EGR1 Promotes Proliferation in Prostatic Hyperplasia Epithelial BPH-1 Cells

Early growth response gene 1(EGR1)is a member of a zinc-nger transcription factor family.EGR1 can be induced by several factors and it regulates more than 30 target genes.As an oncogene,EGR1 expression increases with the degree of malignancy in prostate cancer.Compared to the numerous studies of EGR1 in prostate cancer,the research in benign prostatic hyperplasia(BPH) is not enough while the associated mechanisms and functions are still unclear.In this study,we found that EGR1 was highly expressed in both rat and human BPH tissues.EGR1 plays important roles in the BPH progression.We constructed the EGR1 expression vector and the EGR1 stably transfected BPH-1 cell lines.The cell proliferation was promoted by over-expressed EGR1.Furthermore,EGR1 siRNA inhibited BPH-1 cell proliferation.Estrogen plays important roles in BPH progression.In BPH-1 cell lines,estradiol(E2) promoted EGR1 protein nuclear transfer which activated EGR1's transcriptional activity.Insulin-like growth factor 2(IGF2) was up-regulated in EGR1 stably transfected BPH-1 cell lines.Meanwhile,E2 promoted IGF2 expression and the up-regulation could be abolished by knocking down EGR1 which means E2 up-regulates IGF2 via EGR1.The regulation of EGR1 and its target gene may be critical for E2 to exert its influence on BPH progression.This study adds new insights into the function of E2 and EGR1 in BPH.