Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In papillary thyroid carcinomas, we have identified two tumor-specific rearrangements of the RET proto-oncogene leading to the formation of different transforming fusion products sharing the tyrosine kinase (tk) domain of the proto-oncogene and designated ptc-1 and ptc-2. We have analysed ptc-1 and ptc-2 products by immunoprecipitation with specific anti-RET antibodies followed by immunoblotting with the same reagent or with antibodies specific for phosphotyrosine (P-tyr) residues. The anti-RET antibodies were reactive with 64-kDa (p64ptc-1) and 81-kDa (p81ptc-2) proteins from lysates of ptc-1 and ptc-2 transformed cells, respectively, and identified two proteins of 140 kDa and 160 kDa from extracts of SK-N-SH, a neuroblastoma cell line previously shown to express two differently glycosylated forms of the normal RET product. The anti P-tyr antibodies, while detecting the same p64ptc-1 and p81ptc-2 proteins from ptc-1 and ptc-2 extracts, did not show any specific band in the neuroblastoma lysates. An additional set of experiments led us to conclude that, whereas the normal product of the RET proto-oncogene is a membrane-associated receptor-like molecule not intrinsically phosphorylated on tyrosine, both oncogenic forms of RET, ptc-1 and ptc-2, are constitutively phosphorylated on tyrosine, display an 'in vitro' autophosphorylation activity, are translocated from the membrane to the cytoplasm and are apparently unaffected by protein kinase C modulation.
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PMID:Identification of the product of two oncogenic rearranged forms of the RET proto-oncogene in papillary thyroid carcinomas. 143 45

The accumulation of genetic damage in the forms of activated proto-oncogenes and inactivated tumor-suppressor genes is the driving force in the evolution of a normal cell to a malignant cell. For example, both the activation of ras oncogenes and the inactivation of several suppressor genes, including p53, have been observed in the development of human colon and lung tumors. Point mutations in key codons can activate ras proto-oncogenes and inactivate the p53 suppressor gene. Thus, several critical genes for tumorigenesis are potential targets for carcinogens and radiation that can induce point mutations at low doses. The ras proto-oncogenes are targets for many genotoxic carcinogens. Activation of the ras gene is an early event--probably the "initiating" step--in the development of many chemical-induced rodent tumors. ras Oncogenes are observed in more human tumors and at a higher frequency than any other oncogene, and activation of the proto-oncogene may occur at various stages of the carcinogenic process. Numerous proto-oncogenes other than the ras genes have been shown to be activated in human tumors and to a lesser extent in rodent tumors. Mechanisms that induce aberrant expression of proto-oncogenes are gene amplification and chromosomal translocation or gene rearrangement. Amplification of proto-oncogenes and possibly gene overexpression during the absence of gene amplification occur in the development of many human tumors. For a specific tumor type, amplification of any one proto-oncogene may occur at a low frequency, but the frequency of tumors in which at least one proto-oncogene is amplified can be much higher. Proto-oncogene amplification is usually associated with late stages of tumor progression; however, amplified HER2/neu has been observed in early clinical stages of mammary neoplasia. Activation of proto-oncogenes by chromosomal translocation has been detected at a high frequency in several hematopoietic tumors. Non-ras genes have been detected by DNA transfection assays in both human and rodent tumors. For example, ret and trk genes were found to be activated by gene rearrangements in human papillary thyroid carcinomas. Several potentially new types of oncogenes have also been detected by DNA transfection assays. The etiology of the genetic alterations observed in most human tumors is unclear at present. Examples of ras gene activation and those documented for mutations in the p53 gene demonstrate that exogenous conditions can induce oncogenic mutants of normal genes. The genetic alterations observed in most human tumors are probably generated by both spontaneous events and exogenous conditions.
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PMID:Role of proto-oncogene activation in carcinogenesis. 148 40

Ets proteins have a conserved DNA-binding domain and regulate transcriptional initiation from a variety of cellular and viral gene promoter and enhancer elements. Some members of the Ets family, Ets-1 and Ets-2, cooperate in transcription with the AP-1 transcription factor, the product of the proto-oncogene families, fos and jun, while others, Elk-1 and SAP-1, form ternary complexes with the serum response factor (SRF). Certain ets gene family members possess transforming activity while others are activated by proviral integration in erythroleukaemias.
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PMID:The ets gene family. 150 27

We have recently reported the frequent activation of the TRK oncogene in human papillary thyroid carcinoma. In this paper we describe the isolation and characterization of one of the thyroid TRK oncogenes, designated TRK-T1. A 1746-bp-long cDNA was isolated from a library derived from a primary transformant. The cDNA was able to induce foci in NIH3T3 cells. Sequence analysis revealed that TRK-T1 is created by an intrachromosomal rearrangement that juxtaposes the 5' end of the TPR gene to the TRK tyrosine kinase domain. The resulting hybrid mRNA contains 598 nucleotides of the TPR gene and 1148 nucleotides of the TRK proto-oncogene. TRK-T1 mRNA encodes a protein of 55 kDa reacting with antibodies against the carboxy terminus of the proto-TRK protein. We show also the involvement of TPR in the generation of another TRK-T oncogene.
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PMID:TRK-T1 is a novel oncogene formed by the fusion of TPR and TRK genes in human papillary thyroid carcinomas. 153 41

The TRK proto-oncogene encodes a tyrosine kinase receptor for an, as yet, unidentified ligand. In order to help the identification of this ligand, we have constructed an expression vector capable of overexpressing the TRK protein in an inducible fashion. We report here the characterization of the TRK proto-oncogene products obtained from this expression vector.
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PMID:Overexpression of human TRK proto-oncogene into mouse cells using an inducible vector system. 164 65

The MET proto-oncogene encodes a transmembrane tyrosine kinase receptor for HGF (p190MET). In this work, p190MET was immunoprecipitated, allowed to phosphorylate in the presence of [gamma-32P]ATP, and digested with trypsin. A major phosphopeptide was purified by reverse phase chromatography. The phosphorylated tyrosine was identified as residue 1235 (Tyr1235) by Edman covalent radiosequencing. A synthetic peptide derived from the corresponding MET sequence was phosphorylated by p190MET in an in vitro assay and coeluted in reverse phase chromatography. Tyr1235 lies within the tyrosine kinase domain of p190MET, within a canonical tyrosine autophosphorylation site that shares homology with the corresponding region of the insulin, CSF-1 and platelet-derived growth factor receptors, and of p60src and p130gag-fps. The p190MET kinase is constitutively phosphorylated on tryosine in a gastric carcinoma cell line (GTL16), due to the amplification and overexpression of the MET gene. Metabolic labeling of GTL-16 cells with [32P]orthophosphate followed by immunoprecipitation and tryptic phosphopeptide mapping of p190MET showed that Tyr1235 is a major site of tyrosine phosphorylation in vivo as well. Since phosphorylation activates p190MET kinase, we propose a regulatory role for Tyr1235.
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PMID:Identification of the major autophosphorylation site of the Met/hepatocyte growth factor receptor tyrosine kinase. 165 90

The MET proto-oncogene encodes a 190-kDa disulfide-linked heterodimeric receptor (p190 alpha beta) whose tyrosine kinase activity is triggered by the hepatocyte growth factor. The mature receptor is made of two subunits: an alpha chain of 50 kDa and a beta chain of 145 kDa, arising from proteolytic cleavage of a single-chain precursor of 170 kDa (pr170). In a colon carcinoma cell line (LoVo), the precursor is not cleaved and the Met protein is exposed at the cell surface as a single-chain polypeptide of 190 kDa (p190NC). The expression of the uncleaved Met protein is due to defective posttranslational processing, since in this cell line (i) the proteolytic cleavage site Lys-303-Arg-Lys-Lys-Arg-Ser-308 is present in the precursor, (ii) p190NC is sensitive to mild trypsin digestion of the cell surface, generating alpha and beta chains of the correct size, and (iii) the 205-kDa insulin receptor precursor is not cleaved as well. p190NC is a functional tyrosine kinase in vitro and is activated in vivo, as shown by constitutive autophosphorylation on tyrosine. The MET gene is neither amplified nor rearranged in LoVo cells. Overlapping cDNA clones selected from a library derived from LoVo mRNA were sequenced. No mutations were present in the MET-coding region. These data indicate that the tyrosine kinase encoded by the MET proto-oncogene can be activated as a consequence of a posttranslational defect.
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PMID:Defective posttranslational processing activates the tyrosine kinase encoded by the MET proto-oncogene (hepatocyte growth factor receptor). 165 24

The ERBB2 proto-oncogene was studied in 539 invasive primary breast tumors and was found amplified (2- greater than 30 copies) in 19%. Amplification was correlated to most known risk factors, including; large tumor size, lymph node positivity and many tumor involved nodes, advanced stage, low patient age (less than 40 years), non-diploidy and hypertetraploidy, and most significantly (P less than 0.00001) to the absence of steroid receptors and to a high rate of proliferation (flow cytometric determined S phase fraction). ERBB2 amplification was strongly associated (P less than 0.0001) with early recurrence and death in breast cancer among node-positive patients. This connection did not, however, remain in multivariate analyses. No correlations to clinical outcome were seen among node-negative patients. Similarly, non-diploid, but not diploid, amplified tumors were particularly aggressive. Furthermore, ERBB2 amplification was associated with a high rate of proliferation and poor prognosis in steroid receptor positive, but not receptor negative tumors. In progesterone receptor positive breast cancer, amplification was an independent and with node status equally powerful (P less than 0.0001) predictor of poor survival. It is concluded that ERBB2 activity is related to an increased tumor growth rate but not directly to metastasizing ability. Its clinical relevance as a prognostic factor may be in selecting a high risk subgroup of breast cancer, in general considered as being of good prognosis.
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PMID:ERBB2 amplification in breast cancer with a high rate of proliferation. 167 31

The neu/HER2 proto-oncogene encodes a transmembrane tyrosine kinase homologous to receptors for polypeptide growth factors. The oncogenic potential for the presumed receptor is released through multiple genetic mechanisms including a specific point mutation, truncation at the extracellular domain and overexpression of the protooncogene. Here we show that all these modes of oncogenic activation result in a constitutively phosphorylated neu protein and an increase in tyrosine phosphorylation of a phosphatidylinositol-specific phospholipase (PLC gamma). The examined transforming neu/HER2 proteins, unlike the normal gene product, also co-immunoprecipitated with PLC gamma molecules. A kinase-defective mutant of a transforming neu failed to mediate both tyrosine phosphorylation and association with PLC gamma, suggesting direct interaction of the neu kinase with PLC gamma. This possibility was examined by employing a chimeric protein composed of the extracellular ligand-binding domain of the epidermal growth factor receptor and the neu cytoplasmic portion. The chimeric receptor mediated rapid ligand-dependent modification of PLC gamma on tyrosine residues. It also physically associated, in a ligand-dependent manner, with the phosphoinositidase. Based on the presented results we suggest that the mechanism of cellular transformation by the neu/HER2 receptor involves tyrosine phosphorylation and activation of PLC gamma.
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PMID:Oncogenic forms of the neu/HER2 tyrosine kinase are permanently coupled to phospholipase C gamma. 167 73

The HER2 (c-erbB-2) gene encodes a protein, p185HER2, which possesses all of the structural characteristics and functional properties of a growth factor receptor, although its ligand has not yet been well characterized. HER2 is the human homolog of the rat proto-oncogene neu and is closely related to the gene encoding the epidermal growth factor receptor. Amplification of this gene and overexpression have been found to be a prognostic criterion for a 30% subpopulation of human breast cancer patients. In this study, we investigated the role of the transmembrane-spanning sequence in the biosynthesis and localization of p185HER2. A truncation mutant lacking the cytoplasmic and transmembrane domains was glycosylated and efficiently secreted. However, a mutant lacking only the transmembrane-spanning sequence was incompletely glycosylated and failed to reach the cell surface. Unexpectedly, although this deletion mutant was retained in the endoplasmic reticulum membrane, it was still able to transform NIH 3T3 cells when expressed at high levels.
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PMID:Cell transformation potential of a HER2 transmembrane domain deletion mutant retained in the endoplasmic reticulum. 168 81


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