Egr-1 promotes hypoxia-induced autophagy to enhance chemo-resistance of hepatocellular carcinoma cells.

ABSTRACT

Previous studies suggest that early growth response gene-1 (Egr-1) plays an important role in hypoxia-induced drug-resistance. However, the mechanism still remains to be clarified. Herein, we investigated the role of Egr-1 in hypoxia-induced autophagy and its resulted hypoxia-driven chemo-resistance in Hepatocellular Carcinoma (HCC) cells. Our data demonstrated that Egr-1 was overexpressed in HCC tissues and cells and conferred them drug resistance under hypoxia. Mechanistically, Egr-1 transcriptionally regulated hypoxia-induced autophagy by binding to LC3 promoter in HCC cells, which resulted in resistance of HCC cells to chemotherapeutic agents; while dominant negative Egr-1 could inhibit autophagy level, and thus enhanced the sensitivity of HCC cells to chemotherapeutic agents, indicating that hypoxia-induced Egr-1 expression enhanced drug resistance of HCC cells likely through autophagy. Accordingly, it is suggested that a mechanism of hypoxia/Egr-1/autophagy axis might be involved in drug resistance in HCC.