Abstract: Objective To evaluate the biological effect of cinobufagin(Cin) on nasopharyngeal carcinoma (NPC) cells lines(CNE2 and HONE1) and the mechanism of its efficacy. Methods CNE2 and HONE1 cells were treated with different concentrations (0, 5, 15 and 45 mg/L) of Cin for 24, 48 and 72 h respectively and cell viability was detected by CCK-8 assay. After 48 hrs, cell morphology was observed by phase contrast microscopy; cell apoptosis was detected by TUNEL fluorescence staining; the level of reactive oxygen species (ROS) in cells were assessed by DCF fluorescence assay; the expression levels of apoptosis-related proteins were detected by Western blot. Results Cin inhibited the cell activity of NPC cells in a concentration-dependent manner (P＜0.05, P＜0.01 or P＜0.001) and the cells showed filament and sparse morphology. Cin promoted apoptosis and increased intracellular ROS level in NPC cells (P＜0.05, P＜0.01 or P＜0.001). Cin inhibited the expression of Bax and mitochondrial cytochrome c (Cytc) (P＜0.05, P＜0.01 or P＜0.001) but promoted the expression of Bcl-2, cleaved caspase-3 and cytoplasmic Cytc (P＜0.01 or P＜0.001). Conclusions Cin can inhibit cell proliferation and promote apoptosis of NPC cells.

Key words: cinobufagin, nasopharyngeal carcinoma, apoptosis, proliferation