The Role of Macrophage Polarization-Associated Gene Expression in the Oncological Prognosis of Hepatocellular Carcinoma

Background: The induced repolarization of tumor growth-promoting M2 macrophages into tumor growth-inhibiting M1 macrophages is a matter of intensive research and is expected to lead towards a novel targetable approach in HCC therapy. Methods: Differentially expressed M2 macrophage-related genes between normal and tumor samples with high and low M2 macrophage infiltration in the Gene Expression Omnibus (GEO) and TCGA datasets were identified. A risk score was constructed based on univariate Cox analysis and LASSO-penalized Cox regression analysis. The relationship between the different risk score groups and clinical pathological characteristics as well as immune infiltration characteristics was studied. Subsequently, a nomogram was constructed to predict patients' prognosis. Western blot and RT-qPCR were carried out to validate the results in human HCC samples. Results: Increased M2 macrophage infiltration was associated with a shorter overall survival (OS). Four important M2 macrophage-related genes (SLC22A1, CPS1, SLC10A1, CYP2C9) were discovered to be strongly correlated with OS and M2 macrophage infiltration. A nomogram incorporating the signature and tumor stage was developed for final clinical translation. Conclusions: SLC22A1, CPS1, SLC10A1 and CYP2C9 genes are associated with tumor-promoting M2 macrophage infiltration and might be potential targets for macrophage-related immunotherapy in HCC patients. Further, this four-gene signature is a potential tool for predicting prognosis in these patients.