Abstract 1250: Inhibition of FAK and engagement of migration leads to similar changes in patterns of transcription factor activation in glioma cells

Abstract

Abstract Malignant dispersion of glioma cells is a nemesis to clinical management, provoking the need for a better understanding of the underlying molecular drivers of invasion. The changes in signal transduction and consequent alterations in activation/de-activation of Transcription Factors (TFs) in glioma cells were investigated coincident to migration-engagement or impaired FAK kinase function by small molecule inhibition (PF-562,271). Earlier work showed that FAK and Pyk2 affect proliferation and migration in reciprocal ways in glioma cells (Lipinski CA, et al 2008; Loftus JC, et al 2009). The interaction of FAK and Pyk2 with specific downstream signaling effectors and the resultant activation of disparate signaling pathways is likely to script a signaling “signature” that will reveal to what extent glioma cell malignant behaviors are dependent on these kinases. Inhibition of FAK leads to diminution of signaling by pSrc, pJnk, and pNFkB, and variable activation of pAkt, and pp38. Of the 20 TFs assayed (Marligen, Inc.), the activation state of 7 TFs showed significant and consistent patterns of change across 6 primary GBM cell strains following FAK inhibition. Across a panel of 6 human GBM xenograft lines SP1, p53, E2F1-5, and NFκB evidenced strong activation (heightened nuclear localization), while AR (androgen receptor), Myc-Max, and CREB activation levels dropped by more than 2-fold following PF-562,271 treatment. Separate studies of established glioma cell lines under conditions of sparse plating (migration) and of dense crowded plating (migration-constrained), showed that p53, E2F1-5, and NFκB were standouts for activation accompanying migration, also associated by strong reduced activation of AR, Myc-Max, and CREB. (Because glioma cells following FAK knockdown or FAK inhibition show reduced entry into cell cycle, the signaling linkage between FAK and Myc-Max activation and also between FAK signaling and CREB activation suggest mechanistic ties to phenotype. E2F1 is a transcription factor that regulates genes involved in cell proliferation and cell survival and has even been suggested to fit a paradigm of oncogene addiction in glioma cells. Our findings demonstrate phenotypic responses in glioma cells downstream of FAK signaling linked to the activation or inactivation of specific transcription factors. If these patterns of TF activation state, and the signaling pathways upstream of that activation, associate (or account for) patterns of glioma cell invasion or proliferation in situ, they will suggest points of vulnerability in the underlying pathological processes of this disease. Supported by NIH NS042262 (Berens) and NIH CA103956 (Loftus). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1250.