Exploring the Anticancer Properties and Mode of Action of Copper(II)‐Furan Acylhydrazone on Human Triple Negative Breast Cancer Cells

Triple‐negative breast cancer (TNBC) is an aggressive subtype of breast cancer with limited therapeutic treatments. This study evaluates the anticancer activity and mode of action of the copper(II) complex [Cu(HL 1 )(NO 3 )H 2 O]·H 2 O ( CuHL 1 ), derived from (E)‐N’‐(2‐hydroxy‐3‐methoxybenzylidene)furan‐2‐carbohydrazide ( H 2 L 1 ), against a panel of TNBC cell lines (MDA‐MB‐231, MDA‐MB‐468, MDA‐MB‐157, HCC1806). CuHL 1 exhibits potent cytotoxicity in the low micromolar range (IC 50 ≈ 2 µM), surpassing cisplatin by up to 81‐fold. In MDA‐MB‐231 cells, CuHL 1 inhibits colony formation and induced reactive oxygen species (ROS) generation in a concentration‐dependent manner. Moreover, CuHL 1 triggers apoptosis as evidenced by Annexin V/PI staining and the modulation of Bax, Bcl‐2, caspase‐3, and cleaved caspase‐3 protein levels. Label‐free quantitative proteomics reveal 34 differentially expressed proteins, implicating pathways related to heat shock response, protein folding, lipid metabolism, and cell migration. Notably, CuHL 1 downregulates BCAR3, AJUBA, MPZL1, TP53, FASN, and HMGCS1, suggesting inhibition of prometastatic and lipid biosynthetic processes. Functional assays confirm reduced migratory capacity in MDA‐MB‐231 cells. These findings position CuHL 1 as a promising candidate for TNBC therapy, meriting further in vivo evaluation.