Thymidine phosphorylase activity and angiogenesis in gastric cancer

The dual role of thymidine phosphorylase in cancer development and chemotherapy

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

The expression of thymidine phosphorylase is a prognostic predictor for the intravesical recurrence of superficial bladder cancer

BACKGROUND

Thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor, has been implicated in the angiogenesis of bladder cancer. The aim of this study is to investigate the association between TP expression and the clinicopathologic findings, and the prognostic value.

METHODS

TP immunohistochemical staining was performed in specimens from 71 patients (50 men and 21 women) with superficial bladder cancer (pTa or pT1). Thirty-nine patients had received intravesical instillation of tetrahydropyranyladriamycin (THP) after transurethral resection (TUR) and the other 32 had not. For immunohistochemistry, paraffin-embedded specimens were stained with mouse monoclonal antibody against TP. When more than 10% of tumor cells were positively stained, staining was defined as positive. The correlations between TP immunostaining and clinicopathological features were analyzed. Multivariate analysis, using the Cox proportional hazard model, was performed to determine the risk factors for intravesical recurrence.

RESULTS

Specimens from 29 of the 71 patients (19 men and 10 women) were positive for TP. The expression of TP was not correlated with age, sex, histological grade, multiplicity, or morphology. Also, TP expression was not associated with whether the cases were primary or recurrent. Multivariate analysis demonstrated that the decreased expression of TP and the use of THP instillation could be independent predictors of a higher rate of intravesical recurrence-free bladder cancer.

CONCLUSION

The present study suggests that immunohistochemical TP staining is useful for predicting the intravesical recurrence of superficial bladder cancer after Transurethral resection of bladder tumor (TUR-Bt).