Abstract 4287: Ets-related gene (Erg) expression in developing and adult mouse tissues

Abstract

Abstract Oncogenic activation of the ETS Related Gene (ERG) in human neoplasms was originally identified in subsets of Ewing sarcomas, myeloid leukemias and, recently, in the majority of prostate cancers. Expression of human ERG protein and consequently its functions in normal and disease states needs to be better understood in light of its suggested role in cell differentiation and proliferation. In this study, we analyzed temporal and spatial expression of the Erg protein by immunohistochemical analysis during mouse embryonic and adult organogenesis using a highly specific ERG monoclonal antibody (CPDR ERG-MAb) developed by our group. Initially, we evaluated the specificity of three recently available ERG monoclonal antibodies (Epitomics EPR 3864 and EPR 3863, and CPDR ERG-MAb) using ERG expressing MOLT4, KG1, COLO 320, VCaP tumor cell lines and LNCaP, MCF7, Jurkat cell lines that do not express ERG. Unlike, rabbit monoclonal antibodies to ERG obtained from Epitomics, the ERG MAb did not show cross reactivity to FLI-1 or to the other ETS related proteins. Our comprehensive evaluation of mouse tissues established a widespread immunolocalization of Erg protein in endothelial cells and restricted expression in precartilage and hematopoietic tissues. Intriguingly, Erg is not expressed in any epithelial tissue including prostate epithelium, a common site of tumors with ERG rearrangements and unscheduled ERG expression. Further, use of two different monoclonal antibodies revealed that infiltrating lymphocytes that are occasionally seen in the prostate environment were positive for Fli-1, did not exhibit any Erg expression. These findings will further aid in investigations of Erg functions in normal and disease conditions. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4287. doi:10.1158/1538-7445.AM2011-4287