Suppressing miR-21 activity in tumor-associated macrophages promotes an antitumor immune response
Mahnaz Sahraei, … , Carlos Fernández-Hernando, Yajaira Suárez
Mahnaz Sahraei, … , Carlos Fernández-Hernando, Yajaira Suárez
Published November 11, 2019
Citation Information: J Clin Invest. 2019;129(12):5518-5536. https://doi.org/10.1172/JCI127125.
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Research Article Angiogenesis Immunology

Suppressing miR-21 activity in tumor-associated macrophages promotes an antitumor immune response

Abstract

microRNA-21 (miR-21) is the most commonly upregulated miRNA in solid tumors. This cancer-associated microRNA (oncomiR) regulates various downstream effectors associated with tumor pathogenesis during all stages of carcinogenesis. In this study, we analyzed the function of miR-21 in noncancer cells of the tumor microenvironment to further evaluate its contribution to tumor progression. We report that the expression of miR-21 in cells of the tumor immune infiltrate, and in particular in macrophages, was responsible for promoting tumor growth. Absence of miR-21 expression in tumor- associated macrophages (TAMs), caused a global rewiring of their transcriptional regulatory network that was skewed toward a proinflammatory angiostatic phenotype. This promoted an antitumoral immune response characterized by a macrophage-mediated improvement of cytotoxic T-cell responses through the induction of cytokines and chemokines, including IL-12 and C-X-C motif chemokine 10. These effects translated to a reduction in tumor neovascularization and an induction of tumor cell death that led to decreased tumor growth. Additionally, using the carrier peptide pH (low) insertion peptide, we were able to target miR-21 in TAMs, which decreased tumor growth even under conditions where miR-21 expression was deficient in cancer cells. Consequently, miR-21 inhibition in TAMs induced an angiostatic and immunostimulatory activation with potential therapeutic implications.

Authors

Mahnaz Sahraei, Balkrishna Chaube, Yuting Liu, Jonathan Sun, Alanna Kaplan, Nathan L. Price, Wen Ding, Stanley Oyaghire, Rolando García-Milian, Sameet Mehta, Yana K. Reshetnyak, Raman Bahal, Paolo Fiorina, Peter M. Glazer, David L. Rimm, Carlos Fernández-Hernando, Yajaira Suárez

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Figure 7

miR-21 deletion in TAMs leads to improved immune response to tumors via increased IL-12.

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miR-21 deletion in TAMs leads to improved immune response to tumors via ...
Flow cytometry analysis (A) Left: % of TAMs expressing IL-12 in s.c. LLC tumors of WT or miR-21–/– mice. Right: IL-12 levels (MFI) (n = 4). (B) Left: % of TAMs expressing TNF. Right: TNF levels. (C and D) IL-12 and TNF (as in A and B) of s.c. LLC tumors of WT mice transplanted with WT or miR-21–/– BM, (n = 6). (E) % of TAMs expressing CD40 (left) or CD86 (right), (n = 6). (F) Left: Representative plots of GZMB in CD8+ TILs of s.c. LLC tumors of WT or miR-21–/– mice. Middle: % of CD8+ TILs expressing GZMB. Right: GZMB levels (n = 3). (G) % of CD8+ TILs expressing GZMB of s.c. LLC tumors of WT mice transplanted with WT or miR-21–/– BM (n = 6). (H) Left: Representative plots of extracellular CD107a levels in CD8+ TILs of s.c. LLC tumors of WT and miR-21–/– mice. Right: % of CD8+ TILs expressing extracellular CD107a (n = 3). (I) % of CD8+ TILs expressing extracellular CD107a in s.c. LLC tumors of WT mice transplanted with WT or miR-21–/– BM (n = 6). (J) Alive LLCs, cultured for 12 hours with CD8+ TILs from LLC tumors of WT or miR-21–/– mice at indicated effector:target ratios (n = 4). (K) % of annexin V+ LLCs, cultured (12 hours) with CD8+ TILs from LLC tumors of WT or miR-21–/– mice (n = 4). (L) GZMB expression by CD8+ splenocyte T cells activated with plate-bound anti–CD3-Ab and incubated with conditioned media from cultured WT or miR-21–/– TAMs plus neutralizing anti–IL-12 or IgG Ab (n = 4). Results are mean ± SEM. *P < 0.05. (A–I and K) Mann-Whitney U test. (J and L) Two-way ANOVA with Bonferroni correction. (A, B, F, and H). Representative experiments out of 3 or (C–E, G, I, and J–L) out of 2 with similar results.