Abstract 3060: Changes in mouse gut microbiome upon exposure to N-butyl-N-(4-hydroxybutyl) nitrosamine

Abstract

Abstract Background: BBN (N-butyl-N-(4-hydroxybuytl) nitrosamine), a closely related compound to the carcinogens found in tobacco smoke is an attractive and most commonly used agent to model bladder cancer in mice. BBN closely recapitulates the morphological characteristics of human bladder cancer and conceptually simulates tobacco exposure as the leading risk factor for bladder cancer. We employ the BBN model in mice to decipher the microbial changes that occur in the gut of the mice during the chemical carcinogenesis induced by BBN exposure. Methods: Starting at 8-12 weeks of age, male (N=30) and female (N=21) C57BL/6 mice were administered 0.05% BBN in drinking water for 12 weeks then switched to regular water. Control mice drank regular water. Stool was collected pre-exposure, after 6 and 12 weeks of exposure, and at the time of tumor identification (tumors typically detectable between 14-22 weeks from start of treatment using this model). DNA extracted from stool was subjected to PCR amplification using primers for the V3-V4 regions of the bacterial 16S rRNA. Results: Gender-based differences in the microbial composition were noted in response to BBN treatment. While gut microbial diversity in the female mice was markedly reduced (Shannon, Simpson, Inverse Simpson, and Richness) upon BBN treatment, that of male mice remained unchanged from baseline. Additionally, there was a distinct clustering of microbes based on sex (p=0.024) but not BBN exposure (p=0.86) as evidenced by principal coordinate analysis. Differences in the microbial composition were seen upon BBN exposure, with BBN mice showing an increase in Bacteroidales (53%), Lactobacillales (17.5%), Coriobacteriales (19.87%) in females and male mice exhibited an increase in Erysipelotrichales (14.76%) at the order level. On the other hand while male mice showed no significant decreases, female mice exhibited reduction in abundance of Clostridiales (log change -7.79, padj <0.004), Veeruccomicrobiales (log change -2.21, padj<0.005), and Bacillales (log -17.60, padj =0.005). Conclusions: Pronounced gut microbial changes are induced by BBN in the murine model, with microbiome of the female mice exhibiting more significant variations compared to baseline, suggesting gender-based disparities in the effect of BBN exposure. Citation Format: Rashida Ginwala, Laura Bukavina, Jodie Franklin, Mohit Sindhani, Philip Abbosh. Changes in mouse gut microbiome upon exposure to N-butyl-N-(4-hydroxybutyl) nitrosamine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3060.