MARCKS Drives Immunosuppressive Signaling in Tumor-Associated Macrophages to Promote Lung Cancer Progression 2258297

Abstract Introduction Lung cancer is the deadliest pulmonary malignancy, driven in part by immune evasion and limited treatment options. Among key immunoregulatory players, tumor-associated macrophages (TAMs) promote angiogenesis, immunosuppression, and metastasis via M2-like polarization. MARCKS (myristoylated alanine-rich C-kinase substrate), an oncogenic regulator, is highly expressed in both tumor cells and TAMs, with elevated levels linked to cancer progression. However, its role in TAM-mediated immune modulation remains poorly understood. Methods We analyzed single-cell RNA sequencing data from lung cancer patients. TAMs were stratified into MARCKS-proficient (MARCKS+) and -deficient (MARCKS⁻) subsets. Differential expression and pathway enrichment analyses were performed, and CellChat was used to assess intercellular communication. Results MARCKS+ TAMs were enriched for immunosuppressive pathways, including IL-10 family cytokines, efferocytosis, and CD163-associated M2 programs. CCR5-related pathways implicated proliferative and migratory signaling, while suppression of T cell immunity suggested immune evasion. CellChat analysis showed significantly increased communication by MARCKS+ TAMs. Key outgoing ligands included SPP1, CCL, MIF, VEGF, TNF, and TGF-β, whereas incoming signals featured TGF-β, TNF, ITGB2, and SPP1. MARCKS+ TAMs uniquely received TGF-β, a potent M2 inducer, and secreted SPP1, linked to metastasis, therapy resistance, and fibroblast differentiation into cancer-associated fibroblasts. MIF—CD74—CXCR4 signaling further contributed to Treg recruitment and NK cell suppression. Conclusion MARCKS+ TAMs amplify immunosuppressive signaling that enhances macrophage polarization, immune evasion, and tumor-stromal crosstalk. By driving TGF-β- and SPP1-mediated interactions with tumor and immune compartments, MARCKS emerges as a key regulator of TAM-driven immunosuppression and a potential therapeutic target in lung cancer. Funding Source This work was supported by the NIH grant R01HL146802, the UCOP TRDRP grant T32IR5347, and the DoD PRMRP grant W81XWH2110086 (#PR202411). Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)