Anticancer and apoptotic effects of orange peel extract and naringin on doxorubicin-induced apoptosis in human esophageal squamous carcinoma cell line

Abstract Orange peel contains bioactive compounds with high antioxidant properties that may exhibit pharmacological effects on cancer cells with low toxicity. This study sought to investigate the anticancer and apoptotic effects of orange peel extract (OPE) and its main flavonoid derivative, naringin (NR), on doxorubicin (Dox)-induced apoptosis in a human esophageal squamous carcinoma cell line (ESCC). The cytotoxicity and DNA fragmentation were evaluated using the methylthiazoletetrazolium (MTT) and fluorescent nuclear dye 4’,6-diamidino-2-phenylindole (DAPI) assays, respectively. The protein expression of Bax, Bcl-2, p21, p53, and caspases 8 and 9 were measured using ELISA. A dose-dependent decline was observed in the viability of YM-1 cells treated with OPE, NR, and Dox. The combination effects of Dox with OPE and NR indicated a protective effect against Dox-induced cytotoxicity. Similarly, apoptotic bodies decreased in the interaction between Dox with OPE and NR. Up-regulation of pro-apoptotic Bax gene was found in YM-1 cells subjected to treatments. Interaction between Dox+OPE and Dox+NR resulted in the down-regulation of Bax. Activation of the executioner 8 and 9 caspases was found in the YM-1 cell line exposed to Dox and its combination with OPE and NR. The overexpression of anti-tumor p21 and p53 genes were observed in the YM-1 cells subjected to the treatments. However, down-regulation of P21 and P53 anti-tumor genes were found by the interaction of Dox with OPE and NR. In conclusion, this study suggests that OPE and NR have a pro-apoptotic potential on ESCC through Bax-dependent pathways and are promising agents to attenuate the toxic effect of Dox on ESCC.