Egr1 regulates the coordinated expression of numerous EGF receptor target genes as identified by ChIP on chip

WOS: 000261273100011PubMed ID: 19032775Background: UV irradiation activates the EGF receptor, induces Egr1 expression and promotes apoptosis in a variety of cell types. We examined the hypothesis that Egr1 regulates genes that mediate this process by use of a chip-on-chip protocol in human tumorigenic prostate M12 cells. Results: UV irradiation led to significant binding of 288 gene promoters by Egr1. A major functional subgroup consisted of apoptosis related genes. The largest subgroup of 24 genes; belong to the EGFR-signal transduction pathway. Egr1 promoter binding had a significant impact on gene expression of target genes. Conventional ChIP and qRTPCR were used to validate promoter binding and expression changes. siRNA experiments were used to demonstrate the specific role of Egr1 in gene regulation. UV-stimulation promotes growth arrest and apoptosis of M12 cells and our data clearly show that downstream target of EGFR, namely Egr1, mediates this apoptotic response. Our study also identified numerous previously unknown targets of Egr1. These include FasL, MAX and RRAS2, which may play a role in the apoptotic response/growth arrest. Conclusion: Our results indicate that M12 cells undergo Egr1-dependent apoptotic response upon UV-stimulation and led to the identification of downstream targets of Egr1, which mediate EGFR function.NIHUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [U01 CA114810, R01 CA68822]; Mary Kay Ash Foundation [DAMD17-03-1-0022]; US Department of DefenseUnited States Department of Defense; PCRP [W81XWH-04-1-0029]We are thankful to Nima Aghdam for providing technical support and Veronique Baron for comments on the manuscript. We also thank Xiao-Qin Xia for printing the promoter arrays and Stephen Plymate for the gift of M12 cells. This work was supported in part by grants from the NIH (SPECS program 1 U01 CA114810) and the Mary Kay Ash Foundation to DM. DOD PCRP DAMD17-03-1-0022, NIH grant R01 CA68822 and a prostate cancer foundation grant to MMCC. SA was partially supported by US Department of Defense, PCRP Grant #W81XWH-04-1-0029