Histone Deacetylase Inhibitors Trichostatin A and Vorinostat Inhibit TGFβ2-Induced Lens Epithelial-to-Mesenchymal Cell Transition

PURPOSE: Posterior capsule opacification (PCO) after cataract surgery is due in part to proliferation of the adhering lens epithelial cells and transdifferentiation into mesenchymal cells. The histone deacetylase (HDAC) inhibitors, trichostatin A (TSA) and vorinostat (suberoylanilidehydroxamic acid [SAHA]) are known to modulate cell proliferation and epithelial-mesenchymal transition (EMT). Studies have shown that TGFβ2 can induce EMT similar to that seen during PCO. This study evaluated the effects of TSA and SAHA on TGFβ2-induced EMT in lens epithelial explants. METHODS: Epithelial cells adherent to lens capsules were isolated from fresh pig lenses and human donor lenses and cultured for 12 hours. Explants were pretreated with TSA or SAHA for 1 hour and then treated with TGFβ2 for up to 3 days. Scratch wound healing assay was used to determine epithelial cell proliferation and migration in the samples. The effects of TSA and SAHA on histone acetylation and HDAC 1 to 6 levels were analyzed by Western blotting. RESULTS: Western blotting and immunocytochemistry demonstrated high expression of α-SMA in lens epithelial cells treated with TGFβ2. The HDAC inhibitors exerted dose-dependent inhibition of α-SMA expression, with complete inhibition occurring with 0.5 μM of TSA and 2.5 μM of SAHA. Transforming growth factor β2-induced EMT was suppressed by TSA and SAHA. Histone deacetylase inhibition in pig lens epithelia led to increased acetylation of histone 3 and 4 at multiple sites. CONCLUSIONS: Histone deacetylase inhibitors, TSA, and SAHA prevent EMT in lens epithelial explants. The results also suggest that the epigenetic modifiers are the potential targets to control PCO after cataract surgery.