First non-radioactive assay for in vitro screening of histone deacetylase inhibitors

Inhibitors of histone deacetylase (HD) are of great potential as new drugs due to their ability to influence transcriptional regulation and to induce apoptosis or differentiation in cancer cells. So far only radioactive enzyme activity assays or in-vivo assays with subsequent electrophoresis and immunoblotting existed to study the activity of HD and potential inhibitors. To aid in the search of new inhibitors, a non-radioactive screening assay was sought and we have previously succeeded in establishing this for the first time. The assay uses an aminocoumarin derivative of an omega-acetylated lysine as substrate for the enzyme. Here we report full experimental details, the evaluation of other potential substrates, and comparative analysis of various inhibitors. This advantageous method should have an impact on further developments in the field.