The Identification of FAK-Scaffold Inhibitors Targeted to Y925
Lenzo, Felicia Lynn
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Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase. FAK maintains survival and migratory signaling in cancer and promotes tumor progression. The overexpression of FAK in cancer has been evaluated using multiple modalities: immunohistochemistry (IHC) to visualize FAK expression in patient tumor, polymerase chain reaction (PCR) for amplification of mRNA levels extracted from tumor, and western blot analysis to evaluate protein expression levels from tumor cell lysates. High FAK expression has been correlated with poorer outcome in patients, but there is no standardized method used in a clinical setting to consistently evaluate mean FAK expression. One goal of this project was to create a pan-cancer retrospective study to correlate mean FAK expression with overall survival in patients using a standardized IHC staining and scoring protocol. Colorectal, breast, gastric, pancreatic, and melanoma were evaluated. Only colorectal demonstrated a statistically significant correlation between overall survival and mean FAK expression. Using a standardized process, the evaluation of mean FAK expression has potential to be used to identify patients for FAK-targeted therapeutics. Unfortunately, FAK-kinase inhibitors are not as efficacious as intended, suggesting the need for alternative methods to target FAK. Targeting the C-terminal of FAK as it contains the FAT domain which is quintessential for proper localization to focal adhesions and regulating focal adhesion turnover, migration/invasion, and angiogenesis is a novel approach. The other goal of this project was to develop protein-protein interaction inhibitors targeted to the FAT domain of FAK, specifically to the main phosphosite that drives migration, tyrosine 925 (Y925). In order to accomplish this, screening methodologies were developed in order to identify novel FAT domain binding partners and exploit those interactions in the search for small molecules targeting to those binding interfaces. Overall, this project has developed a standardized method of evaluating mean FAK expression in patient tumor, the creation of screening assays designed to evaluate FAT domain binding partners, and finally the development and utilization of rational structure based drug discovery to identify small molecules that may inhibit Y925 phosphorylation.