Phenotypic characterization of canine urothelial organoids

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Colosimo-Roth, Madeline
Major Professor
Allenspach-Jorn, Karin
Mochel, Jonathan P
Musser, Margaret
Committee Member
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Veterinary Biomedical Sciences
Urothelial carcinoma (UC) is the most common form of bladder cancer and is a devastating disease with a high likelihood of recurrence and metastasis in both humans and dogs. Even with treatment, the prognosis for UC is poor due to the late stage that the disease presents in at the time of diagnosis. Dogs with UC can serve as a model for humans because of the close associations between the two malignancies, including histology, molecular heterogeneity, biologic behavior and response to chemotherapeutic agents. Tumor organoids are a a novel ex vivo tool derived from primary tissue that mimic the in vivo environment and physiologic response of the tumor and can be useful to screen cellular and treatment response in individual patients. The aim of this study is to phenotypically characterize canine UC organoids and healthy canine bladder organoids and to compare the expression of specific surface markers between the two. The characterization of the organoids was accomplished by performing immunohistochemistry, immunofluorescence and RNAscope® using markers commonly expressed on UC cells in both species. The UC biomarkers assessed were a marker expressed by all UC cells (CK7), a luminal cell marker (FoxA1), and a urothelial stem cell marker (CD44). The results showed expression of all biomarkers in canine UC organoids and UC Tissue, and only expression of CK7 and CD44 in healthy canine bladder organoids. Overall, the results showed there was an increased percentage of biomarker expression CK7 and CD44 markers in canine UC organoids compared to healthy canine bladder organoids. Our results indicate that the increased expression of stem cell markers, along with decreased expression of de-differentiation markers such as FoxA1, in tumor organoids suggest that, similar to human UC, there is a different phenotype present in UC compared to a healthy bladder. Future studies include utilizing canine UC organoids to test cytotoxic effects of anticancer drugs.