Hedgehog signaling pathway regulates the invasion of breast cancer cells via epithelial-mesenchymal transition

Objective: To investigate the effect and mechanism of Hedgehog signaling pathway on the invasion of breast cancer cells in vitro. Methods: The SHH, SMO and Gli-1 expression levels of breast cancer cell line MDA-231 and normal mammary epithelial cell line MCF-10A were detected by Western blot at protein level and by Real-time RT-PCR at mRNA level. Next, shRNA vector was transfected into the MDA-231 cells with highly expressed SMO, and the stable transfected cells were selected by G418. Western blot and Real-time RT-PCR were performed to observe the inhibitory effect of RNAi on SMO expression. MTT assay was used to assess the influence of SMO siRNA on cell proliferation. Transwell assay was applied to observe cell invasion ability. The expressions of Gli-1, Snail, MMP-9, E-cadherin and Vimentin protein were determined by Western blot. Results: Compared with those of normal mammary epithelial cell line MCF-10A, the expressions of SHH, SMO and Gli-1 were significantly increased. The invasion of MDA-231 cells was inhibited significantly after SMO silencing. Additionally, the protein expressions of Gli-1, Snail, MMP-9 and Vimentin were obviously inhibited, and E-cadherin was significantly increased. Conclusion: Mutative activation of Hedgehog signaling pathway in breast cancer cells promotes cell invasion probably through induction of epithelial-mesenchymal transition of the tumor cells.