Cytokines induce thymidine phosphorylase expression in tumor cells and make them more susceptible to 5'-deoxy-5-fluorouridine

Vesicular IFN-γ as a cooperative attacker to enhance anti-cancer effect of 5-fluorouracil via thymidine phosphorylase upregulation and tumor microenvironment normalization

On the basis of immuno-modulating effect and upregulating the activity of thymidine phosphorylase (TP), interferon-γ (IFN-γ) as a cooperative attacker was explored to enhance the anticancer activity of 5-fluorouracil (5-FU). We designed and prepared a self-assembled nano-vesicular system IFN-γ-EDP formulated by amphiphilic poly((polyethylene glycol)(dodecylphosphoethanolamine)phosphazene) (EDP) to entrap IFN-γ in the hydrophilic cavity. The IFN-γ-EDP vesicles allowed IFN-γ to accumulate at the tumor site and be taken up by tumor cells, resulting in significantly upregulated expression level of TP, distinct inhibition of cell growth, more cellular apoptosis and more serious cell cycle arrest when administrated combined with 5-FU. Moreover, IFN-γ-EDP could normalize the tumor microenvironment by enhancing the CD4⁺ and CD8⁺ T cell populations, promoting the IL-12 secretion and suppressing the IL-10 secretion in tumor. As a consequence, the combination therapy of IFN-γ-EDP with 5-FU achieved remarkably enhanced tumor inhibition rate of 56.9% against CT26 colorectal cancer.

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy

This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

Non-Coding Micro RNAs and Hypoxia-Inducible Factors Are Selenium Targets for Development of a Mechanism-Based Combination Strategy in Clear-Cell Renal Cell Carcinoma-Bench-to-Bedside Therapy

Durable response, inherent or acquired resistance, and dose-limiting toxicities continue to represent major barriers in the treatment of patients with advanced clear-cell renal cell carcinoma (ccRCC). The majority of ccRCC tumors are characterized by the loss of Von Hippel⁻Lindau tumor suppressor gene function, a stable expression of hypoxia-inducible factors 1α and 2α (HIFs), an altered expression of tumor-specific oncogenic microRNAs (miRNAs), a clear cytoplasm with dense lipid content, and overexpression of thymidine phosphorylase. The aim of this manuscript was to confirm that the downregulation of specific drug-resistant biomarkers deregulated in tumor cells by a defined dose and schedule of methylselenocysteine (MSC) or seleno-l-methionine (SLM) sensitizes tumor cells to mechanism-based drug combination. The inhibition of HIFs by selenium was necessary for optimal therapeutic benefit. Durable responses were achieved only when MSC was combined with sunitinib (a vascular endothelial growth factor receptor (VEGFR)-targeted biologic), topotecan (a topoisomerase 1 poison and HIF synthesis inhibitor), and S-1 (a 5-fluorouracil prodrug). The documented synergy was selenium dose- and schedule-dependent and associated with enhanced prolyl hydroxylase-dependent HIF degradation, stabilization of tumor vasculature, downregulation of 28 oncogenic miRNAs, as well as the upregulation of 12 tumor suppressor miRNAs. The preclinical results generated provided the rationale for the development of phase 1/2 clinical trials of SLM in sequential combination with axitinib in ccRCC patients refractory to standard therapies.

A mitochondrial-targeted prodrug for NIR imaging guided and synergetic NIR photodynamic-chemo cancer therapy

Nontoxic prodrugs, especially activated by tumor microenvironment, are urgently required for reducing the side effects of cancer therapy. And combination of chemo-photodynamic therapy prodrugs show effectively synergetic therapeutic efficiency, however, this goal has not been achieved in a single molecule. In this work, we developed a mitochondrial-targeted prodrug PNPS for near infrared (NIR) fluorescence imaging guided and synergetic chemo-photodynamic precise cancer therapy for the first time. PNPS contains a NIR photosensitizer (NPS) and an anticancer drug 5'-deoxy-5-fluorouridine (5'-DFUR). These two parts are linked and caged through a bisboronate group, displaying no fluorescence and very low cytotoxicity. In the presence of H2O2, the bisboronate group is broken, resulting in activation of NPS for NIR photodynamic therapy and activation of 5'-DFUR for chemotherapy. The activated NPS can also provide a NIR fluorescence signal for monitoring the release of activated drug. Taking advantage of the high H2O2 concentration in cancer cells, PNPS exhibits higher cytotoxicity to cancer cells than normal cells, resulting in lower side effects. In addition, based on its mitochondrial-targeted ability, PNPS exhibits enhanced chemotherapy efficiency compare to free 5'-DFUR. It also demonstrated a remarkably improved and synergistic chemo-photodynamic therapeutic effect for cancer cells. Moreover, PNPS exhibits excellent tumor microenvironment-activated performance when intravenously injected into tumor-bearing nude mice, as demonstrated by in vivo fluorescence imaging. Thus, PNPS is a promising prodrug for cancer therapy based on its tumor microenvironment-activated drug release, synergistic therapeutic effect and "turn-on" NIR imaging guide.

Thymidine phosphorylase: A potential new target for treating cardiovascular disease

We recently found that thymidine phosphorylase (TYMP), also known as platelet-derived endothelial cell growth factor, plays an important role in platelet activation in vitro and thrombosis in vivo by participating in multiple signaling pathways. Platelets are a major source of TYMP. Since platelet-mediated clot formation is a key event in several fatal diseases, such as myocardial infarction, stroke and pulmonary embolism, understanding TYMP in depth may lead to uncovering novel mechanisms in the development of cardiovascular diseases. Targeting TYMP may become a novel therapeutic for cardiovascular disorders. In this review article, we summarize the discovery of TYMP and the potential molecular mechanisms of TYMP involved in the development of various diseases, especially cardiovascular diseases. We also offer insights regarding future studies exploring the role of TYMP in the development of cardiovascular disease as well as in therapy.

Recent discovery of non-nucleobase thymidine phosphorylase inhibitors targeting cancer

Thymidine phosphorylase (TP, EC 2.4.2.4), an enzyme involved in pyrimidine salvage pathway, is identical to platelet-derived endothelial cell growth factor (PD-ECGF) and gliostatin. It is extremely upregulated in a variety of solid tumours. The TP amplification is associated with concomitant overexpression of many angiogenic factors such as matrix metalloproteases (MMPs), interleukins (ILs), vascular endothelial growth factor (VEGF) etc., resulting in promotion of angiogenesis and cancer metastasis. In addition, overshooting TP level protects tumour cells from apoptosis and helps cell survival. Thus, TP is identified as a prime target for developing novel anticancer therapies. Pioneering research activities investigated a large number of TP inhibitors, most of which are pyrimidine or purine analogues. Recently, an array of structurally diverse non-nucleobase derivatives was designed, synthesized and established as promising TP inhibitors. This review, following an outline on the TP structure and functions, gives an overview of the recent advancement of various non-nucleobase TP inhibitors as novel anti-cancer agents.

Generation of a patterned co-culture system composed of adherent cells and immobilized nonadherent cells

Patterned co-culture is a promising technique used for fundamental investigation of cell-cell communication and tissue engineering approaches. However, conventional methods are inapplicable to nonadherent cells. In this study, we aimed to establish a patterned co-culture system composed of adherent and nonadherent cells. Nonadherent cells were immobilized on a substrate using a cell membrane anchoring reagent conjugated to a protein, in order to incorporate them into the co-culture system. Cross-linked albumin film, which has unique surface properties capable of regulating protein adsorption, was used to control their spatial localization. The utility of our approach was demonstrated through the fabrication of a patterned co-culture consisting of micropatterned neuroblastoma cells surrounded by immobilized myeloid cells. Furthermore, we also created a co-culture system composed of cancer cells and immobilized monocytes. We observed that monocytes enhanced the drug sensitivity of cancer cells and its influence was limited to cancer cells located near the monocytes. Therefore, the incorporation of nonadherent cells into a patterned co-culture system is useful for creating culture systems containing immune cells, as well as investigating the influence of these immune cells on cancer drug sensitivity.

STATEMENT OF SIGNIFICANCE

Various methods have been proposed for creating patterned co-culture systems, in which multiple cell types are attached to a substrate with a desired pattern. However, conventional methods, including our previous report published in Acta Biomaterialia (2010, 6, 526-533), are unsuitable for nonadherent cells. Here, we developed a novel method that incorporates nonadherent cells into the co-culture system, which allows us to precisely manipulate and study microenvironments containing nonadherent and adherent cells. Using this technique, we demonstrated that monocytes (nonadherent cells) could enhance the drug sensitivity of cancer cells and that their influence had a limited effective range. Thus, our technique is useful for recreating complex tissues in order to investigate cellular interactions involving nonadherent cells.

Multicomponent Coculture System of Cancer Cells and Two Types of Stromal Cells for In Vitro Evaluation of Anticancer Drugs

In vitro evaluation of anticancer drugs using cancer cells has long been performed for the development of novel drugs and the selection of effective drugs for different patients. Recent studies have suggested that tumor stromal cells affect the drug sensitivity of cancer cells; however, most conventional culture systems for drug evaluation lack stromal cells. In this study, we fabricated a multicomponent coculture system that takes account of cancer-stroma interactions for drug evaluation. In this system, small-cell and nonsmall-cell lung cancer cells embedded in collagen gel were cocultured with two types of stromal cells, including stromal fibroblasts and proinflammatory cytokine-secreting monocytes, thus recreating the in vivo cancer microenvironment. Cancer drug sensitivity was significantly altered by the presence of stromal cells. Fibroblasts induced resistance of cancer cells to anticancer drugs. Monocytes induced the upregulation of thymidine phosphorylase in cancer cells, promoting the conversion of an anticancer prodrug to a cytotoxic drug, and consequently enhanced the sensitivity of cancer cells to the anticancer prodrug. These results clearly show the importance of incorporating stromal cells into culture systems for drug evaluation. Our system will help to improve the accuracy of in vitro drug evaluation and provide useful information for the in vitro recreation of cancer microenvironments.

Biomodulation of capecitabine by paclitaxel and carboplatin in advanced solid tumors and adenocarcinoma of unknown primary

Paclitaxel and carboplatin upregulate thymidine phosphorylase and thus may provide synergistic antitumor activity in combination with capecitabine (CTX). We, therefore, performed a phase I/II study of CTX. In the phase I study, patients with advanced solid tumors received carboplatin on day 1, paclitaxel on days 1, 8, 15 and capecitabine orally twice a day on days 8-21, every 4 weeks. Phase II patients with advanced adenocarcinoma of unknown primary (ACUP) were treated at the maximal tolerable dose. The phase I study enrolled 29 patients evaluable for dose limiting toxicity. The recommended phase II dose was capecitabine 750 mg/m(2) bid, paclitaxel 60 mg/m(2)/week and carboplatin AUC of 6. There were 9 confirmed responses, 5 partial responses and disease stabilization >3 months in 14 patients. The phase II study was prematurely terminated at 25 patients due to cessation of funding. The objective response rate was 32 % (95 % CI 0.15-0.54), the median progression-free survival 5.5 months (95 % CI 2.8-10.8 months) and the median overall survival 10.8 months (95 % CI 6.0-32.0 months). CTX demonstrated acceptable tolerability and antitumor activity. At the recommended dose level in patients with ACUP, this regimen showed encouraging preliminary activity.

Thymidine phosphorylase is both a therapeutic and a suicide gene in a murine model of mitochondrial neurogastrointestinal encephalomyopathy

Suicide gene therapy (SGT) is a promising strategy for treating cancer. In this work, we show that thymidine phosphorylase (TP) deficiency, the underlying genetic defect in mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), presents an opportunity to apply SGT using capecitabine, a commonly used prodrug that is converted into 5-fluorouracil by TP. Using an immortalised B-lymphoblastoid cell line from a patient with MNGIE, the tumourigenic EL-4 cell line, lentiviral vectors encoding TP and a double knockout (Tymp(-/-)Upp1(-/-)) murine model, we found that EL-4 cell-derived TP(+) tumours were exquisitely sensitive to capecitabine and generated a significant local bystander effect. In addition, we detected a spontaneous cytolytic immune response in a significant fraction of the animals surviving more than 20 days after termination of the therapy. These data indicate that, in individuals lacking TP expression, TP is a highly specific suicide gene, which can be used to treat tumours that could hypothetically arise in MNGIE patients undergoing gene therapy, as these tumours will likely originate from the gene-modified cells and will be selectively targeted by capecitabine. These observations have important implications for gene therapy for MNGIE.

Thymidine phosphorylase regulates the expression of CXCL10 in rheumatoid arthritis fibroblast-like synoviocytes

OBJECTIVE

Thymidine phosphorylase (TP) in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS) is induced by tumor necrosis factor α (TNFα) and other cytokines that have been reported to be major inflammation mediators in RA. We previously demonstrated that TP plays an important role in angiogenesis and tumor growth, invasion, and metastasis. The aim of this study was to investigate whether the role of TP in the pathogenesis of RA is similar to its role in tumors.

METHODS

In FLS obtained from 2 patients with RA, the expression of TP, interferon-γ (IFNγ)-inducible protein 10 (CXCL10), and other cytokines was measured by quantitative real-time polymerase chain reaction, immunoblotting, and enzyme-linked immunosorbent assays. Microarray analysis was performed using FLS transfected with TYMP complementary DNA and treated with a TP inhibitor.

RESULTS

The expression of TP in FLS was up-regulated by TNFα, interleukin-1β (IL-1β), IL-17, IFNγ, and lipopolysaccharide. Microarray analysis of FLS overexpressing TP identified CXCL10 as a thymidine phosphorylase-related gene. The expression of CXCL10 was induced by TNFα, and this induction was suppressed by TYMP small interfering RNA and TP inhibitor. Furthermore, the combination of TNFα and IFNγ synergistically augmented the expression of TP and CXCL10. TP-induced CXCL10 expression was suppressed by the antioxidant EUK-8. In the synovial tissue of patients with RA, TP levels were significantly correlated with CXCL10 expression.

CONCLUSION

The combination of TNFα and IFNγ strongly induced the expression of thymidine phosphorylase in RA FLS. The induction of thymidine phosphorylase enhanced the expression of CXCL10, which may contribute to the Th1 phenotype and bone destruction observed in RA.

Factors predicting the response to oral fluoropyrimidine drugs: a phase II trial on the individualization of postoperative adjuvant chemotherapy using oral fluorinated pyrimidines in stage III colorectal cancer treated by curative resection (ACT-01 Study)

We evaluated the predictive relevance of several biomarkers on the survival of patients with stage III colorectal cancer treated with adjuvant chemotherapy of oral fluoropyrimidines. This was a multicenter phase II trial on adult patients with histologically confirmed resected stage III (Dukes' C) colorectal cancer. Patients received oral doxifluridine (800 mg/m2/day) in 3 divided doses, or oral uracil/tegafur (UFT) (400 mg/m2/day) in 2 divided doses for 5 days, every 7 days for 12 months with a 5-year follow-up. Outcome measures were disease-free survival and tissue markers [thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD) protein levels and TP, DPD, thymidylate synthase (TS) and orotate phosphoribosyltransferase (OPRT) mRNA levels in tumor samples and TS tandem-repeat type in blood samples]. There was a significant association between the intratumoral TP/DPD enzyme ratio and disease-free survival when the model included the drug, the parameter and the interactions between them [hazard ratio (HR)=2.76; P=0.00469]. The 5-year disease-free survival rate was statistically significantly higher in patients with high TP/DPD ratios [median ≥2.63: 71.9%; 95% confidence interval (CI) 61.4-80.0] compared to patients with low TP/DPD ratios (<2.63: 57.0%; 95% CI 46.3-66.3) (log-rank P=0.0277) following adjuvant therapy with oral fluoropyrimidines. No significant association was observed between the intratumoral TP/DPD enzyme ratio (cut-off value 2.0) and the disease-free survival rate in the doxifluridine group; primary endpoint (log-rank P=0.6850). The magnitude of the intratumoral TP/DPD enzyme ratio may be a potential indicator for the individualization of postoperative adjuvant chemotherapy with oral fluoropyrimidines for stage III colorectal cancer.

Phase ii trial of a metronomic schedule of docetaxel and capecitabine with concurrent celecoxib in patients with prior anthracycline exposure for metastatic breast cancer

BACKGROUND

This phase ii clinical trial examined the activity of a metronomic dosing schedule of docetaxel and capecitabine chemotherapy in patients with advanced breast cancer. Patients also received daily oral celecoxib in an effort to improve outcome measures and to ameliorate some of the common side effects of chemotherapy.

METHODS

Patients received docetaxel at a starting dose of 15 mg/m² weekly, oral capecitabine 1250 mg/m² once daily, and oral celecoxib 200 mg twice daily. The primary endpoint was clinical benefit: percentage of patients experiencing either an objective response or stable disease (sd) for more than 6 months. In the absence of significant neutropenia, the dose of docetaxel was escalated after 4 and 8 weeks of treatment. Therapy was given until disease progression or development of unacceptable toxicity. The level of thymidine phosphorylase expression in peripheral white blood cells of patients was measured before and during treatment to determine the effect on this capecitabine-activating enzyme.

RESULTS

Of 47 patients enrolled, 38 (81%) completed treatment to a disease endpoint. No complete responses were achieved, but 13 of the 38 patients (34%) experienced a partial response, and another 3 patients (8%) experienced sd for more than 6 months. The clinical benefit rate was therefore 42% (95% confidence interval: 27% to 57%). The median time to disease progression for all evaluable patients was 3.6 months (range: 0.9-21.7 months). The most common nonhematologic toxicities were diarrhea, plantar- palmar erythrodysesthesia, fatigue, mucositis, and vomiting. Most patients (89%) received combination chemotherapy until disease progression.

CONCLUSIONS

The present study demonstrates that metronomic docetaxel-capecitabine chemotherapy with daily celecoxib can produce significant anticancer activity, with predictable toxicity. Efficacy fell short of expectations, with outcome measures being similar to those obtained when the study agents are given in conventional dosing. Furthermore, there is mounting evidence to indicate that a low dose of taxanes fails to induce thymidine phosphorylase expression, an effect believed to be important in achieving therapeutic synergism when taxanes are given concurrently with capecitabine.

Platelet derived endothelial cell growth factor/thymidine phosphorylase enhanced human IgE production

BACKGROUND

Angiogenesis is one pathogenesis of allergic airway disease.

METHODS

A potent angiogenic factor is platelet-derived endothelial cell growth factor (PD-ECGF), also known as thymidine phosphorylase (TP) in the field of cancer-associated research. Vascular endothelial growth factor (VEGF) is another representative angiogenic factor. Both factors were added to the culture system of human peripheral blood mononuclear cells (PBMC) with IL-4 and anti-CD40 monoclonal antibody (mAb). Total IgE levels in the supernatants and signal transduction of stimulated PBMC were evaluated.

RESULTS

Addition of PD-ECGF enhances in vitro IgE production by PBMC in the presence of IL-4 and anti-CD40 mAb, but VEGF does not enhance IgE production. Although PD-ECGF catalyzes the reversible phosphorolysis of thymidine to 2-deoxy-D-ribose-1-phosphate (2DDR), treatment of 2DDR has no effect on IgE production by human PBMC. Both IL-4 and anti-CD40 mAb induce PD-ECGF by human PBMC. Thymidine phosphorylase inhibitor (TPI), 5-chloro-6-[1- (2-iminopyrrolidinyl) methyl] uracil hydrochloride reduce IgE production via blocking of STAT6- phosphorylation.

CONCLUSIONS

Taken together, these results suggest TP involvement in the enhancement of IgE production and suggest that TPI is a novel strategy against IgE-related allergic disease.

Activation of Stat1, IRF-1, and NF-kappaB is required for the induction of uridine phosphorylase by tumor necrosis factor-alpha and interferon-gamma

Uridine phosphorylase (UPase) has been shown to be induced in various human and murine tumors and could potentially serve as a specific target for the modulation of tumor-selectivity of fluoropyrimidines. However, the signaling mechanisms underlying the regulation of UPase gene expression have not been determined. In this study, we investigated the effects of IFN-gamma on the regulation of TNF-alpha-induced UPase activity and have uncovered the molecular mechanisms of this potentiation, utilizing murine EMT6 breast cancer cells. Our data has shown that IFN-gamma can significantly increase UPase mRNA expression and the enzymatic activity induced by TNF-alpha in a dose-dependent manner, resulting in an enhanced sensitivity to 5-fluorouracil (5-FU) and 5'-Deoxy-5-fluorouridine (5'DFUR). We have previously shown that TNF-alpha activates NF-kappaB through increased translocation of NF-kappaB p65 from the cytoplasm into the nuclei. Exposure to IFN-gamma mainly affects nuclear IRF-1 and STAT1 in EMT6, but inhibits NF-kappaB p65 activity, indicating that the cooperative stimulation was the result of the independent activation of NF-kappaB, STAT1 and IRF-1 transcriptional factors through binding to their unique sites in the UPase promoter. Notably, the activation of NF-kappaB and STAT1 in human breast tissues is consistent with UPase activity; signifying their role in the up-regulation of the UPase gene expression in human tumors.

High expression of thymidine phosphorylase in basal-like breast cancers: Stromal expression in EGFR- and/or CK5/6-positive breast cancers

Expression of the estrogen receptor (ER), the progesterone receptor (PgR) or the human epidermal growth factor receptor-2 (HER2) in tumors is a good prognostic marker for breast cancer patients. However, approximately 15-20% of breast cancer patients have triple-negative breast cancer (TNBC; negative for ER, PgR and HER2), and efficient therapeutic modalities for these patients are under investigation. We focused on thymidine phosphorylase (TP), an enzyme metabolizing 5'-DFUR, an intermediate of capecitabine, to 5-fluorouracil in order to investigate the application of well-known therapeutics for TNBC. Results of a gene expression analysis showed that TP expression in TNBC and basal-like breast cancer (BLBC) was higher than that of other subtypes. Immunohistochemically, the high expression of TP in TNBC and BLBC reflected expression in stromal but not tumor cells. Notably, a high TP expression was observed in the stromal cells of EGFR- and/or CK5/6-positive breast tumors. Our present results showing a high expression of TP in BLBC indicate that capecitabine-based chemotherapy would be of benefit for patients with TNBC.

Effects of interferon-alpha on thymidine phosphorylase expression and apoptosis in human hepatocellular carcinoma SMMC-7721 cells

AIM: To investigate the effects of interferon-alpha (IFN-α) on thymidine phosphorylase (TP) expression and apoptosis in human hepatocellular carcinoma SMMC-7721 cells.

METHODS: The expression of TP mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). The expression of TP protein was evaluated by immunocytochemistry. The percentage of apoptotic cells was measured by flow cytometry.

RESULTS: IFN-α upregulated the expression of TP mRNA in a dose-dependent manner in SMMC-7721 cells. IFN-α at a dose of 5000 or 10 000 kU/L induced a 3-fold upregulation of TP mRNA compared to non-treated cells (P < 0.05). Compared with non-treated cells, the intensity of TP staining and the number of TP-positive cells significantly increased in IFN-α treated cells (5000 or 10 000 kU/L). However, no significant difference was found in the percentage of apoptotic cells between IFN-α (10 000 kU/L)-treated cells and non-treated cells (6.42% ± 3.66% vs 7.19% ± 2.76%, P > 0.05).

CONCLUSION: IFN-α at appropriate doses may upregulate the expression of TP mRNA and protein and antagonize TP-induced inhibition of apoptosis in human hepatocellular carcinoma cells.

The dual role of thymidine phosphorylase in cancer development and chemotherapy

Thymidine phosphorylase (TP), also known as "platelet-derived endothelial cell growth factor" (PD-ECGF), is an enzyme, which is upregulated in a wide variety of solid tumors including breast and colorectal cancers. TP promotes tumor growth and metastasis by preventing apoptosis and inducing angiogenesis. Elevated levels of TP are associated with tumor aggressiveness and poor prognosis. Therefore, TP inhibitors are synthesized in an attempt to prevent tumor angiogenesis and metastasis. TP is also indispensable for the activation of the extensively used 5-fluorouracil prodrug capecitabine, which is clinically used for the treatment of colon and breast cancer. Clinical trials that combine capecitabine with TP-inducing therapies (such as taxanes or radiotherapy) suggest that increasing TP expression is an adequate strategy to enhance the antitumoral efficacy of capecitabine. Thus, TP plays a dual role in cancer development and therapy: on the one hand, TP inhibitors can abrogate the tumorigenic and metastatic properties of TP; on the other, TP activity is necessary for the activation of several chemotherapeutic drugs. This duality illustrates the complexity of the role of TP in tumor progression and in the clinical response to fluoropyrimidine-based chemotherapy.

A phase I dose escalation study of a pharmacobiologically based scheduling of capecitabine and mitomycin C in patients with gastrointestinal malignancies

BACKGROUND

Mitomycin C (MMC) produces significant upregulation of thymidine phosphorylase, a principal determinant of the therapeutic index of capecitabine-based treatment, starting 4-6 days after treatment. On the basis of the time-dependency of this upregulation, we performed a phase I dose escalation study of capecitabine and MMC in patients with gastrointestinal malignancies.

METHODS

A total of 29 patients with advanced gastrointestinal malignancies received MMC at 6 mg/m2 on day 1 and capecitabine escalated in four successive patient cohorts of doses 500-1,000 mg/m2/day twice daily on days 8-21, every 28 days. MMC was capped at 36 mg/m2.

RESULTS

A total of 29 patients were enrolled and 90% had at least one prior treatment in the metastatic setting. There was one DLT, grade 3 hand and foot syndrome, at dose level four. The most common toxicity was fatigue (61%). No patients experienced grade 4 toxicities. Nine patients experienced prolonged stability of disease.

CONCLUSION

Capecitabine in combination with MMC in the proposed schedule is well-tolerated with evidence of preliminary activity. The recommended dose for phase II studies are MMC at 6 mg/m2 on day 1 of a 28-day cycle with the dose capped at 36 mg/m2, in combination with capecitabine at 1,000 mg/m2 twice daily on days 8-21.

Different responses to two types of 5-fluorouracil prodrugs in combination with interferon-alpha in pulmonary metastases of renal cell carcinoma: a case report

A 66-year-old Japanese man with pulmonary metastases of renal cell carcinoma found 8 months after radical nephrectomy was treated with interferon-alpha and tegafur-uracil. Since it failed to achieve tumor responses resulting in progression, he was given interferon-alpha and capecitabine. After 2 courses of combination therapy with IFN-alpha and capecitabine, significant tumor responses were obtained; two out of four pulmonary metastatic sites disappeared completely, one site showed over 50% decrease in size, and the remaining one site did no change in size. The regimen was well tolerated and toxicity observed was World Health Organization grade 1 anorexia. His disease status was maintained as stable disease by the repeated treatment with interferon-alpha and capecitabine for 17 months after tumor responses were obtained. However, tumor progression was observed thereafter. He is at present under treatment with sorafenib. This is the first case report of metastatic renal cell carcinoma, which showed different responses to two types of 5-fluorouracil prodrugs in combination with interferon-alpha, suggesting the biochemical modulation of capecitabine by interferon-alpha as a possible mechanism underlying the antitumor effect of the combination of interferon-alpha and capecitabine at the clinical setting. Present case also suggests that a combination of tumor-selective capecitabine with interferon-alpha is a potentially useful therapeutic option in metastatic renal cell carcinoma.

A phase I trial of Capecitabine+Gemcitabine with radical radiation for locally advanced pancreatic cancer

Standard chemoradiotherapy with infusional 5FU for locally advanced pancreatic cancer (LAPC) has limited efficacy in this disease. The combination of Capecitabine (Cap) and Gemcitabine (Gem) are synergistic and are potent radiosensitisers. The aim of this phase I trial was thus to determine the highest administered dose of the Cap plus Gem combination with radical radiotherapy (RT) for LAPC. Patients had LAPC, adequate organ function, ECOG PS 0–1. During RT, Gem was escalated from 20–50 mg m⁻² day⁻¹ (twice per week), and Cap 800–2000 mg m⁻² day⁻¹ (b.i.d, days 1–5 of each week). Radiotherapy 50.4 Gy/28 fractions/5.5 weeks, using 3D-conformal techniques. Three patients were entered to each dose level (DL). Dose-limiting toxicity(s) (DLTs) were based on treatment-related toxicities. Twenty patients were accrued. Dose level (DL) 1: Cap/Gem; 800/20 mg m⁻² day⁻¹ (3 patients), DL2: 1000/20 (12 patients), DL3: 1300/30 (5 patients). Dose-limiting toxicities were observed in DL3; grade 3 dehydration (1 patient) and grade 3 diarrhoea and dehydration (1 patient). Dose level 2 was the recommend phase 2 dose. Disease control rate was 75%: PR=15%, SD=60%. Median overall survival was 11.2 months. The addition of Cap and Gem to radical RT was feasible and active and achieved at relatively low doses.

Decreased expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor in basal cell carcinomas

Thymidine phosphorylase (TP)/platelet-derived endothelial cell growth factor is associated with tumor angiogenesis. We evaluated the TP mRNA and protein expression in basal cell carcinomas (BCC) and in various skin tumors including numerous BCC histological simulants. Immunohistochemistry was performed on 99 paraffin sections of formalin-fixed skin tumors using monoclonal antibodies (mAb) against TP. TP mRNA levels were measured by real time RT-PCR in whole BCCs (wBCC) and laser capture microdissected (LCM) BCC tumor cells. TP immunostaining was negative in all BCC variants and in most of the benign trichogeneic tumors studied. By contrast, TP was constantly immunodetected in actinic keratosis (AK), squamous cell carcinomas (SCC), syringomatous carcinomas (SC), basosquamous carcinomas (BSC) and melanomas. TP mRNA levels were low and statistically not different in wBCC and normal skin but were strongly downregulated in LCM-BCC as compared with LCM-normal epidermis. We concluded that (i) anti-TP mAb is an useful marker to differentiate BCC from AK, SCC, BSC and SC but not from trichoblastic tumors, (ii) the lack of TP protein expression in BCC tumoral cells is linked to transcriptional regulatory mechanisms, (iii) the low TP mRNA levels in whole BCC may be related to the low intra-tumoral microvessel density, the slow growth and the very low metastatic potential of these tumors.

Anti-angiogenic potential of CoenzymeQ10, riboflavin and niacin in breast cancer patients undergoing tamoxifen therapy

Tumour angiogenesis is a complex mechanism consisting of multi-step events including secretion or activation of angiogenic factors by tumour cells, activation of proteolytic enzymes, proliferation, migration and differentiation of endothelial cells. Both primary and metastatic tumours in the breast are dependent on angiogenesis. In the present study, 84 breast cancer patients were randomized to receive a daily supplement of CoQ(10) 100 mg, riboflavin 10 mg and niacin 50 mg (CoRN), one dosage per day along with tamoxifen (TAM) 10 mg twice a day. Serum pro-angiogenic levels were elevated in untreated breast cancer patients (Group II) and their levels were found to be reduced in breast cancer patients undergoing TAM therapy for more than 1 year (Group III). When these group III breast cancer patients were supplemented with CoRN for 45 days (Group IV) and 90 days (Group V) along with TAM, a further significant reduction in pro-angiogenic marker levels were observed. Supplementing CoRN to breast cancer patients has found to decrease the levels of pro-angiogenic factors and increase the levels of anti-angiogenic factors. A reduction in pro-angiogenic marker levels attributes to reduction in tumour burden and may suggest good prognosis and efficacy of the treatment, and might even offer protection from cancer metastases and recurrence.

Induction of platelet derived-endothelial cell growth factor in the brain after ischemia

OBJECTIVES

Platelet derived-endothelial cell growth factor (PD-ECGF) is a highly potent angiogenic factor. Although angiogenesis plays an active role in pathophysiology of stroke, the expression pattern of this molecule in ischemic brain has not been investigated. In the present study, therefore, we investigated the change of PD-ECGF expression in the brain after ischemia.

METHODS

Using male Wistar rats, the right middle cerebral artery was occluded by a nylon thread for 90 minutes. The animals were decapitated 3 hours, 1, 4 and 10 days after the reperfusion, and frozen sections were prepared. We then performed immunohistochemistry for PD-ECGF and identified the cell phenotype which strongly expressed it by fluorescent double staining.

RESULTS

In the sham-operated brain, only small numbers of cells slightly expressed PD-ECGF. The number of positively stained cells increased at the peri-ischemic area from hour 3 of reperfusion. Not only small-sized cells but also large-sized cells became stained. The number of stained cells further increased, and peaked at day 4 for large-sized cells and at day 10 as to small-sized cells. Fluorescent double staining revealed that both large-sized and small-sized cells were neurons, indicating that neurons are the main source of PD-ECGF production in the ischemic brain.

DISCUSSION

PD-ECGF has a strong angiogenic property without vascular permeability increasing effect. This molecule may have a therapeutic potential for ischemic stroke treatment.

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.

The angiogenic factor thymidine phosphorylase up-regulates the cell adhesion molecule P-selectin in human vascular endothelial cells and is associated with P-selectin expression in breast cancers

Thymidine phosphorylase (TP) is an angiogenic enzyme, catalysing the reversible phosphorylation of thymidine to thymine and 2-deoxyribose. TP is up-regulated in neoplasia, being associated with advanced tumour stage, microvessel density and prognosis in several tumour types. Although TP is a non-mitogenic migratory factor for endothelium, the mechanism by which TP mediates these effects is still unclear. We compared the gene expression profile of endothelial cells grown in vitro in the presence or absence of TP by cDNA microarray analysis. To determine the time-course of TP angiogenic induction, endothelial cells were stimulated with TP (10 ng/ml) for 5 and 18 h. Gene expression levels of Tie2, angiopoietin (Ang)1 and Ang2, measured by RNase protection assay (RPA), showed maximal alteration at 18 h. cDNA from human umbilical vein endothelial cells (HUVEC) grown for 18 h in the presence or absence of TP (10 ng/ml) was hybridized to a human cDNA cytokine array representing 375 angiogenic genes. Significantly altered expression occurred in 89 human angiogenic genes (72 genes were up-regulated and 17 down-regulated). Changes in five genes relevant to vascular remodelling biology (Tie2, nNos, P-selectin, ephrin-B1 and TP) were validated in triplicate experiments by real-time RT-PCR. But only P-selectin gene expression remained significant. Correlation between P-selectin and TP was assessed by immunohistochemistry on 161 human breast cancers, using human tissue microarray. Tumour cell TP correlated with tumour cell P-selectin but not with endothelial cell P-selectin. These data show that TP stimulates changes in mRNA expression maximally after 18 h culture in vitro. It confirms a role for TP in vascular remodelling involving several classes of genes, including the cell adhesion molecule, P-selectin. Although confirmation of the role of TP-mediated cell adhesion molecule (CAM) induction is required; however, this pathway may provide an attractive therapeutic target, since it is likely to affect several important tumour processes, including angiogenesis and metastasis.

Tissue levels of pyrimidine nucleoside phosphorylase activity in human and rodent bladder cancer and normal bladder tissue

OBJECTIVES

To assess the relationship between the tissue levels of pyrimidine nucleoside phosphorylase (PyNpase) and clinicopathological parameters in human bladder cancer and to investigate the PyNpase levels in rat and mouse urinary bladder initiated by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN).

METHODS

The PyNpase levels in tumor tissue, normal tissue adjacent to the tumor, and normal tissue apart from the tumor were measured in 102 patients. Additionally, the PyNpase levels were measured in rat and mouse urinary bladders treated with BBN.

RESULT

The PyNpase levels of tumor tissue significantly correlated to the tumor grade and growth pattern (papillary/non-papillary), while stage, multiplicity, and tumor shape (peduncle/sessile) were not independent factors. The low-risk tumor of primary, single, G1-Ta showed significantly low levels of PyNpase. The PyNpase levels in the tumor tissue were significantly higher than those in the normal tissue. The PyNpase levels in the adjacent normal tissue were significantly higher than those in the distant normal tissue. The PyNpase levels in rat bladder tissue were significantly higher in the BBN-treatment groups than in those in the control group, only during the early carcinogenic stage. The PyNpase levels in mouse bladder tissue were significantly higher in BBN-treatment groups than in those in the control group during the whole experiment period.

CONCLUSION

Our results indicated that not only tumor tissue but also normal tissue adjacent to the tumor had a potential of angiogenesis for tumor development, and transurethral resection of the bladder tumor with a wide normal margin seems to be a reasonable strategy for decreasing the risk of recurrence.

Thymidine phosphorylase and dihydropyrimidine dehydrogenase expression levels in tumor and normal tissue specimens of T3 human colorectal carcinoma

PURPOSE

Thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) are important enzymes related to the metabolism of 5-fluorouracil and its derivatives. We evaluated the association between the clinicopathological factors and these enzymes in patients with T3 colorectal carcinoma.

METHODS

The TP and DPD expression levels in 15 patients with T3 colorectal carcinomas were measured in tumor and adjacent normal tissue specimens by enzyme-linked immunosorbent assay. Correlations between each enzyme and clinicopathological factors were also statistically evaluated.

RESULTS

The TP levels in tumor and normal tissue specimens were 77.9 +/- 33.6 and 24.7 +/- 10.3, respectively (P < 0.001). The DPD levels in tumor and normal tissue specimens were 44.1 +/- 18.2 and 53.1 +/- 24.1, respectively (P = 0.46). The TP/DPD ratios in tumor and normal tissue specimens were 1.84 +/- 0.52 and 0.53 +/- 0.26, respectively (P < 0.001). The tumor/normal ratios of TP level in patients with and without liver metastasis were 1.79 +/- 0.91 and 4.67 +/- 2.51, respectively (P = 0.024).

CONCLUSION

The measurement of the enzyme expression levels of TP and DPD is considered to be useful for better understanding the conditions of tumor progression. The mechanisms of regulation of these enzymes thus require further evaluation.

The role of thymidine phosphorylase and uridine phosphorylase in (fluoro)pyrimidine metabolism in peripheral blood mononuclear cells

Thymidine phosphorylase (TP) and uridine phosphorylase (UP) catalyze the (in)activation of several fluoropyrimidines, depending on their catalytic activity and substrate specificity. Blood cells are the first compartment exposed to most anticancer agents. The role of white blood cells in causing toxic side effects and catalyzing drug metabolism is generally underestimated. Therefore we determined the contribution of the white blood cell compartment to drug metabolism, and we investigated the activity and substrate specificity of TP and UP for the (fluoro)pyrimidines thymidine (dThd), uridine (Urd), 5'-deoxy-5-fluorouridine (5' dFUrd) and 5-fluorouracil (5FU) in peripheral blood mononuclear cells (PBMC) and undifferentiated monocytes and differentiated monocytes: macrophages and dendritic cells. PBMC had an IC50 of 742 microM exposed to 5'dFUrd, increasing to > 2000 microM when both TP and UP activities were inhibited. Total phosphorolytic activity was higher with dThd than with Urd, 5'dFUrd or 5FU. Using a specific TP inhibitor (TPI) and UP inhibitor (BAU) we concluded that dThd and Urd were preferentially converted by TP and UP, respectively, while 5'dFUrd and 5FU were mainly converted by TP (about 80%) into 5FU and FUrd, respectively. 5FU was effectively incorporated into RNA. dThd conversion into thymine was highest in dendritic cells (52.6 nmol thymine/h/10(6) cells), followed by macrophages (two-fold) and undifferentiated monocytes (eight-fold). TPI prevented dThd conversion almost completely. In conclusion, PBMC were relatively insensitive to 5'dFUrd, and the natural substrates dThd and Urd were preferentially converted by TP and UP, respectively. TP and UP were both responsible for converting 5'dFUrd/5FU into 5FU/FUrd, respectively.

Validation of real-time reverse-transcription-polymerase chain reaction for quantification of capecitabine-metabolizing enzymes

Capecitabine is an oral fluoropyrimidine carbamate activated sequentially in both liver and tumor tissues by carboxylesterases, cytidine deaminase, and thymidine phosphorylase. 5-Fluorouracil is inactivated by dihydropyrimidine dehydrogenase and targets thymidylate synthase. Here we report the validation of the real-time polymerase chain reaction assay for the quantification of the transcripts of the different enzymes involved in capecitabine activation. The method is specific, sensitive, and linear over 2-3 logs of RNA input. It is reproducible with less than 5% intraday variability and less than 10% interday variability. Five reference genes were tested for normalization. POLR2A was selected since it reduced variability between samples, demonstrated levels of expression similar to those of the genes of interest, and its expression was not modified by capecitabine treatment in samples from preclinical studies. The method was robust as the gene expression profiles from six colon cancer cell lines obtained by this method were similar to microarray data. Finally, the method was able to detect changes in gene expression in xenograft tumors treated with capecitabine. It could therefore constitute the method of choice for future correlative studies in patients receiving capecitabine.

Identification of the angiogenic endothelial-cell growth factor-1/thymidine phosphorylase as a potential target for immunotherapy of cancer

Characterization of the antigens recognized by tumor-reactive T cells isolated from patients successfully treated with allogeneic HLA-matched hematopoietic stem cell transplantation (SCT) can lead to the identification of clinically relevant target molecules. We isolated tumor-reactive cytotoxic CD8(+) T-cell (CTL) clones from a patient successfully treated with donor lymphocyte infusion for relapsed multiple myeloma after allogeneic HLA-matched SCT. Using cDNA expression cloning, the target molecule of an HLA-B7-restricted CTL clone was identified. The CTL clone recognized a minor histocompatibility antigen produced by a single nucleotide polymorphism (SNP) in the angiogenic endothelial-cell growth factor-1 (ECGF1) gene also known as thymidine phosphorylase. The SNP leads to an Arg-to-His substitution in an alternatively translated peptide that is recognized by the CTL. The ECGF1 gene is predominantly expressed in hematopoietic cells, although low expression can also be detected in other tissues. The patient from whom this CTL clone was isolated had mild graft-versus-host disease despite high numbers of circulating ECGF-1-specific T cells as detected by tetramer staining. Because solid tumors expressing ECGF-1 could also be lysed by the CTL, ECGF-1 is an interesting target for immunotherapy of both hematologic and solid tumors.

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.

Phase I study of capecitabine with concomitant radiotherapy for patients with locally advanced pancreatic cancer: expression analysis of genes related to outcome

PURPOSE

To establish the feasibility of capecitabine with concurrent radiotherapy (XRT) in patients with locally advanced (LA) pancreatic cancer and evaluate the effect of XRT on thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD), and tumor necrosis factor-alpha (TNF-alpha).

PATIENTS AND METHODS

Fifteen patients with LA pancreatic cancer received three-dimensional conformal XRT to a dose of 50.4 Gy with capecitabine at escalating doses from 600 to 1,250 mg/m2 bid (Monday through Friday). Following chemo-XRT, stable and responding patients were treated with capecitabine 2,000 mg/m2 orally bid for 14 days every 21 days. Tumor specimens were procured with endoscopic ultrasound-guided fine-needle aspiration 1 week before and 2 weeks after chemo-XRT to evaluate TP, DPD, and TNF-alpha mRNA levels.

RESULTS

Dose-limiting grade 3 diarrhea was observed in two of six patients treated at a capecitabine dose of 1,000 mg/m2 with XRT. Three patients (20%) achieved partial response. Mean percent difference in TP pre- and post-XRT was 119.2% (P = .1934). There was no significant differences in mean TNF-alpha, or DPD levels pre- and post-XRT (P = .1934 and .4922, respectively). TP and TNF-alpha levels were not significantly correlated both at pre- and post-XRT (P = .670 and P < .154, respectively). Median value of TP:DPD ratios at baseline was 2.65 (range, 0.36 to 11.08). No association between TP:DPD ratio and efficacy of capecitabine or severity of toxicities was identified.

CONCLUSION

The recommended dose for phase II evaluation is capecitabine 800 mg/m2 bid (Monday through Friday) with concurrent XRT. This approach offers an easy alternative to intravenous fluorouracil as a radiosensitizer in these patients. Role of TP and TP:DPD ratio warrants further investigation in a larger clinical trial.

Induction of thymidine phosphorylase expression by AZT contributes to enhancement of 5'-DFUR cytotoxicity

Thymidine phosphorylase (TP) regulates intracellular thymidine metabolism and can enhance the anti-tumor effectiveness of 5'-deoxy-5-fluorouridine (5'-DFUR) by conversion of the pro-drug 5'-DFUR to 5-fluorouracil (5-FU) in tumor tissues. 5'-DFUR is an effective anti-tumor drug in cells expressing high levels of TP. 3'-Azido 3'-deoxythymidine (AZT) is a thymidine analog that has been proven useful in the treatment of acquired immunodefiency syndrome (AIDS). In this study, we found that AZT induces TP expression and enhances the sensitivity of human myeloid leukemia U937 cells to 5'-DFUR. Both the protein level and the activity of TP in U937 cells were elevated for 48h after exposure to AZT (20, 100 or 300muM). AZT enhanced TP promoter activity in a dose-dependent manner. AZT also increased TP mRNA levels in U937 cells as assayed by Real-time reverse-transcription PCR. AZT enhanced the cytotoxic effect of 5'-DFUR on U937 cells. A TP inhibitor, TPI, abrogated the cytotoxic activity of 5'-DFUR, and attenuated the combined cytotoxicity of AZT and 5'-DFUR. These results suggest that AZT enhances the cytotoxic effect of 5'-DFUR on U937 cells by upregulating TP activity in addition to its inhibition of thymidine kinase (TK) activity and reduction of intracellular dTTP pools.

Influence of alpha-tumor necrosis factor and beta-interleukin-1 on production of angiogenetic factors and thymidine phosphorylase activity in immortalized human decidual fibroblasts in vitro

AIM

The aim of the present study was to investigate regulatory mechanisms of angiogenesis in the decidua using immortalized human decidual fibroblasts.

METHODS

A sample of decidual fibroblasts was taken from a woman in early pregnancy. A cell line, DE-1, was established by infecting the decidual fibroblasts with the simian virus 40 large T antigen. Using this cell line, the ability to produce vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), beta-transforming growth factor (TGF-beta), and thymidine phosphorylase (TP) activity was investigated using immunohistochemistry, and the influences of beta-interleukin-1 (IL-1beta) and alpha-tumor necrosis factor (TNF-alpha) on these angiogenetic factors was investigated using enzyme-linked immunosorbent assays. Furthermore, the effects of TNF-alpha on proliferative capacity and apoptosis induction in DE-1 were studied.

RESULTS

It was demonstrated that DE-1 produced all of these angiogenetic factors. The production of VEGF, bFGF and TGF-beta respectively was enhanced by both IL-1beta and TNF-alpha. TP activity was increased by TNF-alpha, but no increase was observed as a result of IL-1beta. It was shown that TNF-alpha suppressed the proliferation of DE-1 cells and significantly increased the percentage of apoptotic cells.

CONCLUSION

It is suggested that IL-1beta and TNF-alpha stimulate decidual fibroblasts to up-regulate angiogenesis in the human decidua.

Protection against DNA damage-induced apoptosis by the angiogenic factor thymidine phosphorylase

Thymidine phosphorylase (TP) is involved both in pyrimidine nucleoside metabolism and in angiogenesis. TP also conferred the resistance to hypoxia-induced apoptosis of the cancer cells. In U937 cells, DNA damage-inducing agents significantly enhanced the expression of TP. Cell lines stably transfected with TP cDNA were more resistant to the DNA damage-inducing agents than the mock-transfected cells and showed augmented activity of Akt. The cytoprotective function of TP against DNA damage was independent of its enzymatic activity. The resistance to apoptosis was partially abrogated by treatment with the phosphatidyl inositol 3-kinase (PI3K) inhibitors, suggesting that the cytoprotective function of TP is mediated, at least in part, by regulation of the PI3K/Akt pathway. These findings indicate that TP expression in increased by various stress including DNA damage and that TP molecules confer resistance to DNA damage-induced apoptosis in cancer cells.

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.

Prognostic value of thymidine phosphorylase activity in liver tissue adjacent to hepatocellular carcinoma

BACKGROUND

Measurement of thymidine phosphorylase (TP) activity in normal liver tissue adjacent to hepatocellular carcinoma (HCC) may predict multicentric recurrence a long time after an operation. The authors investigated this activity in 92 patients with HCC who had a single HCC equal to or less than 5 cm.

METHODS

Fresh samples (tumors with adjacent normal tissues) were collected from 92 patients with HCC who underwent curative hepatic resection. The levels of TP activity in nonfixed, fresh, and frozen HCC specimens with adjacent noncancerous liver tissue were biochemically measured by using an enzyme-linked immunosorbent assay method.

RESULTS

Patients who had a high TP level in normal liver tissue had significantly earlier recurrence (median disease-free survival, 819 days; 95% confidence interval [95% CI], 478-1044 days) compared with patients who had a low TP level (median disease-free survival, 1376 days; lower limit of 95% CI, 921 days; P = 0.0171). Multivariate analysis showed that patients who had a low TP level in adjacent liver tissue had a 0.387-fold higher risk of postoperative recurrence compared with patients who had a high TP level (P = 0.0067).

CONCLUSION

TP activity in normal liver tissue adjacent to HCC is related to tumor occurrence and may predict postoperative tumor recurrence.

Molecular profile of androgen-independent prostate cancer xenograft LuCaP 23.1

After castration or therapeutic hormone deprivation, most cancer of the prostate (CaP) cells develop androgen-independent (AI) growth. In this work, we studied the effect of androgen depletion (castration) on the growth of experimental model LuCaP 23.1 xenograft. A total of 101 nude mice were implanted and analysed for their growth profile before experimental period 1 (11 weeks) and after castration experimental period 2 (15 weeks). For specific periods, tumors were harvested and assessed for molecular marker expression specific for CaP. Taking into account tumor dynamic growth, prior to castration we found 37 fast growing (FG) tumors (948.9+/-76.9 mm3) and 63 slow growing (SG) tumors (229.6+/-18.4 mm3). Real-time quantitative RT-PCR showed that in comparison to SGs, FGs contained elevated expression of epidermal growth factor receptor type 1 (HER1), urokinase plasminogen activator (uPA), thymidine phosphorylase (TP) and thymidilate synthase (TS) mRNAs expression and low levels of 5alpha-reductase 2 (5alpha-R2) mRNA. After castration all FG tumors progressed rapidly (by 5 weeks) to AI growth (FG-P). In SG castrated tumors, 66% of tumors showed retarded progression (by 12 weeks) to AI (SG-P), whereas 34% responded to castration (SG-R). Molecular analysis demonstrated distinct molecular profiles integrating different pathways associated with AI progression. The progressive tumors FG-P, and some tumors of SG-P subgroup, presented significantly high levels of HER1, epidermal growth factor receptor type 2 (HER2), TS, uPA, TP, tumor necrosis factor superfamily member 6 (FAS) and peptidylglycine alpha-amidating mono-oxygenase (PAM) mRNA all of which correlated with androgen receptor (AR) mRNA. The second subgroup of SG-P tumors showed a high expression of the anti-apoptotic gene Bcl-2. A third subgroup of SG-P tumors showed significant expression of hypoxia-related genes such as adrenomedullin (AM) after castration. LuCaP 23.1 xenograft represent a useful dynamic model to study pre-clinically new therapeutic molecules and evaluate non-randomized therapeutics protocols combining different target inhibition specific to each AI pathways.

Thymidine phosphorylase expression in tumour cells and tumour response to capecitabine plus docetaxel chemotherapy in non-small cell lung cancer

BACKGROUND

Thymidine phosphorylase (TP) is the key enzyme for capecitabine activation in tumour cells.

AIMS

To examine whether TP expression in tumour cells and stroma is predictive of the tumour response to capecitabine plus docetaxel chemotherapy in patients with advanced non-small cell lung cancer (NSCLC).

METHODS

Tumour samples were available from 30 of 39 patients enrolled in a previous phase II study of capecitabine/docetaxel chemotherapy in patients with advanced NSCLC. Stromal and tumour cell TP expression was evaluated by immunohistochemistry using monoclonal antibody PD-ECGF.

RESULTS

High tumour cell TP expression was found in 13 of 30 cases and was negatively associated with stromal TP expression (p = 0.000). High stromal TP expression was found in 16 of 28 cases and was strongly associated with intense macrophage infiltration (p = 0.002), suggesting that macrophages are the major component of TP expression in the stroma. Tumour response to capecitabine/docetaxel was significantly associated with high tumour cell TP expression (p = 0.004) and low stromal TP expression (p = 0.009). Moreover, high tumour cell TP expression was significantly associated with severe hand-foot syndrome, a toxic side effect of capecitabine (p = 0.01). Improved survival was seen for high tumour cell and low stromal TP expression, although results were not significant (p = 0.6 and 0.3, respectively).

CONCLUSIONS

In advanced NSCLC, TP expression in tumour cells and stroma is associated with tumour response to capecitabine/docetaxel chemotherapy, and might be a useful predictor of tumour response to capecitabine based chemotherapy. A large scale prospective study is needed to confirm the prognostic significance of TP expression in NSCLC.