Antiproliferation and Anti-invasion Activity of Binuclear Copper(II) Complex in BRAFi-Resistant Melanoma Cells

Melanoma lethality is driven by high intratumoral heterogeneity, metastatic competence, and phenotypic plasticity, which foster rapid emergence of resistance to targeted therapies such as BRAF inhibitors (BRAFi, e.g. vemurafenib). Copper-(II) complexes have emerged as promising anticancer candidates, yet their activity against BRAFi-resistant melanoma remains poorly defined. Here, we show that the binuclear copper-(II) complex [Cu₂(apyhist)₂dpam]-(ClO₄)₄ (herein referred to as [Cu-(II)-L]) displays low-micromolar cytotoxicity and antiproliferative activity in parental and BRAFi-resistant melanoma models. Binuclear [Cu-(II)-L] suppresses melanoma migration and invasion and reduces tumor burden and dermal invasion in a reconstructed human skin melanoma model with limited toxicity to normal tissue. Mechanistically, [Cu₂(apyhist)₂dpam]-(ClO₄)₄ triggers a ROS-dependent stress response that is attenuated by N-acetylcysteine, leading to DNA damage, mitochondrial depolarization and caspase-independent cell death. Molecular profiling indicates engagement of cell cycle arrest and stress-adaptation programs, with signatures suggesting ferroptotic-associated, necroptotic and autophagy-related signaling, pointing to a redox-driven, diverse mechanism rather than a single dominant death pathway. Different modulation of key markers (PARP1, H2AX, MLKL, GPX4, LC3B-II, and p62) supports that its multitarget activity can bypass adaptive resistance mechanisms. Collectively, these findings support binuclear [Cu-(II)-L] as a candidate to target invasive and drug-resistant melanoma phenotypes.