Dose-dependent effects of three different HDAC8 specific inhibitors on viability of urothelial cancer cell lines. (A) Several urothelial cancer cell lines were treated with different concentrations of HDAC8 inhibitors. Here, the dose-response curves of the UCC RT-112 are shown for compound 2, compound 5 and compound 6 after 72 h inhibitor treatment as measured by ATP-assay (■ compound 2; ● compound 5; ▲ compound 6). The calculated IC50 value in this cell line for compound 2 is greater than 50 μM, for compound 5 it is 9.7 μM and for compound 6 it is 9.1 μM. (B) Sensitivity of urothelial cancer cell lines and one representative normal uroepithelial control to compound 5 and compound 6 after 72 h of treatment. The IC50 of compound 2 was only reached at concentrations near 50 μM. The cell lines outlined by bold letters were used for the functional experiments.