Non-mutagenic Ru(II)-phosphine-based Complexes Induce Mitochondria-mediated Apoptosis in Breast Cancer Cells: From 2D to 3D Investigations

Three Ruthenium(II)-phosphine based complexes with the general formula [Ru(N–S)(dppm)2]PF6 (Ru1–Ru3) were prepared and studied as anticancer agents [N–S are 2-mercapto-2-thiazoline (Hmtz), mercapto-1-methylimidazole (Hmmi) and 4,6-diamino-2-mercapto-pyrimidine (Hdmp) and dppm is the 1,1`-bis(diphenylphosphino)methane]. The coefficient distribution of these compounds was assessed, and Log P values indicated their preference for the organic phase. After confirming their stability in solution, their in vitro cytotoxicity was investigated on different breast cell lines. Our findings revealed Ru2 as 50-fold more cytotoxic and almost 2-fold more selective than cisplatin control, considering the MCF-7 cells. Also, Ru2 induces morphological changes and inhibits the colony formation in this cell line. Considering the advantages of 3D cell culture models for screening of new anticancer drug candidates, the effect of Ru2, which was found to be the best candidate compound, was investigated on multicellular tumor spheroids. Live/dead assay revealed dead cell population in both 2D-and 3D MCF-7 cell models upon treatment at IC50 concentration. The Ruthenium-phosphine complex was able to affect the cell cycle distribution and the mitochondrial membrane potential, inducing apoptosis cell death. Ames and Micronucleus tests indicated the absence of mutagenicity for Ru2. To the best of our knowledge, this work demonstrated the effects of a ruthenium-phosphine complex on MCF-7 breast cancer cells using 2D and 3D cell based experiments, highlighting its potential as promising antitumor agent.