Design and synthesis of novel azapeptide activators of apoptosis mediated by caspase-9 in cancer cells.

A set of azapeptides was designed based on the Ala-Val-Pro-Ile peptide (derived from Smac protein) to activate caspase-9 and induce apoptosis in breast cancer cells. The diversity-oriented synthesis of the aza-peptides 5-9 was accomplished by alkylation of the aza-residue of aza-Gly-Pro dipeptide 15 using potassium tert-butoxide and a range of different alkyl halides. The resulting protected aza-dipeptide building blocks were then introduced into mimics 5-9 using standard coupling conditions. Biological evaluation of 5-9 was performed in MDA-MB-231 breast cancer cells, and indicated that the aza-Gly and aza-Phe analogs 5 and 7 were most efficient in inducing cell death by a caspase-9 mediated apoptotic pathway. Revealing a relationship between azabicycloalkanone and aza peptide mimics, novel AVPI mimics were synthesized which exhibit utility for studying structure-activity relationships to develop leads for activating apoptosis in cancer cells.