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 enzym e activity assays or in vivo assays with subsequent electrophoresis and imm unoblotting existed to study the activity of HD and potential inhibitors. T o aid in the search of new inhibitors, a non-radioactive screening assay wa s sought and we have previously succeeded in establishing this for the firs t time. The assay uses an aminocoumarin derivative of an Omega-acetylated l ysine 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 furt her developments in the field.