CDC25B–PP2A regulates breast cancer patients derived 3D organoids’ response to metformin. (A) Organoids transfected with siAMPK, and then treated with 20 mM metformin for 6 days. Cell proliferation was monitored every 2 days. (B) Organoids transfected with siCDC25B (KD) were transfected with EV, WT CDC25B (WT), CDC25B S353E or CDC25B C488S constructs, and then treated with increasing doses of metformin for 72 h, and organoid survival was then determined. The x-axis indicates drug dose, and the y-axis indicates the survival fraction after metformin exposure. Organoid lysates were blotted with the indicated antibodies. (C) Organoids were transfected with siPP2A-C, and the growth was monitored every 2 days. (D) Organoids transfected with siPP2A-C were treated with increasing doses of metformin for 72 h, and organoid survival was then determined. The x-axis indicates drug dose, and the y-axis indicates the survival fraction after metformin exposure. Knockdown efficiency is shown in western blots. (E) Organoids were treated increasing doses of metformin alone or in combination with 2 μM of LB100 for 72 h, and organoid survival was then determined. The x-axis indicates drug dose, and the y-axis indicates the survival fraction after metformin exposure. (F) A simplified model depicting how CDC25B might regulate AMPK activity. Data information: all data presented are in the format of mean ± SEM of N = 3 independent experiments with three biological replicates for each experiment. For (A and B), statistically significant differences were determined using the two-way ANOVA plus Tukey (**P < 0.01), ns represents not significant. For (C, D and E), statistically significant differences were determined using the two-way ANOVA (**P < 0.01).