Nuclear localization of EGF receptor and its potential new role as a transcription factor
TL;DR: It is demonstrated that nuclear EGFR is strongly correlated with highly proliferating activities of tissues and associated with promoter region of cyclin D1 in vivo, suggesting that EGFR might function as a transcription factor to activate genes required for highly proliferationating activities.
Abstract: Epidermal growth factor receptor (EGFR) has been detected in the nucleus in many tissues and cell lines. However, the potential functions of nuclear EGFR have largely been overlooked. Here we demonstrate that nuclear EGFR is strongly correlated with highly proliferating activities of tissues. When EGFR was fused to the GAL4 DNA-binding domain, we found that the carboxy terminus of EGFR contained a strong transactivation domain. Moreover, the receptor complex bound and activated AT-rich consensus-sequence-dependent transcription, including the consensus site in cyclin D1 promoter. By using chromatin immunoprecipitation assays, we further demonstrated that nuclear EGFR associated with promoter region of cyclin D1 in vivo. EGFR might therefore function as a transcription factor to activate genes required for highly proliferating activities.
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TL;DR: The recent literature on tumour heterogeneity, field cancerization, molecular pathogenesis and the underlying causative cancer genes that can be exploited for novel and personalized treatments of patients with HNSCC are discussed.
Abstract: Head and neck squamous cell carcinomas (HNSCCs) are caused by tobacco and alcohol consumption and by infection with high-risk types of human papillomavirus (HPV). Tumours often develop within preneoplastic fields of genetically altered cells. The persistence of these fields after treatment presents a major challenge, because it might lead to local recurrences and second primary tumours that are responsible for a large proportion of deaths. Aberrant signalling pathways have been identified in HNSCCs and inhibition of epidermal growth factor receptor (EGFR) has proved a successful therapeutic strategy. In this Review, we discuss the recent literature on tumour heterogeneity, field cancerization, molecular pathogenesis and the underlying causative cancer genes that can be exploited for novel and personalized treatments of patients with HNSCC.
2,090 citations
Cites background from "Nuclear localization of EGF recepto..."
...Most intriguingly, EGF-bound EGFR is also able to translocate to the nucleus and it functions as a transcription factor or co-activator of other transcription factors, such as signal transducer and activator of transcription (STAT) protein...
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TL;DR: Several malignancies are associated with the mutation or increased expression of members of the ErbB family including lung, breast, stomach, colorectal, head and neck, and pancreatic carcinomas and glioblastoma
1,022 citations
TL;DR: The molecular mechanisms that regulate EGFR signal transduction are reviewed, including the EGFR structure and its mutations, ligand binding and EGFR dimerization, as well as the signaling pathways that lead to G1 cell cycle progression.
Abstract: The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is commonly upregulated in cancers such as in non-small-cell lung cancer, metastatic colorectal cancer, glioblastoma, head and neck cancer, pancreatic cancer, and breast cancer Various mechanisms mediate the upregulation of EGFR activity, including common mutations and truncations to its extracellular domain, such as in the EGFRvIII truncations, as well as to its kinase domain, such as the L858R and T790M mutations, or the exon 19 truncation These EGFR aberrations over-activate downstream pro-oncogenic signaling pathways, including the RAS-RAF-MEK-ERK MAPK and AKT-PI3K-mTOR pathways These pathways then activate many biological outputs that are beneficial to cancer cell proliferation, including their chronic initiation and progression through the cell cycle Here, we review the molecular mechanisms that regulate EGFR signal transduction, including the EGFR structure and its mutations, ligand binding and EGFR dimerization, as well as the signaling pathways that lead to G1 cell cycle progression We focus on the induction of CYCLIN D expression, CDK4/6 activation, and the repression of cyclin-dependent kinase inhibitor proteins (CDKi) by EGFR signaling pathways We also discuss the successes and challenges of EGFR-targeted therapies, and the potential for their use in combination with CDK4/6 inhibitors
1,009 citations
Cites background from "Nuclear localization of EGF recepto..."
...it has been shown that nuclear EGFR aids in the transcription of important cell cycle progression mediators, including CYCLIN D1 and c-MYC, among other proto-oncogenes [354,370]....
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...Nuclear EGFR appears to be the full-length receptor [354]....
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TL;DR: The biologic features of squamous-cell carcinoma of the head and neck, including the role of human papillomavirus as a risk factor for cancer of the oropharynx, are considered, along with management approaches.
Abstract: There are more than half a million incident cases of squamous-cell carcinoma of the head and neck worldwide each year, primarily affecting the oropharynx, oral cavity, hypopharynx, and larynx. This review considers the biologic features of these tumors, including the role of human papillomavirus as a risk factor for cancer of the oropharynx. New therapies are considered, along with management approaches.
863 citations
TL;DR: A subsequent cleavage by γ-secretase that releases the ErbB-4 intracellular domain from the membrane and facilitates its translocation to the nucleus is reported.
Abstract: ErbB-4 is a transmembrane receptor tyrosine kinase that regulates cell proliferation and differentiation. After binding of its ligand heregulin (HRG) or activation of protein kinase C (PKC) by 12-O-tetradecanoylphorbol-13-acetate (TPA), the ErbB-4 ectodomain is cleaved by a metalloprotease. We now report a subsequent cleavage by gamma-secretase that releases the ErbB-4 intracellular domain from the membrane and facilitates its translocation to the nucleus. gamma-Secretase cleavage was prevented by chemical inhibitors or a dominant negative presenilin. Inhibition of gamma-secretase also prevented growth inhibition by HRG. gamma-Secretase cleavage of ErbB-4 may represent another mechanism for receptor tyrosine kinase-mediated signaling.
856 citations
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TL;DR: The use of avidin-biotin interaction in immunoenzymatic techniques provides a simple and sensitive method to localize antigens in formalin-fixed tissues.
Abstract: The use of avidin-biotin interaction in immunoenzymatic techniques provides a simple and sensitive method to localize antigens in formalin-fixed tissues. Among the several staining procedures available, the ABC method, which involves an application of biotin-labeled secondary antibody followed by the addition of avidin-biotin-peroxidase complex, gives a superior result when compared to the unlabeled antibody method. The availability of biotin-binding sites in the complex is created by the incubation of a relative excess of avidin with biotin-labeled peroxidase. During formation of the complex, avidin acts as a bridge between biotin-labeled peroxidase molecules; and biotin-labeled peroxidase molecules, which contains several biotin moieties, serve as a link between the avidin molecules. Consequently, a "lattice" complex containing several peroxidase molecules is likely formed. Binding of this complex to the biotin moieties associated with secondary antibody results in a high staining intensity.
13,480 citations
TL;DR: The EGF-MolecularWeight Form of mEGF and the Synthesis of Extracellular Macromolecules, and the Biological Effects of EGF and Urogastrone are presented.
Abstract: During the course of purifying nerve growth factor from the submaxillary gland of the mouse, Cohen (1960) and Levi-Montalcini and Cohen (1960) noticed that daily injections of certain gland extract fractions into newborn mice produced developmental changes that could not be ascribed to nerve growth factor. These changes included precocious opening of the eyelids (7 days compared to the usual 14 days) and a similar early eruption of the incisors. Using these gross anatomical changes as an assay, Cohen (1962) proceeded to isolate the active factor — a polypeptide which he termed epidermal growth factor (EGF).
2,724 citations
TL;DR: The hypothesis that silencing in yeast results from heterochromatin formation is fortified and it is argued that the silencing proteins participate in this formation.
Abstract: Two classes of sequences in the yeast Saccharomyces cerevisiae are subject to transcriptional silencing: the silent mating-type cassettes and telomeres. In this report we demonstrate that the silencing of these regions is strictly associated with acetylation of the epsilon-amino groups of lysines in the amino-terminal domains of three of the four core histones. Both the silent mating-type cassettes and the Y domains of telomeres are packaged in nucleosomes in vivo that are hypoacetylated relative to those packaging active genes. This difference in acetylation is eliminated by genetic inactivation of silencing: The silent cassettes from sir2, sir3, or sir4 cells show the same level of acetylation as other active genes. The correspondence of silencing and hypoacetylation of the mating-type cassettes is observed even for an allele lacking a promoter, indicating that silencing per se, rather than the absence of transcription, is correlated with hypoacetylation. Finally, overexpression of Sir2p, a protein required for transcriptional silencing in yeast, yields substantial histone deacetylation in vivo. These studies fortify the hypothesis that silencing in yeast results from heterochromatin formation and argue that the silencing proteins participate in this formation.
850 citations
TL;DR: Results indicate that the receptor, kinase, and substrate domains are linked, possibly covalently, in epidermal growth factor receptor-kinase complex from A-431 cells.
770 citations
TL;DR: SH2 domains provide a common mechanism by which enzymatically diverse regulatory proteins can physically associate with the same activated receptors and thereby couple growth factor stimulation to intracellular signal transduction pathways.
Abstract: Phospholipase C gamma 1 (PLC gamma 1) and p21ras guanosine triphosphatase (GTPase) activating protein (GAP) bind to and are phosphorylated by activated growth factor receptors. Both PLC gamma 1 and GAP contain two adjacent copies of the noncatalytic Src homology 2 (SH2) domain. The SH2 domains of PLC gamma 1 synthesized individually in bacteria formed high affinity complexes with the epidermal growth factor (EGF)- or platelet derived growth factor (PDGF)-receptors in cell lysates, and bound synergistically to activated receptors when expressed together as one bacterial protein. In vitro complex formation was dependent on prior growth factor stimulation and was competed by intracellular PLC gamma 1. Similar results were obtained for binding of GAP SH2 domains to the PDGF-receptor. The isolated SH2 domains of other signaling proteins, such as p60src and Crk, also bound activated PDGF-receptors in vitro. SH2 domains, therefore, provide a common mechanism by which enzymatically diverse regulatory proteins can physically associate with the same activated receptors and thereby couple growth factor stimulation to intracellular signal transduction pathways.
582 citations