Effects of triclosan exposure on the invasion ability of triple-negative breast cancer cells

Objective·To investigate the effect of triclosan (TCS) exposure on the progression of triple-negative breast cancer (TNBC) and to explore the underlying mechanism.Methods·Cell counting kit-8 (CCK-8) assay was used to detect the half-maximal inhibitory concentration of TCS in the TNBC cell line MDA-MB-231 to screen the exposure concentrations of TCS. The effects of TCS on the migration and invasion abilities of MDA-MB-231 cells were detected by wound-healing assay and Transwell invasion assays, respectively. The effect of TCS on miR-21 expression in MDA-MB-231 cells was detected by quantitative real-time PCR (qPCR). The effects of TCS on the expression of epithelial-mesenchymal transition (EMT)-related proteins, including E-cadherin (E-cad) and vimentin in MDA-MB-231 cells, were detected by Western blotting. The effect of TCS exposure on the miR-21/signal transducer and activator of transcription 3 (STAT3) signaling pathway were detected by immunohistochemistry and Western blotting. Meanwhile, miR-21 mimics were transfected into MDA-MB-231 cells to examine the effects of TCS exposure on the migration and invasion of the cells.Results·According to the CCK-8 assay, the exposure concentrations of TCS were screened to be 0.001, 0.01, 0.1, and 1 μmol/L. Wound-healing assay and Transwell invasion assay both showed that exposure to 0.01, 0.1, and 1 μmol/L TCS enhanced the migration and invasion abilities of MDA-MB-231 cells (all P<0.05). qPCR results indicated that the expression level of miR-21 in TNBC cells was decreased after exposure to 0.01, 0.1, and 1 μmol/L TCS (all P<0.05). Western blotting results revealed that 0.1 and 1 μmol/L TCS downregulated the expression of the epithelial marker E-cad, and 0.01, 0.1, and 1 μmol/L TCS upregulated the expression of the mesenchymal marker vimentin (all P<0.05). Immunohistochemistry and Western blotting results demonstrated that exposure to 0.01, 0.1, and 1 μmol/L TCS increased the phosphorylation of STAT3 in a dose-dependent manner (all P<0.05). Upregulation of miR-21 by transfection with miR-21 mimics attenuated the promoting effect of TCS on the migration and invasion of TNBC cells (both P<0.05).Conclusion·TCS exposure enhances the migration and invasion of TNBC cells via the miR-21/STAT3 signaling axis, suggesting that TCS exposure may exert a promoting effect on the progression of TNBC.