1Departments of Radiation Oncology, 2Medical Oncology, 3Pathology, Cancer Hospital of Shantou University Medical College, Shantou, China
Abstract. Background and aim: the current pilot study was aimed on evaluation of the radiosensitizing effect of arsenic trioxide (As2O3) on nasopharyngeal carcinoma (NPC) cells in vitro. Methods: human NPC cells from CSNE-1 cell line were treated with As2O3. Cell survival was determined by clonogenic assay. Cell cycle distribution after As2O3 treatment was analyzed by flow cytometry. TUNEL assay was adopted to detect apoptotic cells and immunochemistry used to determine p53, bax and bcl-2 expression. Results: As2O3 definitely enhanced radiosensitivity of CSEN-1 cells. Cell survival experiments showed sensitivity enhancement ratio(SER) of 1.33 and 1.57 for 1.0 µmol/L and 1.5 µmol/L of As2O3, respectively. DNA flow cytometric analysis indicated that As2O3 (0.5–1.5 µmol/L) induced G2/M phase arrest in this cell line following 48 h of exposure. Meanwhile, the expression of wild-type p53, as well as the ratio of bax/bcl-2 was obviously increased after As2O3 treatment. Conclusion: As2O3 might be a potential radiosensitizer for NPC. The mechanisms of radiation enhancement may, at least in part, involve more cells being accumulated in G2/M, the radiosensitive phase. The change of wild-type p53 and bax expression induced by As2O3 may also contribute to the radiosensitization.
