Platinum(II) 5-substituted-8-hydroxyquinoline coordination compounds induces mitophagy-mediated apoptosis in A549/DDP cancer cells.

For the first time, two new mononuclear platinum(II) coordination compounds, [Pt(L1)(DMSO)Cl] (PtL1) and [Pt(L2)(DMSO)Cl] (PtL2) with the 5-(ethoxymethyl)-8-hydroxyquinoline hydrochloride (H-L1) and 5-bromo-8-hydroxyquinoline (H-L2) have been synthesized and characterized. The cytotoxic activity of PtL1 and PtL2 were screened in both healthy HL-7702 cell line and cancer cell lines, human lung adenocarcinoma A549 cancer cells and cisplatin-resistant lung adenocarcinoma A549/DDP cancer cells (A549R), and were compared to that of the H-L1, H-L2, H-L3 ligands and 8-hydroxyquinoline (H-L3) platinum(II) complex [Pt(L3)(DMSO)Cl] (PtL3). MTT results showed that PtL1 bearing one deprotonated L1 ligand against A549R was more potent by 8.8-48.6 fold than that of PtL2 and PtL3 complexes but was more selective toward healthy HL-7702 cells. In addition, PtL1 and PtL3 overcomes tumour drug resistance by significantly inducing mitophagy and causing the change of the related proteins expression, which leads to cell apoptosis. Moreover, the inhibitory effect of PtL1 on A549 xenograft tumour was 68.2%, which was much higher than that of cisplatin (cisPt, ca. 50.0%), without significantly changing nude mice weight in comparison with the untreated group. This study helps to explore the potential of the platinum(II) 5-substituted-8-hydroxyquinoline coordination compounds for the new Pt-resistant cancer therapy.