fig1

Figure 1. Drug response profiling validates stable chemoresistant phenotypes in HR+/HER2- BC models. (A) Schematic representation of the generation of anthracycline- and taxane-resistant cell populations from parental HR+/HER2- BC cell lines (MCF-7 and ZR-75-1). Created in BioRender. Corbet, C. (2026) https://BioRender.com/i5zffea; (B) Experimental design of the drug challenge and recovery assays. Cells were treated with chemotherapeutic agents for 72 h, followed by drug WO and a 7-day recovery period (WO+7). Created in BioRender. Corbet, C. (2026) https://BioRender.com/eoukvmv; (C and D) Viability of parental and drug-resistant ZR-75-1 cells after 72 h of treatment (WO) with 25 nM paclitaxel (C) or 10 nM epirubicin (D); (E and F) Viability of parental and drug-resistant MCF-7 cells after 72 h of treatment (WO) with 25 nM paclitaxel (E) or 30 nM epirubicin (F); (G and H) Viability of parental and drug-resistant ZR-75-1 cells following 72 h of treatment with 25 nM paclitaxel (G) or 10 nM epirubicin (H), and subsequent culture in drug-free medium for 7 days (WO+7); (I and J) Viability of parental and drug-resistant MCF-7 cells following 72 h of treatment with 25 nM paclitaxel (I) or 30 nM epirubicin (J), and subsequent culture in drug-free medium for 7 days (WO+7). Data are presented as mean ± SEM from three independent biological experiments (n = 3), each performed with three technical replicate wells per condition (C-J). Individual data points represent the mean of the technical replicates from each independent biological experiment. Statistical significance was determined using two-way ANOVA with Sidák’s multiple comparison test (C-J). ^*P < 0.05; ^**P < 0.01; ns: not significant. HR+/HER2-: Hormone receptor-positive/human epidermal growth factor receptor 2-negative; BC: breast cancer; WO: washout; SEM: standard error of the mean; ANOVA: analysis of variance; Doc-R: docetaxel-resistant; Pac-R: paclitaxel-resistant; Epi-R: epirubicin-resistant.