Figure 3.

ERα could enhance CD44 expression to promote the resistance of ER+ breast cancer cells to paclitaxel. A, Western blot analysis of ERα protein expression in ER+ breast cancer cells treated with E₂ (1 μmol/L). B, Western blot analysis of ERα protein expression in ZR‐75‐1 and MCF‐7 cells transfected with empty vector or ERα expression plasmids. C, Real‐time PCR analysis of CD44 expression in ZR‐75‐1 and MCF‐7 cells transfected with vector or ERα expression plasmids. D, ZR‐75‐1 cells were treated with the indicated concentrations of paclitaxel for 72 h and subjected to cell viability assay. E, MCF‐7 cells were treated with the indicated concentrations of paclitaxel for 72 h and subjected to cell viability assay. F, Real‐time PCR analysis of CD44 transcript expression in both ZR‐75‐1 and MCF‐7 cells treated with E₂ (100 nmol/L) or its combination with IBC (8 μmol/L) for 72 h. G, Western blot analysis of ERα and CD44 protein expression in MCF‐7 and MCF‐7/R cells treated with E₂ (1 μmol/L) or its combination with IBC (8 μmol/L) for 72 h. *P < .05, **P < .01