Thymidine Phosphorylase: A Possible Marker of Cell Maturation in Acute Myeloid Leukaemia

Thymidine Phosphorylase activity has been measured in two populations of human Acute Myeloid Leukaemia cells (AML) and in normal human macrophages. During short-term culture in vitro of AML cells the activity of this enzyme increases progressively and approaches that of normal non-dividing macrophages at a time when the leukaemia cells in culture show evidence of maturation as assayed by functional, enzymatic and morphological criteria. It is suggested that the level of Thymidine Phosphorylase activity may be a marker of maturation in AML.

Can thymidine phosphorylase be a predictive marker for gemcitabine and doxifluridine combination chemotherapy in cholangiocarcinoma?: case series

Unresectable cholangiocarcinoma is poorly responded to chemotherapy, especially for the case refractory to gemcitabine and cisplatin. Here, we tested whether high expression of thymidine phosphorylase (TP) can be a predictive biomarker for the indicator for gemcitabine and doxifluridine combination chemotherapy in the cholangiocarcinoma refractory to gemcitabine and cisplatin. Immunohistochemical staining for TP was performed with a biopsy specimen. We accepted the result as positive when more than 10% of cancer cells were stained with moderate intensity. Here, we report 2 cases of TP-positive cholangiocarcinoma well controlled with gemcitabine and doxifluridine combination chemotherapy, which had been refractory to the first line treatment with gemcitabine and cisplatin combination chemotherapy.

Activity of thymidilate "salvage pathway" enzymes in human gastric cancer and blood serum: correlation with treatment modalities

A comparative study of enzyme activity features of thymidilate "salvage pathway" synthesis in blood serum and tissues of different age patients with gastric cancer (T(3-4)N(0-x)M(0)) was carried out.

AIM

To evaluate the diagnostic relevance of thymidilate metabolism enzymes activities and their association with tumor growth.

METHODS

Enzymes activities were determined by the radioisotope method and spectrophotometrically in tumor tissues and blood serum of 74 patients.

RESULTS

It was demonstrated that thymidine phosphorylase activity in gastric tumors is lower by 2.6 times as compared to non-neoplastic mucosa of resection margin. This being accompanied by decrease of its activity in the blood serum (from 47.9 ± 2.6 to 14.65 ± 2.4 nmol/min·mg, p < 0.001). An increase of thymidine kinase activity was revealed both in tumor tissues (more than 3.5 times) and in blood serum (from 3.9 ± 0,7 nmol/mg·h, to 6.8 ± 1.0 nmol/mg·h, p < 0.01). Changes in their activity in the postoperative period depended on the type of surgical procedure and tumor eradication.

CONCLUSION

It could be suggested that control of individual dynamics of the enzymes activities in blood serum may be used as informative tool for monitoring of patients and treatment optimization.

[Lactate dehydrogenase, adenosine deaminase and thymidine phosphorylase activity of blood and tissues in breast cancer]

Lactate dehydrogenase (LDH), adenosine deaminase and thymidine phosphorylase activity was analyzed in the blood serum, primary tumor and adjacent uninvolved breast tissues from 49 women with adenocarcinoma and from 10 ones with benign adenofibroma. The LDH activity was increased in both cancerous and adjacent tissues. Serum LDH level reflects cell membrane alterations not only in the tumor node cells but also to a greater extent--in the surrounding unmalignant tissues. The discovered changes in nucleosides catabolic enzyme's activity in patients with breast cancer are correlated with LDH activity and its level in the blood serum.

Oxidative stress and tumor progression in colorectal cancer

BACKGROUND/AIMS

Elevated oxidative status has been found in many types of cancer cells. Recent studies have shown that the enzymatic product of thymidine phosphorylase (TP) generated reactive oxygen species (ROS) within cancer cells. The aim of this study was thus to evaluate the signal transduction pathway and the role of ROS in colorectal cancer.

METHODOLOGY

Blood specimens were obtained from the drainage vein of the tumor during operation in 76 patients with colorectal cancer. Serum ROS levels were measured using the derivative-Reactive Oxygen Metabolites (d-ROM) test and serum TP levels were examined by a highly sensitive ELISA method.

RESULTS

There was no significant correlation between serum levels of ROS and TP. Serum ROS levels were elevated in proportion to tumor invasion and had a significant positive correlation with tumor size (p < 0.05). However, they did not increase in patients with liver metastasis.

CONCLUSIONS

These findings suggest that ROS are independent of TP-triggered signaling transduction and are associated with increased tumor invasion, but not liver metastasis in patients with colorectal cancer. From this point of view, new strategies related to ROS may provide improved therapeutic results as well as a preventative effect on carcinogenesis of the colorectum.

Prognostic significance of the serum thymidine phosphorylase levels in venous blood drainage specimens in patients with colorectal cancer

BACKGROUND/AIMS

We investigated whether the serum Thymidine phosphorylase (TP) levels in venous blood drainage specimens were associated with the prognosis and risk of liver metastasis in patients with resectable colorectal cancer.

METHODOLOGY

From 88 patients with colorectal cancer, specimens of venous blood drainage were obtained during operation. The serum TP levels were measured by a highly sensitive Enzyme-Linked Immunosorbent Assay (ELISA) method.

RESULTS

Subsequently, 88 patients were divided into two groups based on the levels of TP. The dividing line was determined to be 55ng/mL. The TP-high group (> 55ng/mL) had a significantly shorter overall survival than the TP-low group (< 55ng/mL). A multivariate analysis indicated that the serum TP level in venous blood drainage specimens to be a better prognostic factor independent of the traditional pathologic parameters. The serum TP levels of 3 patients with metachronous liver metastasis were high (> 55ng/mL).

CONCLUSIONS

These findings suggest that the serum TP levels in venous blood drainage specimens reflect the prognosis of patients with colorectal cancer undergoing curative resection, particularly the risk of liver metastasis.

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.

Determination of thymidine phosphorylase activity in human blood cells and fibroblasts by a nonradiochemical assay using reversed-phase high-performance liquid chromatography

In this study, we demonstrated that the highest activity of thymidine phosphorylase (TP) was found in peripheral blood mononuclear (PBM) cells followed by that of thrombocytes and granulocytes whereas no activity of TP could be detected in erythrocytes. The activity of TP in leukocytes proved to be intermediate compared to the TP activity observed in PBM cells and granulocytes. The activity of TP also was readily detectable in human fibroblasts.

Infusion of platelets transiently reduces nucleoside overload in MNGIE

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is caused by thymidine phosphorylase (TP) deficiency, which leads to toxic accumulations of thymidine (dThd) and deoxyuridine (dUrd). In this work, we report that infusion of platelets from healthy donors to patients with MNGIE restored transiently circulating TP and reduced plasma dThd and dUrd levels, suggesting that treatments to achieve permanent restoration of circulating TP such as allogeneic stem cell transplantation or gene transfer might be therapeutic.

Allogeneic stem cell transplantation corrects biochemical derangements in MNGIE

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a multisystemic autosomal recessive disease due to primary thymidine phosphorylase (TP) deficiency. To restore TP activity, we performed reduced intensity allogeneic stem cell transplantations (alloSCTs) in two patients. In the first, alloSCT failed to engraft, but the second achieved mixed donor chimerism, which partially restored buffy coat TP activity and lowered plasma nucleosides. Thus, alloSCT can correct biochemical abnormalities in the blood of patients with MNGIE, but clinical efficacy remains unproven.

The activity of thymidine phosphorylase as a new ovarian tumor marker

OBJECTIVE

The aim of this study was to evaluate the thymidine phosphorylase (TP) activity of tumor cells and serum as a marker in patients with ovarian cancer.

METHODS

The activity of TP was measured by the spectrophotometric method in the cytosol of ovarian tumor tissues from 47 patients after surgery, and in the presurgery serum from the same patients. Ten women with normal ovaries, treated surgically due to nononcological reasons served as a control. Microvessel density (MD) was evaluated in tumor using immunohistochemical methods. A relationship between TP activity and MD and clinicopathologic features was investigated.

RESULTS

A significantly higher TP activity was stated both in malignant tumor and serum specimens from ovarian cancer patients when compared to the control. A positive correlation between the enzyme activity in the serum and neoplasmatic tissue was found. Neoangiogenesis is higher in ovarian cancer when compared to the group of borderline malignancy tumors but a reverse correlation between MD and TP activity in malignant tumors was observed. TP activity is significantly higher in more advanced neoplasmatic disease (FIGO III and IV) although no correlation between TP activity and grading or histopathological type of ovarian tumor was observed.

CONCLUSION

Thymidine phosphorylase activity might be useful in diagnostic characterization of ovarian cancer.

Thrombocytosis associated with poor prognosis in patients with esophageal carcinoma

BACKGROUND

Thrombocytosis in patients with cancer has been reported to be associated with increased expression of angiogenic factors and with a poor prognosis in some types of cancer. The aim of this study is to analyze the clinicopathologic significance and prognostic value of platelet counts in patients with esophageal cancer.

STUDY DESIGN

Platelet counts were measured before surgery in 374 patients diagnosed between 1987 and 1999 with primary esophageal squamous cell carcinoma. We used the cut-off level of 293 x 10(9)/L (mean of 80 healthy controls +/- standard deviation) to define thrombocytosis. We analyzed the relationship between platelet counts, TNM factors, and white blood cell counts. Among 374 patients, the levels of C-reactive protein were analyzed in 170 patients and serum thymidine phosphorylase concentration was analyzed in 91 patients. The multivariate prognostic value of platelet counts, tumor size, and TNM factors were determined using Cox's proportional hazards model.

RESULTS

Platelet counts were significantly increased in patients with large tumors (p < 0.001), deep tumors, nodal involvement, and distant metastasis in univariate analysis. C-reactive protein level, white blood cell count, and serum thymidine phosphorylase concentration were also significantly increased in patients analyzed with thrombocytosis in univariate analysis. Adjusting for tumor size and TNM factors, multivariate analysis indicated that thrombocytosis as defined in this study was an independent prognostic factor (hazard ratio = 1.52, 95% CI = 1.11 to 2.08, p = 0.009).

CONCLUSIONS

A high platelet count is associated with tumor progression and poor survival in patients with esophageal carcinoma.

Definitive Diagnosis of Mitochondrial Neurogastrointestinal Encephalomyopathy by Biochemical Assays

Background: Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is caused by mutations in the gene encoding thymidine phosphorylase (TP). The clinical manifestations of MNGIE are recognizable and homogeneous, but in the early stages, the disease is often misdiagnosed. This study assesses the reliability of biochemical assays to diagnose MNGIE.

Methods: We studied 180 patients with clinical features suggestive of MNGIE, 14 asymptomatic TP mutation carriers, and 20 controls. TP enzyme activity in the buffy coat was determined by a fixed-time method, and the plasma nucleosides thymidine (dThd) and deoxyuridine (dUrd) were assessed by a gradient-elution reversed phase HPLC method. TP was sequenced through standard procedures in patients who met the clinical criteria for MNGIE.

Results:Twenty-five of the 180 patients fulfilled the clinical criteria for MNGIE and had homozygous or compound heterozygous TP mutations. All had drastically decreased TP activity [mean (SD), 10 (15) nmol thymine formed · h−1 · (mg protein)−1 vs 634 (217) nmol thymine formed · h−1 · (mg protein)−1 for the controls]. Relative to the control mean, TP activities were reduced to 35% in mutation carriers and 65% in MNGIE-like patients. All 25 MNGIE patients had detectable plasma dThd [8.6 (3.4) μmol/L] and dUrd [14.2 (4.4) μmol/L]. Controls, carriers, and MNGIE-like patients showed no detectable plasma dThd and dUrd.

Conclusions:We propose a diagnostic algorithm based on the determination of plasma dThd and dUrd, TP activity in buffy coat, or both to make a definitive diagnosis of MNGIE. Increased concentrations of dThd (&gt;3 μmol/L) and dUrd (&gt;5 μmol/L) in plasma or a decrease in buffy coat TP activity to ≤8% relative to controls is sufficient to diagnose MNGIE.

Monitoring of circulating angiogenic factors in dendritic cell-based cancer immunotherapy

BACKGROUND

A promising treatment approach for patients with malignant disease that recently has found its way into clinical trials is based on vaccination with autologous dendritic cells loaded with tumor antigens. However, adequate assays for monitoring clinical and immunologic responses still are under debate. In recent years, the determination of angiogenic markers has shown considerable potential in the diagnosis and prognosis of patients with malignant disease, because tumor growth and spread are promoted by angiogenesis, the formation of new blood vessels.

METHODS

The authors established a method for measuring the plasma levels of three modulators of angiogenesis: vascular endothelial growth factor, platelet-derived endothelial cell growth factor, and thrombospondin-1. The angiogenic blood profile of a healthy control group was characterized and compared with a group of patients with malignant disease. Ultimately, levels of circulating angiogenic factors were monitored in the course of dendritic cell-based cancer immunotherapy.

RESULTS

Baseline levels of angiogenic mediators varied substantially among healthy individuals but showed consistent values for each individual. Blood levels of circulating angiogenic factors were elevated significantly in patients with advanced disease and were highly sensitive to dendritic cell-based immunotherapy.

CONCLUSIONS

To our knowledge, the current report was the first to analyze circulating levels of angiogenic factors during dendritic cell-based immunotherapy. The authors observed a noteworthy change in the angiogenic blood profile with treatment, and this change was correlated with the induction of an immunologic response.

Quantitative analysis of thymidine phosphorylase and dihydropyrimidine dehydrogenase in renal cell carcinoma

OBJECTIVE

The purpose of the present study was to clarify the clinicopathological significance of both thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) in renal cell carcinoma (RCC) based on a quantitative analysis of RCC patients.

METHODS

Levels of TP and DPD in RCC and/or uninvolved renal tissues from 65 RCC patients were measured by enzyme-linked immunosorbent assay.

RESULTS

The TP level and TP/DPD ratio were significantly higher in RCC than in adjacent uninvolved renal tissues (p < 0.0001). There was no significant difference in DPD levels between RCC and uninvolved renal tissues. The ratio of the highest to the lowest level was 623 in TP level, 28.9 in DPD level, and 985 in TP/DPD ratio. In the univariate analysis, patient's age (p = 0.04), tumor stage (p < 0.0001), tumor size (p = 0.007), TP expression (p = 0.03), and DPD expression (p = 0.04) were significantly associated with increased risk of death. Multivariate analysis showed that patient's age, tumor stage, and TP expression were independent prognostic factors.

CONCLUSIONS

TP and DPD in RCC provide prognostic information although DPD was not an independent prognostic factor. The present finding of a wide range in these enzyme expressions in RCC suggests that a certain subpopulation with a high TP/DPD ratio has potential responsiveness to fluoropyrimidines, especially 5'-deoxy-5-fluorouridine and capecitabine.

Occurrence of hematogenous metastasis and serum levels of thymidine phosphorylase in colorectal cancer

Thymidine phosphorylase (dThdPase) is known to promote the development of new blood vessels. Increased dThdPase expression in solid tumors has been shown to correlate with tumor growth, invasion and metastasis. In the present study, we measured dThdPase levels in the tumor tissue and in the serum from the tumor drainage and peripheral venous blood obtained from patients with resectable colorectal cancer. Serum dThdPase levels, measured by a modified ELISA method, were significantly higher in patients with hematogenous metastasis. In the tumor tissue specimens, no significant difference was observed between patients with or without hematogenous metastasis. These results suggest that the serum dThdPase levels are a novel marker to predict occurrence of hematogenous metastasis in patients with resectable colorectal cancer.

[Thymidine phosphorylase activity and neo-angiogenesis in ovarian cancer]

Neo-angiogenesis seems to play an important role in the progression of ovarian cancer and in formation of distant metastases. Data from literature on role of phosphorylase in neoplasmatic disease and in neo-angiogenesis are controversial. In mammalian cytosole there are two different pirymidine nucleosyde phosphorylases: thymidine (PT) and uridine (PU). Both of them play important role in the metabolism of nucleosides as well as in the recycling of pyrimidine base. Recently thymidine phosphorylase is identified with platelet derived endothelial cell growth factor (PD-ECGF). It has been demonstrated, that PD-ECGF/PT influence on neo-angiogenesis and correlates with degree of neoplasmatic invasion. In literature the data about thymidine phosphorylase activity and its correlation with neoplasmatic angiogenesis in ovarian tumors are controversial. The aim of the study was to evaluate the activity of PT together with the intensity of angiogenesis in epithelial ovarian tumors. 42 patients with ovarian cancer were included into the study. The enzyme activity was measured in ovarian cancer tissue and in the serum in the spectrophotometer. Intratumoral microvessel density (IMD) was evaluated in tumor using immunohistochemical methods. 10 woman with normal ovaries, treated surgically due to non-oncological reasons served as a control. Activity of PT in ovarian tumor and in serum was compared to the control group. Correlation between the intensity of angiogenesis and PT activity in ovarian cancer was also investigated. Significantly higher PT activity was stated both in tumor and serum when compared to the control. Positive correlation between enzyme activity in the serum and neoplasmatic tissue was found. Surprisingly, the negative correlation between neo-angiogenesis and PT activity in ovarian cancer was observed. Neo-angiogenesis is higher in ovarian cancer, when compared to the group of borderline malignancy tumors. Positive correlation between PT activity and staging in ovarian cancer was observed. No correlation between grading and histopathological type of epithelial cancer was observed. PT activity and neo-angiogenesis evaluation might be useful in diagnostics of ovarian cancer.

Treatment of a patient with advanced esophageal cancer with a combination of mitomycin C and capecitabine: activation of the thymidine phosphorylase as active principle?

BACKGROUND

Both capecitabine, an oral prodrug of 5-fluorouracil (5-FU), and mitomycin C (MMC) have demonstrated activity as single agents in patients with gastrointestinal cancer. Furthermore, a combination of MMC with infusional 5-FU can induce tumor remission even in patients pretreated with 5-FU. Capecitabine and MMC act synergistically due to an upregulation of the thymidine phosphorylase activity by MMC in a human xenograft model.

PATIENT

We sought to exploit these preclinically observed effects in a patient with esophageal cancer who was progressive after a first-line radiochemotherapy with 5-FU and cisplatin. He was treated with a combination of MMC and capecitabine on a compassionate use basis. A rapid remission lasting for about 6 months was observed.

CONCLUSION

This is the first report on a combination therapy with capecitabine and MMC. The remission observed in our patient suggests that the preclinically observed synergy has clinical impact. This combination should be further investigated in prospective clinical trials.

Measurement of serum thymidine phosphorylase levels by highly sensitive enzyme-linked immunosorbent assay in gastric cancer

Thymidine phosphorylase (TP) is an enzyme that converts 5'-DFUR to 5-FU and also acts as an angiogenic factor. Measurement of serum TP levels has recently become possible by highly sensitive enzyme-linked immunosorbent assay (ELISA). We examined 38 patients with gastric adenocarcinoma to measure serum TP levels by highly sensitive ELISA method and tissue TP levels by conventional ELISA. In addition, immunohistochemical staining of normal and cancer tissues was also performed. Serum TP levels in patients with stages III and IV and inoperable or recurrent cancer were significantly higher than those in healthy controls. A high correlation was found between serum TP levels and tumor TP levels (r=0.65, p<0.0001). Moreover, serum TP levels were about 1/2500 of tumor TP levels. Tissue TP values in tumor were significantly higher than those in normal tissue. On the other hand, no significant differences among the cancer stages were found in either serum or tumor tissue. In conclusion, we demonstrate that serum TP levels strongly reflect tumor TP levels, and it may predict clinicopathological factors, prognosis, or sensitivity of anti-cancer drugs.

Prognostic significance of serum thymidine phosphorylase concentration in esophageal squamous cell carcinoma

BACKGROUND

Thymidine phosphorylase (dThdPase), which also is referred to as platelet-derived endothelial cell growth factor, is a potent inducer of angiogenesis in malignant tumors. Increased dThdPase expression and activity have been found to be associated with poor prognosis in various solid tumor tissues. Because very little was known about the significance of serum dThdPase concentration (S-dThdPase), the objective of this study was to analyze the clinicopathologic significance of S-dThdPase in the patients with esophageal squamous cell carcinoma.

METHODS

The S-dThdPase was measured by enzyme-linked immunosorbent assay in 77 healthy controls and 153 patients with primary esophageal squamous cell carcinoma. A total of 80 patients underwent surgery alone; 46 patients received chemoradiotherapy alone; 17 patients received chemoradiotherapy followed by surgery; and 10 patients did not receive any treatment. Thymidine phosphorylase expression in esophageal carcinoma tissues was examined by immunohistochemistry. The clinicopathologic value and prognostic value of S-dThdPase was determined in 80 patients treated by surgery alone.

RESULTS

The S-dThdPase is significantly higher in patients with esophageal carcinoma than in healthy controls (30.8 +/- 31.8 ng/mL vs. 13.8 +/- 7.6 ng/mL; P < 0.001). Statistically significant differences in S-dThdPases were observed depending on tumor size (P < 0.01) and tumor depth (P < 0.01). A S-dThdPase of more than 29.0 ng/mL (which represented the mean plus 2 standard deviation of the concentration in healthy controls) was associated with dThdPase expression (P = 0.022), poor response (P = 0.022), and poor survival (P < 0.01). Because S-dThdPase was associated with tumor depth, S-dThdPase was not an independent prognostic factor (P = 0.095).

CONCLUSIONS

A high S-dThdPase is associated with depth of tumor invasion and poor response to treatment.

Serum gliostatin levels in patients with rheumatoid factor-negative and -positive rheumatoid arthritis and changes of these levels after surgical treatments

Gliostatin/platelet-derived endothelial cell growth factor (GLS/PD-ECGF) has a potential for arthritogenic action. The aim of this study was to examine whether measurement of serum GLS can be used to evaluate symptomatic improvements after surgery (arthroplasty or synovectomy) as well as the aggressiveness of disease activity in rheumatoid arthritis (RA). Serum GLS levels were determined by enzyme immunoassay in rheumatoid factor (RF)-positive and -negative RA patients. In those undergoing surgery, levels were measured 3 months before and after the operations. Both RF-positive and -negative RA sera showed higher GLS levels than normal and osteoarthritis sera. Patients undergoing arthroplasty demonstrated a decrease in serum GLS levels after the operations, but patients undergoing synovectomy did not, reflecting the extent of remaining or reproliferating synovial tissues rich in GLS production. These findings suggest that the serum GLS level is a useful indicator for evaluation of synovitis and the systemic efficacy of surgical treatment.

Clinical implications of circulating angiogenic factors in cancer patients

PURPOSE

Angiogenesis, a process fundamental to tumor growth, is regulated by angiogenic factors. This article reviews prognostic and other clinical implications of circulating angiogenic factors in cancer patients.

METHODS

A MEDLINE search of literature was performed using the names of various angiogenic factors as the key words. Studies pertaining to circulating angiogenic factors in cancer patients were reviewed. Pertinent literature regarding tumor expression of common angiogenic factors and their prognostic relevance in human cancers were also examined.

RESULTS

A substantial number of studies have demonstrated a strong association between elevated tumor expression of vascular endothelial growth factor (VEGF) and advanced disease or poor prognosis in various cancers. This supports the pivotal role of VEGF in regulating tumor angiogenesis. More recently, there is mounting evidence that the level of circulating VEGF in patients with different types of cancer may be predictive of tumor status and prognosis. Preliminary data also suggest that circulating VEGF may be useful in predicting and monitoring tumor response to anticancer therapies and in follow-up surveillance for tumor relapse. There are reports supporting the prognostic value of other circulating angiogenic factors such as basic fibroblast growth factor, platelet-derived endothelial cell growth factor, transforming growth factor-beta, and angiogenin, but their clinical significance is less conclusive because of limited data.

CONCLUSION

Circulating VEGF seems to be a reliable surrogate marker of angiogenic activity and tumor progression in cancer patients. Evaluation of circulating angiogenic factors is a promising novel approach of prognostication in cancer patients that has the advantages of being convenient and noninvasive, and it may provide new prognostic information that is not afforded by conventional clinicopathologic prognostic indicators.

The value of platelet-derived endothelial cell growth factor as a novel predictor of advancement of uterine cervical cancers

Serum platelet-derived endothelial cell growth factor (PD-ECGF) in patients with uterine cervical cancers revealed a significantly positive correlation with clinical stage and tumor size and with the advancement indicators lymph node metastasis, parametrial involvement, and vessel permeation in both squamous cell carcinomas and adenocarcinomas. The prognosis of the patients with high serum PD-ECGF was extremely poor, whereas the 36-month survival rate of the other patients with low serum PD-ECGF was 81.3% in squamous cell carcinomas and 80.0% in adenocarcinomas. Our data indicate that serum PD-ECGF levels reflect the status of advancement of uterine cervical cancers and thus may be recognized as a novel tumor marker for both squamous cell carcinomas and adenocarcinomas of the uterine cervix.

Expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase in human bladder cancer

We investigated the expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP) in primary bladder cancer, its association with clinicopathologic findings, and their prognostic value. mRNA was extracted from 20 bladder cancer specimens and 6 normal bladder mucosal tissues. Relative amounts of PD-ECGF/TP mRNA were evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) and compared with the level of glyceraldehyde-3-phosphate dehydrogenase mRNA (used as an internal standard). PD-ECGF/TP expression was examined by immunohistochemistry in 85 patients who underwent cystectomy for bladder cancer. Serum PD-ECGF/TP levels were measured in 23 patients using a sandwich-type enzyme-linked immunosorbent assay. By RT-PCR analysis, expression of PD-ECGF/TP was found to be 7-fold higher in invasive tumors than in superficial tumors (P<0.01) and 9-fold higher than in normal bladder (P<0.01). Out of 85 transitional cell carcinoma tissue samples, 69 (81%) were evaluated as PD-ECGF/TP-positive by immunohistochemical staining. PD-ECGF/TP expression correlated significantly with tumor grade (P = 0.001), depth of invasion (P = 0.012), and lymphatic invasion (P = 0.01). No correlation was found between expression of PD-ECGF/TP and the number of tumors, tumor configuration, lymph node involvement, venous invasion, c-erbB-2 expression, or overall survival. We could not detect a significant serum level of PD-ECGF/TP in any patient. The results suggest that PD-ECGF/TP might give valuable information for bladder cancer management, though it may not be a good new tumor marker for bladder cancer.

Association of thymidine phosphorylase concentration with ultrasound-derived indices of blood flow in ovarian masses

BACKGROUND

The aim of this study was to determine the relationship between the concentration of thymidine phosphorylase (a known angiogenic factor) and indices of blood flow in physiologic ovarian tissues and overt (benign and malignant) tumors.

METHODS

The ovaries of all patients were examined by transvaginal ultrasonography, with color Doppler imaging and pulsed Doppler spectral analysis, within the 24 hours preceding laparotomy. Ovaries removed at surgery were dissected into their main components (follicles, corpus luteum, and tumor) and, where possible, into areas of high blood velocity according to the results of color Doppler imaging. The concentration of thymidine phosphorylase was measured by an enzyme-linked immunosorbent assay.

RESULTS

Thirty-eight tissue aliquots (16 from normal ovaries and 22 from ovarian tumors) were obtained from 33 patients. Twenty-nine tissue samples (76%) came from areas of measurable (high) blood velocity. The concentration of thymidine phosphorylase was significantly higher in tissue associated with high blood velocity (median 17.9, range 1.8-78.3 units per mg of protein vs. median 6.8, range 1.3-24.7 units per mg of protein, respectively; P < 0.05, Mann-Whitney U test). All of 8 corpora lutea, 12 of 14 benign tumors, and 7 of 7 malignant tumors had measurable blood velocity. There was a significant correlation between the concentration of thymidine phosphorylase and the peak systolic velocity in benign tumors (correlation coefficient [r] = 0.79, P < 0.01) and malignant tumors (r = 0.87, P < 0.05).

CONCLUSIONS

High intratumoral peak systolic velocity as determined by transvaginal color Doppler imaging and spectral analysis reflects high production of thymidine phosphorylase. This finding may aid the development of antivascular therapy for patients with ovarian carcinoma.

[Age-related changes in metabolism of DNA precursors in patients with mastopathy]

The activity of thymidine kinase, thymidine phosphorylase, adenosine deaminase and 5'-nucleotedase of AMP was studied in tissues, blood serum and lymphocytes of 60 healthy females and 50 females with fibrocavernous mastopathy aged 23-70. It was revealed that age-related changes in the activity of thymidine kinase in blood serum reflect the analogous changes in enzyme activity in tissues of healthy women. A direct correlation was established between thymidine kinase activity and age both in healthy females and those with mastopathy. A significant decrease in activity of thymidine phosphorylase was demonstrated in blood serum of patients with mastopathy aged 46-60. Determined 4-fold increase in activity of adenosine deaminase in serum was accompanied by decreased enzyme activity in lymphocytes and decreased Lymphocyte Blast Transformation Index in the same age range. The revealed metabolic changes in DNA-precursors' metabolism in patients with mastopathy aged 46-60 might be one of the reasons of increased risk of oncological diseases in this age group.

[Use of enzyme test in chemotherapy of patients with cancer of the breast]

The activity of thymidine kinase, thymidine phosphorylase, adenosine deaminase, AMP 5'-nucleotidase was assessed in the serum of healthy females, patients with mastopathia cystica and those with stage IIIB breast cancer. The females age ranged from 23 to 70 years. The activity of the enzymes had significant differences in cancer patients. Minimal thymidine phosphorylase activity was found to suggest fibrous cancer. Changes in the enzymes levels in cancer patients on combined treatment may serve a biochemical test indicating the efficacy of the chemotherapy conducted.

[Age-dependent characteristics of metabolism of DNA precursors in healthy women, patients with mastopathy and breast cancer]

Activities of thymidine kinase, thymidine phosphorylase, adenosine deaminase and 5'-nucleotidase of AMP were studied in blood serum and lymphocytes of healthy women, patients with mastopathy and with mammary gland cancer of 23-70 years old. Age-dependent alterations in the enzymatic activity were detected in blood serum of healthy women. Activity of thymidine kinase was increased simultaneously with a decrease in thymidine phosphorylase activity in 36-70 years old oncological patients, while adenosine deaminase activity was increased in patients with mastopathy and with mammary gland cancer of all the age groups. Dynamics of the enzymatic activity studied before and during chemotherapeutic treatment may be used as one of biochemical tests for evaluation of the therapy efficiency in oncological patients.

[The dynamics of the enzymatic activity of DNA metabolism during the treatment of stomach cancer patients]

The activity of thymidine kinase was found to be distinctly elevated while the activity of thymidine phosphorylase was markedly reduced in the blood serum of patients with gastric cancer. The dynamics of enzymatic activity depended on the form of surgical intervention. In patients undergoing chemotherapy positive effects were observed in those with a high initial activity of thymidine phosphorylase. This enzyme test is recommended for determination of treatment efficiency and prognosis of the course of the disease.

[Activity of adenosine and thymidine metabolism enzymes in the blood of cancer patients of various ages]

The activity of metabolic enzymes, adenosine and thymidine, has been studied in the blood serum and lymphocytes of healthy people and oncological patients aged 23-80. An increase in the activity of thymidine kinase (EC 2.7.1.2), an enzyme of thymidine biosynthesis, was observed in the blood serum of oncological patients against a background of a sharp decrease in the activity of thymidine phosphorylase (EC 2.4.2.4), a catabolic enzyme. The revealed enzymic shifts have been observed in breast cancer patients after 36, in patients with the stomach cancer--after 46. It is found that an increase in the activity of adenosine deaminase (EC 3.5.4.4) and 5-nucleotidase of AMP (EC 3.1.3.5) in the blood serum of oncological patients is accompanied by a sharp decrease in the activity of these enzymes in lymphocytes.

[Changes in the activities of enzymes of metabolism of DNA precursors in peptic ulcer and cancer of the stomach]

Comparative assessment of the remote results of Hoffmeister-Finsterer gastrectomy with creation of valve anastomoses has demonstrated rare occurrence of postoperative complications owing to anastomoses. The operation is simple as concerns operative techniques and can be recommended as operation of choice in the treatment of peptic ulcer.

The role of blood platelets in nucleoside metabolism: regulation of platelet thymidine phosphorylase

Blood platelets are the smallest cellular elements in mammalian blood. Because of their small size, platelets have an unusually large surface area: volume ratio and are exquisitely sensitive to a multitude of physiological and environmental stimuli. Platelets lack nuclei, but most possess functional mitochondria and remain capable of both anaerobic and aerobic energy metabolism, for which they utilise a variety of substrates including many which are cytotoxic and genotoxic for other (nucleated) cells. Nucleic acid precursors are amongst the potentially genotoxic compounds for which platelets have an apparently insatiable appetite. In particular platelets actively scavenge adenine and adenosine, which they convert to nucleotides and use in energy metabolism, but they also rapidly phosphorylase thymidine and liberate thymine into the extracellular medium. In addition, platelets contain non-metabolisable membrane-bound pools of adenine nucleotides which they secrete in response to strong agonists. Taken together, these observations suggest that blood platelets play an important role in nucleic acid precursor metabolism. In the previous paper we have shown that most thymidine phosphorylase activity present in normal human blood resides in the cytoplasm of platelets. Here we demonstrate that this enzyme activity can be modulated in a dose-dependent fashion, not only by substances recognised as platelet agonists and antagonists, but also by some compounds which are considered to be toxic, mutagenic and/or carcinogenic. The data which we present provide additional support for our previous suggestion that platelets regulate thymidine homeostasis and further imply that this is the normal, physiological, platelet function. Preliminary results suggest that assays of blood platelet thymidine metabolism may provide data with a wide variety of applications.

The role of blood platelets in nucleoside metabolism: assay, cellular location and significance of thymidine phosphorylase in human blood

The enzyme thymidine phosphorylase (thymidine: orthophosphate deoxyribosyltransferase, EC 2.4.2.4), which plays a crucial role in nucleic acid metabolism in both prokaryotic and eukaryotic cells by regulating the availability of thymidine, is present in mammalian blood. Here we describe a simple, rapid HPLC-based micromethod for the assay of blood thymidine phosphorylase. We have arbitrarily defined 1 unit of blood thymidine phosphorylase activity as the activity required to produce a 1-nM increment in the plasma concentration of thymine after incubation for 1 h at 37 degrees C with a saturating concentration of exogenous thymidine. In normal adults, whole (peripheral venous) blood thymidine phosphorylase activity with blood cells intact was 64 +/- 11 units (mean +/- S.D., n = 20, range 45-89). The apparent Michaelis constant for thymidine was of the order of 10(-4) M but varied nearly 5-fold between different individuals. Activity increased when blood cells were permeabilised or lysed with non-ionic detergents, implying that thymidine phosphorylase is an intracellular enzyme which may be influenced by exogenous as well as intracellular factors. When blood from normal donors was fractionated, thymidine phosphorylase activity consistently co-isolated with platelets. Whole-blood thymidine phosphorylase activity correlated well with platelet parameters. Although thymidine phosphorylase activity was also detected in plasma and serum, the small size and notorious fragility of platelets suggest its platelet origin. Blood from leukaemic donors showed significantly increased thymidine phosphorylase activity compared to normal controls (mean activity +/- S.D. was 96 +/- 27 units; range 58-140, n = 8). Thymine formation from thymidine was temperature- and pH-dependent in whole blood. 2'-Deoxyuridine and 3 of its 5-halogenated analogues (but not 3'-azido-3'-deoxythymidine (AZT), were catabolised by blood thymidine phosphorylase, even during blood clotting at room temperature. Assumptions about in vivo concentrations of these compounds should therefore be interpreted cautiously. In the presence of high concentrations of thymine and suitable deoxyribose donors, small amounts of thymidine were formed in some blood samples, so it is conceivable that thymidine catabolism may be reversible in vivo under some circumstances.

[Age-related characteristics of thymidine metabolism in healthy subjects and in patients with stomach ulcer and cancer]

Biosynthesis of pyrimidine nucleotides was intensified in proliferating tissues. Age-dependent alterations in activities of thymidine kinase and thymidine phosphorylase were found in healthy persons of 17-70 years old. Distinct increase in activity of thymidine kinase was observed in patients with gastric ulcer but the activity was decreased with ageing. Alterations in the ratio between anabolic and catabolic reactions involving thymidine were studied also in patients with gastric tumor depending on age.

The human blood platelet: a cellular model to study the degradation of thymidine and its inhibition

Intact platelets catabolize extracellular thymidine into thymine. Studies of the concentration dependent degradation of thymidine by intact platelets indicate a Michaelis mechanism with an apparent Km of about 0.12 mM and a Vmax of 2.5 nmoles/min for 3 X 10(8) platelets. This degradation process is inhibited by various nucleosides, pyrimidine bases and C-5 or C-6 substituted uracils. Cytidine, deoxycytidine, adenosine and deoxyadenosine seem to inhibit thymidine degradation by reducing the intracellular transport of thymidine. Uridine inhibits both the thymidine transport and the activity of the phosphorolytic enzyme, thymidine phosphorylase (EC 2.4.2.4). Some substituted uracils are specific inhibitors of thymidine phosphorylase activity. 6-Amino-5-bromouracil, the most active of them, either with acellular extracts or purified thymidine phosphorylase, is also the best inhibitor of thymidine degradation in intact human platelets. Platelets constitute a new model to study the efficiency of specific inhibitors on thymidine catabolism in an 'human intact cell' which contains only one pyrimidine nucleoside phosphorylase, the thymidine phosphorylase.

A rapid and simple radiometric assay for thymidine phosphorylase of human peripheral blood cells

A radiometric method is described for measuring thymidine phosphorylase activity in human peripheral blood cells. The substrates [14C]thymidine or [14C]thymine are converted to the base or deoxynucleoside, respectively, and two alternative chromatographic methods to isolate the products of the reaction have been employed. With the described methods the specific activity for thymidine phosphorylase in human lymphocytes is 0.21 +/- 0.08; monocytes 0.21 +/- 0.16 and granulocytes 0.17 +/- 0.02 mu mol.h-1.mg-1 protein. For human T- or null lymphoblasts, thymidine phosphorylase activity was found to be approximately 10% of that of B lymphoblasts.

Catabolism of thymidine in human blood platelets: purification and properties of thymidine phosphorylase

A pyrimidine nucleoside phosphorylase was partially purified from human blood platelets. The purified enzyme, as well as crude enzyme preparations, catalyses the phosphorolysis of thymidine and deoxyuridine, but not of uridine, and is able to catalyse direct pentosyl transfer from these deoxyribonucleosides to uracil or thymine; this enzyme has the properties of a thymidine phosphorylase. It has a molecular weight of about 110,000 and is composed of two identical subunits; it is phosphate dependent, has a maximal activity at a pH value of 5.7, and an isoelectric point of 4.4. This enzyme was mainly of cytoplasmic origin. Although platelet thymidine phosphorylase could promote the degradation or synthesis of thymidine, intact platelets degraded thymidine but were not able to synthesize thymidine from thymine. Blood platelets may play an important role in the degradation of plasma thymidine.

[Partial purification and characterization of thymidine phosphorylase in human platelets]

An enzyme which catalyzes the phosphorolytic cleavage of thymidine, and whose behaviour is characteristic of thymidine phosphorylase, was purified 130 times from human blood platelets. The results obtained by chromatography and electrophoresis, enable us to consider the existence of a dimeric form of this enzyme.

Suppressive effect of alcoholic liver disease sera on lymphocyte transformation

The effect of alcoholic patient sera on in vitro lymphocyte transformation was studied using mitogen-induced uptake of (3)H-thymidine to measure blastogenesis. With pokeweed mitogen as the stimulus, transformation of normal lymphocytes in sera of alcoholics with either normal or fatty livers was not significantly different from that obtained in pooled human serum (PHS). However, in sera of patients with either alcoholic hepatitis or inactive cirrhosis mean transformation was significantly reduced (P <0.001, <0.02 respectively). With phytohaemagglutinin-P or concanavalin A as mitogens, suppression of transformation was not as marked but followed the same pattern. A significant negative correlation was observed between the magnitude of transformation and serum bilirubin and aspartate aminotransferase levels. An intra-patient comparison of the effects on transformation of normal lymphocytes by simultaneously collected peripheral and portal venous sera, and of peripheral sera obtained before and after portasystemic shunt surgery, indicated that the factor(s) responsible did not originate in the splanchnic circulation nor did it accumulate in the serum because of failed hepatic clearance. By performing transformation experiments in the presence of inhibitory patient sera diluted with PHS it was possible to show that these sera caused true inhibition of transformation rather than suppression due to failure to sustain cell culture because of nutritional deficiencies. Inhibitory sera did not contain high levels of the enzyme thymidine phosphorylase and did not significantly inhibit binding of (125)I-labelled mitogens to the lymphocyte surface. These findings indicate that the inhibitory effect of sera from alcoholics is of potential in vivo importance, that the effect increases with the degree of heptocyte damage, and that it is unrelated to the nonhepatic metabolic affects of chronic alcoholism.

Thymidine sensitivity of cultured leukaemic lymphocytes

Cultured leukaemic lymphocytes from patients with T, null, or pre-B acute lymphoblastic leukaemia are shown to be highly sensitive to growth inhibition by thymidine. Thymidine sensitivity was correlated with reduced activity of the catabolic enzyme thymidine phosphorylase and sustained elevation of the deoxythymidine triphosphate pool after exposure to thymidine. It is suggested that thymidine may have a role in the management of certain acute lymphoblastic leukaemias of lymphomas.

Degradation of [3H]thymidine by a pentosyltransferase (EC 2.4.2.4) in the plasma of man and different animals

[3H]Thymidine is degraded by an enzyme (thymidine phosphorylase; EC 2.4.2.4) which we have identified in the plasma of man and some animals. The presence of this enzyme in plasma or sera used to supplement culture media may, under certain experimental conditions, limit the validity of measuring the uptake of radiolabeled thymidine as a means of defining DNA synthesis.