Correlations between thymidylate synthase expression and chemosensitivity to 5-fluorouracil, cell proliferation and clinical outcome in head and neck squamous cell carcinoma

Background: 5-Fluorouracil (5-FU) is a widely used drug in head and neck squamous cell carcinoma (HNSCC). Thymidylate synthase (TS), which is the target enzyme of 5-FU, has been demonstrated to be a key regulatory enzyme. In this study, we examined whether TS expression is correlated with chemosensitivity to 5-FU, cell proliferation and clinical outcome in HNSCC. Methods: An antisense TS cDNA was constitutively expressed in the HNSCC cell line. The effects of TS expression on in vitro cell growth and 5-FU cytotoxicity were examined. We also evaluated the association between TS expression and cell proliferation in surgical specimens, and prognosis in HNSCC patients. Results: Antisense TS transfection increases the cytotoxicity of 5-FU and inhibits cell proliferation in HNSCC cellsin vitro. Immunohistochemical expression of TS may have prognostic value in patients with HNSCC. Conclusions: These results indicate that TS expression plays an important role in the sensitivity of HNSCC to 5-FU chemotherapy.