Effects of a novel DNA methyltransferase inhibitor Zebularine on human lens epithelial cells

PURPOSE: Posterior capsular opacification (PCO) is a common long-term complication of modern cataract surgery. We have shown that Zebularine, an inhibitor of DNA methylation, suppresses transforming growth factor-β (TGFβ)-induced lens epithelial cells (LECs)–myofibroblasts transdifferentiation. The purpose of this study is to evaluate the role that Zebularine plays in the inhibition of PCO pathogenesis, including its effect on attachment, migration, and proliferation of LECs in vitro. METHODS: A tetrazolium dye–reduction assay (MTT test) was performed to determine cell proliferation. Cell attachment was assessed by modified MTT test. Migration was determined by the transwell method after incubation of LECs with Zebularine. The effect of Zebularine on DNA-methyltransferase 1 (DNMT1), phospho-p44/42 Map Kinase, and protein kinase B (Akt) were analyzed by western blot. RESULTS: Zebularine was an effective inhibitor of human LEC proliferation, attachment, and migration in vitro. A Zebularine concentration of 100 μM accounted for the following: inhibition of cell proliferation of 57.2%, reduction in cell attachment to 29.6%, and inhibition of cell migration of 58.9%. All effects were dose dependent. Zebularine treatment resulted in dose-dependent decreases of DNMT1, phosphorylated p44/42 MAP Kinase, and phosphorylated Akt. CONCLUSIONS: Zebularine is capable of inhibiting the crucial cellular events in PCO pathogenesis in vitro. Zebularine acts through the inhibition of DNMT1, and it consequently down regulation of the expression of proliferative and survival genes that relate to pathogenesis of PCO. These findings suggest that Zebularine may become a therapeutic approach for the prevention of PCO.