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.