Fig. 5

MTA1 knockout in breast cancer affects estrogen signaling and tamoxifen sensitivity that can be attenuated by the addition of MTA1 exosomes. a MCF7 wildtype, tdTom-MTA1, and MTA1 knockout (KO) cells were transfected with estrogen response luciferase reporter plasmid and treated with 5 or 10 nM 17β-estradiol (E2). After 24-h incubation cells were assayed for luciferase activity, n = 3, *p < 0.05, **p < 0.01, Two-way ANOVA. b Real-time PCR analysis of IGFBP4 and SLC2A1 estrogen response gene expression in wildtype, tdTom-MTA1, and MTA1-KO cells. Cells were grown in phenol-red free medium supplemented with charcoal-stripped serum for 2 days. Cells were treated with 10 nM E2 for 24 h, n = 3, *p < 0.05, **p < 0.01, Student’s t test. c MCF7 wildtype and MTA1-KO cells were transfected with estrogen luciferase reporter and pre-incubated with 5 μg of exosomes from tdTom-MTA1 MCF7 cells. Cells were treated with 5 nM E2 and assayed for luciferase activity after 24 h, n = 3, *p < 0.05, ****p < 0.0001, Two-way ANOVA. d Cell viability assay of MDA-MB-231 wildtype and MTA1 KO cells treated with 4-hydroxytamoxifen (4-OHT) at the indicated doses for 72 h, n = 3, **p < 0.01, Two-way ANOVA. e Cell viability assay of MDA-MB-231 wildtype and MTA1 KO cells were pre-incubated with 5 μg of MTA1 exosomes and then treated with 4-hydroxytamoxifen (4-OHT) at the indicated doses for 72 h, n = 3, *p < 0.05, ***p < 0.001, Two-way ANOVA