INOSITOL HEXAKISPHOSPHATE MEDIATES APOPTOSIS IN HUMAN BREAST ADENOCARCINOMA MCF‐7 CELL LINE VIA INTRINSIC PATHWAY

Inositol polyphosphates $(InsPs)$ are naturally occurring compounds ubiquitously present in plants and animals. Inositol hexakisphosphate $(InsP6)$ is the most abundant among all $InsPs$ and constitutes the major portion of dietary fiber in most cereals, legumes and nuts. Certain derivatives of $InsPs$ also regulate cellular signaling mechanisms. $InsPs$ have also been shown to reduce tumor formation and induce apoptosis in cancerous cells. Therefore, in this study, the effects of InsPs on apoptosis were studied in an attempt to investigate their potential anti‐cancer therapeutic application and understand their mechanism of action. Acridine orange and ethidium bromide staining suggested that $InsP6$ dose dependently induced apoptosis in human breast adenocarcinoma MCF‐7 cells. Among $InsPs$ tested $(InsP3,$ $InsP4,$ $InsP5,$ and $InsP6),$ $InsP6$ was found to be the most effective in inducing apoptosis. Furthermore, effects of $InsP6$ were found most potent inducing apoptosis. Etoposide, the drug known to induce apoptosis in both in vivo and in vitro, was used as a positive control. Western blotting experiments using specific antibodies against known apoptotic markers suggested that $InsP6$ induced apoptotic changes were mediated via an intrinsic apoptotic pathway.