Abstract 1358: Single nuclei sequencing reveals altered gene expression and immune signaling in tumors from obese endometrioid adenocarcinoma patients

Abstract Over the past several decades, the incidence of endometrial cancer has risen. This trend is largely attributed to the increased prevalence of obesity and is especially pronounced in endometrioid adenocarcinoma, the most common histologic subtype of uterine cancer. These cancers are regarded as hormonally driven tumors and are linked to obesity through the production of aromatase, an enzyme that converts androgens into estrogen, in peripheral adipose tissue. Though the association between obesity and endometrial cancer is well-established, whether excess adiposity has an effect outside of this mechanism—and exactly how that hormonal imbalance perturbs the tumor and its microenvironment—is not well understood. Thus, to examine the impact of obesity on the cellular diversity and transcriptome of endometrial cancer and its microenvironment, we integrated single-nuclei RNA-seq data from seven obese and six normal-weight patients' endometrioid tumor samples. Through evaluation of marker gene expression patterns, we annotated seven clusters distributed across normal-weight and obese tumor samples. To pinpoint major changes in biological networks in tumor cells from obese and normal-weight patients, we performed single-nucleus pathway gene ontology analysis on differentially expressed genes. We then independently conducted Weighted Gene Correlation Network Analysis on the cancer cells in our normal and obese groups and compared the resultant networks. Our analysis revealed a large number of differentially expressed genes in both our cancer cluster and macrophage subcluster. In the cancer cluster, most of the differentially regulated genes were associated with estrogen signaling and epithelial-mesenchymal transition. The results from our Weighted Gene Correlation Network Analysis revealed large differences in the networks containing estrogen receptors. To model obesity in vitro, we treated 12Z endometrioid cells and KLE endometrioid adenocarcinoma cells with adipose-conditioned media derived from human omental tissue, which revealed large differences in cellular morphology. In our macrophage subcluster, our gene ontology analysis yielded differences in macrophage organization and function. Few tumor-infiltrating lymphocytes were detected, which is consistent with the classification of most endometrial cancers as immunologically “cold.” Overall, our results show that obesity influences gene expression in the endometrioid adenocarcinoma tumor microenvironment and tumor itself. Furthermore, the outcomes of our experiments provide additional insights into the impact of obesity on endometrioid adenocarcinoma outside of its role in estrogen signaling. Citation Format: Jessica L. Long, Sophia Agrusa, Swornalata Pukhrambam, Areebah Qazi, Katherine Gurdziel, Julie Boerner, Michael Wilson. Single nuclei sequencing reveals altered gene expression and immune signaling in tumors from obese endometrioid adenocarcinoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1358.