Transforming growth factor-β1 regulates epithelial-mesenchymal transition in association with cancer stem-like cells in a breast cancer cell line.

Epithelial-mesenchymal transition (EMT) is associated with altered connection and junctions between cells and changes in abilities of invasion and migration. In this study, we investigated whether SK-BR-3 breast cancer cells induced to undergo EMT exhibit changes in morphological and invasion abilities after Transforming growth factor β1 (TGF-β1) treatment. Serum-deprived SK-BR-3 cells were treated with TGF-β1 (0, 10 ng/mL) for 24 h. The cells morphological changes were observed and imaged using inverted phase contrast microscope. Scratch experiment and invasion experiment were employed to detect changes of invasion ability, cell-flow experiment was used to assess cell cycle, immunohistochemistry technique was used to detect epithelial and mesenchymal markers after the crawling cells were fixed. Our research reveal that SK-BR-3 cells become larger and more messy, the elongated cells extend pseudopodia, the link of the cells became more loosely and cell gap widened after TGF-β1 treatment. SK-BR-3 cells showed faster growing and improved invasion abilities after TGF-β1 treatment, and reduced G1 phase cells proportion in the total number of cells after the conversion, in contrast the S phase cells accounted for the proportion of the total number of cells increased. These findings indicate that TGF-β1-induced EMT in breast cancer cells may be associated with major alterations in morphological and invasion abilities.