Synthetic Bax-Anti Bcl2 combination module actuated by super artificial hTERT promoter selectively inhibits malignant phenotypes of bladder cancer

BACKGROUND

The synthetic biology technology which enhances the specificity and efficacy of treatment is a novel try in biomedical therapy during recent years. A high frequency of somatic mutations was shown in the human telomerase reverse transcriptase (hTERT) promoter in bladder cancer, indicating that a mutational hTERT promoter might be a tumor-specific element for bladder cancer therapy. In our study, we aimed to construct a synthetic combination module driven by a super artificial hTERT promoter and to investigate its influence on the malignant phenotypes of bladder cancer.

METHODS

The dual luciferase assay system was used to verify the driven efficiency and tumor-specificity of the artificial hTERT promoter and to confirm the relationship between ETS-1 and the driven efficiency of the artificial hTERT promoter. CCK-8 assay and MTT assay were used to test the effects of the Bax-Anti Bcl2 combination module driven by the artificial hTERT promoter on cell proliferation. Simultaneously, the cell apoptosis was detected by the caspase 3ELISA assay and the flow cytometry analysis after transfection. The results of CCK-8 assay and MTT assay were analyzed by ANOVA. The independent samples t-test was used to analyze other data.

RESULTS

We demonstrated that the artificial hTERT promoter had a higher driven efficiency which might be regulated by transcription factor ETS-1 in bladder cancer cells, compared with wild-type hTERT promoter. Meanwhile, the artificial hTERT promoter showed a strong tumor-specific effect. The cell proliferation inhibition and apoptosis induction were observed in artificial hTERT promoter- Bax-Anti Bcl2 combination module -transfected bladder cancer 5637 and T24 cells, but not in the module -transfected normal human fibroblasts.

CONCLUSION

This module offers us a useful synthetic biology platform to inhibit the malignant phenotypes of bladder cancer in a more specific and effective way.

Novel tempeh (fermented soyabean) isoflavones inhibitin vivoangiogenesis in the chicken chorioallantoic membrane assay

Anti-angiogenic strategies are emerging as an important tool for the treatment of cancer and inflammatory diseases. In the present investigation we isolated several isoflavones from a tempeh (fermented soyabean) extract. The isolated isoflavones were identified as 5,7,4′-trihydroxyisoflavone (genistein), 7,4′-dihydroxyisoflavone (daidzein), 6,7,4′-trihydroxyisoflavone (factor 2), 7,8,4′-trihydroxyisoflavone (7,8,4′-TriOH) and 5,7,3′,4′-tetrahydroxyisoflavone (orobol). The effects on angiogenesis of these isoflavones were evaluated in the chicken chorioallantoic membrane assay; their capacity to inhibit vascular endothelial growth factor-induced endothelial cell proliferation and expression of the Ets 1 transcription factor, known to be implicated in the regulation of new blood vessel formation, were also investigated. We found that all isoflavones inhibited angiogenesis, albeit with different potencies. Compared with negative controls, which slightly inhibitedin vivoangiogenesis by 6·30 %, genistein reduced angiogensis by 75·09 %, followed by orobol (67·96 %), factor 2 (56·77 %), daidzein (48·98 %) and 7,8,4′-TriOH (24·42 %). These compounds also inhibited endothelial cell proliferation, with orobol causing the greatest inhibition at lower concentrations. The isoflavones also inhibited Ets 1 expression, providing some insight into the molecular mechanisms of their action. Furthermore, the chemical structure of the different isoflavones suggests a structure–activity relationship. Our present findings suggest that the new isoflavones might be added to the list of low molecular mass therapeutic agents for the inhibition of angiogenesis.

Ets transcription factors regulate AIRE gene promoter

Autoimmune regulator (AIRE) directs the expression of self-antigens in thymus. Defects in AIRE gene cause an organ-specific autoimmune disease called autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED). AIRE protein is mainly expressed in thymic medullary epithelial cells, thus implying a strict control over its expression pattern. To date, only limited information is available on mechanisms responsible for the regulation of AIRE gene. Here, we show that Ets transcription factor family members Ets-1, Ets-2, and ESE-1 have positive effect on AIRE transcription. Site-directed mutagenesis and transfection studies revealed that two of the three Ets binding sites in AIRE promoter are functional and this finding has been confirmed by the electrophoretic mobility shift assay. The AIRE promoter activity could be stimulated by phorbol myristate acetate (PMA) and this activation was further enhanced by Ets transcription factors. Our results demonstrate for the first time that AIRE gene is a downstream target for the Ets family of transcription factors.

The transcription factor Ets-1 is expressed in human amniochorionic membranes and is up-regulated in term and preterm premature rupture of membranes

OBJECTIVE

The major tensile strength of fetal membranes is provided by their extracellular matrix (ECM) components. The transcription factor Ets-1 is a critical mediator of ECM remodelling. The purpose of this study was to examine whether Ets-1 is expressed in human fetal membranes and whether it is implicated in premature membrane rupture.

STUDY DESIGN

Amniochorionic membranes from 52 women in the following categories were analyzed for Ets-1 expression: preterm and term premature rupture of membranes, preterm and term labor and delivery, and preterm and term cesarean sections without previous onset of labor. Ets-1 protein was localized with the use of immunohistochemistry. Ets-1 levels were determined with a histoscore.

RESULTS

Ets-1 protein was localized to the trophoblast as well as to the stromal layers. Ets-1 protein expression was up-regulated in the stroma of term and preterm prematurely ruptured membranes.

CONCLUSION

Ets-1 is expressed in human fetal membranes and its expression is up-regulated with premature rupture of membranes, suggesting a role for Ets-1 in ECM remodelling of the membranes.

Classification of neural differentiation-associated genes in P19 embryonal carcinoma cells by their expression patterns induced after cell aggregation and/or retinoic acid treatment

Expression of neural differentiation-associated genes was examined by RT-PCR and macroarray analyses during neural differentiation of P19 embryonal carcinoma cells induced by cell aggregation and/or retinoic acid (RA) treatment. Results revealed that the neural genes examined could be classified into 4 groups based on their expression patterns. The 1st group included the Wnt-1, Id-1, Id-3 and cdc42 genes, expression of which was altered by cell aggregation alone, but not by RA treatment alone. The 2nd group included the alphaN-catenin, Neuro D and GDNFRbeta genes, expression of which was altered by RA treatment alone, but not by cell aggregation. The 3rd group consisted of the Brn-2, TrkA, bcl-X, N-cadherin, E-cadherin and Otx-2 genes, expression of which was altered by either treatment. The 4th group included the ACTH, D4DR, NGC and Oct-3 genes, the expression of which changed only when both treatments were applied simultaneously. Expression of the Ets-1 and Fli-1 transcription factor genes was up-regulated by either treatment alone at initial stages of neural differentiation of P19 cells, although overexpression of these genes alone could not induce cell differentiation. Our results suggest that although both treatments are required for complete neural differentiation of P19 cells, cell aggregation or RA treatment alone drive differentiation to a certain extent at the gene expression level.

Expression of ets-1 transcription factor in human head and neck squamous cell carcinoma and effect of histamine on metastatic potential of invasive tumor through the regulation of expression of ets-1 and matrix metalloproteinase-3

BACKGROUND

Ets-1 controls the expression of critical genes involved in matrix remodeling. The matrix metalloproteinase-3 (MMP-3) and urokinase type plasminogen activator (uPA) are typical ets-1 responsive genes. Recent studies have shown an increase in histamine synthesis and content in various human neoplasias. We hypothesized that the increased local histamine overproduction contributed to activation of matrix remodeling through the activation of MMP-3 expression of peritumoral fibroblasts by means of ets-1 regulation in head and neck squamous cell carcinomas (HNSCCs).

METHODS

Paraffin-embedded sections of 30 HNSCCs were immunostained for ets-1. The presence of ets-1 and MMP-3 mRNA in tumor samples was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR). To simulate stromal reaction in vitro, cultured human mucosal fibroblast was used. The level of ets-1 and MMP-3 mRNA was compared by use of RT-PCR, as was their protein with flow-cytometry, in the presence or absence of basic fibroblast growth factor (bFGF) (10 ng/mL) and histamine (1 microM).

RESULTS

Correlation between ets-1 expression and clinicopathologic background was not significant. In all cases, expression of ets-1 was seen in the stroma. In in vitro study, histamine upregulates production of ets-1 and MMP-3 in cultured fibroblast, and bFGF can stimulate histamine expression in fibroblast. Immunofluorescence staining supported the results of RT-PCR and flow cytometry.

CONCLUSIONS

Ets-1 expression in HNSCCs has no prognostic value; however, ets-1 plays an important role in tumor-host interaction. Histamine may accelerate the spread of HNSCC through an ets-1-related mechanism.

Caspase-1 is a direct target gene of ETS1 and plays a role in ETS1-induced apoptosis

ETS1, the founding member of Ets transcriptional factor family, plays an important role in cell proliferation, differentiation, lymphoid cell development, transformation, angiogenesis, and apoptosis. Previous work has shown that ETS1 represses tumorigenicity of colon carcinoma cells in vivo, and that the p42-ETS1 protein bypasses a defect in apoptosis in colon carcinoma cells through the up-regulation of caspase-1 expression. In this report, we show that expression of p42-ETS1 inhibits tumorigenicity of colon cancer DLD-1 cells through induction of apoptosis in vivo. In support of the hypothesis that caspase-1 might be a target involved in the sensitization of DLD-1 cells to Fas-induced apoptosis by ETS1, overexpression of caspase-1 bypasses Fas-induced apoptosis in these cells as well. Furthermore, ETS1-mediated apoptosis was observed in MOP8 cells, a transformed mouse NIH3T3 cell line. To determine whether ETS1 activates the transcription of caspase-1, luciferase reporters driven by the wild-type and mutant caspase-1 promoters were generated. Both p51-ETS1 and p42-ETS1 transactivated the caspase-1 transcription and a functional Ets binding site is identified in the caspase-1 promoter. Wild-type caspase-1 promoter (pGL3-ICE) was strongly transactivated by ETS1 and this transactivation was dramatically diminished by the mutation of the potential Ets binding site (-525 bp). In addition, electrophoretic mobility shift assay and chromatin immunoprecipitation assay showed complex formation between this binding site and ETS1 proteins. Taken together, ETS1 transcriptionally induces the expression of caspase-1; as such, the regulatory control of caspase-1 expression by ETS1 may underlie the apoptotic susceptibility modulated by ETS1 in specific tumor cells.

Ets-1 expression promotes epithelial cell transformation by inducing migration, invasion and anchorage-independent growth

Ets-1 is the prototype of the family of ETS transcription factors. In human tumors, Ets-1 is expressed in endothelial cells and fibroblasts of the tumor stroma and is proposed to play a role in tumor vascularization and invasion by upregulating expression of matrix-degrading proteases. In human carcinomas, Ets-1 is also expressed by neoplastic cells, but little is known about the functional implications of this observation. We have addressed the role of Ets-1 in epithelial HeLa tumor cells by selecting stably Ets-1 over and underexpressing HeLa cells. Ets-1 expression increases the transformed phenotype of HeLa cells, by promoting cell migration, invasion and anchorage-independent growth, while Ets-1 downregulation reduces cell attachment. In correlation with these results, Ets-1 upregulation increases integrinbeta2 expression but not that of other integrins. These results suggest that, in addition to its role in the tumor stroma, Ets-1 may also promote tumor development and progression by increasing neoplastic transformation.

Transcriptional regulation of parathyroid hormone-related protein promoter P3 by ETS-1 in adult T-cell leukemia/lymphoma

Parathyroid hormone-related protein (PTHrP) plays a primary role in the development of humoral hypercalcemia of malignancy seen in the majority of adult T-cell leukemia/lymphoma (ATLL) patients with human T-cell lymphotropic virus type-1 (HTLV-1) infection. HTLV-1 Tax has been shown to complex with ETS-1 and SP1 to transactivate the PTHrP P3 promoter. Previously, we established a SCID/bg mouse model of human ATL with RV-ATL cells and showed that PTHrP expression was independent of Tax. In this study, we report an inverse correlation of PTHrP with tax/rex mRNA in multiple HTLV-1-positive cell lines and RV-ATL cells. Stimulation of Jurkat T cells with PMA/ionomycin upregulated the PTHrP P3 promoter by a previously characterized Ets binding site and also induced protein/DNA complex formation identical to that observed in RV-ATL cells. Further, we provide evidence that cotransfection with Ets-1 and constitutively active Mek-1 in HTLV-1-negative transformed T cells with stimulation by PMA/ionomycin not only resulted in a robust induction of PTHrP P3 but also formed a complex with ETS-1/P3 EBS similar to that in ATLL cells. Our data demonstrate that transcriptional regulation of PTHrP in ATLL cells can be controlled by T-cell receptor signaling and the ETS and MAPK ERK pathway in a Tax-independent manner.

Characterization of the Murine C3a Receptor Enhancer-Promoter: Expression Control by an Activator Protein 1 Sequence and an Ets-Like Site

The complement anaphylatoxins, C3a and C5a, exert their effects by binding to their respective receptors. A number of studies have implicated these proteins in human disease, yet little is known about anaphylatoxin receptor gene regulation. In this report, we demonstrate that most of the regulatory functions in the murine C3aR gene lie within 50 bp of the transcription start site. This region is critical for macrophage expression but does not have activity in a non-expressing melanoma cell line. Within this small region are putative consensus binding sites for AP-1, NF-kappaB, Ets, and GATA transcription factors. Lack of a corresponding NF-kappaB site in the human sequence and lack of DNA binding activity in macrophage nuclear extracts suggests that the NF-kappaB site is nonfunctional. Luciferase data demonstrate that the GATA site functions as a negative regulatory element in RAW 264.7 macrophages. The AP-1 and Ets sites are critical for C3aR reporter gene expression, such that when each is mutated, a significant loss of activity is observed. Furthermore, we demonstrate that these sequences cooperate to mediate both basal and LPS-induced expression of C3aR. Interestingly, EMSA analyses demonstrate that the AP-1 site binds to c-Jun, and in vivo footprinting shows a typical footprint in this site, but the Ets site does not have a "typical" Ets footprint and does not bind to Ets-1/2 proteins in RAW 264.7 extracts. These data suggest that, although the control region for C3aR is small, interaction of several transcription factors can lead to complex patterns of gene regulation.

Variable Control of Ets-1 DNA Binding by Multiple Phosphates in an Unstructured Region

Cell signaling that culminates in posttranslational modifications directs protein activity. Here we report how multiple Ca2+-dependent phosphorylation sites within the transcription activator Ets-1 act additively to produce graded DNA binding affinity. Nuclear magnetic resonance spectroscopic analyses show that phosphorylation shifts Ets-1 from a dynamic conformation poised to bind DNA to a well-folded inhibited state. These phosphates lie in an unstructured flexible region that functions as the allosteric effector of autoinhibition. Variable phosphorylation thus serves as a "rheostat" for cell signaling to fine-tune transcription at the level of DNA binding.

Fli1, Elf1, and Ets1 regulate the proximal promoter of the LMO2 gene in endothelial cells

Transcriptional control has been identified as a key mechanism regulating the formation and subsequent behavior of hematopoietic stem cells. We have used a comparative genomics approach to identify transcriptional regulatory elements of the LMO2 gene, a transcriptional cofactor originally identified through its involvement in T-cell leukemia and subsequently shown to be critical for normal hematopoietic and endothelial development. Of the 2 previously characterized LMO2 promoters, the second (proximal) promoter was highly conserved in vertebrates ranging from mammals to fish. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) expression analysis identified this promoter as the predominant source of transcription in hematopoietic tissue. Transient and stable transfections indicated that the proximal promoter was active in hematopoietic progenitor and endothelial cell lines and this activity was shown to depend on 3 conserved Ets sites that were bound in vivo by E74-like factor 1 (Elf1), Friend leukemia integration 1 (Fli1), and erythroblastosis virus oncogene homolog E twenty-six-1 (Ets1). Finally, transgenic analysis demonstrated that the LMO2 proximal promoter is sufficient for expression in endothelial cells in vivo. No hematopoietic expression was observed, indicating that additional enhancers are required to mediate transcription from the proximal promoter in hematopoietic cells. Together, these results suggest that the conserved proximal promoter is central to LMO2 transcription in hematopoietic and endothelial cells, where it is regulated by Ets factors.

Stromelysin 3, Ets-1, and vascular endothelial growth factor expression in oral precancerous and cancerous lesions: correlation with microvessel density, progression, and prognosis

PURPOSE

Identification of molecular changes characteristic of development and progression of oral cancer are of paramount importance for effective intervention. Stromelysin 3 (MMP11) is a unique matrix metalloproteinase shown to have dual function during cancer progression. The transcription factor Ets-1 and vascular endothelial growth factor (VEGF) are important proangiogenic factors in cancer. This study was designed to test the hypothesis that concomitant expression of stromelysin 3, Ets-1, and/or VEGF affects the development, progression, and prognosis of oral cancer.

PATIENTS AND METHODS

Immunohistochemical analysis of stromelysin 3, Ets-1, VEGF, and platelet/endothelial cell adhesion molecule 1 (a marker for intratumoral microvessel density) was carried out in serial paraffin embedded tissue sections of 220 oral squamous cell carcinomas (OSCC), 90 precancerous lesions (59 hyperplasias and 31 dysplasias), and 81 matched histologically normal oral tissues.

RESULTS

Ets-1, VEGF, and stromelysin 3 expression independently correlated with increased intratumoral microvessel density in precancerous lesions (P = 0.05, 0.001, and 0.026, respectively) as well as in SCCs (P = 0.005, 0.01, and 0.031, respectively). Logistic regression analysis revealed that concomitant expression of stromelysin 3 and Ets-1 (stromelysin 3(+)/ Ets-1(+) phenotype; odds ratio, 3.7; P = 0.001) was the most significant predictor for transition to precancerous stage, whereas dual expression of stromelysin 3 and VEGF (stromelysin 3(+)/ VEGF(+) phenotype; odds ratio, 2.07; P = 0.004) was the most important predictor for progression from precancerous stage to frank malignancy. Intriguingly, Ets-1 expression was significantly associated with VEGF expression and stromelysin 3 expression in precancerous tissues as well as OSCCs. Follow-up data for 144 patients for a maximum period of 115 months showed that VEGF [hazards ratio (HR), 4.532; P = 0.004] and Ets-1 (HR = 2.182; P = 0.049) expression significantly correlated with reduced disease-free survival in univariate analysis. In bivariate analysis, patients harboring Ets-1(+)/VEGF(+) phenotype had the worst survival (median disease-free survival, 50 months; HR, 2.943; P = 0.003). Multivariate analysis using Cox's proportional hazards model showed that increased VEGF expression was the most significant adverse prognosticator in OSCC patients (HR, 4.470; P = 0.004).

CONCLUSIONS

In conclusion, this study provides the first evidence of concomitant expression of stromelysin 3, VEGF, and Ets-1 in clinical specimens in different stages of development of oral cancer. In early stages, concomitant expression of stromelysin 3 and Ets-1 favors the development of a precancerous state, whereas dual expression of stromelysin 3 and VEGF is associated with progression from precancerous to cancerous state. VEGF expression is an adverse prognosticator for disease-free survival.

STAT1 and Nmi are downstream targets of Ets-1 transcription factor in MCF-7 human breast cancer cell

Ets-1 is a cellular homologue of the product of the viral ets oncogene of the E26 virus, and it functions as a tissue-specific transcription factor. It plays an important role in cell proliferation, differentiation, lymphoid cell development, transformation, angiogenesis, and apoptosis. Ets-1 controls the expression of critical genes involved in these processes by binding to ets binding sites present in the transcriptional regulatory regions. Here, we transiently overexpressed Ets-1 in MCF-7 and comprehensively searched for potential downstream targets of Ets-1 by cDNA microarray analysis. The expressions of several interferon-related genes including STAT1 and Nmi were augmented by the overexpression of Ets-1. RT-PCR and Western blotting confirmed the increase in the levels of STAT1 and Nmi mRNA and protein. In contrast, Ets-1 siRNA decreased the expression of STAT1 and Nmi proteins. As in our transient transfection experiments, stable overexpression of Ets-1, also increased the protein expression of STAT1 and Nmi in MCF-7 cells. Taken together, our results indicate that STAT1 and Nmi are downstream targets of Ets-1 in MCF-7 human breast cancer cells.

Matrix metalloproteinase-1 up-regulation by hepatocyte growth factor in human dermal fibroblasts via ERK signaling pathway involves Ets1 and Fli1

In this study, we clarified the molecular mechanism(s) underlying the regulation of matrix metalloproteinase (MMP)-1 gene by hepatocyte growth factor (HGF) in cultured human dermal fibroblasts. HGF induced MMP-1 protein as well as mRNA at a transcriptional level via extracellular signal-regulated kinase (ERK) signaling pathway. The region in the MMP-1 promoter mediating the inducible responsiveness to HGF, defined by the transient transfection analysis of the serial 5′ deletion constructs, contained an Ets binding site. Mutation of this Ets binding site abrogated the HGF-inducible promoter activity. Ets1 up-regulated the expression of MMP-1 promoter activity, whereas Fli1 had antagonistic effects on them. After HGF treatment, the protein level and the binding activity of Ets1 was increased and those of Fli1 was decreased, which were canceled by PD98059. These results suggest that HGF up-regulates MMP-1 expression via ERK signaling pathway through the balance of Ets1 and Fli1, which may be a novel mechanism of regulating MMP-1 gene expression.

ETS family of genes in leukemia and Down syndrome

The human ETS2 and ERG genes are members of the ETS gene family, with sequence homology to the viral ets gene of the avian erythroblastosis retrovirus, E26. These genes are located on chromosome 21 and molecular genetic analysis of Down syndrome (DS) patients with partial trisomy 21 suggested that ETS2 may be a gene within the minimal DS genetic region. We have, in fact, been able to confirm the presence of the ETS2 gene dosage in triplicate occurring in occult human 21 chromosome abnormalities. It is known that ERG and ETS2 gene translocations occur in certain specific leukemias associated with defined chromosome rearrangements [e.g., t(8;21)]. Moreover, it is known that DS individuals are at greater risk for leukemic disease than their normal familial cohorts, implying that trisomy of that region of human chromosome 21 may play a role in the development of this type of neoplasia. The human ETS genes, first identified in our laboratory, are highly conserved, being found from lower organisms, like Drosophila and sea urchin, to humans. In mammals, the ETS genes are structurally distinct, located on separate chromosomes; they are transcriptionally active and differentially regulated. The ETS2 protein is phosphorylated and turns over with a half-life of approximately 20 min. After activation with the tumor promoter, TPA, the level of ETS2 elevates 5- to 20-fold. The properties of the ETS2 protein, such as nuclear localization, phosphorylation, rapid turnover, and response to protein kinase C, indicate that this protein belongs to a group of oncogene proteins thought to have regulatory functions in the nucleus. In the mouse thymus ets-1 and ets-2 are 8-10-fold higher, respectively, in the CD4+ subset than in other subsets examined, suggesting a role in T-cell development for these genes. Cells transfected with the cellular ets-2 gene, expressing higher levels of ets-2 products, showed a stimulated proliferation response, abolished their serum requirement and formed colonies in soft agar that could induce tumors in nude mice. Collectively, these data suggest that this family of genes might play a role in controlling specific steps of the signaling transduction pathway. Thus, the ETS genes, as other genes with homology to viral oncogenes, might be instrumental in regulating cellular growth and differentiation, as well as organismal development.

The regulation of COUP-TFII gene expression by Ets-1 is enhanced by the steroid receptor co-activators

Recent phenotypic analysis of orphan nuclear receptor chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII) [NR2F2] knockout mice shows that COUP-TFII is involved in the angiogenic process in the developing embryos. Since Ets-1 expression is also correlated with angiogenesis, and both Ets-1 and COUP-TFII mRNA are present in mesenchymal cells, we have sought to determine whether Ets-1 is a potential regulator of COUP-TFII gene expression. For this purpose, we performed transient transfection experiments using a luciferase reporter construct containing the mouse COUP-TFII promoter. We found that the COUP-TFII promoter activity is indeed regulated by Ets-1. We have identified two identical inverted potential ETS-binding sites located 47 nucleotides downstream of the start site. Mutation of both sites reduced the ability of Ets-1 to enhance the COUP-TFII promoter activity. Furthermore, other members of the ETS family such as Ets-2 or ETV1 are also potent regulators of the COUP-TFII promoter. Finally, the induction of the COUP-TFII gene is strongly enhanced by the expression of steroid receptor co-activator factors through a direct interaction with Ets-1. These results indicate that COUP-TFII is a potential downstream target of Ets-1 and it may partially mediate the Ets-1 function in angiogenesis.

Activation of the Rat Renin Promoter by HOXD10·PBX1b·PREP1, Ets-1, and the Intracellular Domain of Notch

Renin gene expression is subject to complex developmental and tissue-specific regulation. A comparison of the promoter sequences of the human, rat, and mouse renin genes has revealed a highly conserved sequence homologous to the DNA recognition sequence for CBF1 (CSL/RBP-Jkappa/Su(H)/LAG1/RBPSUH). Electrophoretic mobility shift assays document that As4.1 cell nuclear protein complex binding to the putative rat renin CBF1-binding site (-175 to -168 bp) contains CBF1. Transient transfection analyses in COS-7 cells further document that a CBF1-VP16 fusion protein and the intracellular domain of Notch1 robustly activate a promoter containing multiple copies of the rat renin CBF1-binding site. An Ets-binding site (-143 to -138 bp) has also been identified in the rat renin promoter by sequence comparisons and electrophoretic mobility shift assays. Transcription factor Ets-1 is capable of activating the rat renin promoter through the Ets-binding site. Mutation of the CBF-binding site significantly increases transcriptional activity of the rat renin promoter in Calu-6 and COS-7 cells but not in As4.1 cells, whereas mutation of the Ets-binding site reduces promoter activity of the rat renin gene in all three cell lines. Finally, we show that the intracellular domain of Notch1, Ets-1, and HOXD10.PBX1b.PREP1 activate the rat renin promoter cooperatively in COS-7 cells. These results strongly suggest that the renin gene is a downstream target of the Notch signaling pathway.

Inactivation of Ets 1 transcription factor by a specific decoy strategy reduces rat C6 glioma cell proliferation and mmp-9 expression

Malignant gliomas represent the most aggressive tumours of the central nervous system and are characterised by both extensive proliferation and invasive growth. Matrix degrading proteases called matrix metalloproteinases (MMPs), particularly MMP-9, play a crucial role in glioma infiltration. The activity of these enzymes is regulated at different levels. In this regard, the control of transcriptional activity by specific transcription factors is believed to be very important. In the present study, we examined whether rat C6 glioma cells express the Ets 1 transcription factor and whether inhibition of Ets 1 by a specific decoy strategy affects C6 glioma cell proliferation and mmp-9 expression. We found that C6 glioma cells express Ets 1 and can efficiently be transfected with an Ets 1-specific decoy oligodesoxynucleotide (ODN). This ODN significantly reduces cell proliferation and mmp-9 expression, the latter in a dose-dependent manner. We conclude that inhibition of transcription factors, which play a role for glioma development and progression such as Ets 1 by specific decoy approaches, might represent useful tools for experimental therapeutic strategies against malignant gliomas.

Evaluation of insulin-like growth factor II, cyclooxygenase-2, ets-1 and thyroid-specific thyroglobulin mRNA expression in benign and malignant thyroid tumours

OBJECTIVE

We evaluated three markers (insulin-like growth factor II (IGF-II), cyclooxygenase-2 (COX-2) and ets-1) of thyroid growth stimulation and cell transformation together with a thyroid-specific marker (thyroglobulin (Tg)) for their potential to differentiate benign and malignant follicular thyroid neoplasia (FN).

DESIGN AND METHODS

mRNA expression levels were determined by real-time PCR in 100 snap-frozen thyroid samples: 36 benign thyroid nodules with different histology and function (19 cold (CTN) and 17 toxic thyroid nodules (TTN)), 36 corresponding normal thyroid tissues of the same patients, eight Graves' disease (GD) thyroids, 10 follicular thyroid carcinomas (FTC) and 10 papillary thyroid carcinomas (PTC).

RESULTS

Mean IGF-II and COX-2 levels were not significantly altered between benign and malignant thyroid nodules (IGF-II) or nodular (FTC, TTN, CTN) and normal thyroid tissues (COX-2). In contrast, eight- to tenfold upregulation of ets-1 was observed in PTC and three- to fourfold upregulation of ets-1 was observed in FTC (and GD) compared with benign thyroid nodules and normal thyroid tissues. In addition, thyroglobulin mRNA expression was markedly downregulated (50- to 100-fold) in FTC, PTC and GD samples compared with benign nodular and normal thyroid tissues. Hence an ets-1/Tg ratio >20 distinguished differentiated thyroid cancer from benign nodular or normal thyroid tissue. We then studied ets1- and Tg mRNA expression levels in fine needle aspiration cytology (FNAC) samples. However, in a consecutive series of 40 FNAC samples only equivocal results were obtained on 38 benign and two malignant (FTC) thyroid tumour samples.

CONCLUSIONS

Upregulation of ets-1 and downregulation of Tg mRNA expression occur in differentiated thyroid cancer and may facilitate pre-operative identification of thyroid malignancy depending on further evaluation of these potentially promising markers in a larger series of benign and malignant thyroid tumours and their FNAC samples.

Expression of the ets-1 proto-oncogene in human breast carcinoma: differential expression with histological grading and growth pattern

The proto-oncogene, ets-1, is a transcription factor known to control the expression of a number of genes and has been postulated to play a role in cell growth, differentiation and tumour invasion. We examined 137 cases of breast carcinoma by immunohistochemistry and compared the degree of Ets-1 expression among the different histological types of invasive carcinomas. Ets-1 was not expressed in the normal breast epithelium nor in noninvasive carcinomas. Among the 137 breast carcinoma cases, 104 (83.2%) showed positive staining for the Ets-1 protein. Histologically, invasive ductal carcinomas expressed immunopositivity with intense staining for Ets-1 in the tumour cells. Ets-1 expression correlated with Bloom-Richardson grading in invasive ductal carcinoma (p<0.01). However, there was no correlation between Ets-1 expression and lymph node metastasis, "t" classification or TNM staging. In situ hybridization confirmed the presence of Ets-1 mRNA in breast carcinomas. The expression of Ets-1 mRNA was detected in two of three different kinds of cultured human breast carcinoma cell lines and one of three human breast carcinoma tissues by the reverse transcription polymerase chain reaction method. These findings suggest that ets-1 is overexpressed in ductal cells of the breast that have undergone malignant conversion and that ets-1 is one of the factors associated with tumour growth and histological differentiation of breast carcinomas.

Overexpression of Ets-1 proto-oncogene in latent and clinical prostatic carcinomas

AIMS

The high incidence of clinically diagnosed prostatic cancer is exceeded by the frequency of tumours detected at autopsy. The Ets-1 proto-oncogene is expressed by a variety of malignant and normal tissues. Therefore, in this study, expression of Ets-1 protein was investigated in 'latent' prostatic cancer detected at autopsy, compared with benign prostatic hyperplasia, normal prostatic tissues and clinical prostatic cancer.

METHODS AND RESULTS

Using immunohistochemistry, we analysed Ets-1 expression in 95 prostatic specimens including 19 cases of latent prostatic carcinoma (LPC) and 55 cases of clinical prostatic carcinoma (CPC), 11 cases of benign prostatic hyperplasia (BPH) and 10 cases of normal prostate (NP). Differences in the incidence of LPC and CPC suggest different courses for the biological progression of prostatic cancer. There was a significant difference in the degree of Ets-1 expression in CPC and LPC (P < 0.05). Ets-1 was not expressed in BPH and NP, but in malignant cases (57 of 74; 77.0%) commonly demonstrated immunoreactivity in the tumour cells. In our study the expression of Ets-1 between benign and malignant, and well, moderately and poorly differentiated adenocarcinomas of prostatic cancer showed significant differences. The presence of Ets-1 mRNA was confirmed by in-situ hybridization in human prostatic tissues.

CONCLUSION

Our results suggest that Ets-1 might play an important role in carcinogenesis and/or the progression of human prostatic carcinomas.

Ets-1, a functional cofactor of T-bet, is essential for Th1 inflammatory responses

To mount an effective type 1 immune response, type 1 T helper (Th1) cells must produce inflammatory cytokines and simultaneously suppress the expression of antiinflammatory cytokines. How these two processes are coordinately regulated at the molecular level is still unclear. In this paper, we show that the proto-oncogene E26 transformation-specific-1 (Ets-1) is necessary for T-bet to promote interferon-gamma production and that Ets-1 is essential for mounting effective Th1 inflammatory responses in vivo. In addition, Ets-1-deficient Th1 cells also produce a very high level of interleukin 10. Thus, Ets-1 plays a crucial and unique role in the reciprocal regulation of inflammatory and antiinflammatory Th responses.

Histamine elevates the expression of Ets-1, a protooncogen in human melanoma cell lines through H2 receptor

Histamine is known to act, at least in part, as a growth factor for several cell types, and as production of this biogen amine has been found to accelerate the rate of tissue proliferation in wound repair, embryogenesis and malignant growth. Abundant experimental and clinical data suggest that histamine augments in vivo tumour cell proliferation via histamine H2 receptors (H2R). Here, we report that exogenously added histamine stimulates Ets-1 (v-ets erythroblastosis virus E26 oncogene homolog 1) synthesis in human melanoma cells. Involvement of histamine receptors in the histamine induced ets-1 expression has been also studied. Our data show that these newly recognized actions of histamine are mediated by the H2R. Modification of local protooncogen Ets-1 level is likely being involved in the regulation of melanoma growth.

Associations and Interactions between Ets-1 and Ets-2 and Coregulatory Proteins, SRC-1, AIB1, and NCoR in Breast Cancer

PURPOSE

Associations between p160 coactivator proteins and the development of resistance to endocrine treatment have been described. We hypothesized that nuclear receptor coregulatory proteins may interact with nonsteroid receptors. We investigated the mitogen-activated protein kinase-activated transcription factors, Ets, as possible interaction proteins for the coactivators SRC-1 and AIB1 and the corepressor NCoR in human breast cancer.

EXPERIMENTAL DESIGN

Expression and coexpression of Ets and the coregulatory proteins was investigated using immunohistochemistry and immunofluorescence in a cohort of breast tumor patients (N = 134). Protein expression, protein-DNA interactions and protein-protein interactions were assessed using Western blot, electromobility shift, and coimmunoprecipitation analysis, respectively.

RESULTS

Ets-1 and Ets-2 associated with reduced disease-free survival (P < 0.0292, P < 0.0001, respectively), whereas NCoR was a positive prognostic indicator (P < 0.0297). Up-regulation of Ets-1 protein expression in cell cultures derived from patient tumors in the presence of growth factors associated with tumor grade (P < 0.0013; n = 28). In primary breast tumor cell cultures and in the SKBR3 breast cell line, growth factors induced interaction between Ets and their DNA response element, induced recruitment of coactivators to the transcription factor-DNA complex, and up-regulated protein expression of HER2. Ets-1 and Ets-2 interacted with the coregulators under basal conditions, and growth factors up-regulated Ets-2 interaction with SRC-1 and AIB1. Coexpression of Ets-2 and SRC-1 significantly associated with the rate of recurrence and HER expression, compared with patients who expressed Ets-2 but not SRC-1 (P < 0.0001 and P < 0.0001, respectively).

CONCLUSIONS

These data describe associations and interactions between nonsteroid transcription factors and coregulatory proteins in human breast cancer.

Ets1 was significantly activated by ERK1/2 in mutant K-ras stably transfected human adrenocortical cells

In our previous study on the tumorigenesis of human functional adrenal tumors, we observed a high frequency of point mutation in the K-ras gene in clinical adrenal tumors. Therefore, we analyzed gene profiles of mutant K-ras transfected adrenocortical cells by DNA microarray to determine the expression pattern of genes related to cell cycle, signal transduction, apoptosis, tumorigenesis, steroidogenesis, and other expressed sequence tags (ESTs). Then we analyzed all of the significant differentially expressed genes by bioinformatics tools, "Matchminer" and "Gominer." The results revealed that expression of mutant K-ras gene induced by IPTG upregulated Ets1, which was mainly related to cell proliferation. After carefully being analyzed by software "DAVID" and "Pathart," Ets1 was found to be activated by being phosphorylated at theronine 38 by ERK1/2, and in turn, to regulate the following genes: uPA, MMP-3, and prolactin (Ling et al., 2003; Duffy and Daggan, 2004; Maupas-Schwalm et al., 2004; van Themsche et al., 2004). The result of Western blotting analysis confirmed that Ets1 was really phosphorylated when mutant K-ras was activated. On the other hand, the membrane blotting analyses indicated that the expression levels of uPA, MMP-3, and prolactin in human adrenocortical cells stably transfected with the mutant K-ras gene were significantly higher than those in normal control cells. Compared to control cells, the level of prolactin raised 1.4-fold, the level of MMP-3 raised 1.8-fold, and the level of uPA raised 2.1-fold in the transfected cells. From the results of this study, we proposed a mechanism of Ets1 in human adrenocortical cells expressing a mutated K-ras gene.

The RING finger protein RNF11 is expressed in bone cells during osteogenesis and is regulated by Ets1

Maturation of MC3T3-E1 osteoblast cells in vitro can be divided into three major stages, namely, proliferation, differentiation, and mineralization. Our microarray analysis identified genes differentially expressed between proliferating and differentiated MC3T3-E1 osteoblastic cells. Immunohistochemical analyses of RNF11 protein encoded by one of the differentially expressed genes revealed it as highly expressed in osteoblasts of multiple skeletal elements during embryonic bone formation in mice. In contrast, cartilage, undifferentiated mesenchymal tissue and osteocytes did not express detectable amounts of the RNF11 protein. The RNF11 mRNA was found to be abundant during the proliferation stage of MC3T3-E1 osteoblast development with a short second peak of expression during the mineralization phase. This pattern of expression is similar to that of the Ets1 transcription factor during osteogenic differentiation of MC3T3-E1 cells, and we used immunohistochemistry to show that, in vivo, Ets1 protein is coexpressed with RNF11 in osteoblasts. The human and mouse RNF11 promoters each contain three Ets transcription factor binding sites (EBS) and we found that Ets1 binds specifically to one of them. The functionality of this site was tested in a transcription-transactivation assay, indicating that RNF11 expression in bone cells is regulated by the Ets1 factor.

Ets-1 expression in gastric cancer

BACKGROUND/AIMS

Ets-1 protein is a transcription factor that has been implicated in both tumor invasion and neovascularization. The purpose of this study was to investigate the clinical significance of Ets-1 expression in gastric cancer.

METHODOLOGY

We examined the expression of Ets-1 protein by immunohistochemical staining in tissues obtained from 124 primary gastric cancers. Ets-1 expression was detected by automated immunodetection (Ventana Medical Systems Inc., Tucon, AZ, USA).

RESULTS

Ets-1 was not expressed in normal gastric epithelium. Ets-1 staining was defined as positive in 51.6% (64 of 124) of gastric cancer cases. There were no significant differences in age, gender, or histopathological grading. With regard to clinicopathological characteristics, significant differences were observed in the depth of tumor invasion, lymph node and distant metastases, increased tumor stage, and histological lymphatic and venous invasion. Patients with Ets-1 expression demonstrated poorer survival rates than patients without Ets-1 expression, as determined by the log-rank test (p=0.017), but multivariable analysis showed that the expression of Ets-1 was not an independent prognostic indicator (p=0.370).

CONCLUSIONS

Ets-1 expression in gastric cancers is correlated with histological prognostic indicators and is a useful marker for predicting the outcome for patients with gastric cancer.

Ets1 is an effector of protein kinase Calpha in cancer cells

PKCalpha and Ets1 are both associated with breast cancer progression. Our previous studies suggested that these proteins are likely to functionally interact with one another. Here, we show that attenuation of endogenous PKCalpha expression (siPalpha) by RNA interference leads to reduced Ets1 protein expression in a variety of cancer cells. Pulse-chase experiments and treatment with proteasome inhibitor MG-132 revealed that siPalpha interferes with both Ets1 protein synthesis and stability. The effect of siPalpha on Ets1 expression could be partially prevented by KN-93, suggesting that calcium/calmodulin-dependent kinase II (CaMKII), a modulator of Ets1 activity, may play a role in PKCalpha-dependent Ets1 regulation. In contrast, Ets1-regulating kinases ERK1/2 were not found to be involved in this process. To assess the importance of the PKCalpha/Ets1 interaction, we compared the biological responses of MDA-MB-231 cells to PKCalpha- and Ets1-specific siRNAs (siE1). While only siPalpha induced changes in cellular morphology and anchorage-independent growth, both siRNAs similarly affected cellular responses to the antitumor drug mithramycin A and to UV light. Microarray analyses further showed that the expression of a certain set of genes was equally affected by siPalpha and siE1. The data suggest that Ets1 serves as an effector for PKCalpha to fulfil certain functions in cancer cells.

Interleukins 2 and 15 Regulate Ets1 Expression via ERK1/2 and MNK1 in Human Natural Killer Cells

Interleukins (IL)-2 and IL-15 regulate natural killer (NK) cell proliferation, survival, and cytolytic activity. Ets1 is a transcription factor expressed early in NK cell differentiation. Because IL-2Rbeta, IL-2Rgamma, IL-15, and Ets1 knock-out mice similarly lack NK cells, we explored a molecular connection between IL-2R signaling and Ets1. Here we report the post-transcriptional regulation of Ets1 by IL-2R signaling in human NK cells. IL-2 and IL-15 stimulation leads to increased Ets1 protein levels with no significant change in mRNA levels. Pulse and pulse-chase experiments show that IL-2 stimulation results in both a marked increase in the nascent translation of Ets1 and an increased protein half-life. Pharmacological inhibition of MEK specifically blocks IL-2- and IL-15-induced translation, whereas p38, phosphatidylinositol 3-kinase, and mTOR inhibitors had no effect on Ets1 levels. Fli1, an Ets family member, exhibited a different mechanism of regulation, illustrating the specificity of IL-2R beta and gamma subunit signaling on the regulation of Ets1 expression. Expression of a dominant negative form of MNK1, a regulator of the translation initiation factor eIF4E, blocks the expression of Ets1 as do the dominant negative forms of the common IL-2R beta and gamma chains. Expression of Ets1 is regulated similarly in normal peripheral human NK cells. Taken together, our findings provide a direct link between IL-2R subunit signaling and Ets1 expression and helps to explain the interdependence of the IL-2R subunits and Ets1 for NK cell development and function.

Role of Ets-2 in the Regulation of Heme Oxygenase-1 by Endotoxin

Ets proteins play a vital role in the regulation of mammalian immunity, and family members Ets-1 and Ets-2 regulate a variety of genes that participate in the propagation of an inflammatory response. Heme oxygenase (HO)-1, although acutely induced by inflammatory stimuli, has cytoprotective properties and prevents an exaggerated inflammatory response. Ets-1 and Ets-2 both induce HO-1 promoter activity; however, Ets-2 was a more potent transactivator of HO-1 in macrophages. A potent inflammatory mediator, bacterial lipopolysaccharide (LPS), induced Ets-2 at the mRNA and protein level, and this induction preceded the up-regulation of HO-1. To further delineate the role of Ets-2 in regulating HO-1 transcription, we performed HO-1 promoter analysis studies in macrophages. Deletion mutants down to -137/+74 maintained an activity analogous to that of the largest construct, -4045/+74. Further deletion constructs (starting with -117/+74) showed a significant reduction in promoter activity when co-transfected with Ets-2 or exposed to LPS. Promoter sequence analysis revealed two putative Ets binding sites (EBSs) in this region, and mutation of these sites showed that EBS -93, more than EBS -125, was critical for full HO-1 promoter activity. Additional studies showed that EBS -93 binds Ets-2 and that mutation of the DNA binding domain of Ets-2 entirely prevented transactivation of HO-1. Finally, overexpression of a dominant negative form of Ets-2 blunted HO-1 promoter induction by LPS, and kinase inhibitors (PI3K more than JNK) that reduced Ets-2 expression markedly decreased endogenous HO-1 expression. Our data provide evidence that Ets-2 contributes to the up-regulation of HO-1 by the potent inflammatory stimulus LPS in macrophages.

Telomere-independent cellular senescence in human fetal cardiomyocytes

Fetal cardiomyocytes have been proposed as a potential source of cell-based therapy for heart failure. This study examined cellular senescence in cultured human fetal ventricular cardiomyocytes (HFCs). HFCs were isolated and identified by immunocytochemistry and RT-PCR. Cells were found to senesce after 20-25 population doublings, as determined by growth arrest, morphological changes and senescence-associated beta-galactosidase activity. Using the telomeric repeat amplification protocol assay, telomerase activity was undetectable in primary HFCs. Cells were transduced to express the human reverse transcriptase subunit (hTERT) of telomerase. This resulted in greatly increased telomerase activity, but no significant lifespan extension. Analysis of telomere length in primary HFCs revealed that the senescent phenotype was not accompanied by telomere shortening. Telomeres in hTERT-positive cells were elongated in comparison with primary cells, and elongation was retained in senescent cells. Levels of the tumor suppressor protein p16INK4A increased in all senescent cells whether telomerase-positive or -negative. Senescence was accompanied by a decline in transcript levels of the polycomb gene Bmi-1, Ets1 and Ets2 transcription factors, and Id1, Id2 and Id3 helix-loop-helix proteins, suggesting roles for these genes in maintenance of cardiomyocyte proliferative capacity. In addition to offering novel insights into the behavior of human fetal cardiomyocytes in culture, these findings have implications for the development of a cell-based therapy for cardiac injury using primary fetal heart tissue.

Sex steroid-dependent angiogenesis in uterine endometrial cancers

In general, tumors induce angiogenic factors specific to them, which leads to angiogenesis with advancement. However, angiogenesis in uterine endometrial cancers is complicated because hormone dependency in growth also modifies the angiogenic potential. Therefore, anti-angiogenic therapy for tumor dormancy in uterine endometrial cancers must be thoroughly considered. The upstream of vascular endothelial growth factor (VEGF) gene conserves estrogen-responsive elements. Progesterone primed with estrogen induces thymidine phosphorylase (TP) in uterine endometrium. Sex steroid-dependent VEGF and TP are highly expressed in cases of early stage and well-differentiated uterine endometrial cancers, and basic fibroblast growth factor (bFGF) in cases of advanced and poorly differentiated uterine endometrial cancers. A transcriptional factor for angiogenesis, ETS-1, is linked to VEGF in well-differentiated uterine endometrial cancers, and to bFGF in poorly differentiated uterine endometrial cancers. Therefore, even if dedifferentiation and angiogenic switching occur due to advancement and long-term hormone therapy, the inhibition of ETS-1 along with main angiogenic factors might be an effective strategy to suppress uterine endometrial cancers as a novel anti-angiogenic therapy.

Expression and function of Ets-1 during experimental acute renal failure in rats

The Ets family of transcription factors is defined by a conserved DNA-binding Ets domain that forms a winged helix-turn-helix structure motif. The Ets family is involved in a diverse array of biologic functions, including cellular growth, migration, and differentiation. The hypothesis in this study was that Ets-1 is re-expressed during regeneration after acute renal failure (ARF) and plays a key role in the transcriptional regulation of cyclin D1 and the cell cycle progression in renal tubular cells. For clarifying the significance of Ets-1 in ARF, a rat ARF model in vivo and LLC-PK1 cells as an in vitro model were used. After the left rat renal artery was clamped for 1 h, the whole kidney homogenate was examined and total RNA was extracted at 6, 12, 24, 48, and 72 h after reperfusion by Western blot analysis and real-time reverse transcription-PCR. Ets-1 mRNA and protein expression were strongly increased at 6 to 24 h after the ischemia, respectively. The expression of hypoxia-inducible factor-1alpha was increased dramatically as early as 6 h after ischemia-reperfusion and decreased at 48 and 72 h after ischemia-reperfusion. In the immunohistologic examination, Ets-1 was expressed in the proximal tubules and coexpressed with proliferating cell nuclear antigen (PCNA). Furthermore, overexpression of Ets-1 promoted the cell cycle and increased the promoter activity and protein expression of cyclin D1 in LLC-PK1 cells. Ets-1 promoter activity increased between 3 and 6 h in hypoxia, and hypoxia also induced changes in the Ets-1 protein level in LLC-PK1 cells. The Ets-1 induction by hypoxia was abolished by the transfection of dominant-negative hypoxia-inducible factor-1alpha. A gel shift assay demonstrated that Ets-1 binds to the ets-1 binding site of the cyclin D1 promoter in the ischemia-reperfusion condition. Overexpression of Ets-1 did not significantly change the caspase 3 activity or the value of cell death ELISA in LLC-PK1 cells. Taken together, these data suggest that Ets-1 plays a key role in the cell-cycle progression of renal tubules in ARF. The Ets-1 pathway may regulate the transcription of cyclin D1 and control the regeneration of renal tubules in ARF.

SP100 inhibits ETS1 activity in primary endothelial cells

SP100 was first identified as a nuclear autoimmune antigen and is a constituent of the nuclear body. SP100 interacts with the ETS1 transcription factor, and we have previously shown that SP100 reduces ETS1-DNA binding and inhibits ETS1 transcriptional activity on the MMP1 and uPA promoters. We now demonstrate that SP100 expression is upregulated by interferons, which have been shown to be antiangiogenic, in primary endothelial cells. As ETS1 is functionally important in promoting angiogenesis, we tested the hypothesis that ETS1 activity is negatively modulated by SP100 in endothelial cells. SP100 directly antagonizes ETS1-mediated morphological changes in human umbilical vein endothelial cell (HUVEC) network formation and reduces HUVEC migration and invasion. To further understand the functional relationship between ETS1 and SP100, cDNA microarray analysis was utilized to assess reprogramming of gene expression by ETS1 and SP100. A subset of the differentially regulated genes, including heat-shock proteins (HSPs) H11, HSPA1L, HSPA6, HSPA8, HSPE1 and AXIN1, BRCA1, CD14, CTGF (connective tissue growth factor), GABRE (gamma-aminobutyric acid A receptor epsilon), ICAM1, SNAI1, SRD5A1 (steroid-5-alpha-reductase 1) and THY1, were validated by real-time PCR and a majority showed reciprocal expression in response to ETS1 and SP100. Interestingly, genes that are negatively regulated by ETS1 and upregulated by SP100 have antimigratory or antiangiogenic properties. Collectively, these data indicate that SP100 negatively modulates ETS1-dependent downstream biological processes.

Mef2c is activated directly by Ets transcription factors through an evolutionarily conserved endothelial cell-specific enhancer

Members of the Myocyte Enhancer Factor 2 (MEF2) family of transcription factors play key roles in the development and differentiation of numerous cell types during mammalian development, including the vascular endothelium. Mef2c is expressed very early in the development of the endothelium, and genetic studies in mice have demonstrated that mef2c is required for vascular development. However, the transcriptional pathways involving MEF2C during endothelial cell development have not been defined. As a first step towards identifying the transcriptional factors upstream of MEF2C in the vascular endothelium, we screened for transcriptional enhancers from the mouse mef2c gene that regulate vascular expression in vivo. In this study, we identified a transcriptional enhancer from the mouse mef2c gene sufficient to direct expression to the vascular endothelium in transgenic embryos. This enhancer is active in endothelial cells within the developing vascular system from very early stages in vasculogenesis, and the enhancer remains robustly active in the vascular endothelium during embryogenesis and in adulthood. This mef2c endothelial cell enhancer contains four perfect consensus Ets transcription factor binding sites that are efficiently bound by Ets-1 protein in vitro and are required for enhancer function in transgenic embryos. Thus, these studies identify mef2c as a direct transcriptional target of Ets factors via an evolutionarily conserved transcriptional enhancer and establish a direct link between these two early regulators of vascular gene expression during endothelial cell development in vivo.

Bone morphogenic proteins are overexpressed in malignant melanoma and promote cell invasion and migration

Malignant melanoma cells are known to have altered expression of growth factors compared with normal human melanocytes. These changes probably favor tumor growth and progression and influence the tumor environment. The induction of transforming growth factor beta1 (TGF-beta1), TGF-beta2, and TGF-beta3 expression in malignant melanoma has been reported before, whereas the expression of related bone morphogenic protein (BMP) molecules has not been analyzed in melanomas until now. Here, we show that BMP4 and BMP7 are up-regulated in nine melanoma cell lines, whereas BMP2 is overexpressed in only two of the analyzed cell lines. Immunohistochemistry of primary and metastatic melanoma also shows increased BMP4 and BMP7 expression compared with nevi. Promoter studies reveal that expression is controlled at the transcriptional level. The transcription factor Ets-1 was identified as a positive regulator for BMP4 expression. In order to determine the functional relevance of BMP expression in malignant melanoma, chordin-expressing cell clones and antisense BMP4 cell clones were generated. The clones in which BMP4 activity and expression are reduced show no changes in proliferation or in attachment-independent growth when compared with controls. However, a strong reduction of migratory and invasive properties was observed in these cells, suggesting that BMP4 promotes melanoma cell invasion and migration and therefore has an important role in the progression of malignant melanoma.

Ras/mitogen-activated protein kinase signaling activates Ets-1 and Ets-2 by CBP/p300 recruitment

Cell signaling affects gene expression by regulating the activity of transcription factors. Here, we report that mitogen-activated protein kinase (MAPK) phosphorylation of Ets-1 and Ets-2, at a conserved site N terminal to their Pointed (PNT) domains, resulted in enhanced transactivation by preferential recruitment of the coactivators CREB binding protein (CBP) and p300. We discovered this phosphorylation-augmented interaction in an unbiased affinity chromatography screen of HeLa nuclear extracts by using either mock-treated or ERK2-phosphorylated ETS proteins as ligands. Binding between purified proteins demonstrated a direct interaction. Both the phosphoacceptor site, which lies in an unstructured region, and the PNT domain were required for the interaction. Minimal regions that were competent for induced CBP/p300 binding in vitro also supported MAPK-enhanced transcription in vivo. CBP coexpression potentiated MEK1-stimulated Ets-2 transactivation of promoters with Ras-responsive elements. Furthermore, CBP and Ets-2 interacted in a phosphorylation-enhanced manner in vivo. This study describes a distinctive interface for a transcription factor-coactivator complex and demonstrates a functional role for inducible CBP/p300 binding. In addition, our findings decipher the mechanistic link between Ras/MAPK signaling and two specific transcription factors that are relevant to both normal development and tumorigenesis.

ETS-1 transcription factor activates the expression of mouse UDP-Gal:GA2/GM2/GD2/GT2 galactosyltransferase gene

UDP-Gal:GA2/GM2/GD2/GT2 galactosyltransferase (Gal-T2) transfers galactose to the terminal N-acetylgalactosamine of either the neutral glycolipid GA2 or of the gangliosides GM2, GD2 and GT2. Previous studies revealed a tight regulation of Gal-T2 activity and mRNA expression during development of the rat CNS. Here, we study in PC12 cells the cis-acting elements involved in the activation of a fragment of 211 bp around the transcription initiation site of the mouse Gal-T2 promoter. Mutagenesis, competition experiments and functional assays showed that the Ets-1 transcription factor is involved in the activation of the Gal-T2 promoter.

Expression of the SH2D1A gene is regulated by a combination of transcriptional and post-transcriptional mechanisms

The SH2D1A gene, which is altered or deleted in patients with X-linked lymphoproliferative disease, encodes the small protein SAP (for SLAM-associated protein) that is expressed in T and NK cells. A 22-bp fragment in close proximity to an initiator-like site was defined as the basal promoter of mouse SH2D1A, and a highly homologous 33-bp segment was defined as the human basal promoter. When an Ets consensus site was mutated, no reporter activity was detectable. Gel mobility supershift assays revealed that the two transcription factors Ets-1 and Ets-2 bind to the human and mouse sequences. The involvement of Ets-1 and Ets-2 in expression of SH2D1A was functionally confirmed by overexpression studies of their dominant-negative forms. We also found that SH2D1A mRNA decays very rapidly in mouse T cells, and its 3' untranslated region (UTR) has RNA-destabilizing activity in transfection studies with reporter/3' UTR constructs. As judged by RNA-gel mobility shift assays, this rapid degradation of SH2D1A mRNA was due to a balance in binding of the factors AUF1 and HuR to its 3' UTR. Although the SH2D1A mRNA level decreased upon triggering of the T cell receptor (TCR), the RNA degradation rate itself was not altered by TCR engagement.

Selective regulation of vitamin D receptor-responsive genes by TFIIH

Mutations in the XPD subunit of the transcription/repair factor TFIIH cause the Xeroderma pigmentosum disorder. We show that in some XP-D deficient cells, transactivation by the vitamin D receptor (VDR) is selectively inhibited for a subset of responsive genes, such as CYP24, and that the XPD/R683W mutation prevents VDR recruitment on its promoter. Contrary to other nuclear receptors, VDR, which lacks a functional A/B domain, is not phosphorylated and consequently not regulated by the cdk7 kinase of TFIIH. In fact, we demonstrate that the VDR transactivation defect resides in Ets1, another activator that cannot be phosphorylated by TFIIH in XP-D cells. Indeed, the phosphorylated Ets1 seems to promote the binding of VDR to its responsive element and trigger the subsequent recruitment of coactivators and RNA pol II. We propose a model in which TFIIH regulates the activity of nuclear receptors by phosphorylating either their A/B domain or an additional regulatory DNA binding partner.

Isolation and characterization of the human Cdc2L1 gene promoter

CDK11 (cyclin-dependent kinase 11, formerly known as PITSLRE) is a member of the p34cdc2-related kinases. It has been previously shown to be involved in a variety of different cellular processes including RNA processing, apoptosis, and cell cycle progression. It is encoded by two different but highly similar genes, Cdc2L1 (cell division control 2 like 1) and Cdc2L2 (cell division control 2 like 2). Previous studies from our group identified and characterized the transcriptional regulation of the human Cdc2L2 gene promoter. The current studies identify and characterize the Cdc2L1 gene promoter. We cloned the promoter and elucidated the different transcriptional regulatory elements that reside within the 5' region of the gene. Deletion analysis of the promoter showed a region of nucleotides -152 to +11 to be necessary for basal transcription of the Cdc2L1 gene. Sequencing analysis found this region of the promoter to be highly GC-rich but is lacking both TATA and CAAT boxes. There are several different transcription factor binding sites that are consensus or near consensus found within this region. The potential binding sites include two Ets-1 sites, one Skn-1 site, and one E2F-1 site. Transfection studies of various site-directed mutagenesis clones for these different sites revealed that both Ets-1 sites play critical roles in sustained transcriptional activity as well as Skn-1. Chromatin immunoprecipitation of the endogenous promoter with Ets-1 and Skn-1 verified an in vivo association of Ets-1 and Skn-1 transcription factors with the endogenous promoter. These results, in addition to our Cdc2L2 results, lead to the further comprehension of the fundamental mechanisms dictating CDK11 gene expression through the Cdc2L1 gene promoter.

Importance of ets1 proto-oncogene for breast cancer progression

Ets proteins are transcription factors, which share a unique DNA binding domain, the Ets domain. Some members of the Ets family are implicated in tumorigenesis. Ets1, the founder of the Ets family, is predominantly expressed in invasive tumors and able to activate certain genes encoding ECM-degrading proteases. We used RNA-interference in combination with DNA chip analysis to identify Ets1-regulated genes in MDA-MB-231 breast cancer cells. Of the Ets1-responsive proteases, matrix metalloproteases MMP1 and MMP9, but not MMP3 or uPA, showed reduced RNA levels when endogenous Ets1 expression was suppressed. These data suggest that Ets1 regulates only a certain subset of ECM-degrading proteases. How Ets1 is regulated in invasive breast cancer cells is unknown. The observations that protein kinase C inhibitors abrogated Ets1 expression and that protein kinase C was able to increase Ets1-dependent transcription imply that protein kinase C is a potential regulator of Ets1 activity in breast cancer cells.

The structural and dynamic basis of Ets-1 DNA binding autoinhibition

The transcription factor Ets-1 is regulated by the allosteric coupling of DNA binding with the unfolding of an alpha-helix (HI-1) within an autoinhibitory module. To understand the structural and dynamic basis for this autoinhibition, we have used NMR spectroscopy to characterize Ets-1DeltaN301, a partially inhibited fragment of Ets-1. The NMR-derived Ets-1DeltaN301 structure reveals that the autoinhibitory module is formed predominantly by the hydrophobic packing of helices from the N-terminal (HI-1, HI-2) and C-terminal (H4, H5) inhibitory sequences, along with H1 of the intervening DNA binding ETS domain. The intramolecular interactions made by HI-1 in Ets-1DeltaN301 are similar to the intermolecular contacts observed in the crystal structure of an Ets-1DeltaN300 dimer, confirming that the latter represents a domain-swapped species. (15)N relaxation studies demonstrate that the backbone of the N-terminal inhibitory sequence is mobile on the nanosecond-picosecond and millisecond-microsecond time scales. Furthermore, hydrogen exchange measurements reveal that amide protons in helices HI-1 and HI-2 exchange with water at rates only approximately 15- and approximately 75-fold slower, respectively, than predicted for an unfolded polypeptide. These findings indicate that inhibitory helices are only marginally stable even in the absence of DNA. The energetic coupling of DNA binding with the facile unfolding of the labile HI-1 provides a mechanism for modulating Ets-1 DNA binding activity via protein partnerships, post-translational modifications, or mutations. Ets-1 autoinhibition illustrates how conformational equilibria within structural domains can regulate macromolecular interactions.

Prostaglandin E2 enhances pancreatic cancer invasiveness through an Ets-1-dependent induction of matrix metalloproteinase-2

Accumulating evidence suggests an important role for cyclooxygenase-2 (COX-2) in the pathogenesis of a wide range of malignancies. Here we tested the hypothesis that the COX-2 product prostaglandin E(2) (PGE(2)) increases cellular invasive potential by inducing matrix metalloproteinase-2 (MMP-2) expression and activity through an extracellular signal-regulated kinase (ERK)/Ets-1-dependent mechanism in pancreatic cancer. PANC-1 and MIAPaCa-2 pancreatic cancer cells were treated with PGE(2) or rofecoxib, a selective COX-2 inhibitor. MMP-2 expression and activity were assayed using Western blot analysis and zymography, respectively. MMP-2 promoter activity was analyzed with a luciferase-based assay. Ets-1 activity was analyzed using gel shift assay. Ets-1 expression was specifically silenced using RNA interference. Cellular invasive and migratory potentials were determined using a Boyden chamber assay with or without Matrigel, respectively. Exogenous PGE(2) induced MMP-2 expression and activity and increased ERK1/2 phosphorylation, Ets-1 binding activity, and MMP-2 promoter activity. PGE(2) also increased cellular migratory and invasive potentials. The mitogen-activated protein kinase kinase inhibitor PD98059 and Ets-1 silencing each abolished PGE(2)-induced increases in MMP-2 expression. PD98059 and Ets-1 silencing each abrogated the effect of PGE(2) on cellular invasive potential but not on cellular migratory potential. Rofecoxib suppressed MMP-2 expression and activity, Ets-1 binding activity, MMP-2 promoter activity, and cellular migratory and invasive potentials. These results suggest that PGE(2) mediates pancreatic cancer cellular invasiveness through an ERK/Ets-1-dependent induction of MMP-2 expression and activity. They also suggest that COX-2 inhibition may represent a strategy to inhibit invasive potential in pancreatic cancer.

Identification and Characterization of the IKKα Promoter

IKKalpha, a subunit of IkBalpha kinase (IKK) complex, has an important role in the activation of nuclear factor-kB (NF-kB), a key regulator of normal and tumor cell proliferation, apoptosis, and response to chemotherapy. However, little is known about the transcriptional regulation of the IKKalpha gene itself. The present study revealed that the transcriptional induction of the IKKalpha gene is positively regulated by binding ETS-1, the protein product of the ETS-1 proto-oncogene. Furthermore, ETS-1 mediated activation of IKKalpha is negatively regulated by p53 binding to ETS-1. By analyzing the genomic DNA sequence, we identified the putative IKKalpha promoter sequence in the 5'-flanking untranslated region of the IKKalpha gene. Transfection of EU-4, an acute lymphoblastic leukemia (ALL) cell line, with plasmids containing the IKKalpha 5'-untranslated region sequence upstream of the luciferase reporter showed that this region possessed major promoter activity. Induction or enforced overexpression of p53 represses IKKalpha mRNA and protein expression as well as IKKalpha promoter activity. Deletion and mutation analyses as well as chromatin immunoprecipitation and electrophoretic mobility shift assay indicated that ETS-1 binds to the core IKKalpha promoter and strongly induces its activity. Although p53 does not directly bind to the IKKalpha promoter, it physically interacts with ETS-1 and specifically inhibits ETS-1-induced IKKalpha promoter activity. These results suggest that the proximal 5'-flanking region of the IKKalpha gene contains a functional promoter reciprocally regulated by p53 and ETS-1. Furthermore, loss of p53-mediated control over ETS-1-dependent transactivation of IKKalpha may represent a novel pathway for the constitutive activation of NF-kB-mediated gene expression and therapy resistance in cancer.

Overexpression of the Ets-1 transcription factor in human breast cancer

The Ets family of transcription factors regulate expression of multiple genes involved in tumour progression. The aim of this study was to investigate the expression of Ets-1 in a large panel of human breast cancers and relate its levels to the parameters of tumour progression and metastasis. Using RT-PCR, Ets-1 mRNA was detected in 30 out of 42 (71%) fibroadenomas and 131 out of 179 (73%) primary breast carcinomas. Similarly, levels of Ets-1 mRNA were not significantly different in fibroadenomas and primary breast carcinomas. Using Western blotting, four forms of the Ets-1 protein were detected, that is, p33, p42, p51 and p52. Levels of both p51 and p52 but not p33 and p42 were present at significantly higher levels in the carcinomas compared to the fibroadenomas (for p51, P<0.007; for p52, P<0.02; Mann-Whitney U-test). Levels of p52, p51 and p33 correlated significantly with uPA protein levels (P<0.01), while only levels of p52 correlated significantly with HER-2/neu protein levels (P<0.01). Using immunohistochemistry, Ets-1 was found predominantly in tumour cells, but was also detected in some stromal cells surrounding tumour islands. We conclude that, while at the mRNA level, Ets-1 was found at similar levels in fibroadenomas and primary breast carcinomas, higher protein levels were detected in the cancers compared to the benign specimens. Since p52, p51 and p33 correlate with uPA levels, these forms of Ets-1 may play a role in breast cancer metastasis.

Ets-1 transcription factor is widely expressed in benign and malignant melanocytes and its expression has no significant association with prognosis

Ets-1 transcription factor has been associated with tumor progression in various carcinomas, but its expression in malignant melanoma was only recently described. The study was conducted in two steps: exploratory and confirmatory. In the first step, we studied 69 primary melanomas, 28 metastatic melanomas, 10 usual intradermal nevi and 13 various melanocytic skin lesions. In the second step, an additional group of 98 patients with follow-up of up to 200 months was also evaluated. Immunohistochemical analysis of formalin-fixed/paraffin-embedded tissues was performed using 1G11 antibody and polymer conjugate for visualization. While Ets-1 was variably expressed in 83% primary melanomas in exploratory and 69% in the confirmatory group, the expression of Ets-1 was also found in normal benign melanocytes and all nevi. Analysis of the exploratory group revealed lower expression of Ets-1 in primary melanomas than in common nevi (P=0.048, Mann-Whitney U-test) and metastatic melanomas expressed significantly less Ets-1 than primary melanomas (P=0.015, Mann-Whitney U-test). There was a negative correlation between Ets-1 expression and the largest dimension of the primary tumors (r=0.23, P=0.034, Spearman's correlation rank test), but no correlation with the depth of tumor invasion (Breslow thickness) or the presence of ulceration was found. Analyses of the confirmatory group revealed no association between Ets-1 expression with disease-specific survival or time to treatment failure. However, a statistical trend was found for worse outcome for those primary melanomas that had strong expression (H-score >100) of Ets-1 (P=0.054). Ets-1 is expressed in benign melanocytes probably due to their neural crest origin. We conclude that Ets-1 expression cannot be used to differentiate between benign and malignant melanocytic lesions and it has no definite association with clinical outcome. At the same time, its role in tumor progression in some cases of malignant melanoma cannot be entirely excluded.

The development of early and mature B?cells is impaired in mice deficient for the Ets-1 transcription factor

The Ets-1 transcription factor is essential for normal development of the natural killer and T cell lineages; however, its role in B cell development remains poorly understood. To address this issue, we used gene targeting to inactivate Ets-1 in mice (Ets-1(-/-)). We show here that the development of B cell precursors, particularly steps requiring pre-B cell receptor function, is defective in Ets-1(-/-) mice. Peripheral B cell subsets were analyzed in RAG2-deficient mice reconstituted with Ets-1(-/-) fetal liver cells. In such Ets-1(-/-) chimeric mice, B cell precursors develop into IgM/IgD-bearing cells, but B-1a cells as well as transitional-2 and marginal zone B cell subsets of the spleen are absent. In response to B cell receptor stimulation, Ets-1(-/-) splenic B cells fail to express the CD69 and CD25 activation markers. Furthermore, despite activation of ERK and JNK signaling pathways, Ets-1-deficient B cells do not proliferate and die following BCR engagement. These findings demonstrate that the effect of Ets-1 inactivation is not restricted to the terminal B cell differentiation stage, but also affects the development and function of earlier B cell subsets.