Abstract LB167: The role of sex hormones and sex chromosomes in urethane-induced lung carcinogenesis

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide and remains among the top ten causes of mortality in the United States. Non-small cell lung cancer (NSCLC) constitutes approximately 85% of all lung cancer cases, with lung adenocarcinoma (LUAD) being the most prevalent subtype. Intriguingly, sex differences in lung cancer incidence and mortality have been observed, particularly among non-smokers, where LUAD is more common in females. Understanding the sex-specific mechanisms underlying LUAD progression is critical for developing targeted therapeutic strategies. In this study, we employed the “four core genotypes” (FCG) model, utilizing ArnoJ (C57BL/6J background) mice in which gonadal sex is decoupled from the sex chromosome complement. Combining this model with the urethane-induced lung cancer protocol (a well-established mimic of human LUAD), we investigated the roles of gonadal hormones and sex chromosomes in LUAD progression. Mice of 6-8 weeks of age received urethane (1 g/kg body mass, weekly for 10 weeks) or the same volume of PBS (control) injections and were evaluated after a 20-week tumorigenesis period. We assessed cytological changes in bronchoalveolar lavage fluid (BALF), changes in mice body weights, and histological features in fixed lung tissue. Upon histological examination, 100% of mice treated with urethane developed neoplasias. All animals experienced increased BALF total counts and weight loss after urethane treatment (vs. control). When comparing animals of different genotypes, we found that the XXM (female chromosomes, male gonads) displayed the most prominent weight reduction between urethane and control groups. When combining mice with the same chromosomes treated with urethane vs. PBS, animals with XX composition displayed a greater difference in weight than those with XY chromosomes. In contrast, when comparing animals with the same gonads, mice with male gonads showed a stronger effect in weight reduction than those with female gonads. Overall, BALF from urethane-treated mice had higher total cell counts than PBS-treated mice. Differences across genotypes were also noted. Our preliminary analysis indicates that mice with female gonads experienced a more prominent increase in cell counts than mice with male gonads. No apparent differences were noted when comparing animals with XX or XY chromosomes. In conclusion, our preliminary analysis of this pilot experiment revealed a potential contribution of sex hormones and sex chromosomes to urethane-induced weight loss and BALF counts. Further analysis of histological and molecular markers in these mice will reveal additional information that could help us understand sex-specific mechanisms of carcinogenesis. Citation Format: Maksat Babayev, Carolyn Damilola Ekpruke, Omar Borges-Sosa, Shikha Sharma, Dustin Rousselle, Chukwudike Igwe, Michelle Christine Boulos, Aakash Parekh, Patricia Silveyra. The role of sex hormones and sex chromosomes in urethane-induced lung carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB167.