Extracellular Vesicles Carrying miR-887-3p Promote Breast Cancer Cell Drug Resistance by Targeting BTBD7 and Activating the Notch1/Hes1 Signaling Pathway

Figure 7

MDA-MB-231-derived EVs promoted BC cell drug resistance in vivo by carrying miR-887-3p. Parental MCF-7 and MCF-7/Dox cells stably expressed or transfected were inoculated subcutaneously into BALB/c nude mice at a dose of per mouse ( in each group). Tumor growth was measured continuously every 5 days, and 20 days later, tumor growth was monitored every 3 days. After bearing the tumors for seven days, 300 mg of EVs was injected into the modeled mice via tail veins. Drug treatments were performed with push of doxorubicin (10 mg/kg) on days 12, 15, and 18 after subcutaneously implantation. At 35 days postimplantation, the mice were euthanized by carbon dioxide asphyxiation. (a) Tumor size. (b) Tumor weight. Tumor sections were obtained and stained with anti-BTBD7 and anti-Ki67 antibodies. (c) Representative views of BTBD7- and Ki67-positive tumor cells and quantification of immunohistochemical staining. (d) Expression of Notch1/Hes1 was detected using western blot. In (a), two-way ANOVA was used to determine statistical significance of quantification of immunohistochemical staining, whereas (b)–(d) one-way ANOVA was used. . miR: microRNA; BTBD7: BTB domain containing 7; ANOVA: analysis of variance.

(a)

(b)

(c)

(d)