Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine the location of sites that may be important for the function of the promoter of the epidermal growth factor (EGF) receptor gene and to characterize the factors that bind to these sites, the promoter region was analyzed by deletion analysis, exonuclease III protection and gel retardation assays with crude and fractionated nuclear extracts and DNase I footprinting using purified Sp1. Transfection of chimeric chloramphenicol acetyltransferase plasmids containing various deletions of the EGF receptor gene promoter into CV-1 cells indicated that the region between -178 and -16 (initiator ATG is +1) is sufficient for promoter activity. Exonuclease III protection assays revealed the presence of eight specific nuclear protein binding sites in the region between -481 and -16. Gel retardation assays confirmed that multiple protein binding sites exist in this region (-481 to -16) and quantitatively agree with exonuclease III protection. DNase I footprinting using purified Sp1 showed that this transcription factor can bind to four sites (-457 to -440, -365 to -286, -214 to -200, and -110 to -84) in the EGF receptor gene promoter and therefore may play a role in its regulation.
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PMID:Epidermal growth factor receptor gene promoter. Deletion analysis and identification of nuclear protein binding sites. 283 11

We have studied in vitro transcription of the human epidermal growth factor (EGF) receptor proto-oncogene using nuclear extracts of A431 human epidermoid carcinoma cells, which overproduce the EGF receptor. With the in vitro system we found that Sp1 and other trans-acting factors bound to the EGF receptor promoter regions and are required for maximal expression. Fractionation showed that a DEAE-Sepharose fraction (BA) contained a novel factor, which specifically stimulated EGF receptor transcription 5- to 10-fold. The molecular mass of the native form of the factor is about 270-kDa based on its migration on Sephacryl S-300. This factor may activate transcription of the proto-oncogene through a weak or indirect interaction with the DNA template.
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PMID:Epidermal growth factor (EGF) receptor gene transcription. Requirement for Sp1 and an EGF receptor-specific factor. 328 24

Analysis of the proximal promoter of the human erbB-2 gene identified a 100 bp region that enhanced activity of the proximal TATA box 200-fold. DNase I footprinting mapped three Sp1 binding sites within this 100 bp region but only one of these sites was of high affinity and strongly correlated to Sp1-dependent activity in vivo. This Sp1 site overlapped the distal of two similar palindromic sequences. The proximal palindrome did not bind Sp1 but overlaps the CAAT box. When placed in the context of a heterologous promoter, the palindrome functioned as a positive response element. However, removal of the 5' half of the proximal palindrome increased promoter activity indicating that it functions as an inhibitory element within the erbB-2 context. Using electrophoretic mobility shift assays, a nuclear protein was detected that bound to either the 5' or 3' half of the palindrome but not to both. Analysis of the function of mutant sequences revealed maximal activity when both halves of the palindrome were intact with decreased but significant activity persisting when the 3' half of the palindrome was disrupted. Disruption of the 5' half of the palindrome impaired activity to a greater extent. These studies indicate erbB-2 promoter activity is positively regulated by Sp1 and negatively regulated in a position-dependent context by a protein that binds to a palindromic sequence.
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PMID:Positive and negative regulatory elements in the human erbB-2 gene promoter. 791 45

The response of the epidermal growth factor (EGF) receptor gene to phorbol 12-myristate 13-acetate (PMA) was analyzed using nuclei and nuclear extracts prepared from PMA-treated KB cells. Transient transfection assays and nuclear run-off experiments showed that PMA increased EGF receptor gene transcription. Cell-free transcription with promoter mutants revealed that the region of the promoter containing nucleotides -150 to -16 was sufficient for PMA inducibility. A promoter fragment containing nucleotides -167 to -105 showed increased binding of a factor present in extracts prepared from PMA-treated cells. When this factor was partially purified by column chromatography, it showed specific PMA-dependent binding to an EGF receptor promoter fragment. This binding was competed by an SV40 fragment containing binding sites for Sp1, AP1, and AP2. Purified AP2 was used in DNase I footprinting experiments to show that this factor can bind to the EGF receptor promoter. Oligonucleotides corresponding to the AP2 binding sites found in the EGF receptor promoter showed the ability to bind AP2 and compete for the binding of a factor induced by PMA treatment. The addition of AP2 to nuclear extract resulted in increased transcription from the EGF receptor promoter. These results demonstrate that AP2 can activate EGF receptor gene expression and may mediate the PMA response of this gene.
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PMID:Activation of epidermal growth factor receptor gene transcription by phorbol 12-myristate 13-acetate is mediated by activator protein 2. 862 97

The neu (c-erbB-2) proto-oncogene encodes a tyrosine kinase receptor that is overexpressed in 20 to 30% of human breast tumors. Herein, cyclin D1 protein levels were increased in mammary tumors induced by overexpression of wild-type Neu or activating mutants of Neu in transgenic mice and in MCF7 cells overexpressing transforming Neu. Analyses of 12 Neu mutants in MCF7 cells indicated important roles for specific C-terminal autophosphorylation sites and the extracellular domain in cyclin D1 promoter activation. Induction of cyclin D1 by NeuT involved Ras, Rac, Rho, extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38, but not phosphatidylinositol 3-kinase. NeuT induction of the cyclin D1 promoter required the E2F and Sp1 DNA binding sites and was inhibited by dominant negative E2F-1 or DP-1. Neu-induced transformation was inhibited by a cyclin D1 antisense or dominant negative E2F-1 construct in Rat-1 cells. Growth of NeuT-transformed mammary adenocarcinoma cells in nude mice was blocked by the cyclin D1 antisense construct. These results demonstrate that E2F-1 mediates a Neu-signaling cascade to cyclin D1 and identify cyclin D1 as a critical downstream target of neu-induced transformation.
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PMID:Cyclin D1 is required for transformation by activated Neu and is induced through an E2F-dependent signaling pathway. 1061 Dec 46

MLN64, is invariably coamplified and coexpressed with erbB-2 in breast cancers. The human MLN64 and ERBB2 genes are positioned at less than 50 kb from each other, on chromosome 17q12. To understand the molecular basis of MLN64 overexpression in cancer, the genomic region containing the MLN64 and ERBB2 genes was isolated and mapped. The two genes, DARPP32 and Telethonin, flanking MLN64 respectively on its centromeric and telomeric sides, although coamplified, are not overexpressed in breast cancer cells, indicating that gene amplification is not sufficient to allow overexpression. The MLN64 minimal promoter was isolated and found to be a housekeeping gene promoter containing four potential Sp1 binding elements. Using Sp1-deficient Drosophila SL2 cells, MLN64 promoter activity was induced in a dose-dependent manner by exogenous Sp1 addition. Furthermore, mutation of each individual Sp1 element resulted in a significant decrease in reporter gene activity, indicating that all the Sp1 binding elements are functional and act together to promote gene expression. Since the ERBB2 promoter is also positively regulated by Sp1, this study indicates that MLN64 and ERBB2 genes share common transcriptional controls together with a physical link on chromosome 17q. We speculate that, in addition to the oncogenic potential of erbB-2 overexpression, the unbalanced action of MLN64 contributes to the poor clinical outcome of breast tumors bearing this amplified region.
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PMID:Metastatic lymph node 64 (MLN64), a gene overexpressed in breast cancers, is regulated by Sp/KLF transcription factors. 1280 84

Matrix metalloproteinase (MMP) inhibitory proteins may negatively regulate MMP activity to suppress tumor metastasis. In this study, we demonstrate that the HER-2/neu oncogene inhibits the expression of the MMP inhibitor RECK to promote cell invasion. RECK was inhibited via transcriptional repression in B104-1-1 cells, which express constitutively active HER-2/neu. Overexpression of HER-2/neu in NIH/3T3 or HaCaT cells also suppressed RECK expression. Deletion and mutation assays showed that HER-2/neu repressed RECK via the Sp1-binding site localized in the -82/-71 region from the translational start site. DNA affinity precipitation and chromatin immunoprecipitation assays indicated that binding of Sp1 and Sp3 to this consensus site was increased in B104-1-1 cells. We also found that HER-2/neu inhibited RECK via the ERK signaling pathway. Sp1 proteins phosphorylated at Thr453 and Thr739 by ERK bound preferentially to the RECK promoter, and this binding was reversed by HER-2/neu and ERK inhibitors. Furthermore, our data indicate that HER-2/neu obviously increased HDAC1 binding to the Sp1-binding site localized in the -82/-71 region of the RECK promoter. The histone deacetylase inhibitor trichostatin A reversed HER-2/neu-induced inhibition of RECK. HER-2/neu activation was associated with increased MMP-9 secretion and activation. Re-expression of RECK in HER-2/neu-overexpressing cells inhibited MMP-9 secretion and cell invasion. Taken together, our results suggest that HER-2/neu induces the binding of Sp proteins and HDAC1 to the RECK promoter to inhibit RECK expression and to promote cell invasion. Restoration of RECK provides a novel strategy for the inhibition of HER-2/neu-induced metastasis.
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PMID:HER-2/neu represses the metastasis suppressor RECK via ERK and Sp transcription factors to promote cell invasion. 1637 29

Expression of cyclooxygenase-2 (COX-2) has been linked to many cancers and may contribute to malignant phenotypes, including enhanced proliferation, angiogenesis, and resistance to cytotoxic therapies. Malignant gliomas are highly aggressive brain tumors that display many of these characteristics. One prominent molecular abnormality discovered in these astrocytic brain tumors is alteration of epidermal growth factor (EGF) receptor (EGFR) through gene amplification and/or mutation resulting in excessive signaling from this receptor. We found that EGF-mediated stimulation of EGFR tyrosine kinase in human glioma cell lines induces expression of both COX-2 mRNA and protein. The p38 mitogen-activated protein kinase (p38-MAPK) pathway was a strong downstream factor in this activation with inhibition of this pathway leading to strong suppression of COX-2 induction. The p38-MAPK pathway can activate the Sp1/Sp3 transcription factors and this seems necessary for EGFR-dependent transactivation of the COX-2 promoter. Analysis of COX-2 promoter/luciferase constructs revealed that transcriptional activation of the COX-2 promoter by EGFR requires the Sp1 binding site located at -245/-240. Furthermore, Sp1/Sp3 binding to this site in the promoter is enhanced by EGFR activation both in vitro and in vivo. Enhanced DNA binding by Sp1/Sp3 requires p38-MAPK activity and correlates with increased phosphorylation of the Sp1 transcription factor. Thus, EGFR activation in malignant gliomas can transcriptionally activate COX-2 expression in a process that requires p38-MAPK and Sp1/Sp3. Finally, treatment of glioma cell lines with prostaglandin E2, the predominant product of COX-2 activity, results in increased vascular endothelial growth factor expression, thus potentially linking elevations in COX-2 expression with tumor angiogenesis in malignant gliomas.
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PMID:EGFR activation results in enhanced cyclooxygenase-2 expression through p38 mitogen-activated protein kinase-dependent activation of the Sp1/Sp3 transcription factors in human gliomas. 1761 68

Recently, the epidermal growth factor (EGF) receptor (EGFR), a member of the ErbB receptor family, and its down-stream signalling have been identified as co-factors for HCV entry and replication. Since EGFR also functions as a heterodimer with other ErbB receptor family members, the subject of the present study was to investigate a possible viral interference with these cellular components. By using genotype 1b replicon cells as well as an infection-based system we found that while transcript and protein levels of EGFR and ErbB2 were up-regulated or unaffected, respectively, HCV induced a substantial reduction of ErbB3 and ErbB4 expression. Down-regulation of ErbB3 expression by HCV involves specificity protein (Sp)1-mediated induction of Neuregulin (NRG)1 expression as well as activation of Akt. Consistently, at transcript level disruption of ErbB3 expression by HCV can be prevented by knockdown of NRG1 or Sp1 expression, whereas reconstitution of ErbB3 protein levels requires inhibition of HCV-induced NRG1 expression and of Akt activity. Interestingly, the NRG1-mediated suppression of ErbB3 expression by HCV results in an enhanced expression of EGFR and ErbB2 on the cell surface, which can be mimicked by siRNA-mediated knockdown of ErbB3 expression. These data delineate a novel mechanism enabling HCV to sway the composition of the ErbB family members on the surface of its host cell by an NRG1-driven circuit and unravels a yet unknown cross-regulation between ErbB3 and the two other family members ErbB2 and EGFR. The shift of the receptor surface expression of the ErbB family towards enhanced expression of ErbB2 and EGFR triggered by HCV was found to promote viral RNA replication and infectivity. This suggests that HCV rearranges expression of ErbB family members to adapt the cellular environment to its requirements.
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PMID:Hepatitis C Virus Activates a Neuregulin-Driven Circuit to Modify Surface Expression of Growth Factor Receptors of the ErbB Family. 2688 48