PS7-8. Increase in Oncogenic Drivers of Tumor Progression and Metastasis in Canine Urothelial Carcinoma.

Abstract Urothelial carcinoma (UC) is a commonly occurring malignancy, comprising up to 2% of all canine cancers. It is found in the bladder and upper urinary tract and is often diagnosed after dogs begin displaying symptoms such as straining to urinate, urinating more frequently, or blood in their urine. UC is an aggressive cancer with a high recurrence rate, and due to limited treatment options, the prognosis is often poor. The tumor microenvironment is characterized by malignant cells, non-malignant cells, signaling molecules, blood vessels and fibroblasts, all of which play an important role in tumor progression and metastasis. We conducted a retrospective study to investigate novel biomarkers of canine UC in the bladder tissue. Tissue samples were collected at necropsy from dogs with UC (n = 9; 11-18 yr) and control dogs (n = 15; 9.6-16.4 yr). Urothelial neoplasia was confirmed by end-of-life pathology reports. Following RNA extraction, gene expression was assessed using the NanoString nCounter® Canine Immune/Onc panel and data were analyzed using the nSolver software. There was a significant increase in c-Rel, a transcription factor in the NFκB signaling pathway, in UC tissue when compared to control (2.2 -fold, p < 0.05). c-Rel can have a pro-tumorigenic effect through multiple signaling mechanisms including activating Tregs which creates an immunosuppressive environment, and by activating pro-tumoral genes including CCL-2 and tumor growth survival gene VEGFA. Consistent with this, there was an increase in VEGFA (1.45-fold, p < 0.05) and CCL-2 (2.54 fold, ns) in UC when compared to controls. There was also a significant increase in secreted phosphoprotein 1 (SPP1), another oncogenic gene promoting tumor cell survival when compared to controls (6.82 fold, P < 0.05). SPP1 has multiple actions that promote tumor progression and metastasis including suppression of cytotoxic T-cells to facilitate tumor evasion and upregulation of VEGFA. In addition, intercellular adhesion molecule -2 (ICAM2), a gene that functions as a tumor suppressor and inhibitor of metastasis, was significantly decreased in UC (-1.54 fold, p < 0.05). A decline in ICAM-2, may promote metastasis of tumor cells through decreased cell to cell adhesion leading to migration of tumor cell to distant sites. SMAD2, a transcription factor in the TGF signaling pathway, was significantly increased in UC (1.59 fold, p < 0.05). While SMAD-2 can have pro-or anti-tumorigenic effects, it is predominantly pro-tumorigenic in advanced cancers. Taken together our results indicate multiple pro-tumorigenic signaling pathways possibly contribute to tumor progression and metastasis in UC. These signaling pathways may be attractive therapeutic targets for nutritional intervention to modify the immune response in dogs with UC. Funding Sources: This study was funded by Hill’s Pet Nutrition, Inc.