The induction of apoptosis in BEL-7402 cells through the ROS-mediated mitochondrial pathway by a ruthenium(II) polypyridyl complex

A new Ru(II) polypyridyl complex [Ru(phen)2(addppn)](ClO4)2 (Ru1) has been synthesized and characterized. The DNA-binding constant of the complex with DNA was determined to be 1.93 (±0.12) × 106 M−1. The complex interacts with DNA by an intercalative mode. Cytotoxicity in vitro, apoptosis, cell cycle distribution, apoptotic pathway, reactive oxygen species and mitochondrial membrane potential assays were performed. The IC50 values of Ru1 toward BEL-7402, HeLa, MG-63 and SKBR-3 cell lines are 3.9 ± 0.4, 9.0 ± 0.8, 6.6 ± 0.6 and 5.1 ± 0.6 μM, respectively. Interestingly, Ru1 shows a higher cytotoxicity than cisplatin on BEL-7402 cells under identical conditions. Ru1 can effectively induce apoptosis in BEL-7402 and induces cell cycle arrest at the G0/G1 phase in BEL-7402 cells and at the G2/M phase in SKBR-3 cells. In addition, Ru1 can enhance the level of reactive oxygen species and induce the decrease of the mitochondrial membrane potential. Western blot analysis shows that Ru1 activates caspase-3 and -7, down-regulates the expression of the anti-apoptotic proteins of Bcl-x and Bag-1, and upregulates the levels of the proapoptotic proteins of Bad, Bak, Bax and Bim in BEL-7402 cells. These results show that Ru1 induces apoptosis in BEL-7402 cells through an ROS-mediated mitochondrial dysfunction pathway.