ABSTRACT
BACKGROUND: Thymidine phosphorylase (TP) is an enzyme catalyzing the reversible phosphorolysis of thymidine to thymine and 2-deoxyribose-1-phosphate. TP plays a role in angiogenesis. Evidences suggest that infiltrating inflammatory cells adjacent cancer cells may affect tumor cell behavior. To evaluate each of these significances of TP expression in cancer cell and cancer-infiltrating inflammatory cells, we investigated TP expression patterns in cancer cells and infiltrating inflammatory cells adjacent cancer cells separately and the relationship between TP expression and angiogenesis or survival. METHODS: Immunohistochemistry assays were performed with anti-TP monoclonal antibody (Roche Japan) and anti-factor VIII polyclonal antibody (Dako) on 92 paraffin-embedded tissue samples from stomach cancer patients. A single pathologist scored the slides for percent positivity of tumor cells, intensity, localization and distribution of expression. TP reactivity in tumor cells (cancer) and infiltrating mononuclear cells adjacent cancer cells (matrix) was separately accessed. According to the pattern of TP expression, subjects were divided into 4 groups for further analysis: cancer(C;+)/matrix(M;+), cancer(+)/matrix(-), cancer(-)/matrix(+) and cancer(-)/matrix(-). With these 4 subsets of TP expression patterns, we evaluated cancer cell differentiation, intratumoral microvessel density, extent of tumor invasion, LN stage, and patient survival to find any differences among the subsets. RESULTS: Of 92 stomach cancer tissue, C/M(+/+), C/M(+/-), C/M(-/+), and C/M(-/-) were observed in 33patients, 19, 30, and 10, respectively. Microvessel density scores were higher in cancer(+)/matrix(-) group compared in cancer(-)/matrix(-) group (p=0.02). Of 4 TP expression subsets, other clinical factors such as histology, extent of tumor invasion, and LN metastasis were not associated with TP expression. CONCLUSION: This study suggested the TP in cancer-infiltrating inflammatory cell as well as cancer cells themselves may play an important role in angiogenesis as co-active factors in stomach cancer.