PMID: 23360348

Authors:

Nacht M, Qiao L, Sheets MP, St Martin T, Labenski M, Mazdiyasni H, Karp R, Zhu Z, Chaturvedi P, Bhavsar D, Niu D, Westlin W, Petter RC, Medikonda AP, Singh J

Title:

Discovery of a Potent and Isoform-Selective Targeted Covalent Inhibitor of the Lipid Kinase PI3Kalpha

Journal:

J Med Chem. 2013 Feb 5.

Abstract:

PI3Kalpha has been identified as an oncogene in human tumors. By use of rational drug design, a targeted covalent inhibitor 3 (CNX-1351) was created that potently and specifically inhibits PI3Kalpha. We demonstrate, using mass spectrometry and X-ray crystallography, that the selective inhibitor covalently modifies PI3Kalpha on cysteine 862 (C862), an amino acid unique to the alpha isoform, and that PI3Kbeta, -gamma, and -delta are not covalently modified. 3 is able to potently (EC(50) < 100 nM) and specifically inhibit signaling in PI3Kalpha-dependent cancer cell lines, and this leads to a potent antiproliferative effect (GI(50) < 100 nM). A covalent probe, 8 (CNX-1220), which selectively bonds to PI3Kalpha, was used to investigate the duration of occupancy of 3 with PI3Kalpha in vivo. This is the first report of a PI3Kalpha-selective inhibitor, and these data demonstrate the biological impact of selectively targeting PI3Kalpha.