Histone deacetylase inhibitors trichostatin A and vorinostat inhibit TGFβ2-induced lens epithelial-to-mesenchymal cell transition.

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. 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. 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. 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.