Isoalantolactone induces apoptosis in human breast cancer cells via ROS-mediated mitochondrial pathway and downregulation of SIRT1.

Isoalantolactone possessed various biological activities. However, whether it could treat breast cancer and its underlying mechanism remained largely unknown. This study was designed to evaluate the anticancer effects of isoalantolactone on breast cancer and explored the molecular mechanism. Two human breast cancer cell lines (MDA-MB-231 and MCF-7) and one normal breast cell line (MCF-10A) were applied. Our data suggested that isoalantolactone decreased breast cancer cell viability in a dose-dependent manner, but showed almost no toxicity to MCF-10A cells. The anticancer effects of isoalantolactone were related to the overexpression of reactive oxygen species. Isoalantolactone significantly induced breast cancer cell apoptosis by activating caspase cascade, cleaving poly (ADP-ribose) polymerase. Increase of Bax/Bcl-2 ratio, depolarization of mitochondrial membrane potential, release of cytochrome c from mitochondria to cytoplasm and cell cycle arrest at G2/M phase were associated to the apoptosis induction. Additionally, isoalantolactone increased the protein expression of p38 MAPK and JNK. The apoptosis-induction of isoalantolactone could be abrogated by co-treatment with SB203580 (inhibitor of p38 MAPK) or SP600125 (inhibitor of JNK). Furthermore, isoalantolactone induced breast cancer cells apoptosis in a caspase-independent pathway, which was downregulation of SIRT1. Therefore, isoalantolactone may serve as a chemotherapeutic agent for the treatment of human breast cancer.