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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.