In vitro effects of histone deacetylase inhibitors and mitomycin C on tenon capsule fibroblasts and conjunctival melanoma cells.

OBJECTIVE To investigate the effects of mitomycin C and the histone deacetylase inhibitors sodium butyrate and trichostatin on the viability and growth of conjunctival melanoma cell lines and Tenon capsule fibroblasts. METHODS Cells were treated with a range of concentrations of sodium butyrate, trichostatin, and mitomycin C. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide) assays were performed 48 hours after treatment. Treated cells were stained with acridine orange/ethidium bromide to assess for cell death. Cell-cycle changes in histone deacetylase inhibitor-treated melanoma cells were quantified using flow cytometry. RESULTS All agents induced dose-dependent cell death in the melanoma cell lines; however, sodium butyrate and trichostatin were relatively nontoxic to Tenon capsule fibroblasts. Acridine orange/ethidium bromide staining indicated that sodium butyrate and trichostatin induced apoptotic cell death. At low doses, sodium butyrate and trichostatin induced a G1 cell-cycle block in the melanoma cells. CONCLUSIONS Sodium butyrate and trichostatin induced cell death in melanoma cells, comparable with mitomycin C, with minimal effect on Tenon capsule fibroblasts. In addition, they induced a G1 cell-cycle block. These findings support the need for further investigation into the in vivo efficacy of these agents.