A cyclometalated iridium(III) complex induces apoptosis and autophagy through inhibition of the PI3K/AKT/mTOR pathway.

An iridium(III) complex [Ir(ppy)₂(MHPIP)]PF₆ (ppy = 2-phenylpyridine, MHPIP = 2-(1-methyl-1<italic>H</italic>-pyrazol-3-yl)-1<italic>H</italic>-imidazo[4,5-f][1, 10]phenanthroline, <bold>Ir-1</bold>) was synthesized and characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR. The in vitro cytotoxic activities of the free proligand MHPIP and the complex <bold>Ir-1</bold> against HepG2, A549, BEL-7402, SGC-7901 and normal LO2 cells were evaluated by the MTT method. MHPIP has no cytotoxic activity toward the selected cell lines, while <bold>Ir-1</bold> shows a moderate cytotoxic effect against HepG2. This complex also displays no cytotoxicity against normal LO2 cells, with an IC₅₀ of more than 200 µM. The apoptosis of HepG2 cells induced by the complex was studied with AO/EB and DAPI staining methods, which showed that the complex can effectively induce apoptosis. A comet assay was performed by gel electrophoresis, and the results further show that the complex can cause apoptosis. The level of reactive oxygen species, mitochondrial membrane potential, autophagy, intracellular Ca²⁺ levels and cell invasion were investigated by fluorescence microscopy, and the cell cycle arrest was studied by flow cytometry. The expression of caspase and Bcl-2 family proteins was investigated by western blot. The results of these experiments indicate that <bold>Ir-1</bold> accumulates preferentially in the mitochondria of HepG2 cells and induces apoptosis through inhibition of the PI3K/AKT/mTOR pathway. [ABSTRACT FROM AUTHOR]