Copper (I) nicotinate complex potentiates chemotherapy-induced apoptosis in HCC-1806 triple negative breast cancer...

Triple negative breast cancer (TNBC) remains a clinically challenging subtype because it lacks established molecular targets and often depends on cytotoxic chemotherapy. Although doxorubicin (DOX) and mTOR inhibitors such as Torin1 (TOR) exhibit antitumor activity, their clinical use may be constrained by toxicity and resistance. Copper (I) Nicotinate Complex (CNC) has emerged as promising candidates due to their superoxide dismutase (SOD) -mimicking and cytoprotective properties. This study aimed to evaluate the potential effect of CNC combined with DOX or TOR to enhance cytotoxicity against HCC-1806 cells while reducing individual drug dosages. Cell viability was assessed via MTT assay. Drug interactions were analyzed by combination index methodology. Mechanistic responses were evaluated using Annexin V/PI flow cytometry, cell cycle analysis, Comet assay, and biochemical quantification of Caspase-3, Survivin, pCHK1^ser317, and SOD activity. CNC containing combinations enhanced cytotoxic responses relative to selected single-agent conditions, with ratio-dependent additive or synergistic interactions. Combination treatments increased apoptotic populations, altered cell cycle progression with enrichment of sub G0-G2/M fractions, and elevated DNA damage associated markers, including comet tail moment and pCHK1^ser317. CNC inclusive regimens also increased caspase-3 activity and reduced survivin expression. Increased SOD activity indicated modulation of oxidative stress related responses. Exploratory analysis showed treatment-associated changes in PD-1 expression. In conclusion, these findings provide preliminary in vitro evidence that CNC may potentiate selected anticancer responses of DOX or TOR in HCC-1806 cells through apoptosis-associated, cell cycle, and DNA damage-related mechanisms. Further validation in additional TNBC models and in vivo systems is required.