Ginsenoside Rh1 inhibits tumor growth in MDA-MB-231 breast cancer cells via mitochondrial ROS and ER stress-mediated signaling pathway.

Ginsenoside-Rh1 (Rh1) is a ginseng-derived compound that has been reported to exert anticancer effects by regulating cell cycle arrest and apoptosis according to reactive oxygen species (ROS) production. However, the effects of Rh1 on mitochondrial dysfunction are involved in triple negative breast cancer (TNBC) cell apoptosis, and the related molecular mechanisms remain unknown. Rh1 treatment induced cell toxicity less than 50% at 50 μM. In addition, Rh1 induced apoptosis in TNBC cells through cleaved caspase-3 activation and G1/S arrest. The Rh1-treated TNBC cells showed a significant increase in mitochondrial ROS (mtROS), which in turn increased protein expression of mitochondrial molecules, such as Bak and cytochrome C, and caused the loss of mitochondrial membrane potential. Pretreatment with mitochondria-targeted antioxidant Mito-TEMPO alters the Rh1-reduced rate of mito- and glycol-ATP. Furthermore, Rh1 induces ER stress-mediated calcium accumulation via PERK/eIF2α/ATF4/CHOP pathway. Inhibition of ATF4 by siRNA transfection significantly inhibited Rh1-mediated apoptosis and calcium production. Interestingly, Mito-TEMPO treatment significantly reduced apoptosis and ER stress induced by Rh1. Finally, Rh1 at 5 mg/kg suppressed tumor growth through increased levels of ROS production, cleaved caspase-3, and ATF4 more than 5-fluorouracil treated group. Overall, our results suggest that Rh1 has potential for use in TNBC treatment.