Objective The current treatment for hepatocellular carcinoma (HCC) to block angiogenesis and immunosuppression provides some benefits only for a subset of patients with HCC, thus optimised therapeutic regimens are unmet needs, which require a thorough understanding of the underlying mechanisms by which tumour cells orchestrate an inflamed tumour microenvironment with significant myeloid cell infiltration. MicroRNA-223 (miR-223) is highly expressed in myeloid cells but its role in regulating tumour microenvironment remains unknown.
Design Wild-type and miR-223 knockout mice were subjected to two mouse models of inflammation-associated HCC induced by injection of diethylnitrosamine (DEN) or orthotopic HCC cell implantation in chronic carbon tetrachloride (CCl4)-treated mice.
Results Genetic deletion of miR-223 markedly exacerbated tumourigenesis in inflammation-associated HCC. Compared with wild-type mice, miR-223 knockout mice had more infiltrated programmed cell death 1 (PD-1+) T cells and programmed cell death ligand 1 (PD-L1+) macrophages after DEN+CCl4 administration. Bioinformatic analyses of RNA sequencing data revealed a strong correlation between miR-223 levels and tumour hypoxia, a condition that is well-documented to regulate PD-1/PD-L1. In vivo and in vitro mechanistic studies demonstrated that miR-223 did not directly target PD-1 and PD-L1 in immune cells rather than indirectly downregulated them by modulating tumour microenvironment via the suppression of hypoxia-inducible factor 1α-driven CD39/CD73-adenosine pathway in HCC. Moreover, gene delivery of miR-223 via adenovirus inhibited angiogenesis and hypoxia-mediated PD-1/PD-L1 activation in both HCC models, thereby hindering HCC progression.
Conclusion The miR-223 plays a critical role in modulating hypoxia-induced tumour immunosuppression and angiogenesis, which may serve as a novel therapeutic target for HCC.
- HEPATOCELLULAR CARCINOMA
- INFLAMMATORY CELLS
- CANCER IMMUNOBIOLOGY
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
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Contributors: YF and YH designed the project and performed in vitro and in vivo experiments. BM, DF, HL, YG, TL, HP, XW performed some experiments, contributed to data analysis, and provided scientific input. YF, YH, and BG wrote the manuscript with contributes from all authors. YH and BG jointly supervised the work. BG is the author responsible for the overall content as the guarantor.
Funding This work was supported by the intramural program of NIAAA, NIH (BG) and the intramural program of the Center for Cancer Research, NCI, NIH (XWW)
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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