Abstract 1366: HMGB1 localization and its effect on the immune response in the lung tumor microenvironment

Abstract

Abstract Lung adenocarcinoma is the leading cause of cancer mortality. High Mobility Group Box 1 (HMGB1) is a master regulator of innate immunity that is elevated in lung cancer tissues. Furthermore, HMGB1 has been previously demonstrated to suppress functional anti-tumor immune responses in this context. However, beyond demonstrating that HMGB1 is elevated and modulates inflammation, studies to date have not comprehensively investigated the influence of HMGB1 on the immune response to lung cancer. HMGB1 contributes to PD-L1 expression in melanoma and promotes secretion of inhibitory cytokines TGF-α and IL-10, which have roles in the differentiation of regulatory T cells. Therefore, HMGB1 sits atop an immunomodulatory signaling cascade in the tumor microenvironment. While treatment of lung cancers with immune checkpoint inhibitors (ICI) (anti-PD-1/PD-L1) has had success, there are limitations. One major limitation is the failure of patients with advanced or refractory disease to generate a strong anti-tumor immune response. Recently, we have identified HMGB1 as a protein that is functionally dependent on monounsaturated fatty acid (MUFA) availability. Utilizing a combination of molecular assays and 3-dimensional cultures, we now show that HMGB1 is sequestered intracellularly, rather than being secreted extracellularly in a MUFA-dependent fashion. We hypothesized that MUFAs promote an anti-tumor immune response via modulating HMGB1 release from cancer cells. Thus, by restricting extracellular HMGB1 levels, HMGB1-responsive proinflammatory/tumor signaling pathways (e.g., NF-kB) are suppressed. Taken together, these observations suggest a novel approach to decreasing maladaptive immune and inflammatory signaling from innate immune cells. Exploiting the MUFA/HMGB1 signaling axis could be a novel approach to improve the efficacy of therapies in populations that are not currently benefiting from current strategies for eliminating tumors. Citation Format: Kisa Jafri, Nicole M. Andre, Glenn E. Simmons. HMGB1 localization and its effect on the immune response in the lung tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1366.