Fig 2: Knockdown of transmembrane protease serine 4 (TMPRSS4) regulated the expression of epithelial-mesenchymal transition (EMT) related genes. (A and B) RT-qPCR demonstrated that EMT markers of E-cadherin and vimentin were upregulated and downregulated respectively after TMPRSS4 knockdown in MDA-MB-468 and MDA-MB-231 cells. For the expression of key EMT transcriptional factors, claudin-1 and slug were upregulated and downregulated after transfection with siRNA, respectively. However, expression of ZEB1 did not show significant change. (C-F) Transfection efficiency and similar results were further observed in western blot analysis. β-actin was an internal control. *P<0.05, **P<0.01 and ***P<0.001. NC, negative control; EMT, epithelial-mesenchymal transition.

Fig 3: Knockdown of transmembrane protease serine 4 (TMPRSS4) suppresses cell proliferation. (A) mRNA (upper) and protein (lower) expression of TMPRSS4 in different breast cancer (BC) cell lines. (B) siRNA transfection significantly reduced TMPRSS4 mRNA expression in MDA-MB-468 and MDA-MB-231 cells. (C and D) Proliferation rates of MDA-MB-468 and MDA-MB-231 cells were reduced after TMPRSS4 knockdown. *P<0.05. NC, negative control.

Fig 4: Kaplan-Meier survival curves for breast cancer (BC) patients stratified according to transmembrane protease serine 4 (TMPRSS4) expression. (A) Overall survival (OS) curves of BC patients according to TMPRSS4 immunostaining. (B) Disease-free survival (DFS) curves of BC patients according to TMPRSS4 immunostaining. P-values were obtained by log-rank test.