Abstract 4056: Differential phosphorylation of focal adhesion kinase and activation of Yes kinase are associated with increased metastatic potential of prostate cancer

Abstract

Abstract Metastatic Prostate Cancer (PCa) is the second leading cause of cancer related-deaths in men in the United States. Understanding the molecular events critical to PCa metastasis should lead to novel therapies for treatment of metastatic disease. To assess molecular alterations required for increased PCa cell migration, a critical step in metastasis, multiple rounds of selection of PC3 and DU145 PCa cells were performed using a modified Boyden chamber assay. Highly migratory cells (termed PC3-Mig-3 and DU145-Mig-3) were obtained, a phenotype that has remained stable. PC3-Mig-3 and DU145-Mig-3 cells were also increased in invasiveness, decreased in adhesion and proliferation; thus acquiring additional properties of metastatic cells. Following orthotopic injection into nude mice, migratory variants were significantly increased in number of lymph node metastases (P<0.05). In examining signaling pathways associated with migration and invasion, we determined both PC3-Mig-3 and DU145-Mig-3 were increased in phosphorylation of FAK at tyrosine 861, but not other sites of FAK phosphorylation, relative to their isogenic parental cells. Overexpression a FAK Y861F mutant in PC3-Mig-3 cells decreased migration, demonstrating the importance of pY861 in migratory and invasive potential. Further, expression of FAK pY861 in human PCa lymph node metastases correlated with decreased overall patient survival, suggesting phosphorylation of FAK Y861 may be a predictive biomarker of clinical outcome. To examine potential mechanisms of differential phosphorylation of FAK Y861, the expression and activity of Src family tyrosine kinases was determined. The expression and activity of the Src family kinase, Yes, but not other members of the Src family, were increased in both migratory variants. This increased Yes expression correlated with increased Yes mRNA expression throughout PCa progression as determined from Oncomine. To determine the role Yes kinase in FAK Y861 phosphorylation, Yes was silenced by shRNA expression in PC3-Mig-3 cells. Decreased Yes expression led to both decreased migration, and selectively decreased phosphorylation of FAK Y861. Overexpression of Yes kinase in PC3 parental cells led to specific increased phosphorylation of FAK Y861. These results suggest: the new models of migration we developed have similar alterations as those that occur during PCa progression in men with PCa; Yes activation may play a unique role in PCa progression by leading to differential phosphorylation of FAK Y861; FAK Y861 phosphorylation is important in metastatic potential of PCa cells; and that Yes and FAK may be important markers of metastatic potential of PCa cells. Further studies are designed to investigate specific signaling pathways affected by increased Yes expression and FAK Y861 phosphorylation. Citation Format: Tanushree Chatterji, Jian H. Song, Nila U. Parikh, Chien-Jui Cheng, Sue-Hwa Lin, Gary E. Gallick. Differential phosphorylation of focal adhesion kinase and activation of Yes kinase are associated with increased metastatic potential of prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4056. doi:10.1158/1538-7445.AM2014-4056