Induction of Apoptosis in HeLa Cervical Cancer Cells Treated with Aqueous and Supercritical Fluid Extracts of Quercus infectoria

Background and objectives: The anticancer properties of extracts from Quercus infectoria galls have been demonstrated in a range of cancer cells, including human cervical cancer cells. This study aimed to elucidate the cell death mechanisms of Q. infectoria aqueous and supercritical fluid extracts on cervical cancer cells, HeLa. Methods: In vitro cytotoxicity was assessed using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay, whereas apoptosis induction was assessed using acridine orange/propidium iodide staining. Flow cytometry was used to analyse phosphatidylserine externalization, cell cycle distribution, and caspase activity. Meanwhile, anti-Bax, anti-Bcl-2, and anti-p53 antibody were used to examine the expression of p53, Bax, and Bcl-2. Results: MTT assay revealed the cytotoxic effects of the aqueous and supercritical fluid extracts on HeLa cells with IC50 values of 12.33±0.35 µg/mL and 14.33±0.67 µg/mL respectively. Acridine orange/propidium iodide analysis revealed morphological changes with apoptotic features in the treated cells. Cell population increase in sub G0 phase showed induction of apoptosis in the treated HeLa cells. Moreover, the activation of caspases in the treated cells revealed the execution of apoptosis. In addition, the expression of p53 and Bax proteins in the treated cells were observed whereas there was no difference in the expression of Bcl-2 in the treated cells compared to untreated control cells. Conclusion: Both aqueous and supercritical fluid extracts inhibited the growth of HeLa cells through induction of cell apoptosis by activation of caspases-8 and caspase-9.