A novel high-through-put assay for screening of pro-apoptotic drugs

Screening for anti-cancer substances iscommonly conducted using viability assays.An inherent problem with this approach isthat all compounds that are toxic andgrowth inhibitory, irrespective ofmechanism of action, will score positive.It would be beneficial to be able to screenfor compounds that specifically induceapoptosis. We here describe an ELISA-assaybased on a monoclonal antibody (M30) whichrecognizes a neo-epitope on cytokeratin 18exposed after cleavage by caspases duringapoptosis. We show that this assay detectsapoptosis in epithelial cells and that thesensitivity is sufficient for screening inthe 96-well format. We used the M30-ELISAassay to screen 500 low molecular weightcompounds from a chemical library from theNational Cancer Institute and identified 16drugs with strong pro-apoptotic activity,suggesting that the assay is a useful toolfor discovery of pro-apoptotic drugs.