[In vitro study of TGF-β1-induced epithelial-mesenchymal transition of keloid epithelial cells]

To construct and characterize the TGF-β1, induced epithelial-mesenchymal transition (EMT) model of keloid epithelial cells in vitro, and to investigate the expression of epithelial stem cells related surface markers in keloid epithelial cells during EMT induction.

The epithelial cells from 3 keloid samples of ears were cultured in vitro and induced by transforming growth factor betal (TGF-β1, 1 ng/ml) for 5 days, which was the experimental group, the same cells untreated were considered as the negative control group. The expressions of EMT-associated markers and regulative genes were detected using immunofluorescence staining, real-time PCR and western blot analysis. Then the surface markers of epithelial stem cells were detected using real-time PCR. Statistical significance was determined using Independent-Samples t Test, a p value less than 0. 05 was considered statistically significant.

The mRNA expression of transcription factor snail2 and mesenchymal-specific marker vimentin increased significantly in TGF-β1, induced keloid epithelial cells (P < 0. 05), in which snail2 increasing from 0. 91 ± 0. 23 to 1. 69 ± 0. 10, and vimentin from 5. 86 ± 2. 07 to 24. 29 ± 5. 39. Whereas the mRNA expression of epithelial-specific marker E-cadherin decreased from 1. 06 ± 0. 19 to 0. 65 ± 0. 09. The mRNA expression of CD29 and Lgr6, two surface markers of epithelial stem cells, significantly increased after induction of the TGF-β1, (P < 0. 05), from 0. 55 ± 0. 14 and 1. 61 ± 0. 31 to 1. 19 ± 0. 12 and 3. 84 t 0. 62 respectively. In induced cells, the immunofluorescence results showed staining of E- cadherin became faint, but the number of positive staining cells of vimentin increased. Western blot confirmed the protein expression of E-cadherin weakened, and the vimentin and p-Smad3 enhanced (P < 0. 05).

TGF-β1, initiated EMT in keloid epithelial cells by inducing the up-regulation of snail2, and TGF-β1,/Smad3 signaling pathway was involved in EMT. EMT could change the phenotype of epithelial stem cells in keloid.