Chrysophyllum cainito stem bark extract induces apoptosis in Human hepatocarcinoma HepG2 cells through ROS-mediated mitochondrial pathway

Hepatocellular carcinoma is the most common type of primary liver cancer in humans. This study aimed to demonstrate anticancer properties of an aqueous extract from Chrysophyllum cainito stem bark (CE) and its underlying mechanisms. Our MTT assay results showed that CE significantly reduced human hepatocellular carcinoma (HepG2) cell viability with the IC₅₀of 100 µg/mL, while human dermal primary fibroblast (HDFa) cells showed less susceptibility in every concentration tested. Determined by Annexin V staining, the proportion of apoptotic HepG2 cells increased in a dose-dependent fashion after 24 hour-exposure of CE. The results from Western blot analysis confirmed that CE reduced procaspase-3, suggesting apoptosis by activating caspase-3 cleavage. Using the DCFH-DA and DiOC6 fluorescent probes, it was found that CE significantly stimulated the generation of reactive oxygen species (ROS) and reduced mitochondrial membrane potential (Δψ _m), respectively. According to cell cycle analysis, CE (100 µg/mL) profoundly increased the percentage of cells in the sub-G1 phase, indicating cell apoptosis. These data suggest that CE induces apoptosis and cell death in human hepatocellular carcinoma via generation of intracellular ROS and disruption of Δψm. This is the first demonstration of the anticancer activity with proposed underlying mechanism of CE in liver cancer cells.

Keywords: Apoptosis; Cell cycles; Chrysophyllum cainito; HepG2 cell; Hepatocellular carcinoma; Reactive oxygen species.