Induction of apoptosis and autophagy by ternary copper complex towards breast cancer cells

Background: Copper complex has been gaining much attention in anticancer research as a targeted agent since cancer cells uptake more copper than non-cancerous cells. Our group synthesised a ternary copper complex, which is composed of 1,10-phenanthroline and tyrosine [Cu(phen)(L-tyr)Cl].3H₂0. These two payloads have been designed to cleave DNA and inhibit protein degradation system (proteasome) concurrently in cancer cells, making this copper complex a dual-target compound. Objective: The current study was carried out to investigate the mode of cell death and the role of autophagy induced by [Cu(phen)(L-tyr)Cl].3H₂0 in MCF-7 and MDA-MB-231 breast cancer cells. Methods: Growth inhibition of [Cu(phen)(L-tyr)Cl].3H₂0 towards MDA-MB-231 and human non-cancerous MCF10A breast cells was determined by MTT assay. Annexin-V-FITC/PI and cell cycle analysis were evaluated by flow cy-tometry. The expression of p53, Bax, caspase-9, caspase-7, caspase-3 and LC3 was determined using western blot analysis. The cells were then co-treated with hydroxychloroquine to ascertain the role of autophagy induced by [Cu(phen)(L-tyr)Cl].3H₂0. Results: [Cu(phen)(L-tyr)Cl].3H₂0 inhibited the growth of cancer cells dose-dependently with less toxicity towards MCF10A cells. Additionally, [Cu(phen)(L-tyr)Cl].3H₂0 induced apoptosis and cell cycle arrest towards MCF-7 and MDA-MB-231 breast cancer cells possibly via regulation of p53, Bax, caspase-9, caspase-3 and capase-7. The expression of LC3II was upregulated in both cancer cell lines upon treatment with [Cu(phen)(L-tyr) Cl].3H₂0, indicating the induction of autophagy. Co-treatment with autophagy inhibitor hydroxychloroquine significantly enhanced growth inhibition of both cell lines, suggesting that autophagy induced by [Cu(phen)(L-tyr) Cl].3H₂0 in both breast cancer cells promoted cell survival. Conclusion: [Cu(phen)(L-tyr)Cl].3H₂0 holds great potential to be developed for breast cancer treatment.