Abstract 861: Selective small-molecule kinase inhibitors of the c-Src:FAK complex

Abstract

Abstract The c-Src protein-tyrosine kinase is the prototype of a large non-receptor kinase family involved in a variety of signaling pathways in virtually every cell type. In normal cells, c-Src controls cell-cell adhesion, cell-matrix adhesion, and cell motility by interacting with and phosphorylating focal adhesion and extracellular matrix (ECM) proteins. Focal adhesion kinase (FAK), a key component of focal adhesions, activates c-Src by binding to its SH2 and SH3 domains and disrupting their negative regulatory influence on the kinase domain. The c-Src:FAK complex plays a major role in the migration and invasion of both normal and cancer cells. Both c-Src and FAK are over-expressed and constitutively active in many tumor types, enhancing focal adhesion turnover, cell migration and metastatic potential. The goal of our project is to determine whether distinct conformational changes occur in the c-Src kinase domain as a function of binding to FAK that can be selectively targeted with small molecule inhibitors. Using the FRET-based Z’-Lyte in vitro kinase assay, we first identified assay conditions where recombinant, downregulated c-Src activation was dependent on a synthetic phosphopeptide based on the FAK SH3- and SH2-binding motifs for c-Src. We then screened a chemical library of about 600 kinase-biased inhibitors for compounds that preferentially inhibited FAK-peptide-dependent c-Src activation compared to c-Src alone. Remarkably, 13 compounds showed at least five-fold selectivity for the FAK peptide:Src complex in the primary screen. Several of these compounds are of the Type II kinase inhibitor class and may exploit unique conformations of c-Src that are induced by FAK peptide binding to the SH3 and SH2 region of c-Src. These compounds are currently being evaluated for their impact on cell growth, invasion and migration in both fibroblasts and epithelial tumor cell lines. Discovery and development of selective inhibitors for a unique FAK-induced c-Src conformation may provide a new approach to targeted therapy for metastatic cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 861. doi:1538-7445.AM2012-861