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The epithelial–mesenchymal transition (EMT) is a key process in tumor invasion and migration. Transforming growth factor-βs (TGF-βs) are multifunctional growth factors and powerful modulators of the EMT. Here, we investigated the relationship between TGF-β expression and invasion by treated triple-negative breast cancer (TNBC) cells. Our results show that invasion capacity of TNBC cells was markedly higher than that of non-TNBC cells. In addition, EMT-related gene signatures, including vimentin (vim), fibronectin (FN), snail, and slug were highly expressed in TNBC cells. Interestingly, our results show that TGF-β1 and β2 mRNA expression levels were higher in TNBC cells than those in non-TNBC cells. Thus, we examined the effect of the TGF-β receptor I/II inhibitor LY2109761 on EMT-related gene expression and cell motility. Our data show that vim, FN, and slug mRNA expression levels dose-dependently decreased in response to LY2109761. TNBC cell motility also decreased in response to LY2109761. Finally, we investigated the effect of LY2109761 on TGF-β1 or TGF-β2-induced E-cadherin (E-cad), vim, and FN mRNA and protein expression. The reduction in E-cad and induction of vim and FN expression by TGF-β1 or TGF-β2 were completely reversed by LY2109761 treatment in HCC1806 TNBC cells. Taken together, we demonstrated that elevated TGF-β expression triggers invasion and migration by TNBCs through the EMT process. Inhibiting the TGF-β signaling pathway is considered a promising therapeutic strategy for treating TNBC. [ABSTRACT FROM AUTHOR]

WNT5A is abnormally increased in a variety of cancers including breast cancer and has an adverse effect on the prognosis. However, the biological function of WNT5A is not fully known in HER2-positive (HER2+) breast cancer. Using public clinical data, we analyzed disease-free survival (DFS) and distant metastasis-free survival (DMFS). Here, we found that abnormal WNT5A induction is a correlation with the poor prognosis of HER2+ breast cancer. WNT5A expression was also decreased by pan-HER inhibitor neratinib but not by trastuzumab. In addition, WNT5A augmented cell invasiveness of HER2+ breast-cancer cells. To find WNT5A-induced metastatic-related factors, we did a human cytokine array. The levels of GM-CSF and CXCL8 were significantly increased by WNT5A. CXCL8 also accelerated cell invasiveness in HCC1954 breast-cancer cells. The expression of CXCL8 induced by WNT5A has been significantly reduced by MEK inhibitor, binimetinib. Finally, we studied the effect of CXCR2 antagonist, SB225002, to verify the relevance of CXCL8 in WNT5A-induced cell invasion. As expected, we found that WNT5A-induced cell invasion is completely inhibited by SB225002. Taken together, we have demonstrated that WNT5A directly mediates cell invasion through the induction of CXCL8 and ultimately affects the survival rate of HER2+ breast cancer. [ABSTRACT FROM AUTHOR]