Abstract 2894: Targeting NOS2 and the Tumor Microenvironment in Endometrioid Ovarian Cancer: Implications for Treatment and Survival

Abstract Purpose of the study: The final aim of the study is to disrupt the deleterious effect of the tumor microenvironment by targeting inducible Nitric Oxide Synthase 2 (NOS2). NOS2 has a role in cancer cell proliferation and immune cells inactivation. It is upregulated by cytokines released from the tumor proinflammatory environment and the adipose tissue. By targeting and reverting NOS2 functions, we want to develop a therapeutic modality that inhibits endometrioid ovarian cancer (EOC) progression and reactivates the immune response in the ovarian cancer tumor microenvironment (OC-TME). Experimental procedures: We analyzed ovarian cancer patients’ cohorts using TNMPlot, Kaplan-Meier Plotter and The Human Protein Atlas. We simulated the tumor proinflammatory microenvironment by administering Interferon-gamma (IFN-ϒ, 25 ng/mL), Interleukin 1 Beta (IL1-β, 10 ng/mL), Tumor Necrosis Factor-alpha (TNF-α, 10 ng/mL) on A2780 EOC human cell line. We also administered conditioned media (CM) from breast fat adipose tissue to assess the influence of lipid components on cytokines release. After upregulating NOS2, we tested the efficacy of Cisplatin in combination with L-NMMA, a NOS2 inhibitor, on A2780 cells through proliferation assays using RealTime-Glo™ MT Cell Viability Assay (Promega®). In addition, to assess the immune landscape in ovarian cancer, we developed a syngeneic model administering ID8 cells (murine OC cell line) through intraperitoneal injection (IP) in C57BL/6 mice. Results: The findings indicated higher NOS2 RNA expression levels in tumors than in normal samples according to TNMPlot (p = 6.84e-01). KMPlotter analysis revealed that patients with high NOS2 expression treated with Cisplatin had a significantly shorter survival rate (10.64 months) compared to those with lower NOS2 expression (25 months, p = 0.0088). Patients untreated with Cisplatin and exhibiting high NOS2 expression also showed lower survival rates (11 months) than those with lower NOS2 expression (34 months, p = 0.056). Furthermore, cytokine treatments increased NOS2 protein levels in A2780 cells after 48 hours, and CM similarly elevated NOS2 protein levels. Subsequent administration of Cisplatin and Cisplatin + L-NMMA to cytokine-treated A2780 cells notably reduced cell proliferation by 85% and 89%, respectively. Conclusion: Taken together, our results showed the importance of a proinflammatory environment and adipose tissue in NOS2 upregulation. These findings show a potential correlation between endometriosis, obesity, and endometrioid ovarian cancer. With the development of an in vivo and in vitro model, we can gain a better understanding of the role of NOS2 in immune inactivation as well as in cell proliferation in EOC. Citation Format: Gianmarco Melone, Mailin Li, Ivonne Uzair, Maria Chervo, Karina Ortega, Wei Qian, Jianying Zhou, Liliana Guzman, Sean Hynes, Sharon Glynn, Christoforos Thomas, Polina Matre, Lewis Francis, Jenny Chang. Targeting NOS2 and the tumor microenvironment in endometrioid ovarian cancer: Implications for treatment and survival [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 2894.