Ecotopic viral integration site 1 (EVI1) regulates multiple cellular processes important for cancer and is a synergistic partner for FOS protein in invasive tumors

Abstract

Ecotropic viral integration site 1 (EVI1) is an oncogenic dual domain zinc finger transcription factor that plays an essential role in the regulation of hematopoietic stem cell renewal, and its overexpression in myeloid leukemia and epithelial cancers is associated with poor patient survival. Despite the discovery of EVI1 in 1988 and its emerging role as a dominant oncogene in various types of cancer, few EVI1 target genes are known. This lack of knowledge has precluded a clear understanding of exactly how EVI1 contributes to cancer. Using a combination of ChIP-Seq and microarray studies in human ovarian carcinoma cells, we show that the two zinc finger domains of EVI1 bind to DNA independently and regulate different sets of target genes. Strikingly, an enriched fraction of EVI1 target genes are cancer genes or genes associated with cancer. We also show that more than 25% of EVI1-occupied genes contain linked EVI1 and activator protein (AP)1 DNA binding sites, and this finding provides evidence for a synergistic cooperative interaction between EVI1 and the AP1 family member FOS in the regulation of cell adhesion, proliferation, and colony formation. An increased number of dual EVI1/AP1 target genes are also differentially regulated in late-stage ovarian carcinomas, further confirming the importance of the functional cooperation between EVI1 and FOS. Collectively, our data indicate that EVI1 is a multipurpose transcription factor that synergizes with FOS in invasive tumors. E cotropic viral integration site 1 (EVI1) is a zinc finger (ZNF) transcription factor (TF), and its overexpression in myeloid leukemia (1-3) and epithelial cancers (1, 2, 4-9) has been extensively studied and correlated with adverse patient outcome (7, 10, 11). EVI1 also controls several aspects of embryonic development, including hematopoiesis, angiogenesis, and heart and neural development (12). Three major alternative splice forms of the MDS1 and EVI1 complex locus (MECOM) locus have been identified, including EVI1, EVI1Δ324, and MDS1-EVI1. The PRDI-BF1 and RIZ homology domain containing Myelodysplastic syndrome (MDS)1-EVI1 isoform acts as a tumor suppressor gene, whereas the shorter isoforms, EVI1 and EVI1Δ324, that lack this domain display oncogenic functions (13). The most oncogenic isoform, EVI1, encodes a 1,051-aa protein containing two DNA binding ZNF domains of seven and three motifs. The N-terminal ZNF domain binds to a GATA-like consensus motif (14), whereas the distal ZNF domain binds to an v-ets erythroblastosis virus E26 oncogene homolog (ETS)-like motif (15). EVI1Δ324 lacks ZNFs motifs 6 and 7, which prevents its binding to GATA-like sites.Despite its discovery in 1988 (16, 17), very few EVI1 target genes have been identified, and most of these loci are known to be bound by EVI1 . This lack of knowledge regarding the genes transcriptionally regulated by EVI1 has precluded a complete understanding of EVI1's role in development and cancer. In general, these biological processes are triggered by gene expression changes coordinate...

The Prdm family: expanding roles in stem cells and development

“…These studies reveal binding at many sites across the genome, and a handful of targets has been validated (Bard-Chapeau et al, 2012;Chia et al, 2010;Doody et al, 2011;Ma et al, 2011;von Hofsten et al, 2008). It has also become clear that the same Prdm factor regulates divergent sets of targets in different cell types.…”

“…Prdm3-bound ETS-like sites lie close to transcriptional start sites (TSS), whereas the Prdm3-bound GATA-like motifs tend to be localized further from TSS. Interestingly, Prdm3 binds to either of these motifs, but not to both motifs at the same promoter at the same time (Bard-Chapeau et al, 2012). Hence, binding site selection (and at least in the case of Prdm3 competition between different binding sites) represents one mechanism for context-dependent control of Prdm factor activity.…”

“…As each of these factors is able to bind Prdm3 directly, binding partner selection may also control context-dependent activity. Notably, the Ap1 transcription factor commonly partners the proto-oncogene Fos, and knockdown of Prdm3 weakens Fos occupancy at Ap1 sites found in close proximity to the Prdm3-binding site, suggesting a regulatory interaction between these two factors (Bard-Chapeau et al, 2012).…”

SOX9 modulates the expression of key transcription factors required for heart valve development

“…Similarly, SOX9 might activate SOX4 in the heart to help coregulate valve-specific genes. Motif analysis revealed EVI1 ( protein product derived from Mecom) as another potential cofactor for SOX9 and comparison of EVI1 peaks in cancer cells (Bard-Chapeau et al, 2012) with SOX9 AVC peaks identified hundreds of overlapping target genes (P.A.H., V.C.G. and R.C., unpublished).…”

Integrated Analyses of Genome-Wide DNA Occupancy and Expression Profiling Identify Key Genes and Pathways Involved in Cellular Transformation by a Marek's Disease Virus Oncoprotein, Meq

“…However, signaling pathways specific to genes with each motif suggest distinct binding motif-dependent signatures in gene regulatory networks. In other transcription factors like ectopic viral integration site 1 (EVI1) and PAX6, two DNA binding domains are associated with distinct motifs and regulate different sets of target genes involved in cellular transformation and development, respectively (31,32). It would be interesting to further assess if the heterodimers and homodimers of Meq regulate distinct subsets of genes using modified constructs of Meq as utilized in some previous studies (30,33,34).…”