Pluchea indica is used in traditional medicine for the treatment of lumbago, ulcer, tuberculosis and inflammation. The anti-cancer activities and the underlying molecular mechanisms of the ethanolic extracts of P. indica root (PIRE) were characterized in the present study. PIRE strongly inhibited the viability of the human nasopharyngeal carcinoma cells (NPC-TW 01 and NPC-TW 04) in a time- and dose-dependent manner. Migration of cancer cells was also suppressed by PIRE. In addition, PIRE significantly increased the occurrence of the cells in sub-G1 phase and the extent of DNA fragmentation in a dose-dependent manner, which indicates that PIRE significantly increased apoptosis in NPC cells. The apoptotic process triggered by PIRE involved up-regulation of pro-apoptotic Bax protein and down-regulation of anti-apoptotic Bcl-2 protein, consequently increasing the ratios of Bax/Bcl-2 protein levels. Moreover, the p53 protein was up-regulated by PIRE in a concentration-dependent manner. Therefore, PIRE could induce the apoptosis-signaling pathway in NPC cells by activation of p53 and by regulation of apoptosis-related proteins.
Keywords: Pluchea indica; apoptosis; nasopharyngeal carcinoma (NPC); p53.