS levels in our study.

Expression of thymidine phosphorylase correlates with microvessel density in prostate cancer

Angiogenesis in the growth and development of prostate cancer was the focus of this study. Various angiogenic factors and their clinicopathologic correlations with the progression of prostate cancer have been examined. Thymidine phosphorylase is identical to platelet-derived endothelial cell growth factor (TP/PD-ECGF) and has angiogenic activity. We investigated the expression of TP/PD-ECGF in prostate cancer and its association with angiogenesis or clinicopathologic findings in 81 cases with prostate cancer. Western blot analysis using a specific monoclonal antibody 654-1 revealed the existence of a 55 kDa TP/PD-ECGF protein in human prostate cancer tissue. Cancer tissue showed low-positive immunostaining in 32 cases (39.5%) and high positivity in 49 cases (60.5%). This protein expression indicated a statistically significant association with microvessel density (low vs. high TP/PD-ECGF expression group: mean +/- SD, 37.3+/-27.0 vs. 53.1+/-28.0 microvessels in three fields, p<0.05). No correlation was found between the expression of TP/PD-ECGF and nuclear grade, glandular differentiation, clinical stage or overall survival rate. TP/PD-ECGF may play an important role in tumor angiogenesis in prostate cancer tissues. Although the expression of TP/PD-ECGF was not correlated with clinical outcome in patients with prostate cancer, there remains the possibility that TP/PD-ECGF may support or modify the tumor growth through angiogenesis in cooperation with other factors.

Thymidine phosphorylase expression and efficacy of adjuvant doxifluridine in advanced colorectal cancer patients

To clarify the correlation between the expression level of thymidine phosphorylase (TP) and efficacy of doxifluridine (5'-DFUR) and 5-fluorouracil (5-FU), samples from 177 colorectal cancer patients who underwent curative resection were evaluated by immunohistochemical staining using a newly developed monoclonal antibody 1C6-203. Patients were randomly given either oral 5'-DFUR or 5-FU as postoperative adjuvant chemotherapy. In Dukes' C staged colon cancer patients treated with 5'-DFUR, better survival was observed in the high TP patients than the low TP patients (P=0.025 by the log-rank test). The observed 5-year survival rates were 91.2 and 74.8%, respectively. No correlation between TP expression and patient prognosis was detected in the 5-FU group. In Dukes' C stage colon patients with high TP expression, the 5'-DFUR group had slightly better survival than the 5-FU group. These findings suggest that TP may be a chemosensitive marker for 5'-DFUR as postoperative adjuvant chemotherapy for advanced colon cancer patients.

Phase II clinical trial of capecitabine in ovarian carcinoma recurrent 6–12 months after completion of primary chemotherapy, with exploratory TS, DPD, and TP correlates: a Gynecologic Oncology Group study

PURPOSE

A phase II trial was conducted to evaluate the anti-tumor activity and adverse effects of capecitabine in women with measurable platinum-sensitive ovarian cancer or platinum-sensitive primary peritoneal cancer and to explore the ability of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and thymidine phosphorylase (TP) to predict response and toxicities.

EXPERIMENTAL DESIGN

Patients were treated with a daily starting dose of 2500 mg/m2/day (divided in two doses given every 12 h) for 14 days of each 21-day cycle. Genotyping in the 5' and 3' ends of TS was performed in DNA from 23/23 pre-treatment blood specimens. Relative gene expression of TS, DPD, and TP was quantified in 18/21 paraffin-embedded tumor specimens.

RESULTS

Of the 27 patients enrolled on study, 2 were never treated leaving 25 patients evaluable. Two patients (8.0%) achieved a partial response, 13 (52%) exhibited stable disease, 5 (20%) displayed increasing disease, and response could not be assessed in 5 (20%). The median time to progression and survival was 3.9 and 21.2 months, respectively. The most common serious toxicities were nausea/vomiting, gastrointestinal, and dermatological. There was one treatment-related death. TS expression was associated with severe nausea/vomiting (P = 0.039), but not with other severe toxicities. TS genotype or expression of DPD or TP was not associated with any of the severe toxicities.

CONCLUSIONS

Based on the low response rate, this trial was closed after the first stage of accrual, the drug was not selected for further study in this patient population, and biomarker associations with response could not be assessed.

Importance of thymidine phosphorylase expression in tumor stroma as a prognostic factor in patients with advanced colorectal carcinoma

Thymidine phosphorylase (TP) is a unique enzyme involved not only in angiogenesis, but in 5-fluorouracil (5-FU) metabolism as well. TP is produced by both tumor and stromal cells. The aim of this study was to reveal the clinical implication of TP localization in tumor tissues. Advanced colorectal cancer specimens (n=97) were prepared for immunohistochemical staining using monoclonal antibodies against TP, p53, vascular endothelial growth factor (VEGF), factor VIII, CD68 and thymidylate synthase (TS). Clinicopathological factors and the clinical prognosis were examined for each indicator. High tumor TP expression and high stromal TP expression were observed in 38% (36/95 cases) and 49% (47/95 cases) of the cases, respectively. High tumor TP expression tended to correlate with microvessel density (MVD) (p=0.0511). Among patients who underwent curative resection, those with high stromal TP expression had a favorable prognosis (p=0.0127). High stromal TP status was also a strong prognostic factor in the group receiving adjuvant 5-FU derivatives (p=0.0222). TP produced by tumor cells has a stimulatory effect on tumor angiogenesis, while that produced by stromal cells plays an entirely different role. The latter may enhance the anticancer effect of 5-FU via its catalyzed function.

Thymidine phosphorylase expression in patients with chronic viral hepatitis

BACKGROUND

The role of thymidine phosphorylase (TP), an angiogenic factor, in chronic viral hepatitis is unclear. In the present study we investigated TP expression in chronic viral hepatitis due to hepatitis B virus (HBV) and hepatitis C virus (HCV) infection.

METHODOLOGY

Fifty-eight patients suffering from chronic viral hepatitis and 13 cirrhotic patients due to either HBV or HCV were studied. TP expression was investigated using a standard immunohistochemical technique and the specific antibody P-GF.44C.

RESULTS

The pattern of TP staining was predominantly nuclear, or mixed nuclear/cytoplasmic, but no significant difference in such expression was noted between chronic hepatitis B and C: nuclear immunostaining, t=0.0616, p=0.9511; cytoplasmic immunostaining, t=0.5188, p=0.6060. There was, however, a marked difference in TP expression between patients with chronic hepatitis B/C and cirrhosis. Notably, this finding applied to both nuclear (p=0.00754, p=0.0143, respectively) and cytoplasmic (p=0.000091, p=0.000031, respectively) expression.

CONCLUSION

These observations indicate that TP expression, although linked to liver cirrhosis, may not be virus-related.

Phase II trial of cisplatin and capecitabine in patients with squamous cell carcinoma of the head and neck, and correlative study of angiogenic factors

The combination of cisplatin and capecitabine was evaluated in patients with recurrent or unresectable squamous cell carcinoma of the head and neck (HNSCC), and outcome parameters were correlated with the expression of thymidine phosphorylase (TP), thymidilate syntetase (TS), vascular endothelial growth factor receptor (VEGFR) 1–3, and microvessel density (MVD). Patients with recurrent or unresectable HNSCC were eligible if they had received prior neoadjuvant chemotherapy, concurrent chemo-radiotherapy, or no prior systemic therapy. Patients received cisplatin (75 mg m⁻² day 1), and capecitabine (2000 mg m⁻² day 1–14) every 3 weeks. A total of 41 patients received 194 cycles. In all, 16 complete responses (39%) and 12 partial responses (29%) were documented, for an overall response rate of 68% (95% CI, 53–80%). Grade 3–4 uncomplicated neutropenia was documented in five subjects. Asthenia, anorexia, hand–foot syndrome, and constipation were the most frequent nonhaematologic events. Median progression-free and overall survival were 6.4 and 12.6 months. Cytoplasmic TP expression was more prevalent in patients with a laryngeal location vs other, and in patients with a recurrence vs primary disease. Microvessel density count was higher in patients with recurrent vs primary disease. The combination of cisplatin and capecitabine is effective in recurrent or unresectable HNSCC, and shows a manageable toxicity.

Upregulation of platelet derived endothelial cell growth factor/thymidine phosphorylase by interferon alpha

Thymidine phosphorylase (TP) catalyzes the phosphorolytic cleavage of thymidine to thymine and deoxyribose-1-phosphate. TP, which is overexpressed in a wide variety of solid tumors, is involved in the activation and inactivation of fluoropyrimidines. TP is known to be regulated by several cytokines and interferons. In our HT29 cell line the TP mRNA and activity expression increased 2-3 fold after treatment with interferon alpha.

Sex steroid-dependent angiogenesis in uterine endometrial cancers

In general, tumors induce angiogenic factors specific to them, which leads to angiogenesis with advancement. However, angiogenesis in uterine endometrial cancers is complicated because hormone dependency in growth also modifies the angiogenic potential. Therefore, anti-angiogenic therapy for tumor dormancy in uterine endometrial cancers must be thoroughly considered. The upstream of vascular endothelial growth factor (VEGF) gene conserves estrogen-responsive elements. Progesterone primed with estrogen induces thymidine phosphorylase (TP) in uterine endometrium. Sex steroid-dependent VEGF and TP are highly expressed in cases of early stage and well-differentiated uterine endometrial cancers, and basic fibroblast growth factor (bFGF) in cases of advanced and poorly differentiated uterine endometrial cancers. A transcriptional factor for angiogenesis, ETS-1, is linked to VEGF in well-differentiated uterine endometrial cancers, and to bFGF in poorly differentiated uterine endometrial cancers. Therefore, even if dedifferentiation and angiogenic switching occur due to advancement and long-term hormone therapy, the inhibition of ETS-1 along with main angiogenic factors might be an effective strategy to suppress uterine endometrial cancers as a novel anti-angiogenic therapy.

Capecitabine plus docetaxel combination chemotherapy for metastatic breast cancer

Doxifluridine(5'-DFUR)is converted to its metabolite 5-FU by the enzyme thymidine phosphorylase(TP). TP is expressed significantly higher in tumor tissue than in normal tissue. Capecitabine(N4-pentoxylcarbonyl -5'-deoxy-5-fluorocytidine)is a pro-drug of 5'-DFUR and a novel fluoropyrimidine carbamate that is converted to 5-FU preferentially in tumor tissue through a three-step enzymatic cascade. Expression of TP in tumor tissue may clinically predict efficacy of capecitabine. Induction of TP activity has brought about enhancement of capecitabine efficacy by taxanes in human cancer xenografts. In addition, a phase III study directly comparison docetaxel monotherapy and docetaxel plus capecitabine has been conducted for metastatic breast cancer patients who had received anthracyclines. The overall response rate of the combination group was 42%(n=255), and that of the monotherapy group was 30%(n=256)(p=0.006). The primary endpoints were time to disease progression, and time to treatment failure, and these parameters were superior in the combination arm than in the single arm, suggesting that capecitabine sensitization by docetaxel might be a new approach to breast cancer treatment.

[Expressions of thymidine phosphorylase, thymidylate synthase and dihydropyrimidine dehydrogenase in breast cancer and their correlations with prognosis]

OBJECTIVE

To study the expression of thymidine phosphorylase (TP), thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) mRNA in breast cancer and its correlation with prognosis.

METHODS

Expression levels of TP, TS and DPD mRNA in 86 micro-selected breast cancer tissues and 9 normal breast tissues were detected by real-time quantitative PCR.

RESULTS

The median expression levels of TP, TS and DPD mRNA in tumor tissue and in normal tissues were 16.54, 0.38, 2.47 and 11.75, 0.25, 8.33, respectively, there were no significant differences (P >0.05). The expression levels of TP, TS and DPD mRNA showed no association with tumor size, lymph node metastasis, pathological grade and clinical stage, except that of DPD showed a negative association with patients' ages. There was no significant difference in disease-free survival or overall survival between the patients with high and low TP or DPD mRNA levels. Disease-free survival tends to be better in the patients with low TS mRNA level than those with high TS mRNA, but the difference was not significant (P=0.069), while the overall survival showed a statistically difference (59.00 month and 70.30 month) (P=0.0496).

CONCLUSION

The expression level of TS mRNA may serve as a prognostic marker for breast cancer patients.

Thymidine phosphorylase and fluoropyrimidines efficacy: a Jekyll and Hyde story

Thymidine phosphorylase (TP) is markedly upregulated in many solid tumors such as colorectal, breast and kidney cancers. Because TP is identical to platelet-derived endothelial cell growth factor, this enzyme is believed to have angiogenic properties, although the precise mechanisms through which it promotes neoangiogenesis are still not fully elucidated. TP is involved as well in the tumoral activation of widely prescribed pyrimidine-derived antimetabolites such as 5-FU, 5'-dFUR and newly marketed capecitabine, and, in this respect, has been presented as a determinant to fluoropyrimidine efficacy in various in vitro and in vivo models. This dual and apparently contradictory role that TP plays yields inconsistent results in the study of relationships between this enzyme expression and clinical outcome in patients treated with fluoropyrimidine analogs. Some studies have shown that high tumoral TP expression was associated indeed with poor clinical response and tumor aggressiveness. Conversely, other reports demonstrated that tumoral TP could be considered as a good response factor in patients exposed to fluoropyrimidine drugs. TP exhibits then its more favorable profile, probably in converting 5-FU to active metabolites responsible for its efficacy as antitumor agent. As a result, TP-targeting as a rationale for anticancer therapy remains unclear. TP inhibitors are being synthesized as an attempt to fight neoangiogenesis, whereas promising new strategies such as taxotere/capecitabine or radiotherapy/fluoropyrimidines associations aim at nothing but boosting TP activity to optimize drug activation in tumors. Such a discrepancy illustrates the complexity of understanding and predicting the exact role of TP in the clinical outcome of patients exposed to fluoropyrimidines, a group of major drugs extensively used in oncology.