Significant increase of anticancer efficacy in vitro and in vivo of liposome entrapped ruthenium(II) polypyridyl complexes

Two polypyridyl ruthenium(II) complexes [Ru(DIP)2(BIP)](PF6)2 (DIP = 4,7-diphenyl-1,10-phenanthrolie, BIP = 2-(1,1'-biphenyl-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline, Ru1) and [Ru(DIP)2(CBIP)](PF6)2 (CBIP = 2-(4'-chloro-1,1'-biphenyl-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline, Ru2) were synthesized. The cytotoxic activities in vitro of Ru1, Ru2 toward B16, A549, HepG2, SGC-7901, HeLa, BEL-7402, non-cancer LO2 were investigated using MTT method (3-(4,5-dimethylthiazole)-2,5-diphenltetraazolium bromide). Unexpectedly, Ru1, Ru2 can't prevent these cancer cells proliferation. To improve the anti-cancer effect, we used liposomes to entrap the complexes Ru1, Ru2 to form Ru1lipo, Ru2lipo. As expectation, Ru1lipo and Ru2lipo exhibit high anti-cancer efficacy, especially, Ru1lipo (IC50 3.4 ± 0.1 μM), Ru2lipo (IC50 3.5 ± 0.1 μM) display strong ability to block the cell proliferation in SGC-7901. The cell colony, wound healing, and cell cycle distribution show that the complexes can validly inhibit the cell growth at G2/M phase. Apoptotic studied with Annex V/PI doubling method showed that Ru1lipo and Ru2lipo can effectively induce apoptosis. Reactive oxygen species (ROS), malondialdehyde, glutathione and GPX4 demonstrate that Ru1lipo and Ru2lipo improve ROS and malondialdehyde levels, inhibit generation of glutathione, and finally result in a ferroptosis. Ru1lipo and Ru2lipo interact on the lysosomes and mitochondria and damage mitochondrial dysfunction. Additionally, Ru1lipo and Ru2lipo increase intracellular Ca2+ concentration and induce autophagy. The RNA-sequence and molecular docking were performed, the expression of Bcl-2 family was investigated by Western blot analysis. Antitumor in vivo experiments confirm that 1.23 mg/kg, 2.46 mg/kg of Ru1lipo possesses a high inhibitory rate of 53.53% and 72.90% to prevent tumor growth, hematoxylin-eosin (H&E) results show that Ru1lipo doesn't cause chronic organ damage and strongly promotes the necrosis of solid tumor. Taken together, we conclude that Ru1lipo and Ru2lipo cause cell death through the following pathways: autophagy, ferroptosis, ROS-regulated mitochondrial dysfunction, and blocking the PI3K/AKT/mTOR.