LAUSR

Background: Bladder cancer (BC) is one of the most common tumors of the male urogenital tract and an important worldwide cause of death. Increasing evidence has indicated the presence of cancer stem cells (CSCs) in many types of tumors, associated with aggressiveness, chemoresistance and relapse. The expression of inducible nitric oxide (NO) synthase (iNOS) in human BC is a poor prognostic factor associated with increased invasion and tumor recurrence. Although there is evidence supporting the role of NO/iNOS in the promotion and progression of BC, the possibility that there are CSCs dependent on endogenous NO generation was not yet been clearly defined. In this study we evaluate the role of NO in CSC maintenance, modulating its production, using pharmacological inhibitors or silencing iNOS expression in a murine BC model. Also, we analyzed the correlation between iNOS expression and stemness-related genes (SG) in human BC samples with different invasion grades. Methods: iNOS pharmacological inhibitors (pan-NOS or iNOS specific) or shRNA were used on murine BC model with different iNOS expression and invasiveness grade: MB49 [iNOS+, non-muscle invasive (NMI)] and MB49-I [iNOS++, muscle invasive (MI)], in order to analyze cell proliferation, number of CSC determined as spheres forming efficiency (SFE) and SG (Sox 2, Oct4 and Nanog expression) by qPCR. iNOS expression and SG were also analyzed in human BC samples (16 NMI low grade (LG), 10 NMI high grade (HG) and 17 MI). Results: The number of CSCs was higher in MB49-I than NMI MB49 line (p Conclusion: Together, this results show that iNOS plays an important role in maintenance of CSC and in vivo BC growth by regulating stemness and self-renewal ability. Thus, iNOS identification and inhibition could be a potential target to eradicate CSC, responsible for tumor recurrences. Citation Format: Denise Belgorosky, Yanina Langle, Julie Girouard, Jovane Hamelin-Morrissette, Lina Marino, Eduardo I. Aguero, Hector Malagrino, Carlos Reyes-Moreno, Ana M. Eijan. Relevance of iNOS expression in bladder cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3091.