['Histone deacetylase (HDAC) inhibitors have shown significant anti-proliferative and apoptotic properties on various cancer cells, including prostate cancer, and are therefore being evaluated as treatment modalities. However, the specific effect of HDAC inhibitors on androgen-sensitive and androgen-independent cell lines have not been thoroughly studied which we hypothesized could be different. We therefore assessed whether three structurally unrelated HDAC inhibitors, trichostatin A (TSA), depsipeptide (FR901228), and sodium butyrate, affect cell death in the prostate cancer cell lines LNCaP, DU-145, and PC-3.', 'To investigate the extent and the nature of cell death, we used Trypan blue exclusion assay, phase-contrast light microscopy, fluorescence microscopy, and Western blot analyses.', 'At concentrations where they potentiate transcriptional activation, all three HDAC inhibitors induced cell death in LNCaP and DU-145 cells, but not in PC-3 cells, within the timeline of the experiments. HDAC inhibitor-induced cell death in LNCaP and DU-145 cells showed several characteristic apoptotic features, such as cell shrinkage, nuclear condensation, and poly(ADP) ribose polymerase cleavage. However, there were differences in the way LNCaP and DU-145 cells responded to treatment with various HDAC inhibitors. For example, whereas TSA and FR901228 were more effective in inducing apoptosis in LNCaP cells compared with DU-145 cells, the reverse was true for sodium butyrate. Moreover, within the same cell line, TSA, FR901228, and sodium butyrate exhibited different potencies for induction of apoptosis.'] Do histone deacetylase inhibitors differentially mediate apoptosis in prostate cancer cells?