Abstract A011: Assessing pro-tumorigenicity of the aging microenvironment in a murine ovarian cancer model
Authors: Cummins Katherine A. , Drapkin Ronny 
Published: November 2024

Abstract
Over 70% of high-grade serous ovarian cancer (HGSOC) patients are diagnosed after age 55 and the average patient who succumbs to HGSOC is 70 years old. Despite this, the majority of ovarian cancer studies, and cancer studies generally, utilize young mice that are more representative of human children. This approach overlooks age as a variable, despite its status as a top risk factor for cancer. Our preliminary studies reveal tumor burden and disease severity is significantly higher in aged mice compared to young animals. We have developed an epithelial cell line derived from C57BL/6 oviducts and used CRISPR-Cas9 genome editing to establish tumorigenic lines for syngeneic studies. One line harbors Trp53, Pten, and Brca2 deletions, is tumorigenic, and can be serially passaged in vitro. When injected intraperitoneally (IP) into 8-week and 56-week-old mice, equating to approximately 10- and 45-year-old humans respectively, a stark increase in tumor mass was evident in aged mice. Furthermore, the aged mice succumbed to disease at a faster rate after inoculation than the young group, where all mice succumbed to disease within 1-month of IP injection compared to some young mice surviving up to 3 months after injection. These findings, combined with epidemiologic data, suggest a metastatic driver in the aged microenvironment that facilitates worsened ovarian cancer progression. We are investigating two factors that change with age, (1) a suppressed immune system and (2) age-related changes to adipose tissue, as possible mechanisms driving this difference. Histologic analysis of tumors from each cohort showed decreased cleaved caspase-3 in aged tumors, indicating a reduction in tumor cell killing in older animals. Characterization of the pre-cancerous, tumor-naive microenvironment via flow cytometry and cytokine array have revealed that aged mice microenvironment is highly inflamed and features changes in immune populations and inflammatory states. Meanwhile, total RNA-sequencing of tumors harvested from aged and young mice showed minimal changes, but DEGs point to possible roles of fat transport and metabolism in these aged tumors, indicated by upregulated CD36 and lipoprotein lipase. Follow-up ex vivo experiments had demonstrated increased adhesion and proliferation of the previously described murine cancer cells to fat pads when cultured in vitro. When assessing tumor-naive fat depots, aged adipose tissue is comprised of significantly larger adipocytes and the omentum, a common secondary site of ovarian cancer and fatty organ, was found to have increased phospholipid content in older animals. Both findings point to a change in metabolic function in aged mice. Our preliminary findings indicate an important role of the aged microenvironment in driving enhanced diseases progression in older individuals and identifying the mechanisms behind this phenotype are critical; an improved understanding of how age affects HGSOC progression could enable the development of treatment strategies to prevent cancer cells from establishing in the peritoneum.
Citation Format: Katherine A. Cummins, Ronny Drapkin. Assessing pro-tumorigenicity of the aging microenvironment in a murine ovarian cancer model [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A011.