Abstract 4589: SRC drives invasion of luminal, but not basal, bladder cancer

Abstract

Abstract Preventing progression from non-muscle invasive to muscle invasive bladder cancer (BC) is a major clinical priority. This transition is defined by tumor invasion through the bladder epithelium basement membrane into the lamina propria and muscle wall. Inhibition of SRC, a pro-invasion, non-receptor tyrosine kinase that signals as part of a complex with Focal Adhesion Kinase (FAK), may prevent BC progression. We hypothesize that SRC inhibition will disrupt migration and invasion of BC cells. Using The Cancer Genome Atlas (TCGA) mRNA expression data of human bladder tumors, we generated a classifier to subtype tumors as either “luminal” or “basal” and compared SRC expression between the groups. We then sequenced a panel of 30 bladder cancer cell lines. Each cell line was given a subtype call based on our luminal- basal classifier, and levels of SRC mRNA expression were examined. To determine the impact of SRC inhibition on luminal and basal subtypes, we exposed BC cell lines to the SRC-Family Kinase inhibitor, AZD0530. The impact of SRC inhibition on proliferation was measured by MTT assay. Transwell assays were used to examine the effect of SRC inhibition on migration, collagen invasion, and Matrigel invasion. Phosphorylation of SRC downstream targets after AZD0530 treatment was assessed by western blot. The role of SRC target and signaling partner FAK in migration was determined by siRNA knockdown and transwell assay. Luminal human bladder tumors had significantly greater SRC mRNA expression than basal tumors (p<0.001). SRC expression was also enriched in luminal BC cell lines (p<0.05). Inhibiting SRC with AZD0530 had minimal impact on proliferation with no subtype specific effects. Migration and collagen invasion of all luminal cell lines was significantly reduced by AZD0530 treatment (p<0.05). The majority of luminal models capable of invading Matrigel were also inhibited by AZD0530. In contrast, invasion and migration of the majority of basal cell lines was not significantly reduced by SRC inhibition, and was significantly increased in several cases (p<0.05). Both luminal and basal models exhibited reduced phosphorylation of SRC downstream targets when exposed with AZD0530. siRNA knockdown of FAK had no impact on migration in a basal cell line. Enrichment of SRC expression in luminal tumors and significant reductions in luminal cell line invasion after AZD0530 treatment suggest SRC promotes invasion in luminal BC. These results suggest AZD0530, and other SRC-Family Kinase inhibitors, could serve as effective anti-progression agents in luminal BC. Citation Format: Bryan Wehrenberg, Andrea Ochoa, Woonyoung Choi, David McConkey. SRC drives invasion of luminal, but not basal, bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4589.