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. 2021 Jul 15;11:697950. doi: 10.3389/fonc.2021.697950

Figure 1.

Figure 1

STAT5a is involved in chemoresistance in breast cancer. (A) Expression of STAT5a and STAT5b in breast cancer samples collected pre- and postchemotherapy in the dataset GSE87455. (B) Survival rates of MCF7 and MCF7/DOX cells after treatment with DOX for 48 h determined by a CCK8 assay. (C) mRNA levels of STAT5a and STAT5b in MCF7 and MCF7/DOX cells assessed via qPCR. (D) Protein levels of STAT5a, p-STAT5a (Tyr694) and STAT5b in MCF7 and MCF7/DOX cells determined by Western blotting. (E) Western blotting was performed to examine the expression of STAT5a and p-STAT5 (Tyr694) in MCF7 cells upon treatment with DOX. (F) Correlation between the pCR rate and STAT5a expression in breast cancer samples obtained from 67 patients. (G) Representative images of IHC staining for STAT5a in chemoresistant and chemosensitive breast cancer samples. (H) Efficiency of vector transfection for overexpression of STAT5a in MCF7 cells and siRNA transfection for knockdown of STAT5a in MCF7/DOX cells determined by Western blotting. (I, J) Flow cytometry was performed to assess apoptosis in MCF7/DOX cells after knocking down STAT5a or control treatment (I). Bar graphs showing the percentage of apoptotic cells (J). (K) Survival rate and IC50 of MCF7 cells transfected with an empty vector or a STAT5a vector after treatment with DOX for 48 h determined by a CCK8 assay. (L) Survival rate and IC50 of MCF7/DOX cells transfected with scramble siRNA or STAT5a-targeting siRNA after treatment with DOX for 48 h determined by a CCK8 assay. (M, N) Representative images and quantification of colonies formed by MCF7 cells transfected with the empty vector or STAT5a vector (M) and MCF7/DOX cells transfected with scramble siRNA or STAT5a-targeting siRNA (N) in medium containing the indicated concentration of DOX. (O) The expression levels of apoptosis markers in MCF7 cells transfected with the empty vector or STAT5a vector and MCF7/DOX cells transfected with scramble siRNA or STAT5a-targeting siRNA under treatment with the indicated concentration of DOX determined by Western blotting. ns, p > 0.05; *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.