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Discovery of Inhibitors of Anti-Apoptotic Protein A1

Publication TypeJournal Article
Year of Publication2010
AuthorsBittker, JA, Weiwer, M, Wei, G, Germain, A, Brown, E, Dandapani, S, Munoz, B, Palmer, M, Golub, T, Schreiber, SL
Date Published2010/01/01

Pro- and anti-apoptotic proteins maintain a regulated balance in cells that allow programmed cell death to occur in response to genetic damage and other stimuli. In cancer cells, this balance is often dysregulated by the overexpression of anti-apoptotic factors. A probe development project was carried out with the goal of identifying small molecules able to specifically inhibit the anti-apoptotic function of one of these proteins, the BCL-2-family member BCL2A1 (A1, Bfl1). A high-throughput screen (HTS) of 325,633 compounds was carried out by measuring caspase activation in a mouse fibroblast cell line primed for death by balanced overexpression of A1 and BIM, a pro-apoptotic BH3 domain-containing protein. A series of secondary assays was used to determine whether compounds identified in the primary screen were specific for caspase activation in an A1-dependent manner. A series of compounds was identified that contained reactive functionality but showed highly specific induction of apoptosis, including a probe (CID701939/ML214) that activates caspases in A1-overexpressing cells at low micromolar concentrations. Due to the reactive nature of the probe series and the necessity of this reactive functionality for biological activity, these compounds are not intended to be candidates for drug development. However, the surprisingly specific activation profile exhibited by these compounds suggests that they may be selectively modifying A1 or a related apoptotic protein. Therefore, the probe ML214 is a valuable research tool for further study of targets or interaction sites that can lead to overcoming the apoptotic blockage of A1 in cancer cells.