The induction of apoptosis in SGC-7901 cells through the ROS-mediated mitochondrial dysfunction pathway by a Ir(III) complex

A new ligand BTCP and its iridium(III) complex [Ir(ppy)₂(BTCP)]PF₆ (Ir-1) were synthesized and characterized by elemental analysis, ESI–MS, IR, ¹H NMR and ¹³C NMR. The cytotoxic activity in vitro of the ligand and its complex against SGC-7901, HeLa, HOS, PC-12, BEL-7402, MG-63, SiHa, A549, HepG2 and normal cell LO2 were evaluated by MTT method [MTT = (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)]. The apoptosis was assayed with AO/EB and Hoechst 33258 staining methods. The reactive oxygen species (ROS), mitochondrial membrane potential, autophagy and cell invasion were studied under fluorescent microscope. The expression of caspases and Bcl-2 family proteins were investigated by western blot. The IC₅₀ values of complex toward SGC-7901, BEL-7402 and MG-63 cells are 3.9 ± 0.5, 5.4 ± 1.2 and 4.2 ± 0.6 µM. The complex can increase the levels of ROS, and induce a decrease in the mitochondrial membrane potential. Ir-1 inhibits the cell growth at G0/G1 phase in SGC-7901 cells, and the complex can induce both autophagy and apoptosis and inhibit the cell invasion. And the complex induces apoptosis through a ROS-mediated mitochondrial dysfunction pathway.