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Nymph Chan, Shikun He, Christine Spee, Stephen Ryan, David Hinton; Choroidal Neovascularization is Regulated by Histone Acetylation. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1785.
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Choroidal neovascularization (CNV) is a serious complication of age-related macular degeneration (AMD). The pathogenesis of CNV is still under investigation, especially the involvement of histone acetylation in the formation of CNV. The aim was to examine through in vitro and in vivo studies, whether the histone deacetylase inhibitor, trichostatin A (TSA), regulates retinal pigment epithelial (RPE) cell proliferation, attachment and migration, and thus the initiation of experimental CNV in mice.
Cultured early passage human fetal RPE cells were used in the study. The proliferation of RPE cells was tested by MTT assay and cell cycle analysis after treatment with TSA (0 µM, 0.05 µM, 0.1 µM, 0.3 µM, 0.5 µM or 0.7 µM; 24 hrs). The ability of TSA-treated RPE cells to attach to fibronectin was tested in a 96-well plate and visualized by a modified MTT assay. The effects of TSA on RPE cell migration were examined with a modified Boyden chamber assay. The activation of Akt and caspase 3 in RPE cells treated with TSA (as above) for 24 hours was investigated by Western blot. Laser-induced CNV in C57/Bl6 mice receiving intraperitoneal injections of either phosphate-buffered saline or 20 mg/kg of TSA every 2 days for 14 days was studied by fluorescein angiography, histological analysis, isolectin B4 staining of the CNV lesions and CNV volumes.
TSA showed a dose-dependent inhibition of proliferation in RPE cells; specifically, it halted cell cycle progression at G1 phase. TSA treatment resulted in increased activated caspase 3 at higher doses. TSA promoted the attachment of RPE cells to fibronectin. Most significantly, TSA attenuated laser-induced CNV formation in mice, as seen by the reduced leakage in fluorescein angiography, smaller lesion sizes in histological analysis, and decreased CNV volumes after isolectin B4 staining.
TSA inhibits CNV formation, possibly by inhibiting RPE cell proliferation, cell migration, and new vessel formation. Epigenetics plays a critical role in the regulation of RPE cellular functions and TSA can be a potential therapeutic candidate for the treatment of CNV.
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