AIM: To observe the expression of N-cadherin and fibronectin in retinal pigment epithelium(RPE)cells in vitro under high glucose conditions, furthermore, to explore the effects of high glucose on epithelial-mesenchymal transition(EMT)in RPE cells.

METHODS: Human RPE(hRPE)cells were cultured in vitro. Containing a final concentration of 60mmol/L glucose was used for high glucose treatment. The cells were divided into normal glucose group(5.5mmol/L, NG)and high glucose group(24, 48 and 72h)respectively. The expression of N-cadherin and fibronectin in hRPE cells were evaluated by immunofluorescence and real-time PCR.

RESULTS:RPE cells became disorganized and swollen over time under high glucose conditions, especially in 72h subgroup. Immunohistochemical analysis revealed that the expression of N-cadherin in RPE cells under high glucose conditions was decreased compared with that in the control group, while the expression of fibronectin was increased. Real-time PCR results showed that the expression of N-cadherin mRNA in high glucose group was decreased at 24h compared with that in the control group, and declined markedly at 72h(F=12.252, P=0.000). There were no significant differences between the control group and the high glucose group at 24h, while the differences between the control group and the high glucose group(48 and 72h)were significant respectively(P<0.05). Meanwhile, the expression of fibronectin mRNA in RPE cells was increased in high glucose group at 24h, and reached the peak at 72h(F=50.543, P=0.000). There were no significant differences between the control group and the high glucose group at 24h. Compared with the control group, the expression of fibronectin mRNA in hRPE cells was increased significantly in high glucose group(48 and 72h)respectively(P=0.000, P=0.000).

CONCLUSION: The expression of epithelium marker N-cadherin is down-regulated under high glucose conditions in hRPE cells in vitro. Meanwhile, the expression of mesenchymal maker fibronectin is induced and appeared to EMT changes. Results of this study will enrich our growing understanding in proliferative diabetic retinopathy and hopefully lead to novel insights for the pathogenesis and therapeutic treatments.