Oncogene database

2118

ETV4

ets variant 4;ETV4;ets variant 4

ETS translocation variant 4|EWS protein/E1A enhancer binding protein chimera|adenovirus E1A enhancer-binding protein|ets variant gene 4 (E1A enhancer-binding protein, E1AF)|polyomavirus enhancer activator 3 homolog

17q21

protein-coding

The PEA3 motif, first recognized in the polyomavirus enhancer, is an oncogene, serum growth factor, and phorbol ester-responsive element. An activity capable of binding to this sequence, termed PEA3 (polyomavirus enhancer activator 3), was identified in mouse 3T6 cell nuclear extracts. We have cloned cDNAs that encode PEA3 from a mouse FM3A cell cDNA library. A continuous open reading frame in the longest cDNA predicts a 555-amino-acid protein with a calculated molecular mass of 61 kD. Recombinant PEA3 binds to DNA with the same sequence specificity as that endogenous to FM3A cells and activates transcription through the PEA3 motif in HeLa cells. Deletion mapping of the protein revealed that the DNA-binding domain is located within a stretch of 102 amino acids near the carboxyl terminus. This region shares extensive sequence similarity with the ETS domain, a conserved protein sequence common to ALL ets gene family members. PEA3 is encoded by a 2.4-kb mRNA that is expressed to differing extents in fibroblastic and epithelial cell lines but not in hematopoietic cell lines. In the mouse, PEA3 expression is highly restricted; only the epididymis and the brain contain readily detectable amounts of its mRNA. Interestingly, the amount of PEA3 mRNA is down-regulated during retinoic acid-induced differentiation of mouse embryonic cell lines. These findings suggest that PEA3 plays a regulatory role during mouse embryogenesis.

Matrix metalloproteinase (MMP) is closely involved in the degradation of extracellular matrix and confers invasive and metastatic potential to malignant tumors. MMP-2 is a type-IV collagenase secreted as a proenzyme that is activated on the surface of the tumor cell by membrane-type 1-MMP (MT1-MMP). MT1-MMP plays a critical role during tumor progression and metastasis. We investigated the expression levels of E1AF and MT1-MMP in malignant melanoma cell lines and specimens from patients in order to clarify the mechanisms responsible for the invasion and metastasis of malignant melanoma. High levels of E1AF and MT1-MMP mRNA expression were observed in melanoma cells by Northern blotting and real-time PCR. The expression level was highly correlated with an invasive potential determined by an in vitro invasion assay. The down-regulation of MT1-MMP was identified when E1AF was knocked down by RNA interference. These results suggest that E1AF plays a crucial role in the invasion and metastasis of malignant melanoma through up-regulating the MT1-MMP expression.

Five years of tamoxifen reduces breast cancer risk by nearly 50% but is associated with significant side effects and toxicities. A better understanding of the direct and indirect effects of tamoxifen in benign breast tissue could elucidate new mechanisms of breast carcinogenesis, suggest novel chemoprevention targets, and provide relevant early response biomarkers for phase II prevention trials. Seventy-three women at increased risk for breast cancer were randomized to tamoxifen (20 mg daily) or placebo for 3 months. Blood and breast tissue samples were collected at baseline and posttreatment. Sixty-nine women completed ALL study activities (37 tamoxifen and 32 placebo). The selected biomarkers focused on estradiol and IGFs in the blood; DNA methylation and cytology in random periareolar fine-needle aspirates; and tissue morphometry, proliferation, apoptosis, and gene expression (microarray and reverse transcriptase PCR) in the tissue core samples. Tamoxifen downregulated Ets oncogene transcription factor family members ETV4 and ETV5 and reduced breast epithelial cell proliferation independent of CYP2D6 genotypes or effects on estradiol, ESR1, or IGFs. Reduction in proliferation was correlated with downregulation of ETV4 and DNAJC12. Tamoxifen reduced the expression of ETV4- and ETV5-regulated genes implicated in epithelial-stromal interaction and tissue remodeling. Three months of tamoxifen did not affect breast tissue composition, cytologic atypia, preneoplasia, or apoptosis. A plausible mechanism for the chemopreventive effects of tamoxifen is restriction of lobular expansion into stroma through downregulation of ETV4 and ETV5. The human equivalent of murine multipotential progenitor cap cells of terminal end buds may be the primary target.

The discovery of translocations that involve one of the genes of the ETS family (ERG, ETV1, ETV4 and ETV5) has been a major advance in understanding the molecular basis of prostate cancer (PC). Each one of these translocations results in deregulated expression of one of the ETS proteins. Here, we focus on the mechanism whereby overexpression of the ETV4 gene mediates oncogenesis in the prostate. By siRNA technology, we show that ETV4 inhibition in the PC3 cancer cell line reduces not only cell mobility and anchorage-independent growth, but also cell proliferation, cell cycle progression and tumor growth in a xenograft model. Conversely, ETV4 overexpression in the nonmalignant human prostate cell line (RWPE) increases anchorage-independent growth, cell mobility and cell proliferation, which is probably mediated by downregulation of p21, producing accelerated progression through the cell cycle. ETV4 overexpression is associated with changes in the pattern of E-cadherin and N-cadherin expression; the cells also become spindle-shaped, and these changes are characteristic of the so-called epithelial to mesenchymal transition (EMT). In RWPE cells overexpressing ETV4 EMT results from a marked increase in EMT-specific transcription factors such as TWIST1, SLUG1, ZEB1 and ZEB2. Thus, whereas ETV4 shares with the other ETS proteins (ERG, ETV5 and ETV1) a major role in invasiveness and cell migration, it emerges as unique in that it increases at the same time also the rate of proliferation of PC cells. Considering the wide spectrum in the clinical course of patients with PC, it may be highly relevant that ETV4 is capable of inducing most and perhaps ALL of the features that make a tumor aggressive.

The cDNA encoding adenovirus E1A enhancer-binding protein E1A-F was isolated by screening a HeLa cell lambda gt11 expression library for E1A-F site-specific DNA binding. One cDNA clone produced recombinant E1A-F protein with the same DNA binding specificity as that endogenous to HeLa cells. Sequence analysis of the cDNA showed homology with the ETS-domain, a region required for sequence-specific DNA binding and common to ALL ets oncogene members. Analysis of the longest cDNA revealed about a 94% identity in amino acids between human E1A-F and mouse PEA3 (polyomavirus enhancer activator 3), a recently characterized ets oncogene member. E1A-F was encoded by a 2.5kb mRNA in HeLa cells, which was found to increase during the early period of adenovirus infection. In contrast, ets-2 mRNA was significantly reduced in infected HeLa cells. The results indicate that E1A enhancer binding protein E1A-F is a member of the ets oncogene family and is probably a human homologue of mouse PEA3.

This report presents data that suggest that the tissue-restricted polyoma enhancer activator protein (PEA3) of the Ets oncogene family of DNA-binding proteins is a putative modulator of the epididymis-specific glutathione peroxidase 5 gene gpx5. Northern and polymerase chain reactions on reverse-transcribed epididymal RNAs were used to show that the PEA3 factor is spatially and temporally expressed within the mouse epididymis in a manner consistent with gpx5 characteristics of expression. Then, using contransfection experiments carried out in heterologous tissue-culture cells with various deletions of the gpx5 promoter driving a CAT reporter gene, we have shown that the transcriptional activity of the gpx5 promoter is modulated by the presence of the PEA3 protein. Subsequently, we have shown using gel-shift assays that DNA sequences located within the 5 flanking region of the gpx5 gene have the ability to bind specifically to the PEA3 protein. Finally, using Northern assays we present data that suggest that PEA3 mRNA accumulation in the mouse caput epididymidis is controlled by androgens and testicular factors. Altogether, these results strongly suggest that the PEA3 factor might participate in the transcriptional control of the murine epididymis caput-specific gpx5 gene.