Oncogenic KRAS signaling drives evasion of innate immune surveillance in lung adenocarcinoma by activating CD47
Huanhuan Hu, … , Chao Yan, Xi Chen
Huanhuan Hu, … , Chao Yan, Xi Chen
Published November 22, 2022
Citation Information: J Clin Invest. 2023;133(2):e153470. https://doi.org/10.1172/JCI153470.
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Oncogenic KRAS signaling drives evasion of innate immune surveillance in lung adenocarcinoma by activating CD47

Abstract

KRAS is one of the most frequently activated oncogenes in human cancers. Although the role of KRAS mutation in tumorigenesis and tumor maintenance has been extensively studied, the relationship between KRAS and the tumor immune microenvironment is not fully understood. Here, we identified a role of KRAS in driving tumor evasion from innate immune surveillance. In samples of lung adenocarcinoma from patients and Kras-driven genetic mouse models of lung cancer, mutant KRAS activated the expression of cluster of differentiation 47 (CD47), an antiphagocytic signal in cancer cells, leading to decreased phagocytosis of cancer cells by macrophages. Mechanistically, mutant KRAS activated PI3K/STAT3 signaling, which restrained miR-34a expression and relieved the posttranscriptional repression of miR-34a on CD47. In 3 independent cohorts of patients with lung cancer, the KRAS mutation status positively correlated with CD47 expression. Therapeutically, disruption of the KRAS/CD47 signaling axis with KRAS siRNA, the KRASG12C inhibitor AMG 510, or a miR-34a mimic suppressed CD47 expression, enhanced the phagocytic capacity of macrophages, and restored innate immune surveillance. Our results reveal a direct mechanistic link between active KRAS and innate immune evasion and identify CD47 as a major effector underlying the KRAS-mediated immunosuppressive tumor microenvironment.

Authors

Huanhuan Hu, Rongjie Cheng, Yanbo Wang, Xiaojun Wang, Jianzhuang Wu, Yan Kong, Shoubin Zhan, Zhen Zhou, Hongyu Zhu, Ranran Yu, Gaoli Liang, Qingyan Wang, Xiaoju Zhu, Chen-Yu Zhang, Rong Yin, Chao Yan, Xi Chen

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Figure 1

Oncogenic KRAS mutations render lung cancer cells insensitive to macrophage phagocytosis.

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Oncogenic KRAS mutations render lung cancer cells insensitive to macroph...
(A) Tumor cells were isolated from 12 KRASWT and 6 KRASMUT lung adenocarcinoma patients, labeled with the fluorescent dye CFSE, incubated with human peripheral blood monocyte–derived macrophages for 2 hours, stained with F4/80, and analyzed by flow cytometry. Phagocytosis rate was calculated as the percentage of CFSE+F4/80+ cells among CFSE+ cells. Representative FACS results and quantification for all patients are shown. (B) KRASG12C H358 cells were transfected with plasmids expressing KRASWT or KRASG12C or with 3 KRAS siRNAs. After 48 hours, the cells were subjected to a phagocytosis assay similar to that in A. Quantitative analysis (n = 5) is shown. NSCLC, non–small cell lung cancer. (C and D) Macrophage phagocytosis of H358 cells gradually decreased with tumor progression in vivo. An animal model of lung cancer was established by tail-vein injection of EGFP-labeled H358 cells into nude mice. (C) Representative images of H&E-stained lung sections at different time points are shown. Scale bar: 2 mm. (D) Macrophage infiltration into lung tumor tissue was assessed by CD11b (red) and iNOS (purple) staining. Representative images and quantification results (n = 5) are shown. Arrows indicate GFP+iNOS+CD11b+ cells. Scale bar: 50 μm. Original magnification, ×40 (enlarged insets). (E and F) Macrophage phagocytosis of tumor cells gradually decreased with tumor progression in genetic models of lung cancer. KrasLSL-G12D/+ p53fl/fl mice were intratracheally administered adeno-Cre to trigger pulmonary adenocarcinoma formation. Tumor growth was monitored by micro-CT at different time points. (E) Representative 3D reconstructions of mouse lungs. Tumors are shown in red. (F) Macrophage infiltration was assessed by staining for CD11b (red), iNOS (purple), and KRASG12D (green). Representative images and quantification results (n = 5) are shown. Arrows indicate KRASG12D+iNOS+CD11b+ cells. Scale bar: 50 μm. Original magnification, ×40 (enlarged insets). Data are shown as the mean ± SEM. **P < 0.01 and ****P < 0.0001, by unpaired t test (A) or 1-way ANOVA (B, D, and F).