Platelet-derived endothelial cell growth factor (thymidine phosphorylase) expression in lung cancer

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.

Preoperative immunonutrition regulates tumor infiltrative lymphocytes and increases tumor angiogenesis in gastric cancer patients

INTRODUCTION

An increased number of tumor infiltrative lymphocytes (TILs) is considered a favorable prognostic factor in various cancers because it is a marker of antitumoral activity of the immune system. In this prospective, non-randomized clinical trial, we evaluated the impact of preoperative immunonutrition on tumor infiltrative lymphocytes and neoangiogenesis in cancerous tissue in patients with locoregional and resectable gastric adenocarcinoma.

MATERIAL AND METHODS

Patients with locoregional and resectable gastric adenocarcinoma were divided non-randomly into two study groups. The first (control) group included patients who had standard nutrition, and the second group included those who had immunonutrition for 7 days before surgery. The biopsy samples taken endoscopically in the preoperative period, as well as the gastrectomy samples, were subjected to immunohistochemical staining for quantitative analysis of CD4, CD8, CD16, CD56, CD31 and CD105 antibodies. Main outcome measures were CD4-to-CD8 ratio and CD105 levels.

RESULTS

Fifty patients were included in the study between January 2013 and December 2014. Twenty-five patients were assigned to each of the first and second group. The CD4-to-CD8 ratio and CD105 levels determined in endoscopic biopsy samples were similar in both groups. The CD4-to-CD8 ratio in gastrectomy samples was significantly higher in the first group (p = 0.0001). The CD105 levels in gastrectomy samples were significantly lower in the first group (p = 0.01).

CONCLUSIONS

Seven-day preoperative immunonutrition use regulates TILs in gastric cancer patients, but prolonged use increases tumor angiogenesis.

A phase 1b trial of the combination of an all-oral regimen of capecitabine and erlotinib in advanced non-small cell lung cancer in Caucasian patients

PURPOSE

Erlotinib is active in advanced non-small cell lung cancer (aNSCLC) particularly in patients with EGFR-sensitizing mutations. The thymidylate synthase inhibitors are active in NSCLC, but capecitabine is not well studied. This study explored the safety and activity of this oral combination.

METHODS

This phase Ib trial used a 3 + 3 escalation design with a combination of erlotinib (100 mg daily) with increasing doses of capecitabine (500, 750 and 1000 mg/m(2) BD, 14/21 days), in first- and second-line aNSCLC of adenocarcinoma histology. The DLT was any drug-induced toxicity ≥grade (G)2 causing dose interruption or dose delay during the first 2 cycles.

RESULTS

Forty patients were recruited, and 1 patient had an EGFR mutation. Dose escalation stopped at capecitabine 1000 mg/m(2) with expansion to 6 patients due to unpredicted DLTs in 2/6 patients: G2 creatinine rise, G2 anaemia, G3 atrial fibrillation and G3 pneumonia. MTD was capecitabine 750 mg/m(2). First-line dose escalation at the MTD led to unpredicted DLTs in 3/4 patients (G3 troponin rise, G2 rash and G2 hyperbilirubinaemia). MTD expansion in the second-line setting was well tolerated. The most common drug toxicities were gastrointestinal (35 %), followed by skin disorders (28 %). The response rate was 3 % with a disease control rate of 34 %. Median progressive-free survival was 1.6 months (95 % CI 1.4-3.5), and median overall survival was 6.1 months (95 % CI 5.1-10.1).

CONCLUSION

The MTD for the combination of capecitabine and erlotinib is 750 mg/m(2) BD, 14/21 days, and 100 mg daily, respectively, which is lower than predicted. Capecitabine did not improve the efficacy of erlotinib in aNSCLC unselected for EGFR mutation.

Assessment of biomarkers in asbestos-exposed workers as indicators of cancer risk

Epidemiological studies have shown that mortality from malignant mesothelioma (MM) and lung cancer have increased with increasing cumulative exposure to asbestos. To investigate whether tumour-related biomarkers can contribute towards the evaluation of the carcinogenic risk in populations exposed to asbestos, the DNA adduct 8-hydroxy-2'-deoxyguanosine (80HdG), interleukine-6 (IL-6), platelet-derived growth factor (PDGF-BB), hepatocyte growth factor (HGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGFbeta) and soluble mesothelin-related peptides (SMRPs) were analysed in a cohort of workers differently exposed to asbestos fibres at the workplace. To document biomarker levels in an unexposed population, 54 age-matched subjects were enrolled. A total of 119 subjects with a history of occupational exposure to asbestos underwent clinical examination and were interviewed by trained personnel, responding to a detailed questionnaire related to duration of asbestos exposure, smoking, and occupational task. According to the occupational tasks, asbestos-exposed subjects were analysed for their asbestos cumulative dose and the association with the biomarkers was evaluated. Among the occupational groups, maintenance workers, pipe fitters and electricians were exposed to a higher cumulative dose of asbestos fibres. Exposure to asbestos significantly increased the steady-state content of 80HdG in DNA. Elevated levels of 80HdG and IL-6 best reflected a high level of SMRPs, which is related to cell transformation. Subjects heavily exposed to asbestos [> 60(ff/cm3) x years] showed also a higher level of angiogenic factors. A combination of angiogenic biomarkers with a specific mesothelioma-biomarker such as SMRPs could be used for close surveillance of workers with a history of asbestos exposure.

Heterogeneous ribonucleoprotein k and thymidine phosphorylase are independent prognostic and therapeutic markers for nasopharyngeal carcinoma

PURPOSE

Heterogeneous ribonucleoprotein K (hnRNP K) regulates thymidine phosphorylase (TP) mRNA stability. The aim of the present study was to analyze hnRNP K and TP expression in nasopharyngeal carcinoma (NPC) and to evaluate the prognostic and therapeutic potential of these two markers.

EXPERIMENTAL DESIGN

We analyzed hnRNP K and TP expression immunohistochemically in 121 clinically proven NPC cases. Statistical analyses were applied to correlate cytoplasmic hnRNP K with elevated TP expression and determine the prognostic significance of these parameters. The therapeutic implication of elevated TP expression was determined by measuring sensitivity of NPC cells to the TP-targeting drug, 5-fluoro-5'-deoxyuridine (5'-DFUR).

RESULTS

There was a high correlation between cytoplasmic hnRNP K and high TP (P < 0.001). Both cytoplasmic hnRNP K and high TP were associated with poor overall survival (OS; P = 0.007 and P < 0.001, respectively) and distant metastasis-free survival (P = 0.003 and 0.001, respectively) of NPC patients. A multivariate analysis confirmed that both cytoplasmic hnRNP K and high TP are independent prognostic predictors for OS (P = 0.020 and 0.010, respectively). NPC cells expressing high TP were more sensitive to treatment with the TP-targeting drug, 5'-DFUR.

CONCLUSIONS

Cytoplasmic hnRNP K and high TP are associated with shorter OS and distant metastasis-free survival in NPC patients. In vitro experiments suggest that NPC tumors with high TP expression may be sensitive to 5'-DFUR treatment. Cytoplasmic hnRNP K and high TP may be potential prognostic and therapeutic markers for NPC, but additional validation studies are warranted.

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.

Pathophysiological mechanisms of angiogenesis

The growth of new blood vessels may be either beneficial or harmful. The angiogenic process may be measured by a variety of techniques, although it may often be the quality rather than quantity of resulting blood vessels that determines function. Endothelial cells play a key role in the initiation of angiogenesis, and vascular endothelial growth factor (VEGF) may be viewed as a prototypical direct-acting angiogenic factor. VEGF acts through multiple cell surface receptors and signaling pathways to stimulate endothelial cell proliferation, survival, and migration. By inducing other growth factor expression, VEGF stimulates a cascade of angiogenic activity. Different tissues may utilize various angiogenic pathways that are modulated by diverse host tissue responses. Furthermore, a single tissue may progress through a sequence of angiogenic pathways, for example, as acute injury progresses to chronic inflammation. The phenotype of the resulting neovasculature is critically dependent on the context in which it is formed. Biomarkers of angiogenesis are being developed as an aid to assessing human disease. Histological assessment of vascular density and angiogenic factor expression, in vivo imaging, Doppler ultrasound, and biofluid assays each may have clinical utility. Therapeutic targeting of angiogenesis will depend both on the generation of acceptable pharmacological agents and on the identification of patients who may and do gain benefit from such treatments.

A possible role of thymidine phosphorylase expression and 5-fluorouracil increased sensitivity in oropharyngeal cancer patients

Thymidine Pi deoxyribosyltransferase (TP) is an enzyme involved in DNA synthesis up-regulated in tumours and it is also a pro-angiogenic factor. TP cannot activate capecitabine, because capecitabine first needs conversion by carboxylesterase and cytidine deaminase into 5-deoxy-fluorouridine. This compound can be activated by TP to 5-fluorouracil (5-FU). Although TP is not necessary for 5-FU toxicity, experimental data suggest that high levels of TP correlate with an enhanced response to 5-FU therapy. In this study, we have analysed by immunohistochemistry CD34, CD68 and TP positive cells in bioptic samples from 53 patients with T_1–3 N_0–1 M₀ oropharyngeal squamous cell carcinoma (OSC) and from 24 patients with non-dysplastic oropharyngeal leukoplakia (NDOLP). Results showed that the mean of TP-positive cells, CD68 positive macrophages and CD34 positive endothelial cells eval-uated as microvessel density (MVD) was significantly higher in OSC than in NDOLP. Moreover, at a median follow-up of 19 months, patients with TP expression and higher MVD showed a better survival rate as compared to those with low MVD, probably as a consequence of 5-FU-based therapy.We hypothesized a role for TP in oropharyngeal tumourigenesis and 5-FU activation in the adjuvant setting of OSC patients.

A phase II trial of docetaxel plus capecitabine in patients with previously treated non-small cell lung cancer

BACKGROUND

A combination of docetaxel (T) and capecitabine (X) showed synergistic effects in preclinical studies and phase III randomized trials of metastatic breast cancer. We conducted this phase II study to examine its efficacy in previously treated non-small cell lung cancer (NSCLC) patients.

METHODS

Patient eligibility required advanced NSCLC with measurable lesion(s), at least one prior regimen failure and Eastern Cooperative Oncology Group (ECOG) performance status 0-2. Treatment consisted of T 36 mg/m(2) i.v. on days 1 and 8 plus X 1000 mg/m(2) p.o. b.i.d. on days 1-14 of a 21-day cycle (level I) or T 30 mg/m(2) i.v. on days 1 and 8 plus X 625 mg/m(2) p.o. b.i.d. on days 1-14 of a 21-day cycle (level II).

RESULTS

A total of 35 patients (M/F=24/11) were enrolled; 29 had received one prior regimen and 19 had received platinum-based regimens. Significant non-hematologic toxicities were observed after the treatment given at level I, including one treatment-related death. Subsequently 29 patients were treated at level II. The treatment at level II was well tolerated with grade 3 or 4 neutropenia only in 10%, grade 3 asthenia in 21% and stomatitis in 14% of patients. Four (15%) of 27 evaluable patients had partial response (PR) at level II and eight (30%) had stable disease (SD).

CONCLUSIONS

The TX regimen showed modest antitumor effects in patients with previously treated NSCLC. For further studies, we recommend T 30 mg/m(2) i.v. on days 1 and 8 plus X 625 mg/m(2) p.o. b.i.d. on days 1-14 of a 21-day cycle.

Angiogenesis in non-small cell lung cancer: The prognostic impact of neoangiogenesis and the cytokines VEGF and bFGF in tumours and blood

BACKGROUND

Due to a dismal prognosis of advanced lung cancer, novel screening tools and more effective treatments are clearly needed. Lately, an increasing number of tumour-released angiogenic cytokines which affect vessel formation, tumour growth, invasion, and metastasis have been identified. Vascular endothelial growth factors (VEGFs) and basic fibroblast growth factor (bFGF) are among the most important angiogenic factors. Based on available literature, we have explored the mechanisms of angiogenesis and its prognostic significance in non-small cell lung cancer, estimated by microvessel density (MVD) and the presence of VEGF and bFGF in the tumour and blood from NSCLC patients.

METHODS

Several comprehensive Pubmed searches for the period January 1993 to May 2005 were performed using strategic combinations of the terms non-small cell lung cancer, angiogenesis, vascular endothelial growth factor, basic fibroblast growth factor, tumour expression, microvessel density, circulating, and serum.

RESULTS

NSCLC neoangiogenesis, as measured by MVD, and tumour expression of VEGF are poor prognostic factors for survival (MVD, HR 1.8-2.0; VEGF, HR 1.5). bFGF tumour expression is also associated with poor survival and more aggressive disease. When evaluating the prognostic impact of elevated VEGF levels in blood, 10 of 16 studies (63%) indicated a negative prognostic impact. Of five studies on the prognostic value of circulating bFGF, three studies reported a negative prognostic impact, while one indicated bFGF as a good prognostic factor and one was inconclusive.

CONCLUSION

Angiogenic factors are poor prognostic indicators for tumour aggressiveness and survival in NSCLC. Assessments of circulating levels of VEGF and possibly bFGF may be valuable future tools for treatment planning and monitoring of treatment effect and relapse. First, however, these blood tests need to be standardised and validated in large-scale prospective clinical trials.

Phase II study of weekly irinotecan plus capecitabine for chemotherapy-naive patients with advanced nonsmall cell lung carcinoma

BACKGROUND

A Phase II study was conducted to evaluate the efficacy and toxicity of an irinotecan plus capecitabine combination, a new nonplatinum regimen, in chemonaive patients with advanced nonsmall cell lung carcinoma (NSCLC).

METHODS

Between July 2003 and April 2004, 53 patients with a histologically confirmed diagnosis of NSCLC were enrolled. All but 5 patients were male, 52 (98%) had an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1, 39 (74%) had AJCC Stage IV disease, and the median age was 61 years. Treatment consisted of intravenous irinotecan at a dose of 90 mg/m(2) on Days 1 and 8 and oral capecitabine at a dose of 1000 mg/m(2) twice daily on Days 1-14 of each 21-day cycle, given up to 12 cycles.

RESULTS

Of 53 patients enrolled, 22 achieved objective tumor responses (all partial responses) for an overall response rate of 41.5% (95% confidence interval [95% CI], 28.2-54.8%). After a median follow-up of 17.4 months, the median survival was 14.6 months with a 1-year survival rate of 60.1% (95% CI, 46.9-73.4%) and a median progression-free survival of 5.1 months. Treatment was very well tolerated, with only 10% of patients experiencing NCI-CTC Grade 3 or 4 toxicities. The most common toxicities were hand-foot syndrome and diarrhea. In multiple logistic regression analysis for overall response, only the stage predicted for significantly better response (P = 0.04). Squamous cell carcinoma was marginally predictive for better response (P = 0.08).

CONCLUSIONS

The irinotecan plus capecitabine regimen demonstrated an antitumor activity that is favorably comparable with other commonly used cisplatin-based regimens. Given the mild toxicity profile and favorable survival outcome, this nonplatinum regimen warrants further evaluation in a randomized trial.

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.

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

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

Mouse models for human lung cancer

In recent years several new mouse models for lung cancer have been described. These include models for both non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). Tumorigenesis in these conditional mouse tumor models can be initiated in adult mice through Cre-recombinase-induced activation of oncogenic mutations in a subset of the cells. They present a marked improvement over mouse models that depend on carcinogen induction of tumors. These models permit us to study the consecutive steps involved in initiation and progression and allow us to address questions like the cell of origin, and the role of cancer stem cells in the maintenance of these tumors. They now need to be validated as suitable preclinical models for intervention studies in which questions with respect to therapy response and resistance can be addressed.

Novel targeted agents in the treatment of lung cancer

Lung cancer is the leading cause of cancer-related mortality in the US. Although an improvement in outcome is possible with the continued advancement of cytotoxic-based treatment, clinical research is currently focused on utilising novel molecular targets with proven efficacy in preclinical models and a low toxicity profile. This is the result of advances in understanding of tumour biology and molecular pathways that have been implicated in cancer pathogenesis and progression. Novel agents targeting cell cycle regulation, angiogenesis and signal transduction pathways have reached clinical testing in lung cancer and are discussed in this review.

Nucleophilic Participation in the Transition State for Human Thymidine Phosphorylase

Recombinant human thymidine phosphorylase catalyzes the reaction of arsenate with thymidine to form thymine and 2-deoxyribose 1-arsenate, which rapidly decomposes to 2-deoxyribose and inorganic arsenate. The transition-state structure of this reaction was determined using kinetic isotope effect analysis followed by computer modeling. Experimental kinetic isotope effects were determined at physiological pH and 37 degrees C. The extent of forward commitment to catalysis was determined by pulse-chase experiments to be 0.70%. The intrinsic kinetic isotope effects for [1'-(3)H]-, [2'R-(3)H]-, [2'S-(3)H]-, [4'-(3)H]-, [5'-(3)H]-, [1'-(14)C]-, and [1-(15)N]-thymidines were determined to be 0.989 +/- 0.002, 0.974 +/- 0.002, 1.036 +/- 0.002, 1.020 +/- 0.003, 1.061 +/- 0.003, 1.139 +/- 0.005, and 1.022 +/- 0.005, respectively. A computer-generated model, based on density functional electronic structure calculations, was fit to the experimental isotope effect. The structure of the transition state confirms that human thymidine phosphorylase proceeds through an S(N)2-like transition state with bond orders of 0.50 to the thymine leaving group and 0.33 to the attacking oxygen nucleophile. The reaction differs from the dissociative transition states previously reported for N-ribosyl transferases and is the first demonstration of a nucleophilic transition state for an N-ribosyl transferase. The large primary (14)C isotope effect of 1.139 can occur only in nucleophilic displacements and is the largest (14)C primary isotope effect reported for an enzymatic reaction. A transition state structure with substantial bond order to the attacking nucleophile and leaving group is confirmed by the slightly inverse 1'-(3)H isotope effect, demonstrating that the transition state is compressed by the impinging steric bulk of the nucleophile and leaving group.

A phase II study of weekly docetaxel plus capecitabine for patients with advanced nonsmall cell lung carcinoma

BACKGROUND

Docetaxel is an active agent in advanced nonsmall-cell lung carcinoma (NSCLC) and demonstrates preclinical and clinical synergism with capecitabine. We conducted the current Phase II study to evaluate the efficacy and safety of the docetaxel/capecitabine combination in chemotherapy-naive patients with advanced NSCLC.

METHODS

Eligibility required Stage IIIB or IV NSCLC, bidimensionally measurable disease, and an Eastern Cooperative Oncology Group performance score of 2 or lower. Treatment consisted of docetaxel 36 mg/m(2) intravenously on Days 1 and 8 plus capecitabine 1000 mg/m(2) orally twice per day on Days 1-14 of a 21-day cycle, for a maximum of 6 cycles.

RESULTS

Of 39 patients enrolled, 39 and 36 patients were evaluated for toxicity and response, respectively. The overall response rate was 53% (95% confidence interval [CI], 37-69%) with 19 partial responses (no complete response). The median duration of response was 6.2 months (range, 2.1-15.7 months). At a median follow-up of 14.2 months, 19 patients died. The median overall survival time was 17.8 months, with a 1-year survival rate of 56.4% (95% CI, 40.9-72.0%). There were two treatment-related deaths (one death due to pneumonia and one due to sepsis). Hematologic toxicity was mild to moderate. Thirteen percent of the patients had Grade 3 or 4 neutropenia. However, Grade 2 or 3 nonhematologic toxicities were frequent, which included asthenia (51%), stomatitis (33%), hand-foot syndrome (33%), and diarrhea (29%).

CONCLUSIONS

The docetaxel/capecitabine combination showed promising antitumor activity for chemotherapy-naive patients with advanced NSCLC, However, it was frequently associated with moderate-to-severe nonhematologic toxicities, suggesting clinical synergism in both efficacy and toxicity. Further adjustment of the dose schedule is recommended to maximize the therapeutic index.

Role of thymidine phosphorylase on invasiveness and metastasis in lung adenocarcinoma

Thymidine phosphorylase (TP) is expressed at higher levels in a variety of human cancers than in adjacent normal tissue. It is reported that the higher expression is associated with an increase of intratumoral microvessel density and a poor prognosis. We investigated the role of TP in human non small cell lung cancers (NSCLCs). The concentrations of TP in the tumors and the adjacent normal tissue from surgically resected specimens of 54 cases of NSCLCs were measured by using an enzyme-linked immunosorbent assay. Tumor specimens were also examined immunohistochemically. TP concentrations in the tumors were 169 +/- 18 units/mg protein (mean +/- SD), whereas those in normal tissue were 43 +/- 4 units/mg protein (mean +/- SD), consistent with TP staining patterns. There was no correlation between TP expression and microvessel density. Among clinicopathologic factors examined, the concentrations of TP but not TP immunoreactivity correlated with tumor differentiation in lung adenocarcinoma. Although a specific TP inhibitor (TPI) and overexpression of TP did not affect the growth of A549 lung adenocarcinoma cells, Matrigel invasion assay showed that A549 transfected with TP had higher invasive potential than mock transfectant, and such enhanced invasive activity was markedly diminished by treatment with TPI. Furthermore, administration of TPI suppressed lung metastasis of TP-overexpressing A549 cells in nude mice. These results demonstrate that TP may play an important role in tumor differentiation, invasiveness and metastasis in lung adenocarcinoma, and suggest that TP could be a novel target for treatment of TP-overexpressing lung adenocarcinoma.

Expression of thymidylate synthase and thymidine phosphorylase in human breast carcinoma: implication for method to detect expression of these molecules in clinic

Thymidine phosphorylase (dThdPase) is identical to platelet-derived endothelial cell growth factor, and has an angiogenic activity in experimental models and human solid tumors. A critical step in the de novo pathway of DNA synthesis is the production of the pyrimidine nucleotide dTMP from dump and this reaction is catalyzed by thymidylate synthase (TS). Both dThdPase and TS levels seemed to be related to response to 5-fluorouracil (5-FU) therapy in different types of human solid tumors. The present study evaluated dThdPase and TS expression levels by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR), using a same set of 39 breast carcinoma tissues for both methods. An inverted-relationship in the expression levels of TS and dThdPase was observed. Further, immunohistochemical analysis may be a better tool than analysis by RT-PCR in detection of dThdPase and TS, because of both dThdPase and TS expression in cells besides carcinoma cells. These imply that immunohistochemical analysis of dThdPase and TS is available for selection of patients who will be received 5-FU based chemotherapy.

Epidermal growth factor receptors and cyclooxygenase-2 in the pathogenesis of non-small cell lung cancer: potential targets for chemoprevention and systemic therapy

The epidermal growth factor receptor (EGFR) is part of a family of plasma membrane receptor tyrosine kinases that control many important cellular functions, from growth and proliferation to cell death. Cyclooxygenase (COX)-2 is an enzyme which catalyses the conversion of arachidonic acid to prostagladins and thromboxane. It is induced by various inflammatory stimuli, including the pro-inflammatory cytokines, Interleukin (IL)-1beta, Tumour Necrosis Factor (TNF)-alpha and IL-2. Both EGFR and COX-2 are over-expressed in non-small cell lung cancer (NSCLC) and have been implicated in the early stages of tumourigenesis. This paper considers their roles in the development and progression of lung cancer, their potential interactions, and reviews the recent progress in cancer therapies that are directed toward these targets. An increasing body of evidence suggests that selective inhibitors of both EGFR and COX-2 are potential therapeutic agents for the treatment of NSCLC, in the adjuvant, metastatic and chemopreventative settings.

Thymidine phosphorylase expression in normal, hyperplastic and neoplastic prostates: correlation with tumour associated macrophages, infiltrating lymphocytes, and angiogenesis

Thymidine phosphorylase is an angiogenic factor primarily expressed by cancer cells, stromal cells and tumour-associated macrophages in many human malignancies. These different types of thymidine phosphorylase-expressing cells, however, may have a distinct place in the angiogenic process, and this question was addressed in the present study. A series of 20 normal/hyperplastic prostate glands and 60 prostate carcinomas was investigated by immunohistochemistry, using specific antibodies for thymidine phosphorylase (P-GF.44C), tumour-associated macrophages (CD68), endothelium (CD31) and prostate specific antigen (ER-PR8). Thymidine phosphorylase expression by normal and hyperplastic epithelial or stromal cells occurred almost exclusively in the context of an intense lymphocytic infiltrate. High thymidine phosphorylase cancer cells and thymidine phosphorylase stromal cells expression was associated with high angiogenesis in prostate carcinomas, and this significant association was extended to include both tumour-associated macrophages and tumour-infiltrating lymphocytes. Thymidine phosphorylase expression and tumour-infiltrating lymphocytes were related inversely with prostate specific antigen reactivity. In conclusion, thymidine phosphorylase is a major angiogenic factor in prostate carcinomas and its up-regulation is likely to occur in the context of a host immune response.

Towards a biological staging model for operable non-small cell lung cancer

Non-small cell lung cancer is the most common cause of cancer-related death in North America and Europe. Despite improvements in the diagnosis and treatment of the disease the prognosis remains poor, the overall 5-year survival being 4-14%. An increased understanding of the molecular biology of the disease may identify novel targets for drug development. We evaluated epidermal growth factor receptor (EGFR), HER-2/neu, matrix metalloproteinase (MMP)-2, MMP-9, p53 and bcl-2 expression and microvessel density (MVD) in patients who underwent surgery with curative intent in our department between 1991 and 1996. Co-expression of EGFR/MMP-9, MVD and bcl-2 were found to be independent prognostic variables, which allowed prediction of patient outcome independent of surgical stage. Other prognostic factors identified in our series were gender, surgical stage, platelet count, extent of necrosis, the hypoxia marker carbonic anhydrase-9 and beta-catenin. In collaboration with groups in Oxford and Greece, we were also able to establish the angiogenic growth factors vascular endothelial growth factor and platelet-derived endothelial growth factor as prognostic variables. The inter-relationships between these factors are currently being examined in an expanded patient series. Through this work we hope to be able to construct an integrated biological prognostic model which can be tested in prospective studies. This work has identified several potential targets for novel therapeutic agents currently in development.

Thymidine phosphorylase activity in nonsmall cell lung carcinoma tissues

BACKGROUND

This is the first study on the quantitative assessment of thymidine phosphorylase (TP) activity in patients with nonsmall lung carcinoma. TP is identical to the platelet-derived endothelial cell growth factor with its angiogenic activity. Thus, it is believed that TP activity in tumor tissues plays an important role in disease progression.

METHODS

Using a sandwich enzyme immunoassay, the TP activity in lung carcinoma tissues was measured quantitatively in 39 patients with primary lung carcinoma who underwent pulmonary lobectomy between July 1999 and May 2000.

RESULTS

The mean value of TP activity in tumor tissues was significantly higher than the level in normal lung tissues (226 U/mg protein vs. 46 U/mg protein, respectively; P < 0.0001). TP activity in normal lung tissues was high in male patients (male vs. female, respectively: 56.1 U/mg protein vs. 29.3 U/mg protein; P = 0.001) and in heavy smokers (Brinkmann index [BI] > or = 600 [57.9 U/mg protein] vs. BI < 600 [31.7 U/mg protein]; P = 0.001). Conversely, the TP activity in tumor tissues was correlated with neither gender nor smoking status. Although there was no difference in the TP activity among histologic types, well-differentiated tumors exhibited a significantly lower level of TP activity compared with the activity in both moderately and poorly differentiated tumors. However, the TP activity in tumor tissues was not correlated with disease progression.

CONCLUSIONS

High TP activity in tumor tissues from patients with primary lung carcinoma did not reflect the malignant potential of the disease.

The intratumoral expression of vascular endothelial growth factor and interleukin-8 associated with angiogenesis in nonsmall cell lung carcinoma patients

BACKGROUND

Angiogenesis has important effects on tumor growth and metastasis. It is regulated by a variety of angiogenic and angiostatic factors.

METHODS

To evaluate the effects of tumor cell-derived angiogenic factors, we performed an immunohistochemic study to evaluate the intratumoral expression of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) in relation to intratumoral microvessel density (IMD) in tumors from 104 nonsmall cell lung carcinoma (NSCLC)patients.

RESULTS

Fifty-four carcinomas were VEGF-positive, 47 carcinomas were IL-8-positive, and 53 carcinomas were hypervascular tumors. There was no significant correlation between the percentages of positive VEGF-staining and positive IL-8-staining in NSCLCs (rho = 0.174, P = 0.080). The IMD of VEGF-positive carcinomas was significantly greater than that of VEGF-negative carcinomas (P = 0.023). In addition, the IMD of IL-8-positive carcinomas was significantly greater than that of IL-8-negative carcinomas (P =0.013). The overall survival rate of patients with hypervascular tumors was significantly lower than that of patients with hypovascular tumors (41.0% versus 67.0%, P = 0.004). Cox proportional-hazards regression model also demonstrated that angiogenesis was one of the significant factors in predicting the survival of NSCLC patients (relative risk = 1.944, P = 0.041).

CONCLUSIONS

Intratumoral expression of VEGF and IL-8 was associated with angiogenesis in NSCLCs. Tumor angiogenesis significantly affected the prognosis of NSCLC patients.

'Invading edge vs. inner' (edvin) patterns of vascularization: an interplay between angiogenic and vascular survival factors defines the clinical behaviour of non-small cell lung cancer

Neo-angiogenesis during neoplastic growth involves endothelial mitogenic and migration stimuli produced by cancer or tumour stromal cells. Although this active angiogenesis takes place in the tumour periphery, the process of vessel growth and survival in inner areas and its clinical role remain largely unexplored. The present study compared the microvessel score (MS) as well as the single endothelial cell score (ECS) in the invading edge and in inner areas of non-small cell lung carcinomas (NSCLCs). Three different patterns of vascular growth were distinguished: the edvin (edge vs. inner) type 1, where a low MS was observed in both peripheral and inner tumour areas; the edvin type 2, where a high MS was noted in the invading front but a low MS in inner areas; and the edvin type 3, where both peripheral and inner tumour areas had a high MS. The ECS was high in the invading edge in edvin type 2 and 3 cases and was sharply decreased in both types in inner areas, suggesting that endothelial cell migration is unlikely to contribute to the angiogenic process in areas away from the tumour front. Expression of the vascular endothelial growth factor (VEGF) and of thymidine phosphorylase (TP) was associated with a high MS in the invading edge. VEGF was associated with a high MS in inner areas (edvin 3), while TP expression was associated with edvin type 2, showing that VEGF (and not TP) contributes to the preservation of the inner vasculature. Both edvin type 2 and 3 cases showed an increased incidence of node metastasis, but edvin type 3 cases had a poorer prognosis, even in the N1-stage group. The present study suggests that tumour factors regulating angiogenesis and vascular survival are not identical. A possible method is reported to quantify these two parameters by comparing the MS in the invading edge and inner areas (edvin types). This observation may contribute to the evaluation of the effectiveness of different therapeutic approaches, namely vascular targeting vs. anti-angiogenesis.

Thymidine phosphorylase expression in normal and hyperplastic endometrium

AIMS

To investigate the expression of thymidine phosphorylase (TP), a known angiogenic factor for endothelial cells, in normally cycling endometrium and various forms of endometrial hyperplasia.

METHODS

TP expression was assessed with the P-GF.44C monoclonal antibody, using the alkaline phosphatase anti-alkaline phosphatase method. Ninety two normal and hyperplastic endometria were studied.

RESULTS

In normal proliferative endometrium, TP is found exclusively in the basal layer and the inner third of the functionalis; expression is cytoplasmic in glandular epithelium and nuclear in stromal cells. It is invariably patchy. This immunohistochemical picture remains almost unaltered during the early and mid secretory phase of the normal menstrual cycle but, most impressively, TP is expressed uniformly in the epithelium of all endometrial glands towards the end of the cycle. At this stage, expression is mixed nuclear/cytoplasmic and there is very little stromal nuclear staining. In simple endometrial hyperplasia, the staining pattern for TP is identical to normal proliferative endometrium, with a distribution that is usually limited to a few rather weakly proliferating glands and to the adjacent periglandular stroma of the deep endometrium. The distribution is more extensive in complex and atypical endometrial hyperplasias, where a mixed nuclear/cytoplasmic pattern usually prevails over the pure cytoplasmic reaction.

CONCLUSIONS

TP is expressed consistently in normal and hyperplastic endometrium, suggesting a role in physiological and pathological angiogenesis. In normal endometrium, TP has a definite pattern of distribution, which is dependent on the phase of the menstrual cycle, whereas in all forms of endometrial hyperplasia the enzyme is randomly distributed and lacks an orderly pattern.

Induction of thymidine phosphorylase as a pharmacodynamic end-point in patients with advanced carcinoma treated with 5-fluorouracil, folinic acid and interferon alpha

Thymidine phosphorylase (TP) is an essential enzyme for the biochemical activation of 5-fluorouracil (5-FU). Interferon upregulates TP in vivo, although the dose and schedule of interferon for optimal biomodulation of 5-FU is not known. In this study, TP activity was measured in peripheral blood lymphocytes (PBLs) from patients with advanced carcinoma receiving treatment with 5-FU and folinic acid. Cohorts of patients were treated with interferon alpha (IFNalpha), immediately prior to 5-FU/folinic acid, at doses of 3 MIU m(-2), 9 MIU m(-2) and 18 MIUm(-2). IFNalpha was administered on day 0 cycle two, day-1 and day 0 cycle three and day-2, day-1 and day 0 cycle four. A fourth cohort was treated with IFNalpha 9 MIU m(-2) three times per week from cycle 2 onwards. Twenty-one patients were entered into the study with 19 evaluable for response. Six patients (32%) had stable disease and 13 (68%) progressive disease. There were no grade-IV toxicities. TP activity was detected in PBLs from all patients with wide interpatient variability in constitutive TP activity prior to chemotherapy, and in response to IFNalpha. 5-FU/folinic acid alone did not induce TP activity but a single dose of IFNalpha led to upregulation of TP within 2 h of administration with a further increase by 24 h (signed rank test, P = 0.006). TP activity remained elevated for at least 13 days (signed rank test, P= 0.02). There were no significant differences in TP activity between schedules or with additional doses of IFNalpha. A single dose of IFNalpha as low as 3 MIU m(-2) can cause sustained elevation of PBL TP activity in vivo indicating that biochemical markers are important pharmacodynamic endpoints for developing optimal schedules of IFNalpha for biomodulation of 5-FU.

Novel nonsubstrate inhibitors of human thymidine phosphorylase, a potential target for tumor-dependent angiogenesis

Thymidine phosphorylase/platelet-derived endothelial cell growth factor (TP/PD-ECGF) is an enzyme involved in thymidine metabolism and homeostasis, and its catalytic activity appears to play an important role in angiogenesis. Here we describe the cloning and expression of a His-tagged human TP/PD-ECGF and its assay with uracil and thymine analogues. We present the design, synthesis, and biological evaluation of novel 6-(phenylalkylamino)uracil derivatives which, at micromolar concentrations, inhibit both catabolic and anabolic reactions of human TP in vitro. These base analogues are not converted by the enzyme into the nucleoside form, thus representing pure nonsubstrate inhibitors of the enzyme.

Vascular endothelial growth factor, platelet-derived endothelial cell growth factor and angiogenesis in non-small-cell lung cancer

High microvessel density, an indirect measure of angiogenesis, has been shown to correlate with increased tumour size, lymph node involvement and poor prognosis in non-small-cell lung cancer (NSCLC). Tumour cell vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) expression correlate with angiogenesis and a poor outcome in this disease. In a retrospective study VEGF and PD-ECGF expression and microvessel density were evaluated immunohistochemically in surgically resected specimens (T1-3, N0-2) from 223 patients with operable NSCLC using the VG1, P-GF.44C and JC70 monoclonal antibodies respectively. High VEGF immunoreactivity was seen in 104 (46.6%) and PD-ECGF in 72 (32.3%) cases and both were associated with high vascular grade tumours (P= 0.009 and P= 0.05 respectively). Linear regression analysis revealed a weak positive correlation between VEGF and PD-ECGF expression in cancer cells (r= 0.21; P = 0.002). Co-expression of VEGF and PD-ECGF was not associated with a higher microvessel density than VEGF or PD-ECGF only expressing tumours. Furthermore a proportion of high vascular grade tumours expressed neither growth factor. Univariate analysis revealed tumour size, nodal status, microvessel density and VEGF and PD-ECGF expression as significant prognostic factors. Tumour size (P < 0.02) and microvessel density (P < 0.04) remained significant on multivariate analysis. In conclusion, VEGF and PD-ECGF are important angiogenic growth factors and have prognostic significance in NSCLC. Furthermore the study underlines the prognostic significance of microvessel density in operable NSCLC.

Expression of angiogenic growth factors in paragangliomas

OBJECTIVE/HYPOTHESIS

To determine if angiogenic growth factors including vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) are expressed in human paragangliomas.

STUDY DESIGN

A histopathologic and molecular examination of paraganglioma specimens obtained from surgical cases or retrieved from the Pathology Department of the Massachusetts Eye and Ear Infirmary.

METHODS

Fresh tumor or archival, paraffin-embedded paraganglioma specimens were analyzed by immunohistochemistry, Western blotting, and ELISA.

RESULTS

Positive immunohistochemical staining for VEGF was observed in five of nine surgical specimens and in six of eight archival specimens (11/17, or 65%). PD-ECGF immunoreactivity was detected in four of five surgical specimens and six of eight archival specimens (10/13, or 77%). The presence of PD-ECGF was confirmed by Western blot assay and ELISA confirmed the presence of VEGF in tumor extract.

CONCLUSIONS

Both VEGF and PD-ECGF are expressed in paragangliomas and may contribute to the extreme vascularity of these tumors. Key Words. Vascular endothelial growth factor, platelet-derived, endothelial cell growth factor, hypoxia, tumor vasculature.

The relationship between angiogenesis and the immune response in carcinogenesis and the progression of malignant disease

Recent studies have demonstrated that angiogenesis and suppressed cell-mediated immunity (CMI) play a central role in the pathogenesis of malignant disease facilitating tumour growth, invasion and metastasis. In the majority of tumours, the malignant process is preceded by a pathological condition or exposure to an irritant which itself is associated with the induction of angiogenesis and/or suppressed CMI. These include: cigarette smoking, chronic bronchitis and lung cancer; chronic oesophagitis and oesophageal cancer; chronic viral infections such as human papilloma virus and ano-genital cancers, chronic hepatitis B and C and hepatocellular carcinoma, and Epstein-Barr virus (EBV) and lymphomas; chronic inflammatory conditions such as Crohn's disease and ulcerative colitis and colorectal cancer; asbestos exposure and mesothelioma and excessive sunlight exposure/sunburn and malignant melanoma. Chronic exposure to growth factors (insulin-like growth factor-I in acromegaly), mutations in tumour suppressor genes (TP53 in Li Fraumeni syndrome) and long-term exposure to immunosuppressive agents (cyclosporin A) may also give rise to similar environments and are associated with the development of a range of solid tumours. The increased blood supply would facilitate the development and proliferation of an abnormal clone or clones of cells arising as the result of: (a) an inherited genetic abnormality; and/or (b) acquired somatic mutations, the latter due to local production and/or enhanced delivery of carcinogens and mutagenic growth factors. With progressive detrimental mutations and growth-induced tumour hypoxia, the transformed cell, to a lesser or greater extent, may amplify the angiogenic process and CMI suppression, thereby facilitating further tumour growth and metastasis. There is accumulating evidence that long-term treatment with cyclo-oxygenase inhibitors (aspirin and indomethacin), cytokines such as interferon-alpha, anti-oestrogens (tamoxifen and raloxifene) and captopril significantly reduces the incidence of solid tumours such as breast and colorectal cancer. These agents are anti-angiogenic and, in the case of aspirin, indomethacin and interferon-alpha have proven immunomodulatory effects. Collectively these observations indicate that angiogenesis and suppressed CMI play a central role in the development and progression of malignant disease.

Thymidine phosphorylase expression in endometrial carcinomas

Thymidine phosphorylase (TP) is a potent angiogenic molecule shown to induce endothelial cell migration and proliferation. We investigated the expression of TP in a series of 156 endometrial carcinomas, using immunohistochemical methods. Histopathological parameters of known prognostic significance and the molecular factors of p53, bcl-2 and angiogenesis were also assessed. Thymidine phosphorylase was expressed in cancer cells, stromal fibroblasts and myometrial cells. The pattern of TP staining was nuclear or mixed nuclear/cytoplasmic, and only exceptionally was purely cytoplasmic. An exclusively cytoplasmic staining was documented for the tumour-associated foamy macrophages. Cancer cell reactivity was rather limited; only 3.2% of endometrial carcinomas expressed TP in more than 50% of the neoplastic cell population and only 12% expressed the enzyme in more than 10% of the cancer cells. By contrast, TP reactivity was frequent in the fibroblasts of the tumour supporting stroma and the fibroblasts/myometrial cells at the invading tumour front, where approximately 1/3 of the cases expressed TP in more than 50% of the respective constituent cells. A high TP reactivity in the stromal fibroblasts was significantly associated with the presence of foamy macrophages and an intense lymphocytic response. A high TP reactivity at the invading tumour front was significantly associated with an intense lymphocytic response and the adverse prognostic parameters of high tumour grade, deep myometrial invasion, advanced stage of disease and the non-endometrioid carcinomas. There was no significant association of cancer cell TP reactivity with any of the parameters studied, including nuclear p53 accumulation, cytoplasmic/perinuclear bcl-2 expression, microvessel density (MVD) and prognosis. Similarly, no relationship was established between fibroblastic or fibroblastic/myometrial TP reactivity and MVD. It is concluded that TP is not a major angiogenic factor in endometrial carcinomas. However, a prominent TP activity at the invading tumour front, which is probably induced by cytokines of histiocytic and lymphocytic origin, may promote tumour invasion and progression.

Expression and localization of thymidine phosphorylase/platelet-derived endothelial cell growth factor in skin and cutaneous tumors

Thymidine phosphorylase/platelet-derived endothelial cell growth factor (TPase/PD-ECGF) is a catabolic enzyme that has been shown to be chemotactic for endothelial cells in vitro and angiogenic in vivo. TPase/PD-ECGF expression is increased in a variety of tumors. In the skin, TPase is active in normal keratinocytes in vitro and in vivo. Our objective was to study the expression and localization of TPase/PD-ECGF by immunohistochemical analysis in normal skin and cutaneous tumors and to correlate this information with enzymatic activity of TPase. TPase/PD-ECGF expression was observed in keratinocytes with intense staining of the infundibulum of hair follicles but no staining of hair bulbs. Expression localized primarily to the nucleus of keratinocytes in the basal layer but was more intense and cytoplasrmic in suprabasal keratinocytes. Increased expression of TPase/PD-ECGF in differentiated cells was confirmed by in vitro studies of TPase activity. In cutaneous tumors, there was positive staining for TPase/ PD-ECGF in squamous cell carcinomas (10/10), eccrine poromas (3/4), eccrine syringomas (4/4), trichoepitheliomas (1/3), and tumors of the follicular infundibulum (2/3) and melanomas (5/8). There was no staining of any intradermal nevi (0/2), basal cell carcinomas (0/10) or Merkel cell carcinoma (0/1). We conclude TPase/PD-ECGF is found throughout the epidermis and its expression increases with differentiation of keratinocytes. In cutaneous tumors, expression of TPase/PD-ECGF may be linked to the cell of origin of the tumor as well as the tumor's degree of differentiation.

Platelet-derived endothelial cell growth factor/thymidine phosphorylase concentrations differ in small cell and non-small cell lung cancer

OBJECTIVE

Platelet-derived endothelial cell growth factor (PD-ECGF)/thymidine phosphorylase (TP) has been implicated in cancer angiogenesis, which is critical for tumor growth and metastasis. We investigated the relationship between the tissue concentration of PD-ECGF/TP and the clinicopathologic status in human lung cancer.

METHODS

The concentrations of PD-ECGF/TP in the tumor extracts of 139 primary human lung carcinomas were measured by using a highly specific and sensitive enzyme-linked immunosorbent assay.

RESULTS

PD-ECGF/TP was detected in the extracts from 137 of 139 specimens at concentrations that ranged from 2.0 to 169.5 U/mg protein. PD-ECGF/TP concentrations in patients with adenocarcinoma (n = 73) and squamous cell carcinoma (n = 49) were (mean +/- SD) 30.7+/-22.9 U/mg protein (range, 7.6 to 169.5 U/mg protein) and 32.0+/-19.8 U/mg protein (range, 8.0 to 84.4 U/mg protein), respectively. No significant difference was found in the PD-ECGF/TP concentration between these two types of non-small cell lung cancer (NSCLC). However, a > 8-fold lower mean concentration of PD-ECGF/TP was found in tissue extracts from small cell lung cancer (SCLC) (n = 17; 3.65+/-2.01 U/mg protein, ranging from undetectable to 6.1 U/mg protein) than in those from adenocarcinomas (p = 0.00005) or squamous cell carcinomas (p < 0.00001).

CONCLUSIONS

The striking difference in PD-ECGF/TP concentrations between SCLC and NSCLC suggests that these two types of lung cancer use alternative pathways for angiogenesis. The present study suggests that inhibitors of PD-ECGF/TP, which have been recently developed and are under laboratory investigation to test their effectiveness as treatments for various types of cancer, may not be effective against SCLC.

Expression of the thymidine phosphorylase gene in epithelial ovarian cancer

Thymidine phosphorylase (TP) is associated with angiogenesis and the progression of solid tumours. High intracellular levels of this enzyme indicate increased chemosensitivity to pyrimidine antimetabolites. TP gene expression in 56 cases of epithelial ovarian cancer (27 of serous, 10 mucinous, 12 endometrioid, five clear cell and two undifferentiated) were analysed by polymerase chain reaction of RNA after reverse transcription. These included eight of low malignant potential. Twenty were stage I, four stage II, 27 stage III and five stage IV. The level of TP gene expression was presented by the relative yield of the TP gene to the beta2-microglobulin gene. TP gene expression ranged from 0.19 to 5.38 (median 0.93). The value of TP gene expression in stage III-IV was significantly higher than that of TP gene expression in stage I-II (P = 0.0005). Histological grade significantly associated with TP gene expression (P = 0.008), but histological subtype did not (P = 0.166). A follow-up study of 34 cases after complete resection of the primary tumours by surgical operation was performed. TP gene expression of the cases with recurrence showed significantly higher levels compared to cases without recurrence (P = 0.049). Survival data were available for 47 of the 56 patients. The prognosis of the patients with high TP gene expression (equal to, or greater than, median) was to be significantly worse than patients with low TP gene expression (less than median) (P = 0.021). The TP gene expression level may play one of the key roles in the biology of ovarian epithelial cancer and define a more aggressive tumour phenotype. A new therapeutic intervention mediated by TP protein activity is anticipated.

Expression of pyrimidine nucleoside phosphorylase mRNA plays an important role in the prognosis of patients with oesophageal cancer

To clarify the significance of the expression of pyrimidine nucleoside phosphorylase (PyNPase) mRNA as a predictive factor for the prognosis of patients with oesophageal carcinoma, the PyNPase mRNA in the tumours and normal tissues from 55 resected cases of oesophageal carcinoma was examined by a reverse transcription polymerase chain reaction (RT-PCR). As a result, a positive correlation was observed between the tumour/normal (T/N) ratio of the expression of PyNPase mRNA by RT-PCR and that of the enzyme activity of PyNPase based on the findings of an enzyme linked immunosolvent assay (r = 0.594, P = 0.009). The T/N ratio of the expression of PyNPase mRNA was significantly higher in the cases with lymph vessel invasion (P = 0.013), lymph node metastasis (P = 0.0016), and an advanced stage of the disease (P = 0.021) than those without these factors. The patients with a higher T/N ratio of PyNPase mRNA showed significantly worse prognosis than those with a lower T/N ratio (P = 0.023 with log-rank tests). A multivariate analysis for the cumulative survival rates revealed that a high T/N ratio of the expression of PyNPase mRNA was independently related to a poor prognosis. These findings suggested that the determination of PyNPase mRNA by RT-PCR thus appears to be a new useful parameter for identifying both a poor prognosis and a highly malignant potential of oesophageal carcinoma.

The crystal structure of pyrimidine nucleoside phosphorylase in a closed conformation

BACKGROUND

Pyrimidine nucleoside phosphorylase (PYNP) catalyzes the reversible phosphorolysis of pyrimidines in the nucleotide synthesis salvage pathway. In lower organisms (e.g. Bacillus stearothermophilus) PYNP accepts both thymidine and uridine, whereas in mammalian and other higher organisms it is specific for thymidine (designated thymidine phosphorylase, TP). PYNP shares 40% sequence similarity (and presumably significant structural similarity) with human TP, which has been implicated as a growth factor in tumor angiogenesis. It is thought that TP undergoes a major conformational change upon substrate binding that consequently produces an active conformation.

RESULTS

The crystal structure of PYNP from B. stearothermophilus with the substrate analog pseudouridine in its active site has been solved to 2.1 A resolution. This structure confirms the similarity of PYNP to TP and supports the idea of a closed active conformation, which is the result of rigid body movement of the alpha and alpha/beta domains. The active-site cleft, where the pyrimidine and phosphate substrates bind, is between the two domains. The structure reveals an asymmetric dimer in which one subunit is fully closed and the other is only partially closed.

CONCLUSIONS

The closed conformation of PYNP serves as a good model to better understand the domain movement and overall function of TP. Active-site residues are confirmed and a possible mechanism for substrate binding and subsequent domain movement is suggested. Potent inhibitors of TP might have significant therapeutic value in various chemotherapeutic strategies, and the structure of PYNP should provide valuable insight into the rational design of such inhibitors.

Neo-angiogenesis in locally advanced squamous cell head and neck cancer correlates with thymidine phosphorylase expression and p53 nuclear oncoprotein accumulation

Thymidine phosphorylase (Th.P) is an angiogenic factor shown to induce endothelial cell migration and proliferation. On the other hand, loss of wild type p53 function leads to down-regulation of thrombospondin-1, an inhibitor of angiogenesis. In this immunohistochemical study we investigated the intratumoural angiogenesis and thymidine phosphorylase (Th.P) expression in paraffin-embedded bioptical material from 104 locally advanced squamous cell head and neck cancers. The nuclear accumulation of mutant p53 protein and the cytoplasmic expression of bcl-2 protein was also assessed. High vascular grade was observed in 56% and high Th.P tumour cell reactivity in 48% of cases. High microvessel score was associated with an increased percentage of cancer cells expressing thymidine phosphorylase (P = 0.001). Increased p53 nuclear accumulation also correlated with high vascular grade (P = 0.001). High histological grade and absence of bcl-2 overexpression were associated with lymph node involvement (P = 0.002 and P = 0.02 respectively). No correlation of clinically detected lymphadenopathy with angiogenesis and p53 was observed. We conclude that intense neo-angiogenesis in locally advanced squamous cell head neck cancer is a frequent event, which is associated with nuclear p53 accumulation and thymidine phosphorylase overexpression.

Different patterns of stromal and cancer cell thymidine phosphorylase reactivity in non-small-cell lung cancer: impact on tumour neoangiogenesis and survival

Angiogenesis is recognized as an important step in tumour pathogenesis that is related to invasion and metastatic spread and which consequently results in poor clinical outcome. In this study, we have examined the role of tumour stroma-activated fibroblasts and macrophage infiltration in the development of the angiogenic and metastatic phenotype in non-small-cell lung cancer (NSCLC). A total of 141 cases of early stage I-II NSCLC treated with surgery alone were analysed. The JC-70 (anti-CD31) MAb was used for the assessment of vascular grade. The P-GF.44C MAb was used to assess thymidine phosphorylase (TP) reactivity in cancer cells, stromal fibroblasts and macrophages. Cancer cell TP overexpression related to high vascular grade and to advanced T stage (P = 0.0004 and P = 0.02). Expression of TP in stromal fibroblasts also correlated with high angiogenesis (P = 0.01), but was independent of cancer cell expression. Fibroblast TP overexpression was related to abundant stroma (P = 0.003), suggesting that TP may be a marker of active stroma. Moreover, intense macrophage infiltration was associated with fibroblast TP reactivity, regardless of the amount of stroma, suggesting that macrophages may be a major contributor to TP expression in stroma. Survival analysis showed that cancer cell TP overexpression was related to poor prognosis (P = 0.005). Although stroma TP is related to angiogenesis, in the low vascular grade group it defined a group of patients with better prognosis (P = 0.02). It may be that fibroblast TP reactivity is an indirect marker of tumour infiltration by functional macrophages, which have an antitumour effect. We conclude that stromal macrophage and fibroblast TP reactivity may have an important role in non-small-cell lung cancer behaviour. Understanding the role of stromal fibroblasts and inflammatory cells and their interaction with oncoprotein expression is essential for the elucidation of lung cancer pathogenesis.

Immunohistochemical expression of thymidine phosphorylase in human endometrial cancer

OBJECTIVE

To investigate correlations between the expression of thymidine phosphorylase (TP) by endometrial cancer cells and the density of microvessels within the tumor, the clinicopathologic features, and the prognosis.

METHODS

We examined tumor specimens obtained from 46 patients with endometrial cancer (9 FIGO stage IA, 16 stage IB, 8 stage IC, 1 stage IIA, 6 stage IIB, and 6 stage IIIC). The cellular expression of TP and the intratumoral density of microvessels were determined by immunohistochemistry using monoclonal antibodies to TP and factor VIII-related antigen, respectively. We investigated the relationship between the cellular expression of TP and the following factors: clinicopathologic features (menopausal status, histologic type, tumor size, histologic grade, myometrial invasion, cervical invasion, and metastasis), the microvessel count, and the disease-free survival period.

RESULTS

Of the 46 tumors, 19 (41%) were TP-positive. The microvessel count was significantly higher in TP-positive tumors than in TP-negative tumors (P = 0.01, Mann-Whitney U test). There was no significant correlation between TP expression and clinicopathologic features, and there was no significant difference in the disease-free survival period between patients with TP-positive tumors and patients with TP-negative tumors.

CONCLUSION

TP expression was not correlated with clinicopathologic features or prognosis, but was associated with an increased density of microvessels in endometrial cancer. These findings suggest that TP may play an important role in angiogenesis and may be involved in the tumorigenesis of endometrial cancer.

Tumor cell motility and metastasis : Autocrine motility factor as an example of ecto/exoenzyme cytokines

Cellular locomotion plays a critical role in such normal processes as embryonic development, tissue segregation, as well as the infiltration of fibroblasts and vascular cells during wound repair and the inflammatory responses of the adult immune system. During tumor invasion and metastasis the processes of cell migration achieve dire significance. Disruption of normal homeostatic mechanisms to benefit the survival of the individual tumor cell is a common theme discovered during the characterization of factors once thought to be tumor-specific. One such molecule, tumor cell autocrine motility factor, was so described and has only recently been identified as a normal protein involved in intracellular glycolysis as well as implicated as an extracellular effector of normal cell functions including survival of certain populations of neurons. This molecule represents a member of the newly emerging family of intracellular enzymes whose disparate functions as extracellular mediators of cellular responses defines a new class of ecto/exoenzymes which play a role in normal cellular processes and are inappropriately utilized by tumor cells to elicit new survival strategies.