Expression of early growth response 2 in hepatocellular carcinoma and its effect on proliferation of HepG2 cells

Abstract

Objective To investigate the expression and biologic function of early growth response 2 (EGR2) in hepatocellular carcinoma (HCC). Methods RNAseqV2 data sets of 50 pairs of HCC tissues (T) and their paired adjacent non-cancerous tissues (N) were downloaded from the cancer genome atlas (TCGA) website to analyze the expression of EGR2. Meanwhile, real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) was performed to compare the expression of EGR2 between HCC samples (T) and their paired adjacent non-cancerous tissues (N) from a same patient. The stable cell lines overexpressing EGR2 were established, and the expression of EGR2 protein was confirmed by Western blotting. The effect of overexpression of EGR2 on HCC cell proliferation was analyzed by MTT assay and colony formation assay. Western blotting and FQ-PCR were employed to analyze the protein and RNA levels of Cyclin D1 in EGR2 overexpressing- and vector control-HCC cells. Results The results from TCGA database analysis showed that the relative mRNA expression of EGR2 (89.95±16.04) in HCC tissues was obviously lower than that (440.59±60.60) in adjacent non-cancerous tissues (P<0.05). The mRNA expression level of EGR2 was down-regulated in primary HCC samples as compared with their paired adjacent non-cancerous tissues. MTT assay showed that ectopic expression of EGR2 decreased the growth of HepG2 cells as compared with vector-control cells (P<0.05). Our data from colony formation assay also showed that the EGR2 over-expressing cells exhibited fewer colonies (86.00±5.51) than control cells (177.00±8.18). Furthermore, over-expression of EGR2 decreased the expression levels of Cyclin D1 in HCC cells. Conclusion EGR2 is down-regulated in HCC. Moreover, EGR2 inhibits the proliferation of HCC cells partly through regulation of Cyclin D1. Key words: Carcinoma, hepatocellular; Early growth response 2; Proliferation; Cyclin D1