Curcumin suppresses copper accumulation in non-small cell lung cancer by binding ATOX1.

Background: Non-small cell lung cancer (NSCLC) is associated with intracellular copper accumulation. Antioxidant 1 (ATOX1) is a copper chaperone. This study aimed to analyze the anti-cancer effects of curcumin on the ATOX1-mediated copper pathway in NSCLC.

Methods: A binding activity between curcumin and ATOX1 was measured using molecular docking. NSCLC cells, A549 and H1299, were treated with different doses of curcumin (10, 20, 40 µM) or DC-AC50 (5, 10, 20 µM) for 24 h. The cell viability and levels of ATOX1, ATP7A and COX17 proteins were observed in cells. Overexpressing ATOX1 in cells was established by pcDNA3.1-ATOX1 transfection for 24 h. The ATOX1 overexpressing cells were treated with 40 µM curcumin or 20 µM DC-AC50 for 24 h to analyze the mechanism of curcumin in NSCLC treatment. Cell viability was measured by CCK-8, and levels of proteins were measured by western blotting. The copper level in cells was labeled by copper sensor-1. Moreover, nude mice models were induced by injection of A549 cells and treated with 20 mg/kg/d DC-AC50 or 40 mg/kg/d curcumin. Tumor growth was observed by measuring tumor volume and tumor weight. The levels of ATOX1, ATP7A and COX17 in tumors were measured by immunohistochemistry and western blotting.

Results: Curcumin bound to ATOX1 (score = -6.1 kcal/mol) and decreased the levels of ATOX1, ATP7A and COX17 proteins in NSCLC cells. The curcumin or DC-AC50 treatment suppressed cell viability by inhibiting the ATOX1-mediated copper signaling in NSCLC cells. The ATOX1 overexpression in cells significantly weakened the effects of curcumin on suppressing copper accumulation and the ATOX1-mediated copper pathway (p < 0.05). In mice models, curcumin or DC-AC50 treatment also suppressed tumor growth by suppressing the ATOX1-mediated copper pathway in tumors.

Conclusion: This study demonstrated that curcumin bound ATOX1 to suppress copper accumulation in NSCLC cells, providing a new mechanism of curcumin for NSCLC treatment.