Abstract 5326: Selective deletion of estrogen receptor β in lung epithelium suppresses K-ras mutant lung tumorigenesis

Abstract Although lung cancer is the most prolific cause of global cancer-related deaths, outcomes by sex have gained traction as a means to stratify patients and tailor therapies accordingly. In recent years, females have begun to shoulder a greater burden of lung cancer diagnoses, specifically within the lung adenocarcinoma (LUAD) subtype; conversely, mortality is worsened for males. However, other sex-dependent effects in lung cancer are harder to predict. For example, hormone replacement therapy for post-menopausal women has been shown to predict better survival in some cohorts while auguring worse outcomes in others. Similar controversy exists regarding menopausal status, gender affirming care, and castration/oophorectomy status. However, there is consensus that these differential effects relate to a patient’s sex hormone composition. Estrogen, a sex hormone abounding in females, boasts well-described pro-tumor signaling in breast cancer. Unfortunately, its role in lung cancer remains elusive. Estrogen is reported to exert inflammatory properties in the lung environment, to drive immune function, and to induce proliferation of lung cancer cells. This functional antagonism has led to questions about how these compartment-specific effects are balanced. In the lung, estrogen signaling occurs mainly via estrogen receptor beta (ERβ), a nuclear hormone receptor highly expressed in lung tissue and lung tumors. ERβ is understudied relative to its sibling ERα, a well-known oncogene in breast cancer. While it is tempting to analogize ERα oncogene function to ERβ, the literature lacks consensus on the role of ERβ in lung cancer, with some authors classifying it as an oncogene and others as a tumor suppressor. In LUAD, Kras mutations encompass a quarter of driver mutations, and interaction of Kras with ERβ is understudied. Here, we tested the effects of genetic ablation of ERβ in a murine model of Kras mutant LUAD (KM-LUAD) termed CCSPCre/LSL-KrasG12D (CC-LR). Esr2 floxed mice were crossed with CC-LR mice to create a lung epithelial-specific conditional knockout of ERβ (LR/Esr2Δ/Δ). LR/Esr2Δ/Δ mice show significant decrease in tumor burden and total lung immune infiltration, indicating reduced tumor development and tumor-promoting inflammation. Of note, this effect manifests regardless of sex. RNA and protein-level analysis further suggest that ERβ deletion alters the balance of inflammatory transcription factors, resulting in skewing from STAT3- to NF-κB-driven inflammation and a net anti-tumor response. These data suggest that ERβ offers a promising early target in nascent KM-LUAD tumors with therapeutic intervention possible regardless of sex-specific effects. Acknowledgement: supported by NIH/NCI grant awarded to Seyed Javad Moghaddam (R01 CA225977); Michael J Clowers partly supported by NIH/NCI (F31 CA261121); Annamarie L Thompson supported by CPRIT Research Training Award (RP210028). Citation Format: Michael Joseph Clowers, Annamarie L. Thompson, Carlos Ignacio Rodriguez Reyna, Shanshan Deng, Seyed Javad Moghaddam. Selective deletion of estrogen receptor β in lung epithelium suppresses K-ras mutant lung tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5326.