A select thiosemicarbazone copper(II) complex induces apoptosis in gastric cancer and targets cancer stem cells reducing pluripotency markers

Copper(II)-based complexes are promising candidates as anti-cancer agents due to their ability to target cancer cells. Here we describe the synthesis and characterization of two copper(II) thiosemicarbazone complexes with the ligands 4-(dimethylamino)benzaldehyde N4-methylthiosemicarbazone (HL¹) and 4-(dimethylamino)benzaldehyde N4-(4-(dimethylamino)phenylthiosemicarbazone (HL²) and general formula [Cu(L)₂]. The complexes show stability in aqueous solution with 1 % of DMSO that allows to stablish its solution profile in biological buffers. Compound [Cu(L¹)₂] lipophilicity was lower than [Cu(L²)₂], however, its solubility in biological buffer was not only better but also its DLS and ζ-potential data. In vitro studies demonstrate a higher cytotoxic effect of [Cu(L¹)₂] on gastric cancer cells. The proposed mechanism of action consists in the generation of free radicals that induce DNA lesions, oxidative stress and ultimately autophagy deregulation and apoptosis. Additionally, [Cu(L¹)₂] is equally active on gastric cancer stem cells and tumor cells resistant to cisplatin. More importantly, stem cells treated with [Cu(L¹)₂] show a downregulation of pluripotency markers such as TWIST, NANOG and OCT4. Overall, our results with [Cu(L¹)₂] prompt a significant advancement in the development of rational-designed pharmaceuticals for combating cancer.