Abstract 1537: CD63 acts as a key modulator of tumor progression and innate immune evasion in non-small cell lung cancer

Abstract

Abstract Introduction: Lung cancer is a major reason for cancer-related mortality worldwide, causing more than two million cancer deaths per year. Over the last decade, new therapies have allowed long-term survival for patients even in advanced stages. However, only a minority of patients benefits from these therapies and patients often grow resistant over time. An important mechanism that contributes to cancer growth and the development of therapy resistances is the cross-talk between cancer cells and their tissue microenvironment, in particular fibroblasts and macrophages. In this context, we explored whether the tetraspanin CD63 - which is commonly found on intra- and extracellular membranes - stimulates cancer growth and mediates pro-tumorigenic functions of the tissue microenvironment in NSCLC. Methods: We analyzed patient tissue via immunohistochemistry and in-situ-hybridization. We deleted CD63 in cancer cell lines (A549, H810, LC19) and primary fibroblasts via CRISPR-Cas9. To assess phagocytosis, we used in vitro EdU assays and adaptive transfer models in vivo, and identified changes in cell signaling via mass spectrometry. We used an in vitro phagocytosis assay to determine the effect of CD63 on cancer cell phagocytosis through macrophages and analyzed the expression of M1 and M2-associated surface markers through flow cytometry upon co-culturing PBMC with cancer cells over one week. Results: In patient sections, cancer tissue did not only express more CD63 on the gene expression and protein level but a stronger CD63 expression also correlated with a denser macrophage infiltrate. Looking for pro-tumorigenic functions, deleting CD63 in three cancer cell lines reduced cancer cell growth both in vitro and in an adaptive transfer model in vivo. Additionally, deleting CD63 impaired the pro-tumorigenic focal adhesion signaling in primary fibroblasts. Concerning the interaction between cancer cells and macrophages, deleting CD63 reduced the macrophage-mediated phagocytosis of cancer cells and co-culturing primary monocytes with CD63-deficient lung cancer cells induced the expression of M1-associated surface markers on the PBMC. Conclusion: In conclusion, these results demonstrate that the tetraspanin CD63 drives NSCLC growth by stimulating cancer cell proliferation - in part by interfering with focal adhesion signaling - and facilitating immune evasion by preventing cancer cell phagocytosis through macrophages and inducing an immunosuppressive phenotype in macrophages. Citation Format: Tristan Lerbs, Lu Cui, Cristabelle De Souza, Reinhard Buettner, Gerlinde Wernig. CD63 acts as a key modulator of tumor progression and innate immune evasion in non-small cell lung cancer [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 1537.