Induction of apoptosis in A431 skin cancer cells by Cissus quadrangularis Linn stem extract by altering Bax-Bcl-2 ratio, release of cytochrome c from mitochondria and PARP cleavage

Skin is generally damaged through genetic and environmental factors such as smoking, exposure to xenobiotics, heat, hormonal changes, and ultraviolet light. These factors can cause skin diseases. Cissus quadrangularis Linn. (CQ) has been used in folk medicine for the treatment of skin diseases since ancient times. Taking in to consideration the medicinal properties exhibited by this genus, it was decided to investigate the anti-cancer activity of CQ. Extracts obtained from CQ and their phenolic contents were subjected to in vitro evaluation of anticancer activity by using A431 (skin epidermoid carcinoma, human) cell line. The A431 cells were treated with different extracts of CQ in a dose dependent manner. Out of five extracts, the acetone extract demonstrated significant anti-cancer activity in the A431 cell line. Hexane, chloroform, ethyl acetate and methanol extracts also exhibited cytotoxicity but to a comparatively lesser extent than the acetone extract. The GI(50) value of the acetone extract was found to be 8 mu g mL(-1), whereas GI(50) value of purified fraction of acetone extract, termed as AFCQ (active acetone fraction of CQ) with respect to A431 cells, was found to be 4.8 mu g mL(-1). Furthermore, the mechanism of anticancer activity exhibited by AFCQ was investigated by comparing its effect with the standard anticancer drug Doxorubicin (DOX) by evaluating the status of apoptotic markers after treatment of A431 cells with AFCQ and DOX. Bax-Bcl-2 ratio along with the release of cytochrome c from mitochondria to cytoplasm, which is a hallmark of apoptosis, was also evaluated. Cleavage of PARP revealed that AFCQ induces apoptosis in A431 cells with reference to DOX.