EGR2 promotes liver cancer metastasis by enhancing IL-8 expression through transcription regulation of PDK4 in M2 macrophages

Abstract

Liver tumor is a common digestive system tumor, and its development is closely related to complex cytokines, tumor microenvironment and immunoregulatory mechanisms. Tumor-associated macrophages play a great role in a series of liver cancer development by secreting various cytokines and transmitting multiple signals, but how macrophages regulate the various biological behaviors of liver cancer cells at the microscopic level is a challenge we still need to overcome. In this research, we first identified the Early Growth Response 2 (EGR2) gene, which exhibited significant expression in M2 macrophages in comparison to M0 and M1 cell types, utilizing RNA sequencing. Subsequently, we validated this finding through a battery of methodologies, including WB, qRT-PCR, and immunofluorescence assays. We further employed a co-culture model involving MHCC97L and macrophages to investigate the impact of EGR2 downregulation within M2 cells on the in vivo and in vitro metastatic and invasive capabilities of MHCC97L cells. Subsequently, we directed our attention to investigating the impact of EGR2 on the levels of interleukin-8 (IL-8). Through comprehensive analyses including RNA sequencing, CUT-and-Tag, and ChIP techniques, we demonstrated that EGR2 can bind to the promoter region of the Pyruvate Dehydrogenase Kinase 4 (PDK4) gene. Finally, we introduced a virus overexpressing PDK4 and demonstrated that EGR2 could regulate the transcriptional level of PDK4 to affect the expression of IL-8, and ultimately alter the metastatic ability of hepatocellular carcinoma cells. Our study demonstrates that EGR2 may be a valuable target for future intervention in the disease process of hepatocellular carcinoma and refines the mechanism at the microscopic level of Tumor-associated macrophages.

Keywords: IL-8; Liver cancer;EGR2; PDK4; Tumor associated macrophages.