Molecular cloning and characterization of PEA3, a new member of the Ets oncogene family that is differentially expressed in mouse embryonic cells

ETV4 is a mechanical transducer linking cell crowding dynamics to lineage specification

Dynamic changes in mechanical microenvironments, such as cell crowding, regulate lineage fates as well as cell proliferation. Although regulatory mechanisms for contact inhibition of proliferation have been extensively studied, it remains unclear how cell crowding induces lineage specification. Here we found that a well-known oncogene, ETS variant transcription factor 4 (ETV4), serves as a molecular transducer that links mechanical microenvironments and gene expression. In a growing epithelium of human embryonic stem cells, cell crowding dynamics is translated into ETV4 expression, serving as a pre-pattern for future lineage fates. A switch-like ETV4 inactivation by cell crowding derepresses the potential for neuroectoderm differentiation in human embryonic stem cell epithelia. Mechanistically, cell crowding inactivates the integrin-actomyosin pathway and blocks the endocytosis of fibroblast growth factor receptors (FGFRs). The disrupted FGFR endocytosis induces a marked decrease in ETV4 protein stability through ERK inactivation. Mathematical modelling demonstrates that the dynamics of cell density in a growing human embryonic stem cell epithelium precisely determines the spatiotemporal ETV4 expression pattern and, consequently, the timing and geometry of lineage development. Our findings suggest that cell crowding dynamics in a stem cell epithelium drives spatiotemporal lineage specification using ETV4 as a key mechanical transducer.

ETV4 facilitates angiogenesis in hepatocellular carcinoma by upregulating MMP14 expression

Abnormal vascularization plays a crucial role in cell proliferation, tumor invasion and metastasis of hepatocellular carcinoma (HCC). It has been reported that ETV4 functions as an oncogenic gene in driving the carcinogenesis and progression, and promoting invasion and metastasis of HCC. However, the function of ETV4 on angiogenesis in HCC remains unclear. In the current study, immunohistochemistry showed that knockdown of ETV4 reduced angiogenesis in HCC xenograft tumor tissues. In vitro, tube formation assay verified that ETV4 expression promoted angiogenesis through simulating the angiogenic environment in HCC cells. Transcriptome sequencing indicated that MMP14 was one of the differentially expressed genes enriched in angiogenesis process. Subsequently, it was confirmed that MMP14 was regulated by ETV4 at the transcription level in HCC cells, clinical tissue samples and online databases. Further, we demonstrated that MMP14 induced angiogenesis in ETV4-mediated HCC microenvironment. Collectively, this research further reveals the biological mechanism of ETV4 in promoting the migration and invasion of HCC, and provides novel mechanistic insights and strategic guidance for anti-angiogenic therapy in HCC.

Distinct Prognostic and Immunological Roles of ETS1 and ETS2: A Pan-Cancer Analysis

Objective

ETS1 and ETS2, the main ETS family of transcription factors, have been found to act as downstream effectors of the RAS/MAPK pathway. This study explores the expression and prognostic values of ETS1 and ETS2 across cancers. We also aimed to explore the significance of ETS1 and ETS2 expression in normal immune cells with relation to tumorigenesis.

Methods

The expression of ETS1 and ETS2 was examined in the HPA and GEPIA2 databases. The KM plotter was applied to examine prognostic value of ETS1 and ETS2. Correlation between ETS1/ETS2 and infiltrating immune cells and immune checkpoints was assessed using TIMER2.0. The mutation landscape of ETS1/ETS2 was explored using the cBioPortal. STRING and GEPIA2 were used to screen ETS1/ETS2 binding and correlated genes. Enrichr was applied to perform GO and KEGG enrichment analyses.

Results

ETS1 showed enhanced expression in lymphoid tissue, while ETS2 showed low tissue specificity. ETS1 was increased in 12 and decreased in 6 cancers, while ETS2 was increased in 4 and decreased in 13 cancers. Both ETS1 and ETS2 were favorable prognostic markers in LIHC and KIRC, while they showed different prognostic roles in more cancers. ETS1 showed stronger correlation with several infiltrating immune cells and immune checkpoints compared with ETS2. Both ETS1 and ETS2 harbored low mutation ratio. ETS1 interacting and correlated genes were enriched in GO terms in response to cadmium ion and response to oxidative stress, while those of ETS2 were enriched in transcription regulation.

Conclusion

ETS1 and ETS2 showed different patterns in expression, prognostic values, correlation with immune infiltrating, and immune checkpoints. ETS1 and ETS2 play distinct roles across cancer.

Oncogenic role and drug sensitivity of ETV4 in human tumors: a pan-cancer analysis

Background

Increasing evidence supports a relationship between E twenty-six variant transcription factor 4 (ETV4) and several cancers, but no pan-cancer analysis has been reported.

Methods

The present study surveyed the effects of ETV4 on cancer using RNA sequencing data obtained from The Cancer Genome Atlas and GTEx, and further explored its role in drug sensitivity using data from Cellminer. Differential expression analyses were conducted for multiple cancers using R software. Cox regression and survival analysis were employed to calculate correlations between ETV4 levels and survival outcomes in multiple cancers using the online tool Sangerbox. ETV4 expression was also compared with immunity, heterogeneity, stemness, mismatch repair genes, and DNA methylation among different cancers.

Results

ETV4 was found to be significantly upregulated in 28 tumors. Upregulation of ETV4 was associated with poor overall survival, progression free interval, disease-free-interval, and disease specific survival in several cancer types. Expression of ETV4 was also remarkably correlated with immune cell infiltration, tumor heterogeneity, mismatch repair gene expression, DNA methylation, and tumor stemness. Furthermore, ETV4 expression seemed to affect sensitivity to a number of anticancer drugs.

Conclusions

These results suggest that ETV4 may be useful as a prognostic factor and therapeutic target.

Transcription factor gene Pea3 regulates erectile function during copulation in mice

Male mice with homozygous loss of function mutations of the transcription factor gene Pea3 (Pea3 null) are infertile due to their inability to inseminate females, however the specific deficits in male sexual behaviors that drive this phenotype are unknown. Here, the copulatory behavior of male mice (Pea3 null and control) with hormonally primed ovariectomized females was monitored via high-speed and high-resolution digital videography to assess for differences in female-directed social behaviors, gross sexual behaviors (mounting, thrusting), and erectile and ejaculatory function. Pea3 null male mice exhibit greatly reduced erectile function, with 44% of males displaying no visible erections during copulation, and 0% achieving sustained erections. As such, Pea3 null males are incapable of intromission and copulatory plug deposition, despite displaying largely normal female-directed social behaviors, mounting behaviors, and ejaculatory grasping behavior. Additionally, the organization and timing of thrusting behaviors is impaired in Pea3 null males. Our results show that the transcription factor gene Pea3 regulates the ability to achieve and maintain erections during copulation in mice.

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.

ETV4 promotes breast cancer cell stemness by activating glycolysis and CXCR4-mediated sonic Hedgehog signaling

Cancer stem cells (CSCs) are a major cause of tumor treatment resistance, relapse and metastasis. Cancer cells exhibit reprogrammed metabolism characterized by aerobic glycolysis, which is also critical for sustaining cancer stemness. However, regulation of cancer cell metabolism rewiring and stemness is not completely understood. Here, we report that ETV4 is a key transcription factor in regulating glycolytic gene expression. ETV4 loss significantly inhibits the expression of HK2, LDHA as well as other glycolytic enzymes, reduces glucose uptake and lactate release in breast cancer cells. In human breast cancer and hepatocellular carcinoma tissues, ETV4 expression is positively correlated with glycolytic signaling. Moreover, we confirm that breast CSCs (BCSCs) are glycolysis-dependent and show that ETV4 is required for BCSC maintenance. ETV4 is enriched in BCSCs, its knockdown and overexpression suppresses and promotes breast cancer cell stem-like traits, respectively. Mechanistically, on the one hand, we find that ETV4 may enhance glycolysis activity to facilitate breast cancer stemness; on the other, ETV4 activates Sonic Hedgehog signaling by transcriptionally promoting CXCR4 expression. A xenograft assay validates the tumor growth-impeding effect and inhibition of CXCR4/SHH/GLI1 signaling cascade after ETV4 depletion. Together, our study highlights the potential roles of ETV4 in promoting cancer cell glycolytic shift and BCSC maintenance and reveals the molecular basis.

Expression of Pea3 protein subfamily members in hippocampus and potential regulation following neuronal stimulation

Pea3 proteins belong to a subfamily of the E-twentysix (ETS) domain superfamily of transcription factors, which play various roles during development. Polyoma Enhancer-Activator 3 (Pea3) proteins Pea3, ERM and Er81 are particularly involved in tissues with branching morphogenesis, including kidney, lung, mammary gland and nervous system development. A recent transcriptomic study on novel targets of Pea3 transcription factor revealed various axon guidance and nervous system development related targets, supporting a role of Pea3 proteins in motor neuron connectivity, as well as novel targets in signaling pathways involved in synaptic plasticity. This study focuses on the expression of Pea3 family members in hippocampal neurons, and regulation of putative Pea3 targets in Pea3-overexpressing cell lines and following induction of long-term potentiation or seizure in vivo. We show that Pea3 proteins are expressed in hippocampus in both neuronal and non-neuronal cells, and that Pea3 represses Elk-1 but activates Prkca and Nrcam expression in hippocampal cell lines. We also show that mRNA and protein levels of Pea3 family members are differentially regulated in the dentate gyrus and CA1 region upon MECS stimulation, but not upon LTP induction.

The ETS family of oncogenic transcription factors in solid tumours

Findings over the past decade have identified aberrant activation of the ETS transcription factor family throughout all stages of tumorigenesis. Specifically in solid tumours, gene rearrangement and amplification, feed-forward growth factor signalling loops, formation of gain-of-function co-regulatory complexes and novel cis-acting mutations in ETS target gene promoters can result in increased ETS activity. In turn, pro-oncogenic ETS signalling enhances tumorigenesis through a broad mechanistic toolbox that includes lineage specification and self-renewal, DNA damage and genome instability, epigenetics and metabolism. This Review discusses these different mechanisms of ETS activation and subsequent oncogenic implications, as well as the clinical utility of ETS factors.

ETS-targeted therapy: can it substitute for MEK inhibitors?

BACKGROUND

The RAS/MAPK pathway has been intensively studied in cancer. Constitutive activation of ERK1 and ERK2 is frequently found in cancer cells from a variety of tissues. In clinical practice and clinical trials, small molecules targeting receptor tyrosine kinases or components in the MAPK cascade are used for treatment. MEK1 and MEK2 are ideal targets because these enzymes are physiologically important and have narrow substrate specificities and distinctive structural characteristics. Despite success in pre-clinical testing, only two MEK inhibitors, trametinib and cobimetinib, have been approved, both for treatment of BRAF-mutant melanoma. Surprisingly, the efficacy of MEK inhibitors in other tumors has been disappointing. These facts suggest the need for a different approach. We here consider transcription factor ETS1 and ETS2 as alternate therapeutic targets because they are major MAPK downstream effectors.

MAIN TEXT

The lack of clinical efficacy of MEK inhibitors is attributed mostly to a subsequent loss of negative feedback regulation in the MAPK pathway. To overcome this obstacle, second-generation MEK inhibitors, so-called "feedback busters," have been developed. However, their efficacy is still unsatisfactory in the majority of cancers. To substitute ETS-targeted therapy, therapeutic strategies to modulate the transcription factor in cancer must be considered. Chemical targeting of ETS1 for proteolysis is a promising strategy; Src and USP9X inhibitors might achieve this by accelerating ETS1 protein turnover. Targeting the ETS1 interface might have great therapeutic value because ETS1 dimerizes itself or with other transcription factors to regulate target genes. In addition, transcriptional cofactors, including CBP/p300 and BRD4, represent intriguing targets for both ETS1 and ETS2.

CONCLUSIONS

ETS-targeted therapy appears to be promising. However, it may have a potential problem. It might inhibit autoregulatory negative feedback loops in the MAPK pathway, with consequent resistance to cell death by ERK1 and ERK2 activation. Further research is warranted to explore clinically applicable ways to inhibit ETS1 and ETS2.

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.

Evaluation of ETV4 and WT1 expression in CIC-rearranged sarcomas and histologic mimics

A distinct subset of round cell sarcomas harbors capicua transcriptional repressor (CIC) rearrangement. Diagnosing these sarcomas can be difficult owing to their resemblance to Ewing sarcoma and other 'small round blue cell tumors'; molecular techniques are generally required. Recent gene expression studies of CIC-rearranged sarcomas identified the upregulation of ETV4. We assessed the sensitivity and specificity of ETV4 and WT1 immunohistochemistry for CIC-rearranged sarcoma. We evaluated whole-tissue sections from 40 CIC-rearranged sarcomas, 40 Ewing sarcomas, 4 BCOR-CCNB3 sarcomas, 6 unclassified round cell sarcomas, and 150 histologic mimics. Moderate-to-strong nuclear immunoreactivity for ETV4 in at least 50% of cells was observed in 36 (90%) CIC-rearranged sarcomas and 10 (5%) other tumors, including 5 unclassified round cell sarcomas, 2 Wilms tumors, and 1 each desmoplastic small round cell tumor, melanoma, and small cell carcinoma. Thirty-eight (95%) CIC-rearranged sarcomas showed nuclear staining for WT1, and 34 (85%) were positive for both ETV4 and WT1. Of 182 other tumors evaluated, 34 (19%) showed nuclear WT1 positivity, including all Wilms tumors and desmoplastic small round cell tumors, 5 unclassified round cell sarcomas, and a subset of lymphoblastic lymphomas, rhabdomyosarcomas, mesenchymal chondrosarcomas, carcinomas, and melanomas. In summary, diffuse moderate-to-strong ETV4 expression is present in most CIC-rearranged sarcomas and unclassified round cell sarcomas. More limited expression is seen in small subsets of various other round cell neoplasms. Nuclear WT1 expression is also present in most CIC-rearranged sarcomas and unclassified round cell sarcomas, along with Wilms tumors and desmoplastic small round cell tumors, and subsets of various histologic mimics. The sensitivity and specificity of diffuse ETV4 expression for CIC-rearranged sarcomas are 90% and 95%, respectively, whereas the sensitivity and specificity of WT1 are 95% and 81%, respectively. Diffuse ETV4 along with at least focal WT1 expression is helpful to distinguish CIC-rearranged sarcoma from Ewing sarcoma and other histologic mimics.

Regulation of the pannexin-1 promoter in the rat epididymis

Pannexins (PANXs) are channel-forming proteins implicated in cellular communication through the secretion of biomolecules, such as ATP and glutamate. PANX1 and PANX3 are expressed in the male rat reproductive tract and their levels are regulated by androgens in the epididymis. There is currently no information on the regulation of the Panx1 promoter. The objective of the present study was to characterize the Panx1 promoter in order to understand its regulation in the epididymis. RNA ligase-mediated rapid amplification of cDNA ends identified three transcriptional start sites, at positions -443, -429, and -393. In silico analysis revealed that transcription was initiated downstream of binding sites for CREB and ETV4 transcription factors, in a CpG island context. To determine the importance of this region in gene transactivation, a 2-kb fragment of the promoter was cloned into a vector containing a luciferase reporter gene. Deletion constructs indicated that the highest transactivation levels were achieved with shorter constructs (-973 to -346 and -550 to -346). Electrophoretic mobility shift assay and supershifts indicated that both transcription factors were able to bind to the promoter region. Chromatin immunoprecipitation using rat caput epididymis cells confirmed the binding of ETV4 and CREB on the Panx1 promoter. Site mutation of either the ETV4 or CREB binding site decreased the transactivation of the reporter gene. Previous studies indicated that orchidectomy increased epididymal PANX1 levels. Likewise, we observed an increase in both ETV4 and CREB in orchidectomized rats. These results indicate that ETV4 and cAMP response elements play a role in the transcriptional regulation of Panx1 in the epididymis.

Transcriptional activation of OCT4 by the ETS transcription factor PEA3 in NCCIT human embryonic carcinoma cells

We examined the molecular mechanism of OCT4 gene regulation by polyomavirus enhancer activator 3 (PEA3) in NCCIT cells. Endogenous PEA3 and OCT4 were significantly elevated in undifferentiated cells and reduced upon differentiation. PEA3 knockdown led to a reduction in OCT4 levels. OCT4 promoter activity was significantly up-regulated by dose-dependent PEA3 overexpression. Deletion and site-directed mutagenesis of the OCT4 promoter revealed a putative binding site within the conserved region 2 (CR2). PEA3 interacted with the binding element within CR2 in NCCIT cells. This study reveals the molecular details of the mechanism by which the oncogenic factor PEA3 regulates OCT4 gene expression as a transcriptional activator.

Pea3 transcription factor promotes neurite outgrowth

Pea3 subfamily of E–twenty six transcription factors consist of three major -exhibit branching morphogenesis, the function of Pea3 family in nervous system development and regeneration is only beginning to unfold. In this study, we provide evidence that Pea3 can directs neurite extension and axonal outgrowth in different model systems, and that Serine 90 is important for this function. We have also identified neurofilament-L and neurofilament-M as two putative novel targets for Pea3.

Impaired c-src activation and motility defects in PEA3-null fibroblasts

Null mutations in the pea3 allele compromise the capacity of mammary tumors to metastasize in MMTV-Neu/ErbB2/HER2 transgenic mice, indicating a motility defect in PEA3-null cells. Cellular and biochemical analyses of established PEA3-null fibroblasts show impaired motility and aberrant localization of adhesion proteins in spreading cells. Our results show that PEA3-/- cells express normal levels of key adhesion components, but that spreading PEA3-null cells fail to activate c-src and to downregulate phospho-FAK(Y397), suggesting that focal adhesion signaling is impaired. Supporting this, biochemical analysis revealed that adhesion complex-associated proteins such as p130Cas failed to undergo tyrosine phosphorylation and dissociated from the adhesion complex with delayed kinetics. Overall our data show that the motility defects observed in PEA3-null cells are due to altered adhesion signaling.

Etv5, a transcription factor with versatile functions in male reproduction

Transcription factors govern diverse aspects of cell growth and differentiation as major switches of gene expression. Etv5, a member of the E26 transformation-specific family of transcription factors, has many stories to share when it comes to reproduction. Etv5 deficient mice show complex infertility phenotypes both in males and females. In males, the infertility phenotype exhibited by Etv5 deficiency is sexually dimorphic, and it involves both somatic cells and germ cells. In Etv5^-/- female mice, the problem is more complicated by hormonal involvement. This review synthesizes old and new information on this versatile transcription factor-from the inadvertent discovery of its role in the testes to its newly discovered role in maintaining spermatogonial stem cells.

RAS/ERK pathway transcriptional regulation through ETS/AP-1 binding sites

The RAS/RAF/MEK/ERK signaling pathway is activated by mutation in many cancers. Neighboring ETS and AP-1 DNA binding sequences can act as response elements for transcriptional activation by this pathway. ERK phosphorylation of an ETS transcription factor is one mechanism of activating the RAS/ERK gene expression program that can promote cancer cell phenotypes such as proliferation, invasion, and metastasis. Recent genome-wide mapping of ETS proteins over-expressed by chromosomal rearrangement in prostate cancer reveals a second mechanism for activation of this gene expression program. An oncogenic subset of ETS transcription factors can activate RAS/ERK target genes even in the absence of RAS/ERK pathway activation by binding ETS/AP-1 sequences. Thus, regulation of cancer cell invasion and metastasis via ETS/AP-1 sequence elements depends on which ETS protein is bound, and the status of the RAS/ERK pathway. This commentary will focus on what is known about the selectivity of ETS/AP-1 sequences for different ETS transcription factors and the transcriptional consequences of ETS protein selection.

Opposing functions of the ETS factor family define Shh spatial expression in limb buds and underlie polydactyly

Sonic hedgehog (Shh) expression during limb development is crucial for specifying the identity and number of digits. The spatial pattern of Shh expression is restricted to a region called the zone of polarizing activity (ZPA), and this expression is controlled from a long distance by the cis-regulator ZRS. Here, members of two groups of ETS transcription factors are shown to act directly at the ZRS mediating a differential effect on Shh, defining its spatial expression pattern. Occupancy at multiple GABPα/ETS1 sites regulates the position of the ZPA boundary, whereas ETV4/ETV5 binding restricts expression outside the ZPA. The ETS gene family is therefore attributed with specifying the boundaries of the classical ZPA. Two point mutations within the ZRS change the profile of ETS binding and activate Shh expression at an ectopic site in the limb bud. These molecular changes define a pathogenetic mechanism that leads to preaxial polydactyly (PPD).

ETV1, 4 and 5: an oncogenic subfamily of ETS transcription factors

The homologous ETV1, ETV4 and ETV5 proteins form the PEA3 subfamily of ETS transcription factors. In Ewing tumors, chromosomal translocations affecting ETV1 or ETV4 are an underlying cause of carcinogenesis. Likewise, chromosomal rearrangements of the ETV1, ETV4 or ETV5 gene occur in prostate tumors and are thought to be one of the major driving forces in the genesis of prostate cancer. In addition, these three ETS proteins are implicated in melanomas, breast and other types of cancer. Complex posttranslational modifications govern the activity of PEA3 factors, which can promote cell proliferation, motility and invasion. Here, we review evidence for a role of ETV1, 4 and 5 as oncoproteins and describe modes of their action. Modulation of their activation or interaction with cofactors as well as inhibiting crucial target gene products may ultimately be exploited to treat various cancers that are dependent on the PEA3 group of ETS transcription factors.

Synthetic transactivation screening reveals ETV4 as broad coactivator of hypoxia-inducible factor signaling

The human prolyl-4-hydroxylase domain (PHD) proteins 1–3 are known as cellular oxygen sensors, acting via the degradation of hypoxia-inducible factor (HIF) α-subunits. PHD2 and PHD3 genes are inducible by HIFs themselves, suggesting a negative feedback loop that involves PHD abundance. To identify novel regulators of the PHD2 gene, an expression array of 704 transcription factors was screened by a method that allows distinguishing between HIF-dependent and HIF-independent promoter regulation. Among others, the E-twenty six transcription factor ETS translocation variant 4 (ETV4) was found to contribute to PHD2 gene expression particularly under hypoxic conditions. Mechanistically, complex formation between ETV4 and HIF-1/2α was observed by mammalian two-hybrid and fluorescence resonance energy transfer analysis. HIF-1α domain mapping, CITED2 overexpression and factor inhibiting HIF depletion experiments provided evidence for cooperation between HIF-1α and p300/CBP in ETV4 binding. Chromatin immunoprecipitation confirmed ETV4 and HIF-1α corecruitment to the PHD2 promoter. Of 608 hypoxically induced transcripts found by genome-wide expression profiling, 7.7% required ETV4 for efficient hypoxic induction, suggesting a broad role of ETV4 in hypoxic gene regulation. Endogenous ETV4 highly correlated with PHD2, HIF-1/2α and several established markers of tissue hypoxia in 282 human breast cancer tissue samples, corroborating a functional interplay between the ETV4 and HIF pathways.

High prevalence of CIC fusion with double-homeobox (DUX4) transcription factors in EWSR1-negative undifferentiated small blue round cell sarcomas

Primitive round cell sarcomas of childhood and young adults have been problematic to diagnose and classify. Our goal was to investigate the pathologic and molecular characteristics of small blue round cell tumors (SBRCT) that remained unclassified after exhaustive immunohistochemistry and molecular screening to exclude known sarcoma-related translocations. As rare examples of EWSR1-negative SBRCT have been shown to carry rearrangements for FUS and CIC genes, we undertook a systematic screening for these two genes. CIC rearrangements by FISH were detected in 15/22 (68%), while none showed FUS abnormalities. RACE, RT-PCR, and/or long-range DNA PCR performed in two cases with frozen material showed that CIC was fused to copies of the DUX4 gene on either 4q35 or 10q26.3. Subsequent FISH analysis confirmed fused signals of CIC with either 4q35 or 10q26.3 region in six cases each. Tumors positive for CIC-DUX4 fusion occurred mainly in male young adult patients (median age: 29 years), with the extremities being the most frequent location. Microscopically, tumors displayed a primitive, round to oval cell morphology with prominent nucleoli, high mitotic count, and areas of necrosis. O13 expression was variable, being either diffuse or patchy and tumors mostly lacked other markers of differentiation. Although CIC-DUX4 resulting in a t(4;19) translocation has been previously described in primitive sarcomas, this is the first report implicating the related DUX4 on 10q26 in oncogenesis. These results suggest the possibility of a newly defined subgroup of primitive round cell sarcomas characterized by CIC rearrangements, distinct from Ewing sarcoma family of tumors.

PEA3 activates CXCR4 transcription in MDA-MB-231 and MCF7 breast cancer cells

CXC chemokine receptor 4 (CXCR4) is a cell surface receptor that has been shown to mediate the metastasis of many solid tumors including lung, breast, kidney, and prostate tumors. In this study, we found that overexpression of ets variant gene 4 (PEA3) could elevate CXCR4 mRNA level and CXCR4 promoter activity in human MDA-MB-231 and MCF-7 breast cancer cells. PEA3 promoted CXCR4 expression and breast cancer metastasis. Chromatin immunoprecipitation assay demonstrated that PEA3 could bind to the CXCR4 promoter in the cells transfected with PEA3 expression vector. PEA3 siRNA attenuated CXCR4 promoter activity and the binding of PEA3 to the CXCR4 promoter in MDA-MB-231 and MCF-7 cells. These results indicated that PEA3 could activate CXCR4 promoter transcription and promote breast cancer metastasis.

Detection of EWS/FLI-1 by Immunostaining. An Adjunctive Tool in Diagnosis of Ewing's Sarcoma and Primitive Neuroectodermal Tumour on Cytological Samples and Paraffin-Embedded Archival Material

Purpose. Recently we showed that the 68-kDa fusion protein derived from the EWS/FLI1 hybrid gene can be specifically detected by Western blotting using a polyclonal antibody to the C-terminal of FLI1 on biopsy material from Ewing's sarcoma. The aim of this study was to investigate whether this antibody also could be used for immunocytochemistry and immunohistochemistry in diagnosis of Ewing's sarcoma.

Methods. Immunostaining on paraffin-embedded archival material, fine-needle aspirates and tumour touch imprints from Ewing's sarcomas and primitive neuroectodermal tumours (PNET) for detection of the fusion protein was performed. Most cases were also analysed by Western blotting.Tumours of differential diagnostic importance were also included.

Results. Eighty per cent (12/15 cases) of the Ewing tumours exhibited a positive immunoreactivity for the FLI1 antibody. The signal was mainly localised in the nuclei of the tumour cells, which seems reasonable since EWS/FLI1 is a transcription factor. The signal was found to be specific since it did not appear when the blocking peptide was added to the antibody solution.Moreover, two other types of small-round cell tumours (i.e. neuroblastoma and alveolar rhabdomyosarcoma) were negative as well as most normal tissues.

Discussion. Immunostaining of histological and cytological specimens with the FLI1 antibody can be of diagnostic relevance in Ewing tumours carrying t(11;22).The absence of immunoreactivity in non-Ewing cells is most likely due to a low expression of the wild-type FLI1 protein.

Dynamic modification of the ETS transcription factor PEA3 by sumoylation and p300-mediated acetylation

Transcription factor activity is often controlled through the dynamic use of post-translational modifications. Two such modifications are acetylation and sumoylation, which both occur on lysine residues, providing the opportunity for cross-talk at the molecular level. Here, we focussed on the ETS-domain transcription factor PEA3 and studied the potential interplay between these two modifications. We demonstrate that PEA3 is acetylated in a p300-dependent manner. ERK MAPK pathway signalling potentiates acetylation of PEA3, and enhances its trans-activation capacity. However, the major acetylation and sumoylation events take place on the same sites in PEA3 making simultaneous modification impossible. Indeed, manipulation of either the sumoylation or acetylation pathways causes reciprocal changes in PEA3 acetylation and sumoylation respectively. However, despite the mutually exclusive nature of these modifications, both contribute to the trans-activation capacity of PEA3, implying that a dynamic series of modification events occurs during the activation process.

Expression and function of the Ets transcription factor pea3 during formation of zebrafish pronephros

Polyomavirus enhancer activator 3 (Pea3), belonging to the PEA3 subfamily of Ets transcription factors, is essential for certain organogenesis in mammals. Previously, we found that pea3 correlated with wt1 expression and may contribute to nephrogenesis in rats. Here, we observed that pea3 was mainly expressed in the zebrafish pronephric glomerulus. We further performed functional analyses by in situ hybridization of pea3 in zebrafish embryos after pea3 messenger RNA (mRNA) overexpression and inhibition of double-target genes (pea3 and erm, another member of the PEA3 subfamily) by antisense morpholino-oligonucleotides (MO). Overexpression of pea3 induced abnormal pronephrogenesis. However, MO-pea3 coinjected with MO-erm, but not alone, inhibited zebrafish pronephros development, and these defects were rescued by overexpression of the zebrafish wt1a gene. Thus, pea3 and erm are required for zebrafish pronephrogenesis and can functionally complement each other, and the wt1a gene may be one of their downstream targets.

Involvement of MyoD and PEA3 in regulation of transcription activity of MDR1 gene

Overexpression of multidrug resistance 1 (MDR1) in cancer remains one of the major causes for the failure of chemotherapy. In the present study, we found that MyoD and PEA3 could activate P-glycoprotein (P-gp) expression in SGC7901 cells. Knockdown of MyoD and PEA3 attenuated MDR1 expression and increased the sensitivity of multidrug resistant cancer cells to cytotoxic drugs that were transported by P-gp in SGC7901/VCR cells. MyoD or PEA3 could bind to the E-box and PEA3 sites on the MDR1 promoter and activate its transcription. The regulation of MDR1 expression by MyoD and PEA3 may provide potential ways to overcome MDR in cancer treatment.

Pea3 transcription factors and wnt1-induced mouse mammary neoplasia

The role of the PEA3 subfamily of Ets transcription factors in breast neoplasia is controversial. Although overexpression of PEA3 (E1AF/ETV4), and of the related factors ERM (ETV5) and ER81 (ETV1), have been observed in human and mouse breast tumors, PEA3 factors have also been ascribed a tumor suppressor function. Here, we utilized the MMTV/Wnt1 mouse strain to further interrogate the role of PEA3 transcription factors in mammary tumorigenesis based on our previous observation that Pea3 is highly expressed in MMTV/Wnt1 mammary tumors. Pea3 expression in mouse mammary tissues was visualized using a Pea3^NLSlacZ reporter strain. In normal mammary glands, Pea3 expression is predominantly confined to myoepithelial cells. Wnt1 transgene expression induced marked amplification of this cell compartment in nontumorous mammary glands, accompanied by an apparent increase in Pea3 expression. The pattern of Pea3 expression in MMTV/Wnt1 mammary glands recapitulated the cellular profile of activated β-catenin/TCF signaling, which was visualized using both β-catenin immunohistochemistry and the β-catenin/TCF-responsive reporter Axin2^NLSlacZ. To test the requirement for PEA3 factors in Wnt1-induced tumorigenesis, we employed a mammary-targeted dominant negative PEA3 transgene, ΔNPEA3En. Expression of ΔNPEA3En delayed early-onset tumor formation in MMTV/Wnt1 virgin females (P = 0.03), suggesting a requirement for PEA3 factor function for Wnt1-driven tumor formation. Consistent with this observation, expression of the ΔNPEA3En transgene was profoundly reduced in mammary tumors compared to nontumorous mammary glands from bigenic MMTV/Wnt1, MMTV/ΔNPEA3En mice (P = 0.01). Our data provide the first description of Wnt1-mediated expansion of the Pea3-expressing myoepithelial compartment in nontumorous mammary glands. Consistent with this observation, mammary myoepithelium was selectively responsive to Wnt1. Together these data suggest the MMTV/Wnt1 strain as a potential model of basal breast cancer. Furthermore, this study provides evidence for a protumorigenic role of PEA3 factors in breast neoplasia, and supports targeting the PEA3 transcription factor family in breast cancer.

PEA3 activates VEGF transcription in T47D and SKBR3 breast cancer cells

Vascular endothelial growth factor (VEGF) is a potent stimulator of angiogenesis and a prognostic factor for many tumors, including those of endocrine-responsive tissues such as the breast and uterus. In this study, we found that overexpression of PEA3 could increase VEGF mRNA levels and VEGF promoter activity in human T47D and SKBR3 breast cancer cells. Chromatin immunoprecipitation assay demonstrated that PEA3 could bind to the VEGF promoter in the cells transfected with PEA3 expression vector. PEA3 small interfering RNA attenuated VEGF promoter activity and the binding of PEA3 to the VEGF promoter in T47D and SKBR3 cells. These results indicated that PEA3 could activate VEGF promoter transcription.

Small DNA tumour viruses and their contributions to our understanding of transcription control

The study of small DNA tumour viruses like SV40 and polyoma was one of the major entry points for the study of eukaryotes. It opened fields like gene structure, transcription or replication control, chromatin structure and cell transformation. This review outlines the breakthroughs that occurred at the end of the 1970s and during the 1980s in our understanding of gene structure and the basic processes involved in control of gene expression starting with DNA tumour viruses and reaching their cellular hosts. These developments were made possible by concomitant advances in the isolation of restriction enzymes, developing DNA sequencing protocols, DNA cloning, DNA transfections, in vitro transcription systems and isolation of sequence specific DNA binding protein among others. The conceptual and methodological advances that resulted from the studies of small DNA tumour viruses opened the era for the study of host genomes far more complex, culminating with the establishment of the sequence and a functional map of the human genome.

The Pea3 Ets transcription factor regulates differentiation of multipotent progenitor cells during mammary gland development

The Pea3 Ets transcription factor is overexpressed in breast tumors suggesting that it plays a role in mammary oncogenesis. However, the normal biological function of Pea3 in the mammary gland is not known. Here we report that Pea3 was expressed in the epithelium of the mouse mammary anlagen commensurate with their genesis, and at later times in the nipple and mammary ducts of female embryos. In adult mice Pea3 transcripts peaked at the onset of puberty and early pregnancy, times of active epithelial cell proliferation and differentiation. Pea3 was expressed in all progenitor cap cells and rare body cells of terminal end buds, and in the myoepithelial cells of ducts and alveoli. Analyses of the mammary glands of Pea3-null mice during puberty revealed an increased number of terminal end buds and an increased fraction of proliferating progenitor cells within these structures compared to their wild type littermates. Tissue transplant experiments demonstrated that these phenotypes were intrinsic to the Pea3-null mammary epithelium. During pregnancy, mammary glands isolated from Pea3-null females had impaired alveolar development as revealed by a decreased fraction of alveolar structures. We performed in vitro colony forming assays of mammary epithelial cells and discovered that loss of Pea3 altered the distribution of specific multipotent progenitor cells. Double-immunofluorescence confirmed that multipotential progenitors co-expressing markers of the myoepithelial and luminal epithelial lineage were amplified in the mammary glands of Pea3-null mice by comparison to their wild type counterparts. We propose that Pea3 functions in multipotential progenitors to regulate their lineage-specific differentiation potential.

Polyomavirus middle T antigen induces the transcription of osteopontin, a gene important for the migration of transformed cells

Middle T antigen (MT) is the principal oncoprotein of murine polyomavirus. Experiments on the acute immediate effects of MT expression on cellular RNA levels showed that expression of osteopontin (OPN) was strongly induced by MT expression. Osteopontin is a protein known to be associated with cancer. It has a role in tumor progression and invasion. Protein analysis confirmed that MT induced the secretion of OPN into the extracellular medium. Expression of antisense OPN RNA had no effect on the growth of MT-transformed cells. However, it had a strong effect on the ability of MT transformants to migrate or to fill a wound. Analysis of MT mutants implicated both the SHC and phosphatidylinositol 3-kinase pathways in OPN induction. Reporter assays showed that MT regulated the OPN promoter through two of its PEA3 (polyoma enhancer activator 3) sites. As critical PEA3 sites are also part of the polyomavirus enhancer, the same signaling important for viral replication also contributes to virally induced metastatic potential.

Bfk, a novel member of the bcl2 gene family, is highly expressed in principal cells of the mouse epididymis and demonstrates a predominant nuclear localization

B-cell lymphoma 2 (BCL2) family kin (BFK) is a recently identified novel protein that is similar to proteins of the BCL2 family. In the present study, we discovered that the mouse Bfk transcript is expressed at the highest level in the epididymis. Two transcripts of 0.9 and 2.6 kb in size were identified, with alternative exon 4 structures, resulting in a difference in the last three to five amino acids of the variants. However, the 0.9-kb transcript was found to be the predominant form in the epididymis and mammary gland, another tissue with strong Bfk expression. Epididymal Bfk expression was regulated both by androgens and other testicular factors. It is thus one of the few initial-segment enriched genes under androgen control, the majority of them being regulated by other testicular factors. BFK protein was expressed specifically in the principal cells of the epididymis. Its nuclear localization was evident in the initial segment and caput epididymis and in the epithelium of pregnant female mammary gland. The expression of BFK-enhanced green fluorescent protein recombinant protein in epididymal cells further confirmed the predominant nuclear localization of BFK with nucleo-cytoplasmic shuttling. Overexpressing BFK in epididymal cells did not induce apoptosis. However, enhanced caspase 3 activation was observed in the presence of BFK upon staurosporine-induced apoptosis. This suggests that BFK may have a proapoptotic role only after the process has been initiated by other mechanisms. Being exceptionally highly expressed in the initial segment, Bfk is suggested to have a role in the differentiation of this segment of the epididymis.

Repression of E1AF transcriptional activity by sumoylation and PIASy

E1AF is a member of the Ets transcriptional factor family, and it plays a crucial role in tumor metastasis. However, the molecular mechanisms regulating its activity are not well characterized. In this study, we show that E1AF is sumoylated at four lysine residues, both in vivo and in vitro. Replacement of these lysines by arginine enhanced the transcriptional activity of E1AF, suggesting that sumoylation negatively regulates E1AF activity. We further demonstrated that PIASy enhanced sumoylation of E1AF as a specific SUMO-E3 ligase. In addition, PIASy repressed the transcriptional activity of both the wild-type and sumoylation defective mutants. However, the C342A mutant of PIASy, which abrogates SUMO-E3 ligase activity, had a significantly decreased ability to repress E1AF activity. Taken together, our results indicate that PIASy negatively regulates E1AF-mediated transcription by both E1AF sumoylation in a dependent and independent fashion.

Involvement of the oncoprotein c-Myc in viral telomerase RNA gene regulation during Marek's disease virus-induced lymphomagenesis

Marek's disease virus (MDV) is an alphaherpesvirus that induces a highly malignant T-lymphoma in chickens. The viral genome encodes two identical copies of a viral telomerase RNA subunit (vTR) that exhibits 88% sequence identity to its chicken ortholog chTR. The minimal telomerase ribonucleoprotein complex consists of a protein subunit with reverse transcriptase activity (TERT) and an RNA subunit (TR). The active complex compensates for the progressive telomere shortening that occurs during mitosis and is involved in the cell immortalization process. We show here that the upregulation of telomerase activity is associated with an increase in vTR gene expression in chickens infected with the highly oncogenic MDV strain RB-1B. A comparative functional analysis of the viral and chicken TR promoters, based on luciferase reporter assays, revealed that the vTR promoter was up to threefold more efficient than the chTR promoter in avian cells. We demonstrated, by directed mutagenesis of the vTR promoter region, that the stronger transcriptional activity of the vTR promoter resulted largely from an E-box located two nucleotides downstream from the transcriptional start site of the vTR gene. Furthermore, transactivation assays and chromatin immunoprecipitation assays demonstrated the involvement of the c-Myc oncoprotein in the transcriptional regulation of vTR. Finally, an Ets binding site was specifically implicated in the transcriptional regulation of vTR in the MDV-transformed lymphoblastoid cell line MSB-1.

Adenovirus E1A negatively regulates E1AF, an ets family of the protein

E1AF was first identified as a transcription factor that binds to enhancer motifs of the adenovirus E1A gene and is thought to be a human homologue of mouse PEA3, one of the ets oncoprotein families. Here we show the effect of E1A on the gene expression and function of E1AF. E1A repressed the activity of E1AF promoter, and the N-terminal region of E1A, which is involved in the oncogenic activity of E1A, was essential for this repression. The ability as a transcription factor of E1AF, as well as those of the other PEA3 subfamily members ER81 and ERM, was also repressed by E1A via the same oncogenic domain. Furthermore, E1AF repressed the transformation activity of E1A cooperating with E1B, whereas the other ets family Ets-1 enhanced this activity. These results suggest that E1AF is one of the targets of E1A.

Antitumor activity of an Ets protein, PEA3, in breast cancer cell lines MDA-MB-361DYT2 and BT474M1

Polyomavirus enhancer activator 3 (PEA3) is a member of the Ets family of transcription factors. We demonstrated in a previous study that, by downregulating the HER-2/neu oncogene at the transcriptional level, PEA3 can inhibit the growth and development into tumors of HER-2/neu-overexpressing ovarian cancer cells. Here, we establish stable clones of the human breast cancer cell line MDA-MB-361DYT2 that express PEA3 under the control of a tetracycline-inducible promoter. Ectopic expression of PEA3 in this cell line inhibited cell growth and resulted in cell cycle accumulation in the G1 phase. We demonstrate that expression of PEA3 in an orthotopic breast cancer model inhibited tumor growth and prolonged the survival of tumor-bearing mice. In a parallel experiment with another breast cancer cell line, BT474M1, we were unable to obtain stable PEA3-inducible transfectants, suggesting that PEA3 may exert a strong growth inhibition effect in this cell line. Indeed, PEA3 coupled with the liposome SN2 demonstrated therapeutic effects in mice bearing tumors induced by BT474M1. These results provide evidence for the antitumor activity of PEA3 in human breast cancers.

HOXBES2: a novel epididymal HOXB2 homeoprotein and its domain-specific association with spermatozoa

The sperm from the testis acquires complete fertilizing ability and forward progressive motility following its transit through the epididymis. Acquisition of these characteristics results from the modification of the sperm proteome following interactions with epididymal secretions. In our attempts to identify epididymis-specific sperm plasma membrane proteins, a partial 2.83-kb clone was identified by immunoscreening a monkey epididymal cDNA library with an agglutinating monoclonal antibody raised against washed human spermatozoa. The sequence of the 2.83-kb clone exhibited homology to the region between 1 and 1097 bp of the homeobox gene, Hoxb2. This sequence was found to be species conserved, as revealed by RT-PCR analysis. To obtain a full-length clone of the sequence, 5' RACE-PCR (rapid amplification of cDNA ends PCR) was carried out using rat epididymal RNA as the template. It resulted in a full-length 1.657-kb cDNA encoding a 32.9-kDa putative protein. The protein designated HOXBES2 exhibited homology to the conserved 61-amino acid homeodomain region of the HOXB2 homeoprotein. However, characteristic differences were noted in its amino and carboxyl termini compared with HOXB2. A putative 30-kDa protein was detected in the tissue extracts from adult rat epididymis and caudal spermatozoa, and a 37-kDa protein was detected in the rat embryo when probed with a polyclonal antibody against HOXB2 protein. Multiple tissue Western blot and immunohistochemical analysis further indicated its expression in the cytoplasm of the principal and basal epithelial cells, with maximal expression in the distal epididymal segments. Northern blot analysis detected a single approximately 2.5-kb transcript from the adult epididymis. Indirect immunofluorescence localized the protein to the acrosome, midpiece, and equatorial segments of rat caudal and ejaculated human and monkey spermatozoa, respectively. In conclusion, we have identified and characterized a novel epididymal homeoprotein different from HOXB2 protein and hereafter referred to as HOXBES2, (HOXB2 homeodomain containing epididymis-specific sperm protein) with a probable role in fertilization.

A positive role for PEA3 in HER2-mediated breast tumour progression

Overexpression of HER2 is associated with an adverse prognosis in breast cancer. Despite this, the mechanism of its transcriptional regulation remains poorly understood. PEA3, a MAP kinase (MAPK)-activated member of the Ets transcription factor family has been implicated in the transcriptional regulation of HER2. The direction of its modulation remains controversial. We assessed relative levels of PEA3 expression and DNA binding in primary breast cultures derived from patient tumours (n=18) in the presence of an activated MAPK pathway using Western blotting and shift analysis. Expression of PEA3 in breast tumours from patients of known HER2 status (n=107) was examined by immunohistochemistry. In primary breast cancer cell cultures, growth factors induced interaction between PEA3 and its DNA response element. Upregulation of PEA3 expression in the presence of growth factors associated with HER2 positivity and axillary lymph node metastasis (P=0.034 and 0.049, respectively). PEA3 expression in breast cancer tissue associated with reduced disease-free survival (P<0.001), Grade III tumours (P<0.0001) and axillary lymph node metastasis (P=0.026). Co-expression of PEA3 and HER2 significantly associated with rate of recurrence compared to patients who expressed HER2 alone (P=0.0039). These data support a positive role for PEA3 in HER2-mediated oncogenesis in breast cancer.

Expression of PEA3 and lack of correlation between PEA3 and HER-2/neu expression in breast cancer

The ETS protein PEA3 functions as a transcription factor to regulate gene expression. Although members of the ETS family have been reported to be involved in tumor progression, ectopic expression of PEA3 has been shown to suppress tumor formation. Despite several studies demonstrated frequent expression of PEA3 and its high association with HER-2/neu and have suggested a potential role of PEA3 in breast cancer, contradictory result has shown that the PEA3 was associated with better survival rate in breast cancer. In the current study, we address this discrepancy by examining the expression of PEA3 and HER-2/neu on 289 archived breast cancer tumor tissues and their correlation with clinicopathologic factors and prognosis. The staining of PEA3 was further validated by in situ hybridization for PEA3 mRNA. We found PEA3 was positive in 22.2% (64/289) of all cases and only 25.6% (21/82) of HER-2/neu-overexpressing cases showed co-expression of PEA3. In contrast to HER-2/neu, PEA3 expression was not correlated with prognosis or major clinicopathologic factors, except for a negative correlation with lymphovascular permeation ( p=0.007). This study demonstrates that PEA3 expression is not correlated with HER-2/neu expression in breast cancer tumor tissues, nor is it associated with adverse clinicopathologic factors or prognosis.

The Ets transcription factors of the PEA3 group: transcriptional regulators in metastasis

The PEA3 group is composed of three highly conserved Ets transcription factors: Erm, Er81, and Pea3. These proteins regulate transcription of multiple genes, and their transactivating potential is affected by post-translational modifications. Among their target genes are several matrix metalloproteases (MMPs), which are enzymes degrading the extracellular matrix during normal remodelling events and cancer metastasis. In fact, PEA3-group genes are often over-expressed in different types of cancers that also over-express these MMPs and display a disseminating phenotype. Experimental regulation of the synthesis of PEA3 group members influences the metastatic process. This suggests that these factors play a key role in metastasis.

Gene expression of gamma-glutamyltranspeptidase

gamma-Glutamyltranspeptidase is a heterodimeric glycoprotein that catalyzes the transpeptidation and hydrolysis of the gamma-glutamyl group of glutathione and related compounds. It is known that the enzyme plays a role in the metabolism of glutathione and in salvaging constituents of glutathione. In the adult animal, high levels of gamma-glutamyltranspeptidase are constitutively expressed in the kidney, intestine, and epididymis. On the other hand, although gamma-glutamyltranspeptidase is up-regulated in the liver during the perinatal stage, its expression is nearly undetectable in the adult. In addition, it has long been observed that the intake of certain xenobiotics, including carcinogens and drugs, induces the hepatic expression of the enzyme. This induction seems to be associated with both transcriptional regulation and the growth of certain types of cells in the injured liver. A number of studies have been carried out to explain the mechanism by which gamma-glutamyltranspeptidase expression is regulated. 5'-Untranslated regions of mRNAs of the enzyme differ in a tissue-specific manner but share a common protein coding region, and the tissue-specific and developmental stage-specific expression, as well as hepatic induction, are conferred by different promoters. As suggested by the capability of enzymatic activity-independent induction of osteoclasts, the expression of gamma-glutamyltranspeptidase may also be involved in various biological processes that are not directly associated with glutathione metabolism. This chapter briefly summarizes studies to date concerning the tissue-specific expression and induction of gamma-glutamyltranspeptidase and transcriptional regulation by the multiple promoter system is discussed.

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.

Putative regulation of expression of members of the Ets variant 4 transcription factor family and their downstream targets in the rat epididymis

Several genes expressed in the initial segment of the epididymis depend on factors from the testis that reach the epididymis via the luminal system. These include gamma-glutamyl transpeptidase mRNA IV (Ggt_pr4), steroid 5 alpha reductase (Srd5a1), glutathione peroxidase 5 (Gpx5), and cystatin-related epididymal spermatogenic (Cst8) genes. Promoter analyses indicated that these genes contain several ETS DNA-binding sites. Members of the polyomavirus enhancer activator 3 (ETV4) family bind to ETS sites on the promoter of target genes to regulate transcription. In this study, the role of ETV4 family members (ETV4, ETV5, ETV1) in the transcription of initial segment specific genes was evaluated. All three ETV4 family mRNAs are expressed in the principal cells of the initial segment and depend upon the presence of testicular luminal fluid factors. ETV4 protein was localized to principal cell nuclei and displayed the highest expression in the most proximal region of the initial segment. In addition, ETV4 protein levels were diminished after loss of testicular luminal fluid factors. A dominant-negative construct of ETV5 was in vivo electroporated into the initial segment to determine if ETV4 family members can regulate the transcription of testicular luminal fluid factor-regulated genes. Quantitative PCR indicated that 1 day postelectroporation, all three ETV4 family member mRNAs were significantly decreased. In addition, Ggt_pr4, Srd5a1, and Gpx5 mRNA levels were also significantly decreased. The data suggest that ETV4 family members regulate their own expression, and that they regulate transcription of a subset of genes that are dependent upon testicular luminal fluid factors.

Global gene expression profiles associated with retinoic acid-induced differentiation of embryonal carcinoma cells

We have evaluated the effects of retinoic acid (RA) treatment of F9 embryonal carcinoma (EC) cells, which induces differentiation into primitive endoderm, on gene expression patterns. F9 cells were exposed to RA in culture, and global expression patterns were examined with cDNA-based microarrays at early (8 hr) and later times (24 hr) after exposure. Of the 1,176 known transcripts examined, we identified 57 genes (4.8%) that were responsive to RA at 8 and/or 24 hr: 35 were induced, 20 were repressed, and 2 were differentially regulated at these time points. To determine if our results were dependent on the array technology employed, we also evaluated the response to RA at 24 hr with oligonucleotide-based arrays. With these more dense arrays (12,488 genes), we identified an additional 353 RA-regulated genes (2.8%): 173 were upregulated and 180 were downregulated. Thus, a total of 410 genes regulated by RA were identified with roughly equivalent numbers induced or repressed. Although the expression of many genes found on both array platforms was consistent, the results for some genes were disparate. Quantitative PCR studies on a subset of these genes supported the results obtained with the cDNA arrays. Our results confirmed the regulation of several known RA-responsive genes and we also identified a number of genes not previously known to be RA-responsive. Those novel genes that were induced presumably contribute to the cellular processes required for a shift from proliferation to differentiation, whereas those new genes that were downregulated may possibly contribute to the maintenance of cell proliferation.

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.