Hypoxic lung cancer cell-derived exosomal miR-21 mediates macrophage M2 polarization and promotes cancer cell proliferation through targeting IRF1

Abstract

Background Hypoxia is the hallmark of the tumor microenvironment (TME) and plays a critical role during the progress of tumor development. A variety of microRNAs (miRNAs) transmitted by tumor-derived exosomes were involved in intercellular communication. We aimed to elucidate the precise mechanism by which tumor cell-derived exosomes promote lung cancer development by affecting macrophage polarization under hypoxic conditions. Methods CD163 signal in tumor tissue from lung cancer patients was detected by immunohistochemical (IHC). The M2 polarization-related markers were assessed by flow cytometry and western blot. Exosomes were isolated from normoxic and hypoxic lung cancer cell culture and characterized by transmission electron microscope (TEM), dynamic light scattering (DLS), and western blot. RNA sequencing was performed to show the abnormally expressed miRNAs in exosomes from normoxic and hypoxic lung cancer cell culture. In addition, CCK-8 and clone formation assays were used to assess cell proliferation. Dual luciferase reporter assay was used to evaluate the relationship between miR-21 and IRF1. For in vivo experiment, the male nude mice were injected with H1299 cells with exosomes and miR-21 mimic treatment. Results Firstly, we found a strong CD163 signal in tumor tissue from lung cancer patients by IHC. Subsequently, we co-cultured lung cancer cell line H1299 with M0 macrophage THP-1 and found that H1299 in a hypoxic environment promoted THP-1 M2 polarization. PKH67 fluorescence staining experiments confirmed that exosomes of H1299 origin were able to enter THP-1 and induced M2 polarization. RNA sequencing of exosomes showed that miR-21 level was significantly higher in the hypoxic culture group compared to the normoxic group. Subsequent cellular assays showed that miR-21 inhibited the expression of IRF1 by targeting it. In addition, the overexpression of IRF1 reversed the role of miR-21 on macrophage M2 polarization. Finally, we have confirmed through animal experiments that either hypoxic environment or high miR-21 level promoted tumor progression. Conclusions High miR-21 level in hypoxic environments promoted macrophage M2 polarization and induced lung cancer progression through targeting IRF1.

Tumor cell-derived exosomal microRNA-146a promotes non-small cell lung cancer cell invasion and proliferation by inhibiting M1 macrophage polarization

“…Although the findings in this study was not validated by animal model, this is the first study investigating the role of exosomal miR-146a in regulating TAM polarization in lung cancer. Some studies have revealed that NSCLC cells can release In addition, NSCLC cells can also promote M2 macrophage polarization by enhancing the oxygen consumption rate of macrophages (30) or releasing circRNA (31), lncRNA (32) or miRNA (18,33,34) in it. A previous study indicated that the exosomes released by hypoxic NSCLC cells have a higher level of miR-21, which can be transmitted to macrophages and induce M2 macrophage polarization by targeting interferon regulatory factor 1 (IRF1) (33).…”

“…Some studies have revealed that NSCLC cells can release In addition, NSCLC cells can also promote M2 macrophage polarization by enhancing the oxygen consumption rate of macrophages (30) or releasing circRNA (31), lncRNA (32) or miRNA (18,33,34) in it. A previous study indicated that the exosomes released by hypoxic NSCLC cells have a higher level of miR-21, which can be transmitted to macrophages and induce M2 macrophage polarization by targeting interferon regulatory factor 1 (IRF1) (33). Another study shows that NSCLC cells released exosomal miR-181b to promote M2 polarization and suppress M1 polarization (34).…”

“…For example, under hypoxic conditions, NSCLC cell-derived exosomes could enhance M2 macrophage polarization and NSCLC progression by regulating the PKM2/AMPK pathway ( 29 ). In addition, NSCLC cells can also promote M2 macrophage polarization by enhancing the oxygen consumption rate of macrophages ( 30 ) or releasing circRNA ( 31 ), lncRNA ( 32 ) or miRNA ( 18 , 33 , 34 ) in it. A previous study indicated that the exosomes released by hypoxic NSCLC cells have a higher level of miR-21, which can be transmitted to macrophages and induce M2 macrophage polarization by targeting interferon regulatory factor 1 (IRF1) ( 33 ).…”

Exosomal Non-Coding RNAs: Novel Regulators of Macrophage-Linked Intercellular Communication in Lung Cancer and Inflammatory Lung Diseases

“…Interferon-regulatory factor 1 (IRF1) is a downstream target of miR-21. Under hypoxia, lung cancer cell exosomal miR-21 restricts IRF1 expression, which stimulates M2 macrophage polarization and ultimately contributes to lung cancer cell proliferation [ 65 ]. miR-101 is down-regulated in blood samples collected from lung cancer patients who had high levels of hypoxia-inducible factor 1α (HIF1α).…”

The Potential Use of Exosomes in Anti-Cancer Effect Induced by Polarized Macrophages

“…Under the condition, hypoxic lung cancer cells were found to enhance the secretion of exosomes containing miR-21, which induces macrophage polarization toward the M2 phenotype by binding the 3′UTR of interferon-regulatory factor 1 (IRF1) followed by the downregulated expression of IRF1 in macrophages. This skewed macrophage polarization caused lung cancer proliferation [ 96 ]. Circular RNAs (circRNAs) and LncRNAs have been reported to be involved in tumor progression.…”