Colony-stimulating factor-1-induced AIF1 expression in tumor-associated macrophages enhances the progression of hepatocellular carcinoma

ABSTRACTM2-polarized (alternatively activated) macrophages play an important role in the progression of hepatocellular carcinoma (HCC). Allograft inflammatory factor 1 (AIF1) is overexpressed in M2-polarized macrophages. This study explored the role of AIF1 in tumor-associated macrophages in HCC. Macrophages were stimulated with colony-stimulating factor 1 (CSF1) to characterize the regulatory pathway of AIF1 in macrophages. The chromatin immunoprecipitation and luciferase reporter gene assay were conducted to examine transcription factors associated with AIF1 expression. AIF1 was down or upregulated, and the effects on tumor progression were evaluated by using in vitro and in vivo co-culture systems. A cytokine array was performed to screen the downstream functional components of AIF1. Tumor tissue from 206 patients with HCC were used to explore the clinical significance of AIF1. AIF1 induced a M2-like phenotype of macrophages. By facilitating the binding of c-Jun to the promoter of AIF1, CSF1 secreted f...