Abstract 4096: FAK inhibition with small molecule inhibitor Y15 decreases viability in thyroid cancer cell lines.

Introduction: Thyroid cancer is the most common endocrine malignancy and papillary the most common subtype. While low stage papillary carcinomas are treatable, for nonresectable tumors that do not respond to iodine, a treatment is still needed. In comparison, for advanced medullary cancer, a tyrosine kinase inhibitor, Vandetanib, is currently being used. Focal Adhesion Kinase (FAK) is a tyrosine kinase involved in many protein-protein interactions that control important cellular functions. FAK is upregulated in many cancer cell lines, including thyroid. It contains an autophosphorylation site Y397, which is blocked by 1,2,4,5-Benzenetetraamine tetrahydrochloride (Y15), a small molecule FAK inhibitor. We propose that this inhibitor, Y15, will decrease viability of thyroid cancer cell lines. Methods: Four human thyroid cancer cell lines were cultured in vitro. K1, BCPAP, and TPC1 were derived from papillary thyroid carcinomas, and TT was derived from a medullary thyroid carcinoma. Western blots were used to detect expression of FAK and pY397 FAK in each untreated line. These were repeated with differing concentrations of Y15 plus the Novartis FAK inhibitor TAE226 as a positive control. MTS assays of each cell line were used to measure cell viability with increasing doses of Y15. Untreated medium, DMSO, and TAE226 were used as negative and positive controls. Results: All untreated thyroid cancer cell lines expressed FAK and phosphorylated Y397 FAK on Western blotting. Increasing doses of Y15 in Western blotting decreased the expression of pY397 FAK in all cell lines. This was also associated with increased cell detachment. In MTS assays, viability was also decreased with Y15 in a dose-dependent manner across all cell lines. Significant inhibition was reached at relatively low doses: there was a 90% decrease in viability with 10μM Y15 in TPC1 cells and 5μM Y15 in TT cells. The effects were seen across all lines, but most profound in TPC1 and TT. Conclusions: Papillary thyroid cancer cell lines and medullary carcinoma cells express FAK and pY397. The FAK inhibitor Y15 causes a dose-dependent decrease of phosphorylated FAK, and this disruption decreases cell viability. Our data suggests Y15 may be an effective potential treatment for advanced papillary thyroid cancer. Citation Format: Shalana B. O9Brien, Vita M. Golubovskaya, William G. Cance. FAK inhibition with small molecule inhibitor Y15 decreases viability in thyroid cancer cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4096. doi:10.1158/1538-7445.AM2013-4096