Antiproliferative effects of isoalantolactone in human liver cancer cells are mediated through caspase-dependent apoptosis, ROS generation, suppression of cell migration and invasion and targeting Ras/Raf/MEK signalling pathway

The main objective of this study was to evaluate the in vitro antiproliferative effects of isoalantolactone against liver cancer cells (Hep-G2) and also monitor its mechanism of action. The MTT assay was involved in proliferation assessments and phase contrast microscopy was used to check cellular morphology. Acridine orange/ethidium bromide staining along with western blotting was used to evaluate proapoptotic effects of isoalantolactone. DCFH-DA staining was used in ROS measurements. Transwell migration and invasion assay were executed to check the effects of isoalantolactone on migration and invasion of Hep-G2 cells. Western blotting was used to check the expressions of Ras/Raf/MEK signalling pathway in Hep-G2 cells. Results demonstrated that isoalantolactone significantly (*p<0.05 and **p<0.01) inhibited the proliferation of Hep-G2 cells in a concentration and time-reliant fashion. The IC50 value of the tested isoalantolactone molecule was found to be 71.2 mu M and 53.4 mu M at 12 h and 24 h time intervals respectively. Moreover, the antiproliferative effects of isoalantolactone were mediated through induction of caspase-dependent apoptosis and oxidative stress (ROS mediated). The proapoptotic effects of isoalantolactone were evident from morphological assessments and improved expressions of caspase-3, -8, and -9 and Bax while antiapoptotic Bcl-2 was reduced significantly. Additionally, antiproliferative and proapoptotic effects of isoalantolactone were found to be a consequence of blocking of Ras/Raf/MEK signalling in Hep-G2 cells. Furthermore, isoalantolactone significantly (*p<0.05) targeted the migration and invasion of Hep-G2 cells. In conclusion, these results validated that isoalantolactone shows strong antiproliferative activity against Hep-G2 liver cancer cells. Therefore, it could prove as a leading candidate in liver cancer research, drug discovery and design.