Objective To evaluate the effect of transforming growth factor-β (TGF-β) on the expressions of epithelial-to-mesenchymal transition (EMT)-related molecules in human A431 epidermal squamous cell carcinoma cells.Methods Cultured A431 cells were classified into two groups:TGF-β group treated with TGF-β of 7.5 μg/L for 72 hours,and control group remaining untreated.Subsequently,cell morphology was observed under an inverted microscope,and real time-PCR and Western blot were performed to quantify the mRNA and protein expressions of EMT-related molecules including E-cadherin,N-cadherin,vimentin and β-catenin respectively.Results After TGF-β treatment,the cells became dispersed and spindle in shape.The mRNA expression levels of E-cadherin,Ncadherin,vimentin,and β-catenin in TGF-β group were 0.317,2.475,11.340 and 2.615 folds those in the control group respectively.Western blot showed a marked increase in the expression of N-cadherin,vimentin,and β-catenin proteins but a notable decrease in that of E-cadherin in the TGF-β group compared with the control group.Conclusions TGF-β can induce EMT in A431 cells,and increased expression of TGF-β may contribute to the invasion and metastasis of SCC.

Objective:To evaluate the effect of all-trans retinoic acid (ATRA) on the expression of epithelial-mesenchymal transition (EMT) -related molecules in human malignant melanoma A375 cells.Methods:Cultured A375 cells were divided into 4 groups: control-1 and -2 groups treated with Dulbecco′s modified Eagle medium (DMEM) for 24 and 48 hours respectively, and ATRA-1 and ATRA-2 groups treated with DMEM containing 10 μmol/L ATRA for 24 and 48 hours respectively. After the treatment, real-time quantitative PCR was performed to determine the mRNA expression of EMT-related genes E-cadherin, N-cadherin, vimentin and β-catenin in the above 4 groups, Western blot analysis to determine the relative expression of the above proteins, and direct immunofluorescence study to assess the fluorescence intensity of E-cadherin and vimentin in the ATRA-1, ATRA-2 and control-1 groups. Statistical analysis was carried out by using two-way analysis of variance, one-way analysis of variance and least significant difference- t test. Results:Real-time quantitative PCR showed that the E-cadherin mRNA expression was significantly higher in the ATRA-1 group than in the control -1 group ( F = 13.148, P < 0.05) , and higher in the ATRA-2 group than in the control-2 group ( F = 31.529, P < 0.05) ; the mRNA expression of N-cadherin, vimentin and β-catenin was significantly lower in the ATRA-1 group than in the control-1 group ( P < 0.05) , and lower in the ATRA-2 group than in the control-2 group ( P < 0.05) ; the ATRA-2 group showed significantly increased mRNA expression of E-cadherin ( F = 13.148, P < 0.05) , but significantly decreased mRNA expression of the other 3 proteins compared with the ATRA-1 group (all P < 0.05) ; there was no significant difference in the mRNA expression of the above molecules between the control-1 and -2 groups (all P > 0.05) . Western blot analysis showed that the protein expression of E-cadherin significantly increased, but the protein expression of N-cadherin, vimentin and β-catenin significantly decreased in the ATRA-1 and ATRA-2 groups compared with the control-1 group (all P < 0.05) ; compared with the ATRA-1 group, the ATRA-2 group showed significantly increased protein expression of E-cadherin ( P < 0.05) , but significantly decreased protein expression of N-cadherin, vimentin and β-catenin (all P < 0.05) . Direct immunofluorescence study showed that the fluorescence intensity of E-cadherin was significantly higher in the ATRA-1 group and ATRA-2 group (6.23 ± 0.08, 10.37 ± 0.13, respectively) than in the control-1 group (2.37 ± 0.14, both P < 0.05) , while the fluorescence intensity of vimentin was significantly lower in the ATRA-1 group and ATRA-2 group (15.17 ± 0.18, 10.29 ± 0.03, respectively) than in the control-1 group (50.16 ± 0.26, both P < 0.05) , and the cells in the ATRA-1 group and ATRA-2 group transformed from spindle- to cobble-stone-like in shape. Conclusion:ATRA can up-regulate the expression of E-cadherin, down-regulate the expression of N-cadherin, vimentin and β-catenin in A375 cells, and may inhibit the EMT of A375 cells.