Lysosome-targeted ruthenium(II) complexes induce both apoptosis and autophagy in HeLa cells

Ruthenium complexes with good biological properties have attracted increasing attention in recent decades. In this work, three ruthenium polypyridine complexes containing 5-fluorouracil derivatives as ligands, [Ru(bpy)2(L)]2+ (Ru1), [Ru(phen)2(L)]2+ (Ru2), [Ru(dip)2(L)]2+ (Ru3) (L = 1-((1,10-phenanthroline-5-amino) pentyl)-5-fluorouracil; bpy = 2,2′-bipyridine; phen =1,10-phenanthroline; dip = 4,7-diphenyl-1,10-phenanthroline), were synthesized and characterized. Based on in vitro cytotoxicity tests, Ru3 (IC50 = 7.35 ± 0.39 μM) showed the best anticancer activity among three compounds in the selected cell lines. It is worth noting that Ru3 also exerts less cytotoxicity on LO2 cell lines, with an IC50 value 5 times higher than that on HeLa cells, indicating its selective activity. Mechanism studies revealed that Ru3 can specifically target lysosomes and induce cell apoptosis in a caspase-dependent manner. Specifically, Ru3 can arrest cell cycle at the G0/G1 phase, increase the intracellular reactive oxygen species (ROS) level, and then damage DNA. In short, Ru3 can eventually cause cell death through the synergy of inducing apoptosis and autophagy, which was further proven by western blot assay results.