The PEA3 group of ETS-related transcription factors. Role in breast cancer metastasis

CIC-DUX4 Sarcoma Involving the Skull Base: A Rare Presentation and Review of the Literature

Background  CIC-DUX4 sarcoma is a rare, aggressive tumor that is difficult to diagnose. Although it is closely related to Ewing's sarcoma, each is a distinct pathologic entity and both have been previously reported in the skin, lymph nodes, and viscera. We report the first description of CIC-DUX4 involving the posterior cranial fossa and review the distinctive symptomatology, morphology, immunoprofile, and genetic signature that differentiate this rare tumor. Case Report  A 32-year-old man presented with an enlarging right lateral neck mass, progressive hoarseness, and orofacial pain. Biopsy revealed a high-grade undifferentiated malignant neoplasm. Imaging demonstrated an 8-cm mass in the right neck extending to the skull base and abutting the carotid sheath, in addition to pulmonary nodules and pelvic lymphadenopathy. Despite initial response to chemotherapy, he experienced disease progression and underwent surgical resection, radical neck dissection, and brachytherapy. Definitive pathologic diagnosis was achieved with next-generation sequencing. Within weeks of treatment, he developed symptoms reflecting progression of disease involving the neck, posterior cranial fossa, and lung. Adjuvant chemotherapy was planned, but the patient succumbed to his disease prior to initiation of further therapy. Conclusion  CIC-DUX4 sarcomas are uncommon and can progress rapidly. Diagnosis requires either fluorescence in situ hybridization or next-generation sequencing. Due to its rarity, there is no standard-of-care treatment for this tumor and further investigations are needed to understand disease behavior and develop targeted therapeutic modalities.

Identification and characterization of novel ETV4 splice variants in prostate cancer

ETV4, one of ETS proteins overexpressed in prostate cancer, promotes migration, invasion, and proliferation in prostate cells. This study identifies a series of previously unknown ETV4 alternatively spliced transcripts in human prostate cell lines. Their expression has been validated using several unbiased techniques, including Nanopore sequencing. Most of these transcripts originate from an in-frame exon skipping and, thus, are expected to be translated into ETV4 protein isoforms. Functional analysis of the most abundant among these isoforms shows that they still bear an activity, namely a reduced ability to promote proliferation and a residual ability to regulate the transcription of ETV4 target genes. Alternatively spliced genes are common in cancer cells: an analysis of the TCGA dataset confirms the abundance of these novel ETV4 transcripts in prostate tumors, in contrast to peritumoral tissues. Since none of their translated isoforms have acquired a higher oncogenic potential, such abundance is likely to reflect the tumor deranged splicing machinery. However, it is also possible that their interaction with the canonical variants may contribute to the biology and the clinics of prostate cancer. Further investigations are needed to elucidate the biological role of these ETV4 transcripts and of their putative isoforms.

A critical ETV4/Twist1/Vimentin axis in Ha-RAS-induced aggressive breast cancer

RAS oncogenes are major drivers of diverse types of cancer. However, they are largely not druggable, and therefore targeting critical downstream pathways and dependencies is an attractive approach. We have isolated a tumorigenic cell line (FE1.2), which exhibits mesenchymal characteristics, after inoculating Ha-Ras-expressing retrovirus into mammary glands of rats, and subsequently isolated a non-aggressive revertant cell line (FC5). This revertant has lost the rat Ha-Ras driver and showed a more epithelial morphology, slower proliferation in culture, and reduced tumorigenicity in vivo. Re-expression of human Ha-RAS in these cells (FC5-RAS) reinduced mesenchymal morphology, higher proliferation rate, and tumorigenicity that was still significantly milder than parental FE1.2 cells. RNA-seq analysis of FC5-RAS vs FC5-Vector cells identified multiple genes whose expressions were regulated by Ha-RAS. This analysis also identified many genes including those controlling cell growth whose expression was altered by loss of HA-Ras in FC5 cells but remained unchanged upon reintroduction of Ha-RAS. These results suggest that targeting the Ha-Ras driver oncogene induces partial tumor regression, but it still denotes strong efficacy for cancer therapy. Among the RAS-responsive genes, we identified Twist1 as a critical mediator of epithelial-to-mesenchymal transition through the direct transcriptional regulation of vimentin. Mechanistically, we show that Twist1 is induced by the ETS gene, ETV4, downstream of Ha-RAS, and that inhibition of ETV4 suppressed the growth of breast cancer cells driven by the Ha-RAS pathway. Targeting the ETV4/Twist1/Vimentin axis may therefore offer a therapeutic modality for breast tumors driven by the Ha-RAS pathway.

Contribution of Stemness-linked Transcription Regulators to the Progression of Breast Cancer

Although there are currently several factors that allow measuring the risk of having breast cancer or predicting its progression, the underlying causes of this malignancy have remained unknown. Several molecular studies have described some mechanisms involved in the progress of breast cancer. These have helped in identifying new targets with therapeutic potential. However, despite the therapeutic strategies implemented from the advances achieved in breast cancer research, a large percentage of patients with breast cancer die due to the spread of malignant cells to other tissues or organs, such as bones and lungs. Therefore, determining the processes that promote the migration of malignant cells remains one of the greatest challenges for oncological research. Several research groups have reported evidence on how the dedifferentiation of tumor cells leads to the acquisition of stemness characteristics, such as invasion, metastasis, the capability to evade the immunological response, and resistance to several cytotoxic drugs. These phenotypic changes have been associated with a complex reprogramming of gene expression in tumor cells during the Epithelial-Mesenchymal Transition (EMT). Considering the determining role that the transcriptional regulation plays in the expression of the specific characteristics and attributes of breast cancer during ETM, in the present work, we reviewed and analyzed several transcriptional mechanisms that support the mesenchymal phenotype. In the same way, we established the importance of transcription factors with a therapeutic perspective in the progress of breast cancer.

Bioinformatics screening of ETV4 transcription factor oncogenes and identifying small-molecular anticancer drugs

This bioinformatics study aimed to identify ETV4 transcription factor oncogenes and outline anticancer drugs for these genes. First, we collected known 61 ETV4 cancer targets that were framed as two classes of queries to screen against the multiomics resources in GeneMANIA. This method accessed and added functionally similar 20 genes to each set. These data were interpreted by hub genes, network clustering, gene ontology, and pathway analyses, and the results confirmed that all resultant genes were cancer promoters. The ETS-binding motifs were identified from the promoter regions of these genes. Thus, 23 ETV4 targets were figured and those involved in oncogenesis were filtered as the following 16 putative nodes: MMP8, MMP14, KDR, BRIP1, CXCR1, GRB14, SHC2, SHC4, SH2B1, SH2B2, INPPL1, PTPN3, GNG12, SEMA4D, RHOA, and SPSB2. The transcriptional regulation of these oncogenes was coordinated by an extensive miRNA network that found to deregulate many cancer pathways. Using DgIb database, the high quality 6 oncogene-drug combinations (MMP8-CHEMBL1231240, MMP8-Aminomethylamide, CXCR1-Reparixin, SEMA4D-Pepinemab, RHOA-Clausine E, and SPSB2-CHEMBL175296) were proposed. These findings may advance our understanding of novel neoplastic gene nexus of ETV4 and design treatment strategies for its modulation.

ETV4 plays a role on the primary events during the adenoma-adenocarcinoma progression in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most common cancers worldwide; it is the fourth leading cause of death in the world and the third in Brazil. Mutations in the APC, DCC, KRAS and TP53 genes have been associated with the progression of sporadic CRC, occurring at defined pathological stages of the tumor progression and consequently modulating several genes in the corresponding signaling pathways. Therefore, the identification of gene signatures that occur at each stage during the CRC progression is critical and can present an impact on the diagnosis and prognosis of the patient. In this study, our main goal was to determine these signatures, by evaluating the gene expression of paired colorectal adenoma and adenocarcinoma samples to identify novel genetic markers in association to the adenoma-adenocarcinoma stage transition.

METHODS

Ten paired adenoma and adenocarcinoma colorectal samples were subjected to microarray gene expression analysis. In addition, mutations in APC, KRAS and TP53 genes were investigated by DNA sequencing in paired samples of adenoma, adenocarcinoma, normal tissue, and peripheral blood from ten patients.

RESULTS

Gene expression analysis revealed a signature of 689 differentially expressed genes (DEG) (fold-change> 2, p< 0.05), between the adenoma and adenocarcinoma paired samples analyzed. Gene pathway analysis using the 689 DEG identified important cancer pathways such as remodeling of the extracellular matrix and epithelial-mesenchymal transition. Among these DEG, the ETV4 stood out as one of the most expressed in the adenocarcinoma samples, further confirmed in the adenocarcinoma set of samples from the TCGA database. Subsequent in vitro siRNA assays against ETV4 resulted in the decrease of cell proliferation, colony formation and cell migration in the HT29 and SW480 colorectal cell lines. DNA sequencing analysis revealed KRAS and TP53 gene pathogenic mutations, exclusively in the adenocarcinomas samples.

CONCLUSION

Our study identified a set of genes with high potential to be used as biomarkers in CRC, with a special emphasis on the ETV4 gene, which demonstrated involvement in proliferation and migration.

Transcriptome Analysis of the Inhibitory Effect of Sennoside A on the Metastasis of Hepatocellular Carcinoma Cells

Sennoside A (SA) is a bioactive component of Rheum officinale Baill. with an activity of irritant laxative, which has been reported to possess therapeutic potential in various diseases or conditions including obesity, insulin resistance, liver steatosis, prostate cancer and pancreatic cancer progression. However, whether SA has therapeutic potential in hepatocellular carcinoma (HCC) treatment remains elusive. In this study, we treated two HCC cell lines, HepG2 and SMMC-7721 with SA and found that SA selectively inhibited the growth of HCC cells by proliferation assay. SA has a good inhibitory effect on proliferation of HepG2 cells in a concentration dependent manner, but there was no effect on SMMC-7721 cells. Then we conducted transwell assays and transcriptome analysis in HCC cells and examined the effects of SA on HCC in vivo. The results showed that SA significantly inhibited the migration and invasion of HCC. Comparison of RNA-seq transcriptome profiles from control groups and SA-treated groups identified 171 and 264 differentially expressed genes (DEGs) in HepG2 and SMMC-7721 cells respectively, in which includes 2 overlapping up-regulated DEGs and 12 overlapping down-regulated DEGs between HepG2 and SMMC-7721 cells. The qPCR were applied to investigate the transcriptional level of 9 overlapping down-regulated DEGs related to cancer metastasis, and the results were consistent with RNA-seq data. The dominate pathways including Wnt signaling pathway, TNF signaling pathway, VEGF signaling pathway, and NF-κB signaling pathway were strongly inhibited by SA, which are involved in regulating cancer metastasis. Finally, we confirmed that the downregulation of KRT7 and KRT81 could inhibit HCC metastasis. This study has provided new insight into the understanding of the inhibitory effects and potential targets of SA on the metastasis of HCC.

Transcriptomic profile of Pea3 family members reveal regulatory codes for axon outgrowth and neuronal connection specificity

PEA3 transcription factor subfamily is present in a variety of tissues with branching morphogenesis, and play a particularly significant role in neural circuit formation and specificity. Many target genes in axon guidance and cell-cell adhesion pathways have been identified for Pea3 transcription factor (but not for Erm or Er81); however it was not so far clear whether all Pea3 subfamily members regulate same target genes, or whether there are unique targets for each subfamily member that help explain the exclusivity and specificity of these proteins in neuronal circuit formation. In this study, using transcriptomics and qPCR analyses in SH-SY5Y neuroblastoma cells, hypothalamic and hippocampal cell line, we have identified cell type-specific and subfamily member-specific targets for PEA3 transcription factor subfamily. While Pea3 upregulates transcription of Sema3D and represses Sema5B, for example, Erm and Er81 upregulate Sema5A and Er81 regulates Unc5C and Sema4G while repressing EFNB3 in SH-SY5Y neuroblastoma cells. We furthermore present a molecular model of how unique sites within the ETS domain of each family member can help recognize specific target motifs. Such cell-context and member-specific combinatorial expression profiles help identify cell-cell and cell-extracellular matrix communication networks and how they establish specific connections.

ETV4 promotes late development of prostatic intraepithelial neoplasia and cell proliferation through direct and p53-mediated downregulation of p21

BACKGROUND

ETV4 is one of the ETS proteins overexpressed in prostate cancer (PC) as a result of recurrent chromosomal translocations. In human prostate cell lines, ETV4 promotes migration, invasion, and proliferation; however, its role in PC has been unclear. In this study, we have explored the effects of ETV4 expression in the prostate in a novel transgenic mouse model.

METHODS

We have created a mouse model with prostate-specific expression of ETV4 (ETV4 mice). By histochemical and molecular analysis, we have investigated in these engineered mice the expression of p21, p27, and p53. The implications of our in vivo findings have been further investigated in human cells lines by chromatin-immunoprecipitation (ChIP) and luciferase assays.

RESULTS

ETV4 mice, from two independent transgenic lines, have increased cell proliferation in their prostate and two-thirds of them, by the age of 10 months, developed mouse prostatic intraepithelial neoplasia (mPIN). In these mice, cdkn1a and its p21 protein product were reduced compared to controls; p27 protein was also reduced. By ChIP assay in human prostate cell lines, we show that ETV4 binds to a specific site (-704/-696 bp upstream of the transcription start) in the CDKN1A promoter that was proven, by luciferase assay, to be functionally competent. ETV4 further controls CDKN1A expression by downregulating p53 protein: this reduction of p53 was confirmed in vivo in ETV4 mice.

CONCLUSIONS

ETV4 overexpression results in the development of mPIN but not in progression to cancer. ETV4 increases prostate cell proliferation through multiple mechanisms, including downregulation of CDKN1A and its p21 protein product: this in turn is mediated through direct binding of ETV4 to the CDKN1A promoter and through the ETV4-mediated decrease of p53. This multi-faceted role of ETV4 in prostate cancer makes it a potential target for novel therapeutic approaches that could be explored in this ETV4 transgenic model.

ETV4 transcription factor and MMP13 metalloprotease are interplaying actors of breast tumorigenesis

BACKGROUND

The ETS transcription factor ETV4 is involved in the main steps of organogenesis and is also a significant mediator of tumorigenesis and metastasis, such as in breast cancer. Indeed, ETV4 is overexpressed in breast tumors and is associated with distant metastasis and poor prognosis. However, the cellular and molecular events regulated by this factor are still misunderstood. In mammary epithelial cells, ETV4 controls the expression of many genes, MMP13 among them. The aim of this study was to understand the function of MMP13 during ETV4-driven tumorigenesis.

METHODS

Different constructs of the MMP13 gene promoter were used to study the direct regulation of MMP13 by ETV4. Moreover, cell proliferation, migration, invasion, anchorage-independent growth, and in vivo tumorigenicity were assayed using models of mammary epithelial and cancer cells in which the expression of MMP13 and/or ETV4 is modulated. Importantly, the expression of MMP13 and ETV4 messenger RNA was characterized in 456 breast cancer samples.

RESULTS

Our results revealed that ETV4 promotes proliferation, migration, invasion, and anchorage-independent growth of the MMT mouse mammary tumorigenic cell line. By investigating molecular events downstream of ETV4, we found that MMP13, an extracellular metalloprotease, was an ETV4 target gene. By overexpressing or repressing MMP13, we showed that this metalloprotease contributes to proliferation, migration, and anchorage-independent clonogenicity. Furthermore, we demonstrated that MMP13 inhibition disturbs proliferation, migration, and invasion induced by ETV4 and participates to ETV4-induced tumor formation in immunodeficient mice. Finally, ETV4 and MMP13 co-overexpression is associated with poor prognosis in breast cancer.

CONCLUSION

MMP13 potentiates the effects of the ETV4 oncogene during breast cancer genesis and progression.

In silico analyses and global transcriptional profiling reveal novel putative targets for Pea3 transcription factor related to its function in neurons

Pea3 transcription factor belongs to the PEA3 subfamily within the ETS domain transcription factor superfamily, and has been largely studied in relation to its role in breast cancer metastasis. Nonetheless, Pea3 plays a role not only in breast tumor, but also in other tissues with branching morphogenesis, including kidneys, blood vasculature, bronchi and the developing nervous system. Identification of Pea3 target promoters in these systems are important for a thorough understanding of how Pea3 functions. Present study particularly focuses on the identification of novel neuronal targets of Pea3 in a combinatorial approach, through curation, computational analysis and microarray studies in a neuronal model system, SH-SY5Y neuroblastoma cells. We not only show that quite a number of genes in cancer, immune system and cell cycle pathways, among many others, are either up- or down-regulated by Pea3, but also identify novel targets including ephrins and ephrin receptors, semaphorins, cell adhesion molecules, as well as metalloproteases such as kallikreins, to be among potential target promoters in neuronal systems. Our overall results indicate that rather than early stages of neurite extension and axonal guidance, Pea3 is more involved in target identification and synaptic maturation.

Transcription factor ETV1 is essential for rapid conduction in the heart

Rapid impulse propagation in the heart is a defining property of pectinated atrial myocardium (PAM) and the ventricular conduction system (VCS) and is essential for maintaining normal cardiac rhythm and optimal cardiac output. Conduction defects in these tissues produce a disproportionate burden of arrhythmic disease and are major predictors of mortality in heart failure patients. Despite the clinical importance, little is known about the gene regulatory network that dictates the fast conduction phenotype. Here, we have used signal transduction and transcriptional profiling screens to identify a genetic pathway that converges on the NRG1-responsive transcription factor ETV1 as a critical regulator of fast conduction physiology for PAM and VCS cardiomyocytes. Etv1 was highly expressed in murine PAM and VCS cardiomyocytes, where it regulates expression of Nkx2-5, Gja5, and Scn5a, key cardiac genes required for rapid conduction. Mice deficient in Etv1 exhibited marked cardiac conduction defects coupled with developmental abnormalities of the VCS. Loss of Etv1 resulted in a complete disruption of the normal sodium current heterogeneity that exists between atrial, VCS, and ventricular myocytes. Lastly, a phenome-wide association study identified a link between ETV1 and bundle branch block and heart block in humans. Together, these results identify ETV1 as a critical factor in determining fast conduction physiology in the heart.

Prognostic gene signature identification using causal structure learning: applications in kidney cancer

Identification of molecular-based signatures is one of the critical steps toward finding therapeutic targets in cancer. In this paper, we propose methods to discover prognostic gene signatures under a causal structure learning framework across the whole genome. The causal structures are represented by directed acyclic graphs (DAGs), wherein we construct gene-specific network modules that constitute a gene and its corresponding regulators. The modules are then subsequently used to correlate with survival times, thus, allowing for a network-oriented approach to gene selection to adjust for potential confounders, as opposed to univariate (gene-by-gene) approaches. Our methods are motivated by and applied to a clear cell renal cell carcinoma (ccRCC) study from The Cancer Genome Atlas (TCGA) where we find several prognostic genes associated with cancer progression - some of which are novel while others confirm existing findings.

Pea3 expression promotes the invasive and metastatic potential of colorectal carcinoma

AIM: To investigate the function of Pea3 in colorectal carcinoma (CRC) invasion and metastatic potential.

METHODS: The expression of Pea3 during clinical progression of human CRC was investigated using Oncomine Research Edition. To assay Pea3 expression in established CRC cell lines, we performed western blotting of cell lysates. We employed shRNA-mediated knockdown of Pea3 in HCT116 (HCT) and LS174T CRC cells which was confirmed by real-time quantitative PCR (qPCR) and western blotting. Transwell invasion assays, MTS proliferation assays, anoikis assays, and fluorometric matrix metalloprotease (MMP) assays were performed to determine the effects of Pea3 knockdown on invasion, proliferation, anoikis and MMP activity in CRC cells in vitro. Alterations in epithelial-mesenchymal transition (EMT) and matrix metalloprotease (MMP) mRNA levels were determined by qPCR. CRC cells were injected into the flanks of nude mice to generate xenografts and tumor growth monitored with serial calliper measurements. To assay metastatic potential, CRC cells were injected into the spleen of nude mice, and histological analysis performed on the livers 21 d later.

RESULTS: We demonstrated that reduction of Pea3 expression in CRC cells significantly impaired their invasive capacity (HCT.shPea3, 0.28 ± 0.04 fold, P < 0.01; LS.shPea3, 0.15 ± 0.04 fold; SW.shPea3, 0.23 ± 0.03, P < 0.01), reduced anoikis resistance (HCT.shPea3 75.4% ± 1.9% viable cells vs HCT.shCtrl 88.6% ± 0.6% viable cells, P < 0.01; LS.shPea3 71.7% ± 0.5% viable cells vs LS.Ctrl 89.6% ± 0.3% viable cells, P < 0.005, but had no effect on proliferation (HCT.shCtrl AUC 5098 ± 123 vs HCT.shPea3 5689 ± 151, P < 0.05; LS.shCtrl AUC 5600 ± 324.1 vs LS.shPea3 6423 ± 400, P < 0.05). In vivo, HCT.shPea3 and HCT.shCtrl tumour xenografts grew at a similar rate (HCT.shPea3 2.64 ± 0.82 fold vs HCT.shCtrl 2.88 ± 0.80 fold, P > 0.05). In keeping with a pro-metastatic function for Pea3 in CRC, several EMT markers and MMPs were downregulated in shPea3-expressing cells, suggesting that Pea3 may exert its effects through these processes. A reduction in overall MMP activity was observed in HCT.shPea3 cells compared to their control counterparts (HCT.shPea3 0.61 ± 0.04 fold, P < 0.005). This translated in vivo to the complete absence of metastases in the livers of mice that were grafted with CRC cells lacking Pea3. Conversely, CRC cells expressing Pea3 formed liver metastases in all mice.

CONCLUSION: Our study implicates Pea3 as a mediator of metastases, and provides a biological rationale for the adverse prognosis associated with elevated Pea3 expression in human CRC.

Overexpression of ETV4 protein in triple-negative breast cancer is associated with a higher risk of distant metastasis

BACKGROUND

Patients with triple-negative breast cancer (TNBC) present a higher probability of distant metastasis and lack of effective targeted therapy. ETS translocation variant 4 (ETV4) is an ETS (E-26) transcription factor and has been associated with tumor metastasis. However, the clinical and functional significance of ETV4 in TNBC still remains unclear.

METHODS

A human tumor metastasis polymerase chain reaction array was used to profile differential expression of tumor metastasis-related genes in TNBC tissue. Real-time reverse transcription and Western blot analyses were performed to verify ETV4 expression in TNBC cells and tissue. Immunohistochemistry was used to detect expression of ETV4 protein in 135 TNBC tissue samples for association between ETV4 protein expression and clinical outcomes.

RESULTS

A total total of eight upregulated (CCL7, KISS1, MET, MMP7, NR4A3, ETV4, TIMP3, and TSHR) and three downregulated (ITGA7, SSTR, and MMP2) genes were identified between TNBC tissue and the luminal subtype of breast cancer tissue. ETV4 messenger ribonucleic acid was more than five-fold upregulated in TNBC tissue compared with the control tissue. ETV4 overexpression was found in 57.0% of 135 TNBC cases. Overexpression of ETV4 protein was associated with an advanced stage and a higher proportion of positive lymph node and lymphovascular invasion. Patients with an ETV4-overexpressed tumor had a significantly higher risk of developing distant metastasis (P<0.0001) and shorter overall survival and disease-free survival. Overexpression of ETV4 protein was an independent predictor of short disease-free survival of TNBC patients (P=0.021).

CONCLUSION

Overexpression of ETV4 protein increases risk of developing distant metastasis and results in a poor prognosis for TNBC patients. Thus, ETV4 might be a novel target for developing an alternative therapeutic strategy for prevention of TNBC distant metastasis.

Molecular mechanisms of ETS transcription factor-mediated tumorigenesis

The E26 transformation-specific (ETS) family of transcription factors is critical for development, differentiation, proliferation and also has a role in apoptosis and tissue remodeling. Changes in expression of ETS proteins therefore have a significant impact on normal physiology of the cell. Transcriptional consequences of ETS protein deregulation by overexpression, gene fusion, and modulation by RAS/MAPK signaling are linked to alterations in normal cell functions, and lead to unlimited increased proliferation, sustained angiogenesis, invasion and metastasis. Existing data show that ETS proteins control pathways in epithelial cells as well as stromal compartments, and the crosstalk between the two is essential for normal development and cancer. In this review, we have focused on ETS factors with a known contribution in cancer development. Instead of focusing on a prototype, we address cancer associated ETS proteins and have highlighted the diverse mechanisms by which they affect carcinogenesis. Finally, we discuss strategies for ETS factor targeting as a potential means for cancer therapeutics.

Loss of a negative feedback loop involving pea3 and cyclin d2 is required for pea3-induced migration in transformed mammary epithelial cells

The Ets family transcription factor Pea3 (ETV4) is involved in tumorigenesis especially during the metastatic process. Pea3 is known to induce migration and invasion in mammary epithelial cell model systems. However, the molecular pathways regulated by Pea3 are still misunderstood. In the current study, using in vivo and in vitro assays, Pea3 increased the morphogenetic and tumorigenic capacity of mammary epithelial cells by modulating their cell morphology, proliferation, and migration potential. In addition, Pea3 overexpression favored an epithelial-mesenchymal transition (EMT) triggered by TGF-β1. During investigation for molecular events downstream of Pea3, Cyclin D2 (CCND2) was identified as a new Pea3 target gene involved in the control of cellular proliferation and migration, a finding that highlights a new negative regulatory loop between Pea3 and Cyclin D2. Furthermore, Cyclin D2 expression was lost during TGF-β1-induced EMT and Pea3-induced tumorigenesis. Finally, restored Cyclin D2 expression in Pea3-dependent mammary tumorigenic cells decreased cell migration in an opposite manner to Pea3. As such, these data demonstrate that loss of the negative feedback loop between Cyclin D2 and Pea3 contributes to Pea3-induced tumorigenesis.

IMPLICATIONS

This study reveals molecular insight into how the Ets family transcription factor Pea3 favors EMT and contributes to tumorigenesis via a negative regulatory loop with Cyclin D2, a new Pea3 target gene.

ShRNA-mediated down-regulation of the ETV1 transcription factor gene reduces invasive ability of gastrointestinal stromal tumor-T1 (GIST-T1) cells

AIM: To investigate the effect of shRNA-mediated knockdown of the ETV1 transcription factor gene on the invasive ability of gastrointestinal stromal tumors-T1 (GIST-T1) cells.

METHODS: A recombinant lentiviral vector carrying a shRNA targeting the etv1 gene (PLVX-shRNA-ETV1) was constructed and used to infect GIST-T1 cells. GIST-T1 cells were divided into three groups: blank control group, negative control group (PLVX-shRNA), and experimental group (PLVX-shRNA-ETV1). After infection, expression of ETV1 protein was detected by Western blot, cell invasion was detected by Transwell assay, and expression of C-kit and MMP-2 proteins was detected by immunohistochemistry.

RESULTS: Expression of ETV1 protein was significantly decreased in cells infected with the PLVX-shRNA-ETV1 vector compared to other groups. The number of cells passing through the martrigel-coated Transwell membrane was significantly lower in the experimental group than in the blank control group and negative control group (60.2000 ± 4.8503 vs 166.2000 ± 14.4201, 142.2000 ± 4.3787, both P < 0.05). Expression of C-kit and MMP-2 proteins was significantly lower in the experimental group than in the blank control group and negative control group (both P < 0.05).

CONCLUSION: ShRNA-mediated knockdown of the ETV1 transcription factor significantly reduces invasive ability of GIST-T1 cells.

Overexpression of ETV4 is oncogenic in prostate cells through promotion of both cell proliferation and epithelial to mesenchymal transition

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.

Deletion analysis of Ad5 E1a transcriptional control region: impact on tumor-selective expression of E1a and E1b

The regulatory sequences upstream of E1a, the first viral protein expressed upon infection of cells with adenovirus, have binding sites for multiple transcription factors including two binding sites for E2f and five binding sites for Pea3. We evaluated the impact of deletions, which remove one or more of these transcription factor-binding sites on the expression of E1a in a panel of tumor cells and non-transformed cells. We demonstrated that specific deletions in the E1a enhancer markedly reduced the expression of E1a in growth-arrested cells while having a minimal impact on the expression of E1a in a panel of tumor cells. In particular, deletion of a 50-bp region located from -305 to -255 upstream of the E1a initiation site resulted in marked reduction of E1a and E1b expression and cytolytic activity in growth-arrested cells, while retaining near wild-type of expression of E1a and E1b and cytolytic activity in tumor cells. This deletion removed two Pea3 sites and one E2f site. The characteristics of this vector, TAV-255, was compared with dl1520 (Onyx-015) and demonstrated restricted cytolytic activity in growth-arrested cells similar to dl1520 and superior cytolytic activity in a panel of tumor cell lines. In this current study, we demonstrate that TAV-255, an E1a enhancer deletion vector, possesses tumor selective expression of both E1a and E1b along with potent tumor-selective oncolytic activity.

Cell Adhesion and Transcriptional Activity - Defining the Role of the Novel Protooncogene LPP

Integrating signals from the extracellular matrix through the cell surface into the nucleus is an essential feature of metazoan life. To date, many signal transducers known as shuttle proteins have been identified to act as both a cytoskeletal and a signaling protein. Among them, the most prominent representatives are zyxin and lipoma preferred (translocation) partner (LPP). These proteins belong to the LIM domain protein family and are associated with cell migration, proliferation, and transcription. LPP was first identified in benign human lipomas and was subsequently found to be overexpressed in human malignancies such as lung carcinoma, soft tissue sarcoma, and leukemia. This review portrays LPP in the context of human neoplasia based on a study of the literature to define its important role as a novel protooncogene in carcinogenesis.

PEA3/ETV4-related transcription factors coupled with active ERK signalling are associated with poor prognosis in gastric adenocarcinoma

Background:

Transcription factors often play important roles in tumourigenesis. Members of the PEA3 subfamily of ETS-domain transcription factors fulfil such a role and have been associated with tumour metastasis in several different cancers. Moreover, the activity of the PEA3 subfamily transcription factors is potentiated by Ras-ERK pathway signalling, which is itself often deregulated in tumour cells.

Methods:

Immunohistochemical patterns of PEA3 expression and active ERK signalling were analysed and mRNA expression levels of PEA3, ER81, MMP-1 and MMP-7 were determined in gastric adenocarcinoma samples.

Results:

Here, we have studied the expression of the PEA3 subfamily members PEA3/ETV4 and ER81/ETV1 in gastric adenocarcinomas. PEA3 is upregulated at the protein level in gastric adenocarcinomas and both PEA3/ETV4 and ER81/ETV1 are upregulated at the mRNA level in gastric adenocarcinoma tissues. This increased expression correlates with the expression of a target gene associated with metastasis, MMP-1. Enhanced ERK signalling is also more prevalent in late-stage gastric adenocarcinomas, and the co-association of ERK signalling and PEA3 expression also occurs in late-stage gastric adenocarcinomas. Furthermore, the co-association of ERK signalling and PEA3 expression correlates with decreased survival rates.

Conclusions:

This study shows that members of the PEA3 subfamily of transcription factors are upregulated in gastric adenocarcinomas and that the simultaneous upregulation of PEA3 expression and ERK pathway signalling is indicative of late-stage disease and a poor survival prognosis.

The role of Pea3 group transcription factors in esophageal squamous cell carcinoma

The transcription factors Pea3, Erm, and Er81 can promote cancer initiation and progression in various types of solid tumors. However, their role in esophageal squamous cell carcinoma (ESCC) has not been elucidated. In this study, we found that the expression levels of Pea3 and Erm, but not that of Er81, were significantly higher in ESCC compared with nontumor esophageal epithelium. A high level of Pea3 expression was significantly correlated with a shorter overall survival in a cohort of 81 patients with ESCC and the subgroup with N1 stage tumor (Wilcoxon-Gehan test, P = 0.016 and P = 0.001, respectively). Pea3 was overexpressed in seven ESCC cell lines compared with two immortalized esophageal cell lines. Pea3 knockdown reduced cell proliferation and suppressed nonadherent growth, migration, and invasion in ESCC cells in vitro. In addition, Pea3 knockdown in ESCC cells resulted in a down-regulation of phospho-Akt and matrix metalloproteinase 13, whereas a significant positive correlation in the expression levels was observed between Pea3 and phospho-Akt (r = 0.281, P < 0.013) and between Pea3 and matrix metalloproteinase 13 in the human specimens (r = 0.462, P < 0.001). Moreover, Pea3 modulated the sensitivity of EC109 cells to doxorubicin, probably via reduced activity of the phosphatidylinositol 3-kinase-Akt-mammalian target of Rapamycin complex 1 pathway on Pea3 knockdown. In conclusion, our results suggest that Pea3 plays an important role in the progression of ESCC.

Functional cooperation between Stat-1 and ets-1 to optimize icam-1 gene transcription

Intercellular adhesion molecule-1 (ICAM-1) plays an important role in the immune system, enabling the interactions between effector cells and target cells. It is also known to be involved in tumor growth and metastasis. Its expression is transcriptionally regulated by several proinflammatory cytokines including IFN-gamma, which induces ICAM-1 transcription via the JAK-STAT signaling pathway in a Stat1-dependent fashion. The ICAM-1 promoter contains several cis-active regulatory elements including 2 Ets binding sites (EBSs) located at positions -158 and -138 relatively to the AUG, which were previously shown to play a role in the constitutive activity of the ICAM-1 promoter. In the present study, we have determined whether the EBSs are also involved in the regulation of ICAM-1 gene transcription by pro-inflammatory cytokines. Transient transfection assays were performed with reporter genes containing ICAM-1 promoter constructions cloned upstream from the firefly luciferase gene. Site-specific mutations of the EBS diminished the promoter activity stimulated by IFN-gamma, although the IFN-gamma responsive element (pIgammaRE), which binds Stat1, was intact. Stimulation of the transcriptional activity following IFN-gamma treatment was significantly reduced when both EBSs were inactivated. Co-immunoprecipitation experiments provided evidence of a physical interaction involving Ets1 and Stat1. In COS-1 and HEK 293 cells cotransfected with CFP-Stat1 and YFP-Ets fusion protein, fluorescence resonance energy transfer experiments confirmed the close proximity of these 2 proteins in living cells following treatment with IFN-gamma.

The E3 ubiquitin ligase complex component COP1 regulates PEA3 group member stability and transcriptional activity

In this study, we report that the PEA3 group members interact with the mammalian really interesting new gene (RING) E3 ubiquitin ligase constitutive photomorphogenetic 1 (COP1), which mediates ubiquitylation and subsequent proteasome degradation of the p53 and c-Jun transcription factors. This interaction is mediated by the central region of COP1 including the coiled-coil domain and two COP1-interacting consensus motifs localized in the well-conserved N-terminal transactivation domain of the PEA3 group members. At the transcriptional level, COP1 reduces the transcriptional activity of ERM and the two other PEA3 group proteins on Ets-responsive reporter genes; this effect being dependent on the RING domain of COP1 and the two COP1-interacting motifs of ERM. Reduced transcriptional activity was, however, not related to COP1-induced changes in ERM stability. In fact, increased ubiquitylation and subsequent proteasome-mediated degradation of ERM is achieved only when COP1 is expressed with DET1, a key COP1 partner within the ubiquitylation complex. Conversely, we show that the depletion of COP1 or DET1 by small interference RNA (siRNA) in U2OS cells stabilizes endogenous ERM whereas only COP1 knockdown enhances expression of ICAM-1, a gene regulated by this transcription factor. These results indicate that COP1 is a complex regulator of ERM and the two other PEA3 group members.

Fusion of EWSR1 with the DUX4 facioscapulohumeral muscular dystrophy region resulting from t(4;22)(q35;q12) in a case of embryonal rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma and rarely occurs in adults. There are six main subtypes, each histologically, clinically, and cytogenetically distinct. Embryonal RMS is characterized by chromosomal gains, usually not associated with any consistent structural anomaly. We describe here a case of embryonal RMS in a 19-year-old female patient. The conventional cytogenetic analysis showed a t(4;22)(q35;q12) translocation as the sole cytogenetic change. Complementary fluorescence in situ hybridization analysis showed that the translocation breakpoints were located in the EWSR1 gene at 22q12 and the region of the DUX4 and FSHMD1A at 4q35. This constitutes a novel example of the high frequency of EWSR1 rearrangements in various types of sarcomas as well as of its ability to fuse with a large variety of partner genes. Because DUX4 is involved in myogenic differentiation and cell-cycle control, the striated muscle differentiation observed in the present case might be a direct consequence of the alteration of the DUX4 region generated by the t(4;22). The involvement of the DUX4 region might represent the genetic hallmark of a novel subclass of small round cell tumors.

Characterization of TMPRSS2:ETV5 and SLC45A3:ETV5 gene fusions in prostate cancer

Recurrent gene fusions involving oncogenic ETS transcription factors (including ERG, ETV1, and ETV4) have been identified in a large fraction of prostate cancers. The most common fusions contain the 5' untranslated region of TMPRSS2 fused to ERG. Recently, we identified additional 5' partners in ETV1 fusions, including TMPRSS2, SLC45A3, HERV-K_22q11.23, C15ORF21, and HNRPA2B1. Here, we identify ETV5 as the fourth ETS family member involved in recurrent gene rearrangements in prostate cancer. Characterization of two cases with ETV5 outlier expression by RNA ligase-mediated rapid amplification of cDNA ends identified one case with a TMPRSS2:ETV5 fusion and one case with a SLC45A3:ETV5 fusion. We confirmed the presence of these fusions by quantitative PCR and fluorescence in situ hybridization. In vitro recapitulation of ETV5 overexpression induced invasion in RWPE cells, a benign immortalized prostatic epithelial cell line. Expression profiling and an integrative molecular concepts analysis of RWPE-ETV5 cells also revealed the induction of an invasive transcriptional program, consistent with ERG and ETV1 overexpression in RWPE cells, emphasizing the functional redundancy of ETS rearrangements. Together, our results suggest that the family of 5' partners previously identified in ETV1 gene fusions can fuse with other ETS family members, suggesting numerous rare gene fusion permutations in prostate cancer.

c-Jun has multiple enhancing activities in the novel cross talk between the androgen receptor and Ets variant gene 1 in prostate cancer

The multiple transcriptional roles of c-Jun are shown in a novel cross-talk between the androgen receptor (AR) and its new target gene, Ets variant gene 1 (ETV1). In this report, we show that c-Jun can mediate AR induction of ETV1 expression independent of c-Jun transactivation function. Interestingly, c-Jun can transactivate the cloned ETV1 promoter also in the absence of ligand-activated AR, suggesting two mechanisms by which c-Jun can induce ETV1 expression. In addition, both wild-type c-Jun and a transactivation-deficient mutant can enhance the transcriptional activity of ETV1, as measured by both reporter gene assay and endogenous expression of matrix metalloproteinase genes, well-known targets of Ets proteins. Overexpression of the c-Jun mutant protein also led to increased prostate cancer cell invasion. Immunoprecipitation and immunocytochemistry experiments showed copurification and colocalization of c-Jun with AR or ETV1, suggesting that c-Jun acts on AR or ETV1 via a physical association. Collectively, these results, together with a parallel overexpression of ETV1, c-Jun, and AR in prostate tumors, imply that c-Jun plays a pivotal role in the pathway that connects ligand-activated AR to elevated ETV1 expression, leading to enhanced expression of matrix metalloproteinases and prostate cancer cell invasion.

The C-terminal region of CHD3/ZFH interacts with the CIDD region of the Ets transcription factor ERM and represses transcription of the human presenilin 1 gene

Presenilins are required for the function of gamma-secretase: a multiprotein complex implicated in the development of Alzheimer's disease (AD). We analyzed expression of the presenilin 1 (PS1) gene. We show that ERM recognizes avian erythroblastosis virus E26 oncogene homolog (Ets) motifs on the PS1 promoter located at -10, +90, +129 and +165, and activates PS1 transcription with promoter fragments containing or not the -10 Ets site. Using yeast two-hybrid selection we identified interactions between the chromatin remodeling factor CHD3/ZFH and the C-terminal 415 amino acids of ERM used as bait. Clones contained the C-terminal region of CHD3 starting from amino acid 1676. This C-terminal fragment (amino acids 1676-2000) repressed transcription of the PS1 gene in transfection assays and PS1 protein expression from the endogenous gene in SH-SY5Y cells. In cells transfected with both CHD3 and ERM, activation of PS1 transcription by ERM was eliminated with increasing levels of CHD3. Progressive N-terminal deletions of CHD3 fragment (amino acids 1676-2000) indicated that sequences crucial for repression of PS1 and interactions with ERM in yeast two-hybrid assays are located between amino acids 1862 and 1877. This was correlated by the effect of progressive C-terminal deletions of CHD3, which indicated that sequences required for repression of PS1 lie between amino acids 1955 and 1877. Similarly, deletion to amino acid 1889 eliminated binding in yeast two-hybrid assays. Testing various shorter fragments of ERM as bait indicated that the region essential for binding CHD3/ZFH is within the amino acid region 96-349, which contains the central inhibitory DNA-binding domain (CIDD) of ERM. N-Terminal deletions of ERM showed that residues between amino acids 200 and 343 are required for binding to CHD3 (1676-2000) and C-terminal deletions of ERM indicated that amino acids 279-299 are also required. Furthermore, data from chromatin immunoprecipitation (ChIP) indicate that CHD3/ZFH interacts with the PS1 promoter in vivo.

ETV1 is a novel androgen receptor-regulated gene that mediates prostate cancer cell invasion

Androgens and the androgen receptor (AR) act in cells by modulating gene expression. Through gene microarray studies, we have identified Ets Variant Gene 1 (ETV1) as a novel androgen-regulated gene. Our data demonstrate that ETV1 mRNA and protein are up-regulated in response to ligand-activated AR in androgen-dependent LNCaP cells, but there is no detectable ETV1 expression in normal prostate cells. The ETV1 promoter is induced by androgens and recruits the AR in the context of chromatin. ETV1-regulated endogenous matrix metalloproteinase genes can be induced by ligand-activated AR. In contrast to the hormone-induced expression in androgen-dependent LNCaP cells, ETV1 expression in androgen-independent LNCaP cells is high and unresponsive to androgen. This androgen-independent ETV1 expression contrasts with the hormone-dependent expression observed for TMPRSS2 in these androgen-independent prostate cancer cells. ETV1 is overexpressed in prostate cancer independent of the TMPRSS2:ETV1 translocation. Disruption of ETV1 expression in both androgen-dependent and androgen-independent prostate cancer cells significantly compromises the invasion capacity of these cells, suggesting an important role for ETV1 in prostate cancer metastasis. Collectively, these results demonstrate that ETV1 expression transitions from androgen-induced to androgen-independent as prostate cancer cells switch from hormone-dependent to hormone-refractory and suggest that this transition may be in part responsible for the elevated levels of ETV1 observed in prostate tumors. Additionally, our data provide an indirect mechanism of AR regulation of gene expression, via the transactivation of the transcription factor ETV1.

The LIM domain protein LPP is a coactivator for the ETS domain transcription factor PEA3

PEA3 is a member of a subfamily of ETS domain transcription factors which is regulated by a number of signaling cascades, including the mitogen-activated protein (MAP) kinase pathways. PEA3 activates gene expression and is thought to play an important role in promoting tumor metastasis and also in neuronal development. Here, we have identified the LIM domain protein LPP as a novel coregulatory binding partner for PEA3. LPP has intrinsic transactivation capacity, forms a complex with PEA3, and is found associated with PEA3-regulated promoters. By manipulating LPP levels, we show that it acts to upregulate the transactivation capacity of PEA3. LPP can also functionally interact in a similar manner with the related family member ER81. Thus, we have uncovered a novel nuclear function for the LIM domain protein LPP as a transcriptional coactivator. As LPP continually shuttles between the cell periphery and the nucleus, it represents a potential novel link between cell surface events and changes in gene expression.

Fusion between CIC and DUX4 up-regulates PEA3 family genes in Ewing-like sarcomas with t(4;19)(q35;q13) translocation

Ewing's family tumors (EFTs) are highly malignant tumors arising from bone and soft tissues that exhibit EWS-FLI1 or variant EWS-ETS gene fusions in more than 85% of the cases. Here we show that CIC, a human homolog of Drosophila capicua which encodes a high mobility group box transcription factor, is fused to a double homeodomain gene DUX4 as a result of a recurrent chromosomal translocation t(4;19)(q35;q13). This translocation was seen in two cases of soft tissue sarcoma diagnosed as Ewing-like sarcoma. CIC-DUX4 exhibits a transforming potential for NIH 3T3 fibroblasts, and as a consequence of fusion with a C-terminal fragment of DUX4, CIC acquires an enhanced transcriptional activity, suggesting that expression of its downstream targets might be deregulated. Gene expression analysis identified the ETS family genes, ERM/ETV5 and ETV1, as potential targets for the gene product of CIC-DUX4. Indeed, CIC-DUX4 directly binds the ERM promoter by recognizing a novel target sequence and significantly up-regulates its expression. This study clarifies the function of CIC and its role in tumorigenesis, as well as the importance of the PEA3 subclass of ETS family proteins in the development of EFTs arising through mechanisms different from those involving EWS-ETS chimeras. Moreover, the study identifies the role of DUX4 that is closely linked to facioscapulohumeral muscular dystrophy in transcriptional regulation.

Expression, purification, and structural prediction of the Ets transcription factor ERM

The PEA3 group within the Ets family comprises PEA3, ER81, and ERM, three transcription factors of about 500 residues. These factors are highly conserved in their ETS DNA-binding domain and in their two transcriptional activation domains. They are involved in many developmental processes and regulate cancer development via metastasis, as in the case of some breast tumors. Here, we describe the oversynthesis of human ERM from a baculovirus expression vector in Spodoptera frugiperda (Sf9) cells, and the subsequent purification and structural characterization of this protein. Oversynthesis of ERM was confirmed by measuring band intensities on SDS-PAGE gels and by Western blot analysis. Two-step purification by affinity chromatography led to a highly stable protein. Electromobility shift assays suggested that this purified protein is functional, since it recognizes specific Ets DNA-binding sites. We then used circular dichroism and infrared spectrometry to perform a structural analysis of the purified full-length ERM, and compared the results with those of current structural prediction algorithms. Our study indicates that ERM contains a highly structured ETS-domain and suggests that each of the N- and C-terminal transactivating domains also contains an alpha-helix. In contrast, the 250-residue central domain seems to have very little structure.

E1AF/PEA3 activates the Rho/Rho-associated kinase pathway to increase the malignancy potential of non-small-cell lung cancer cells

E1AF/PEA3, an Ets family transcription factor, is frequently overexpressed in non-small-cell lung cancers (NSCLCs). Overexpression of E1AF increases motility and invasion of VMRC-LCD and NCI-H226 NSCLC cells, which lack endogenous E1AF expression, and the effect is synergistically increased by hepatocyte growth factor (HGF). The small GTPase Rho/Rho-associated kinase (ROCK) pathway is also involved in motility and invasion. To determine the role of the Rho/ROCK pathway in malignant phenotypes induced by E1AF, we analyzed VMRC-LCD cells transfected with an E1AF expression vector (LCD-E1AF cells) or with empty vector (LCD-vector cells). LCD-E1AF cells had more GTP-bound (active) Rho than LCD-vector cells and Rho activation was synergistically increased by HGF. The Rho activation by E1AF and HGF was also shown in NCI-H226 cells. Phosphorylation of myosin light chain (MLC), a downstream effector of ROCK signaling, was higher in LCD-E1AF cells than in LCD-vector cells, especially under HGF treatment. A specific ROCK inhibitor, Y27632, strongly suppressed MLC phosphorylation, cell motility, and invasion. In nude mice implanted s.c. and intrapulmonarily, LCD-E1AF cells made more local tumors than LCD-vector cells (six of six versus one of seven mice and four of seven versus one of seven mice, respectively). Three of the four mice with lung tumors from LCD-E1AF cells had lymph node metastases whereas the mouse with LCD-vector tumors did not. LCD-E1AF tumors showed higher MLC phosphorylation than LCD-vector tumors. These results suggest that E1AF activates the Rho/ROCK pathway in an HGF-enhanced manner and its activation is important in E1AF-induced motility and invasion as well as tumorigenesis and metastasis in NSCLC cells.

Ets2 transcription factor in normal and neoplastic human breast tissue

The Ets family of transcription factors regulate the expression of multiple genes involved in tumour formation and progression. The aim of this work was to test the hypothesis that the expression of Ets2 in breast cancers was associated with parameters of tumour progression and metastasis. Using reverse-transcriptase polymerase chain reaction (RT-PCR), Ets2 mRNA was detected in 69% of 181 breast carcinomas, 63% of 43 fibroadenomas and 47% of 43 specimens of normal breast tissue. Levels were significantly higher in carcinomas compared with normal breast tissue (P = 0.006). Using Western blotting, Ets2 protein was found to migrate as two bands with molecular masses of 52 kDa (p52) and 54kDa (p54). Levels of both proteins were significantly higher in the carcinomas compared with both fibroadenomas (P = 0.0001) and normal breast tissue (P = 0.0001). In the carcinomas, a significant relationship was found between the p52 and p54 form of Ets2 (r = 0.51, P < 0.0001; Spearman correlation). Also, in the carcinomas, a significant correlation was found between both forms of Ets2 protein and urokinase plasminogen activator (uPA) (for p52, r = 0.43, P = 0.0005, n = 68; for p54, r = 0.50, P = 0.0001, n = 68). As Ets2 binding sites are present on the uPA promoter, Ets2 may be one of the transcription factors regulating uPA expression in human breast cancer.

Genomic structure and promoter activity of the E1AF gene, a member of the ETS oncogene family

E1AF is a member of the ETS oncogene family and is thought to be a human homologue of mouse PEA3. We have isolated a genomic clone of E1AF and analyzed the promoter activity of its 5'-flanking region. We identified a variation in exon 1, which depends on the cell type. There was no typical TATA box in the 5'-flanking region, but putative binding sites of a number of transcription factors including PEA3 as well as CAAT boxes were seen. A luciferase reporter assay indicated that the 5'-flanking region possesses promoter activity. Northern blot studies demonstrated significant expression of the E1AF gene in restricted tissues such as the pituitary gland, placenta, and fetal kidney. Moreover, the E1AF promoter was activated by E1AF itself and estrogen receptor. These findings suggest that E1AF is a housekeeping gene, whose expression is controlled in specific tissues.

ETV6 gene rearrangements in invasive breast carcinoma

The ETV6/TEL gene encodes a transcription factor frequently rearranged in several types of cancer. We looked for ETV6 rearrangements in invasive breast cancer using fluorescence in situ hybridization (FISH) of BAC probes on sections of tissue microarrays containing 632 tumor samples. Of these samples, signal of sufficient quality for screening by FISH was obtained for 356. Five cases (one lobular, one nontypical secretory, one mixed, and two ductal carcinomas) showed ETV6 rearrangement.

Defective postnatal neurogenesis and disorganization of the rostral migratory stream in absence of the Vax1 homeobox gene

The subventricular zone (SVZ) is one of the sources of adult neural stem cells (ANSCs) in the mouse brain. Precursor cells proliferate in the SVZ and migrate through the rostral migratory stream (RMS) to the olfactory bulb (OB), where they differentiate into granule and periglomerular cells. Few transcription factors are known to be responsible for regulating NSC proliferation, migration, and differentiation processes; even fewer have been found to be responsible for the organization of the SVZ and RMS. For this reason, we studied the ventral anterior homeobox (Vax1) gene in NSC proliferation and in SVZ organization. We found that Vax1 is strongly expressed in the SVZ and in the RMS and that, in the absence of Vax1, embryonic precursor cells proliferate 100 times more than wild-type controls, in vitro. The SVZ of Vax1(-/-) brains is hyperplastic and mostly disorganized, and the RMS is missing, causing a failure of precursor cell migration to the OBs, which as a result are severely hypoplastic. Moreover, we found that Vax1 is essential for the correct differentiation of ependyma and astrocytes. Together, these data indicate that Vax1 is a potent regulator of SVZ organization and NSC proliferation, with important consequences on postnatal neurogenesis.

Prognostic value of ERM gene expression in human primary breast cancers

We measured the expression of ERM gene, a nuclear transcription factor belonging to the ets family, in a series of 364 unselected primary breast cancers from patients who underwent locoregional surgery in the Centre Oscar Lambret between May 1989 and December 1991. The expression of ERM was quantified with a real-time one-step reverse transcription-PCR assay based on the 5'-nuclease activity of the TaqDNA polymerase and with an Abi Prism 7700 Sequence Detector System (Applied Biosystems, Courtaboeuf, France). ERM was positively correlated (Spearman test) to epidermal growth factor receptor (EGFR; P < 0.001, r = 0.296) and to histoprognostic grading (P = 0.044, r = 0.112), whereas it was negatively correlated to estradiol receptors (P = 0.019, r = -0.124), HER3 (c-erbB-3; P = 0.01, r = -0.135), and HER4 (c-erbB-4; P = 0.003, r = -0.154). Using the chi2 test, a positive relationship was found between the expression of ERM and EGFR (chi2 = 7.795, P = 0.007). In overall survival studies, Cox univariate analyses demonstrated a prognostic value of ERM (P = 0.006; risk ratio, 2.95) besides the classical prognostic factors histoprognostic grading, node involvement, tumor size, estradiol receptors, progesterone receptors, EGFR, HER3, and HER4. In multivariate analyses, ERM preserved its prognostic value (P = 0.004; risk ratio, 3.779) together with histoprognostic grading, tumor size, estradiol receptors, and progesterone receptors. In relapse-free survival studies, univariate analyses demonstrated that histoprognostic grading, node involvement, tumor size, and HER4 were prognostic factors. These parameters, except histoprognostic grading, retained their prognostic value in multivariate analyses. This study demonstrates for the first time that ERM gene expression is an independent adverse prognostic factor for overall survival in breast cancer patients.

SUMO modification of the Ets-related transcription factor ERM inhibits its transcriptional activity

A variety of transcription factors are post-translationally modified by SUMO, a 97-residue ubiquitin-like protein bound covalently to the targeted lysine. Here we describe SUMO modification of the Ets family member ERM at positions 89, 263, 293, and 350. To investigate how SUMO modification affects the function of ERM, Ets-responsive intercellular adhesion molecule 1 (ICAM-1) and E74 reporter plasmids were employed to demonstrate that SUMO modification causes inhibition of ERM-dependent transcription without affecting the subcellular localization, stability, or DNA-binding capacity of the protein. When the adenoviral protein Gam1 or the SUMO protease SENP1 was used to inhibit the SUMO modification pathway, ERM-dependent transcription was de-repressed. These results demonstrate that ERM is subject to SUMO modification and that this post-translational modification causes inhibition of transcription-enhancing activity.

Expression of the Ets transcription factor Erm is regulated through a conventional PKC signaling pathway in the Molt4 lymphoblastic cell line

Erm, a member of the PEA3 group within the Ets family of transcription factors, is expressed in murine and human lymphocytes. Here, we show that in the human Molt4 lymphoblastic cell line, the erm gene expression is regulated by the conventional PKC (cPKC) pathway. To better characterize the molecular mechanism by which cPKC regulates Erm transcription in Molt4 cells, we tested proximal promoter deletions of the human gene, and identified a specific cPKC-regulated region between positions -420 and -115 upstream of the first exon.

Pea3 Transcription Factor Cooperates with USF-1 in Regulation of the Murine bax Transcription without Binding to an Ets-binding Site

The Pea3 transcription factor (which belongs to the PEA3 group) from the Ets family has been shown to be involved in mammary embryogenesis and oncogenesis. However, except for proteinases, only few of its target genes have been reported. In the present report, we identified bax as a Pea3 up-regulated gene. We provide evidence of this regulation by using Pea3 overexpression and Pea3 silencing in a mammary cell line. Both Pea3 and Erm, another member of the PEA3 group, are able to transactivate bax promoter fragments. Although the minimal Pea3-regulated bax promoter does not contain an Ets-binding site, two functional upstream stimulatory factor-regulated E boxes are present. We further demonstrate the ability of Pea3 and USF-1 to cooperate for the transactivation of the bax promoter, mutation of the E boxes dramatically reducing the Pea3 transactivation potential. Although Pea3 did not directly bind to the minimal bax promoter, we provide evidence that USF-1 could form a ternary complex with Pea3 and DNA. Taken together, our results suggest that Pea3 may regulate bax transcription via the interaction with USF-1 but without binding to DNA.

Activation of the MDR1 upstream promoter in breast carcinoma as a surrogate for metastatic invasion

PURPOSE

Activation of the MDR1 upstream promoter (USP) has been described previously in four lymphoblastic leukemia patients, where it is the major MDR1 promoter associated with P-glycoprotein overexpression. We asked whether MDR1 USP-derived transcripts were also present in breast carcinoma and assessed their potential as a biomarker.

EXPERIMENTAL DESIGN

We developed a sensitive method for detecting transcripts derived from the MDR1 USP and used it to identify MDR1 USP-derived transcripts in cell model systems, in 61 breast carcinoma biopsies of the primary tumor, and in isolated malignant epithelial cells both from the primary tumor and from the associated invaded lymph nodes.

RESULTS

The MDR1 USP was not active in several independent leukemic and breast cancer cell lines or nucleated peripheral blood cells (n = 9). However, transcripts derived from the MDR1 USP were detected in some drug-resistant cell lines and a high proportion of primary breast tumors (71.6%; n = 61), whereas they were present at low frequency in normal breast tissue (10%; n = 10). Activation of MDR1 USP was not due to chromosomal amplifications or rearrangements at the MDR1 locus. Transcription from the MDR1 USP correlated with metastatic node invasion [N = 0-3 versus N > 3 (N = number of lymph nodes invaded); Fisher's exact test, P = 0.011] and was detected in malignant epithelial cells from the primary tumor and those that metastasized to the lymph nodes.

CONCLUSIONS

MDR1 USP activation is a surrogate marker for breast carcinoma progression and can be used as a marker to study breast cancer susceptibility.

Identification of the protein Zibra, its genomic organization, regulation, and expression in breast cancer cells

The mRNA that encodes zibra (zinc, in-between-ring finger, ubiquitin-associated domain), previously known as hypothetical protein FLJ10111, or RNF31 is expressed in several distinct cancers. Little is known about the genomic organization, expression, or regulation of zibra. Using RNA ligase-mediated rapid amplification of cDNA ends (RLM-RACE), we cloned the full-length zibra cDNA from a transformed breast cell line. We identified a novel exon, the 5' untranslated region including the +1 start site, and three alternatively spliced zibra transcripts. The zibra protein contains three zinc ring-finger motifs, an ubiquitin-associated domain, and an in-between-ring-finger domain, characteristic of ubiquitin ligases. We obtained an antibody to zibra and confirmed the presence of translated zibra protein for the first time. Promoter studies localized a core element responsible for basal activity to a 14-bp region in the 5' untranslated region. Although there are numerous consensus Ets factor binding sites in the zibra promoter, we found no affect on promoter activity from Ets-1, PDEF, or PEA-3/E1A-F. Treatment of cells with the proteasome inhibitor I (PSI) decreased zibra protein to an undetectable level after 8 h. Zibra remained undetectable even after 32 h, while mRNA levels remained essentially unchanged. In conclusion, zibra is a translationally regulated putative ubiquitin ligase that is frequently overexpressed in different forms of cancer.

Concerted Activation of ETS Protein ER81 by p160 Coactivators, the Acetyltransferase p300 and the Receptor Tyrosine Kinase HER2/Neu

Activator of thyroid and retinoic acid receptor (ACTR) is overexpressed in approximately 60% of primary human breast tumors and belongs to the p160 steroid receptor coactivator family. In this study, we identified a novel interaction partner of ACTR, the ETS transcription factor ER81 that is also heavily implicated in mammary tumor formation. ACTR and related p160 family members (steroid receptor coactivator-1 and glucocorticoid receptor-interacting protein-1 (GRIP-1)) augment ER81-mediated transcription. Although ACTR and GRIP-1 can acetylate ER81, this posttranslational modification of ER81 is not required for its stimulation by ACTR or GRIP-1. In addition, ACTR collaborates with the p300 coactivator, a joint interaction partner of ACTR and ER81, to stimulate ER81 function and the ability of p300 to acetylate ER81 is indispensable for this collaboration. Furthermore, the receptor tyrosine kinase HER2/Neu, an oncoprotein particularly found overexpressed in breast tumors, cooperates with both ACTR and p300 to stimulate ER81-mediated transcription. Thus, oncogenic HER2/Neu and ACTR may synergize to orchestrate mammary tumorigenesis through the dysregulation of the transcription factor ER81 and its target genes.

Ets gene PEA3 cooperates with beta-catenin-Lef-1 and c-Jun in regulation of osteopontin transcription

Osteopontin (OPN) is a multifunctional protein implicated in mammary development, neoplastic change, and metastasis. OPN is a target gene for beta-catenin-T cell factor signaling, which is commonly disturbed during mammary oncogenesis, but the understanding of OPN regulation is incomplete. Data base-assisted bioinformatic analysis of the OPN promoter region has revealed the presence of T cell factor-, Ets-, and AP-1-binding motifs. Here we report that beta-catenin, Lef-1, Ets transcription factors, and the AP-1 protein c-Jun each weakly enhanced luciferase expression from a OPN promoter-luciferase reporter construct, transiently transfected into a rat mammary cell line. OPN promoter responsiveness to beta-catenin and Lef-1, however, was considerably enhanced by Ets transcription factors including Ets-1, Ets-2, ERM, and particularly PEA3. PEA3 also enhanced promoter responsiveness to the AP-1 protein c-Jun. Co-transfection of cells with beta-catenin, Lef-1, PEA3, and c-Jun in combination increased luciferase expression by up to 280-fold and induced expression of endogenous rat OPN. In six human breast cell lines, those that highly expressed OPN also expressed PEA3 and Ets-1. Moreover, there was a significant association of immunocytochemical staining for OPN and one of beta-catenin, Ets-1, Ets-2, PEA3, or c-Jun, in the 29 human breast carcinomas tested. This study shows that beta-catenin/Lef-1, Ets, and AP-1 transcription factors can cooperate in a rat mammary cell line in stimulating transcription of OPN and that their independent presence is associated with that of OPN in a group of human breast cancers. These results suggest that the presence of these transcription factors in human breast cancer is responsible in part for the overexpression of OPN that, in turn, is implicated in mammary neoplastic progression and metastasis.

Changes in the expression of many Ets family transcription factors and of potential target genes in normal mammary tissue and tumors

Interfering with Ets transcription factor function reverses multiple aspects of the transformed phenotype of mouse or human tumor cells. However, the unknown number of individual Ets factors expressed in any cellular context and the similar DNA binding specificities of Ets family members complicates the identification of those that mediate transformation. By utilizing quantitative PCR assays for 25 mouse Ets factors, we analyzed the expression of essentially the entire Ets family in normal mammary tissue, mammary-related cell lines, and mammary tumors. In normal mammary tissue, 24 Ets factors were expressed. Even clonal derived cell lines expressed 14-20 Ets members. The most abundant Ets factor mRNAs measured in normal mammary tissue were Elk4, Elf1, and Ets2. Subtractive analysis of mammary tissue identified which Ets factors were predominantly expressed in the myeloid/lymphoid or epithelial cell compartments. Comparison of Ets factor expression in normal mammary tissue and mammary tumors identified significantly elevated expression of Pse/PDEF, Ese2/Elf5, Ese3/Ehf, TEL/Etv6, and Elf2/NERF in mammary tumors and confirmed previously reported alterations in expression of Ese1/Elf3 and the PEA3 subfamily. Expression of 13 Ets target genes, implicated in various aspects of tumor progression, was also analyzed. Altered expression of particular Ets target genes was significantly correlated with particular Ets factors (e.g. maspin and Ese2), suggesting specific in vivo regulatory roles. Together, this comprehensive analysis revealed unexpectedly diverse Ets family gene expression, characterized novel Ets factor changes in mammary tumors, and implicated specific Ets factors in the regulation of multiple genes involved in mammary tumor progression.

HER2/Neu- and TAK1-mediated up-regulation of the transforming growth factor beta inhibitor Smad7 via the ETS protein ER81

The cytokine transforming growth factor beta (TGF-beta) plays an important role in preventing tumor formation by blocking cell cycle progression. Accordingly, many cancers demonstrate mutations in TGF-beta signaling components or enhanced expression of inhibitors of the TGF-beta pathway such as Smad7. In this report we show that the oncoprotein HER2/Neu is able to collaborate with the ETS transcription factor ER81 to activate Smad7 transcription in breast, endometrial, and ovarian cancer cell lines. ER81 binds to two ETS sites within the Smad7 promoter, and mutation of one of these ETS sites greatly decreases Smad7 induction by HER2/Neu and ER81. Furthermore, we show that Smad7 activation involves the processing of signals from HER2/Neu to ER81 via the ERK mitogen-activated protein kinase pathway. Thus, we have uncovered a novel mechanism by which oncogenic HER2/Neu, in collaboration with ER81, can induce carcinogenesis through Smad7 up-regulation. Moreover, we show that TAK1, a TGF-beta-activated protein kinase, stimulates ER81 via the p38 mitogen-activated protein kinase pathway and thereby induces the Smad7 promoter. This suggests that attenuation of TGF-beta signaling by activating Smad7 transcription may proceed not only through TGF-beta receptor-regulated Smad proteins but also through an independent pathway involving ER81 and TAK1.

Role for ETS domain transcription factors Pea3/Erm in mouse lung development

During the development of the mouse lung, the expression of a number of genes, including those encoding growth factors and components of their downstream signaling pathways, is enriched in the epithelium and/or mesenchyme of the distal buds. In this location, they regulate processes such as cell proliferation, branching morphogenesis, and the differentiation of specialized cell types. Here, we report that the expression of Pea3 and Erm (or Etv5, Ets variant gene 5), which encode Pea3 subfamily ETS domain transcription factors, is initially restricted to the distal buds of the developing mouse lung. Erm is transcribed exclusively in the epithelium, while Pea3 is expressed in both epithelium and mesenchyme. Erm/Pea3 are downstream of FGF signaling from the mesenchyme, but their responses toward different FGFs are not the same. The functions of the two proteins were investigated by transgenic expression of a repressor form of Erm specifically in the embryonic lung epithelium. When examined at E18.5, the distal epithelium of transgenic lungs is composed predominantly of immature type II cells, while no mature type I cells are observed. In contrast, the differentiation of proximal epithelial cells, including ciliated cells and Clara cells, appears to be unaffected. A model is proposed for the role of Pea3/Erm during the dynamic process of lung bud outgrowth and proximal-distal differentiation, in response to FGF signaling. Our results provide the first functional evidence that Pea3 subfamily members play a role in epithelial-mesenchymal interactions during lung organogenesis.