Antrodia salmonea-induced oxidative stress abrogates HER-2 signaling cascade and enhanced apoptosis in ovarian carcinoma cells.

Antrodia salmonea is well known in Taiwan as a traditional Chinese medicinal fungus and has demonstrated antioxidant, anti-inflammatory, and anticancer effects. However, the anticancer activity of A. salmonea against human ovarian cancer is still elusive. Therefore, we investigated the antiovarian tumor activity of a fermented culture broth of A. salmonea and exhibits its underlying molecular mechanism. A. salmonea shows a significant effect on cell viability in human ovarian carcinoma (SKOV-3 or A2780) cell lines with an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Increased terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive cells and annexin V-propidium iodide stained cells indicate that A. salmonea induces late apoptosis in SKOV-3 cells. Notably, treatment with A. salmonea induced the following events: Apoptosis; caspase-3, -8, -9 and poly(ADP-ribose) polymerase activation; first apoptosis signal (Fas) and Fas ligand activation; Bid cleavage; and Bax2-B-cell lymphoma 2 dysregulation. The results show that A. salmonea-induced apoptosis was mediated by both mitochondrial and death receptor pathways. An increase in intracellular reactive oxygen species (ROS) was also observed in A. salmonea-treated cells, whereas the antioxidant N-acetylcysteine (NAC) prevented A. salmonea-induced cell death and DNA fragmentation, indicating that A. salmonea-induced apoptosis was mediated by ROS generation. Interestingly, A. salmonea-induced apoptosis is associated with the suppression of human epidermal growth factor receptor-2 (HER-2/neu) and phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) expression in HER-2/neu overexpressing SKOV-3 cells. NAC significantly prevented A. salmonea-induced HER-2/neu depletion and PI3K/AKT inactivation, indicating that A. salmonea-triggered apoptosis is mediated by ROS-inhibited HER-2/neu signaling cascades. To our knowledge, this is the first report describing the anticancer activity of this potentially beneficial mushroom against human ovarian carcinoma.