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)

Proteins mediating the transmission of the signal from an activated transforming growth factor beta (TGF beta) receptor complex have not been identified. Using a yeast interaction screen to search for proteins that associate with the type II TGF beta receptor (RII), we isolated a protein which was identical to apolipoprotein J (apoJ)/clusterin. ApoJ interacts with both the type I (RI) and type II (RII) TGF beta receptors but does not interact with the epidermal growth factor (EGF) receptor. The interaction between RII and apoJ occurs through the C-terminal 127 amino acids of RII. Deletion of this region, which contains the kinase insert 2 domain, abrogates binding to apoJ. The binding of apoJ to either the RI and the RII receptors is direct, not requiring other proteins, and is not specific for the alpha or beta subunit of apoJ since both subunits are effective in competing for binding. RI and RII fusion proteins are capable of precipitating the 60 kDa intracellular form of apoJ from [35S]methionine-labeled cellular lysates, suggesting that this form of the protein may play some role in TGF beta signaling or TGF beta receptor processing.
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PMID:Interaction of transforming growth factor beta receptors with apolipoprotein J/clusterin. 855 89

The RET proto-oncogene encodes a member of the receptor tyrosine kinase family. Multiple endocrine neoplasia type 2B (MEN 2B) is caused by the mutation of a conserved methionine to a threonine in the catalytic domain of the RET kinase. When the MEN 2B point mutation was introduced into the epidermal growth factor (EGF) receptor (M857T EGFR), the intrinsic tyrosine kinase activity of the mutant receptor was similar to that of wild-type EGF receptor and remained ligand-dependent. However, the mutant receptor showed an enhanced transforming capacity compared to the wild-type receptor as judged by its ability to mediate the growth of NIH 3T3 cells in soft agar. Using the oriented peptide library approach to examine substrate specificity, the M857T mutation was found to be associated with a decrease in the selectivity of the receptor for Phe and an increase in the selectivity for acidic residues at the P + 1 position as compared to wild-type EGF receptor. Short-term responses to EGF were similar in cells expressing wild-type and M857T EGF receptors. However, significant differences in receptor down-regulation were observed between the two receptors. These data demonstrate that the MEN 2B point mutation alters the substrate specificity of receptor tyrosine kinases and suggest that the enhanced oncogenesis associated with the MEN 2B mutation may be due in part to alterations in receptor regulation.
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PMID:The multiple endocrine neoplasia type 2B point mutation alters long-term regulation and enhances the transforming capacity of the epidermal growth factor receptor. 862 56

The c-erbB-2 proto-oncogene encodes a 185000 molecular weight protein (p185(erbB-2)) which shares structural homology with the epidermal growth factor (EGF) receptor. We examined the effects of dihydrotestosterone (DHT) on the expression of p185(erbB2) and c-erbB-2 mRNA in the human malignant prostatic cell line LNCaP. LNCaP cells grown in steroid-depleted media were treated with DHT (10(-11)-10(-6) M) for 48 h and p185(erbB-2) expression was determined by Western blotting and immunoprecipitation of 35S-methionine labelled p185(erbB-2). c-erbB-2 mRNA levels were determined using a competitive quantitative reverse transcription-polymerase chain reaction (RT-PCR) based technique. DHT at concentrations of 10(-9) M or greater resulted in decreased expression of p185(erbB-2). In contrast, DHT at these levels stimulated EGF receptor protein expression and cellular proliferation. c-erbB-2 mRNA levels declined to 30-50% of control levels following treatment with DHT of 10(-10) M or greater. Furthermore, the inhibitory effects on c-erbB-2 mRNA were rapid, occurring within 6-12 h of treatment. In summary, these results demonstrate that DHT, at concentrations that stimulate cell growth, inhibits the expression of p185(erbB-2) and c-erbB-2 mRNA.
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PMID:The effects of dihydrotestosterone on the expression of p185(erbB-2) and c-erbB-2 mRNA in the prostatic cell line LNCaP. 901 Mar 49

Nerve growth factor (NGF) treatment causes a profound down-regulation of epidermal growth factor receptors during the differentiation of PC12 cells. This process is characterized by a progressive decrease in epidermal growth factor (EGF) receptor level measured by 125I-EGF binding, tyrosine phosphorylation, and Western blotting. Treatment of the cells with NGF for 5 days produces a 95% reduction in the amount of [35S]methionine-labeled EGF receptors. This down-regulation does not occur in PC12nnr5 cells, which lack the p140(trk) NGF receptor. However, in PC12nnr5 cells stably transfected with p140(trk), the NGF-induced heterologous down-regulation of EGF receptors is reconstituted in part. NGF-induced heterologous down-regulation, but not EGF-induced homologous down-regulation of EGF receptors, is blocked in Ras- and Src-dominant-negative PC12 cells. Treatment with either pituitary adenylate cyclase-activating peptide (PACAP) or staurosporine stimulates neurite outgrowth in PC12 cell variants, but neither induces down-regulation of EGF receptors. NGF treatment of PC12 cells in suspension induces down-regulation of EGF receptors in the absence of neurite outgrowth. These results strongly suggest a p140(trk)-, Ras- and Src-dependent mechanism of NGF-induced down-regulation of EGF receptors and separate this process from NGF-induced neurite outgrowth in PC12 cells.
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PMID:Down-regulation of epidermal growth factor receptors by nerve growth factor in PC12 cells is p140(trk)-, Ras-, and Src-dependent. 911 Sep 95

The phage library derived, nonphosphorylated and thioether-cyclized peptide, termed G1TE, cyclo(CH(2)CO-Glu(1)-Leu-Tyr(3)-Glu-Asn-Val-Gly-Met-Tyr-Cys(10))-amid e, represents a new structural motif that binds to the Grb2-SH2 domain in a pTyr-independent manner, with an IC(50) of 20 microM. The retention of binding affinity is very sensitive with respect to peptide ring-size alterations and Ala mutations. We demonstrated previously that the Glu(1) side chain and its closely related analogs partially compensate for the absence of the phosphate functionality on Tyr(3), and, based on molecular modeling, these acidic side-chains complex with the Arg67 and Arg86 side-chains of the protein in the binding cavity. In this study we judiciously altered and incorporated various natural and unnatural amino acids as Tyr replacements within the -YEN- motif, and we demonstrate the functional importance and structural requirement of Tyr(3) for effective binding of this novel non-phosphorylated ligand to the Grb2-SH2 domain. The phenyl side-chain moiety and a polar functional group with specific orientation in position Y(3) of the peptide are particularly required. Using SPR binding assays, a submicromolar inhibitor (IC(50) = 0.70 microM) was obtained when Glu(1) was replaced with alpha-aminoadipate and Tyr(3) was replaced with 4-carboxymethyl-Phe, providing peptide 14, G1TE(Adi(1), cmPhe(3)). Peptide 14 also inhibited Grb2/p185(erb)(B-2) protein association in cell homogenates of erbB-2-overexpressing MDA-MA-453 cancer cells at near one micromolar concentrations.
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PMID:Structural requirements for Tyr in the consensus sequence Y-E-N of a novel nonphosphorylated inhibitor to the Grb2-SH2 domain. 1054 28

A wide repertoire of transmembrane proteins are proteolytically released from the cell surface by a process known as 'ectodomain shedding', under both normal and pathophysiological conditions. Little is known about the physiological mechanisms that regulate this process. As a model system, we have investigated the metalloproteinase-mediated cleavage of the hepatocyte growth factor receptor, Met. We show that epidermal growth factor (EGF) receptor activation, either directly by EGF or indirectly via the G-protein coupled receptor (GPCR) agonist lysophosphatidic acid (LPA), induces cleavage of Met through activation of the Erk MAP kinase signalling cascade. The tyrosine kinase activity of the EGFR was a prerequisite for this stimulation, since treatment of cells with a synthetic inhibitor of this receptor, AG1478, completely abrogated shedding. The metalloproteinase mediating Met cleavage was specifically inhibited by the tissue inhibitor of metalloproteinases (TIMP)-3, but not by TIMP-1 or TIMP-2. Furthermore, the level of Met shedding could be modulated by different cell-matrix interactions. Our results indicate that ectodomain shedding is a highly regulated process that can be stimulated by EGFR signalling pathways and integrin ligation.
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PMID:Shedding of c-Met is regulated by crosstalk between a G-protein coupled receptor and the EGF receptor and is mediated by a TIMP-3 sensitive metalloproteinase. 1122 64

Control of cell growth and differentiation occurs via extracellular signals known as growth factors. Growth factors are high affinity ligands for transmembrane receptors belonging to the family of receptor tyrosine kinases (RTKs). A number of genetic evidences have implicated RTKs in human diseases including developmental disorders and cancer. For instance, germline missense mutations involving the Ret receptor are found in patients affected by multiple endocrine neoplasia types 2A and 2B (MEN2A and MEN2B) or familial medullary thyroid carcinomas. Somatic mutations in the Kit receptor are found in mastocytomas and in gastrointestinal tumors. Germline and sporadic mutations of the Met receptor have been described in kidney and hepatocellular carcinomas. Overexpression of the HER-2/neu receptor in breast cancer has been associated with tumor progression. The enzymatic activity of RTKs is strictly regulated and is usually inhibited under basal conditions. Receptor activation triggers a biochemical signalling cascade inside the cytoplasm, named signal transduction, which is subverted during the malignant transformation of cells. Signal transduction by RTKs is a multistep process which includes: (i) Ligand binding and receptor dimerization, (ii) receptor phosphorylation on tyrosine residues; (iii) recruitment to the receptor and activation of cytoplasmic signaling molecules that transmit signals to the nucleus. Each of the steps involved in this process can potentially be targeted to block the aberrant properties of tyrosine kinase receptors. By using the MET oncogene as a model this review focuses on the strategies that can be applied to therapeutically target RTKs.
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PMID:Receptor tyrosine kinases as therapeutic targets: the model of the MET oncogene. 1146 38

The tyrosine kinase (TK) family includes many growth factor receptors, cell cycle regulators, and oncoproteins. Moreover, the receptor TKs HER2/neu and epidermal growth factor receptor are overexpressed in a subgroup of breast tumors and correlate with more aggressive behavior. Thus, TKs are being actively pursued as therapeutic targets. The purpose of this study was to determine the expression pattern of TKs in breast cancer. Reverse transcription-PCR was performed with degenerate primers based on conserved motifs of the catalytic domains of TKs, and the identities of the reverse transcription-PCR products were determined by digestion with a panel of restriction enzymes. Using a TK display assay, we studied the TK profiles of 13 breast cancer cell lines and two normal immortalized breast epithelial cell lines. The TK display assay reproducibly demonstrated known differences in HER-2/neu expression between cell lines. Several TKs, including receptor TKs Axl, Cak, fibroblast growth factor receptor 4, HEK8, HER2/neu, c-MET, RET, and nonreceptor TKs ARG, BRK, Janus kinase 1, Rak, and YES were detected in breast cancer cells. Several kinases were differentially expressed among the cell lines. Similar TK profiles were found using RNA from human breast tumors. We conclude that there is significant variability in the TK expression pattern of breast cancers. This variability should be considered when selecting TK inhibitors to treat patients.
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PMID:Expression profile of tyrosine kinases in breast cancer. 1183 50

Quantitative immunohistochemistry of ERBB-2 and MET receptor proteins and of cyclooxygenase 2 (COX-2) was undertaken to determine if there is a positive correlation between overexpression of either ERBB-2 or MET and up-regulation of COX-2 in human cholangiocarcinogenesis. ERBB-2, MET, and COX-2 immunoreactivities were measured in cancerous parenchyma of 71 archival cases of human cholangiocarcinoma (ChC) compared with hyperplastic small biliary ducts in surrounding nonneoplastic liver and with bile ducts of normal adult human liver. ERBB-2, MET, and COX-2 immunoreactivities were also assessed in both large and small hyperplastic biliary ducts (HBDs) in 27 archival cases of hepatolithiasis and 20 archival cases of primary sclerosing cholangitis (PSC), both of which are risk conditions for human cholangiocarcinogenesis. There was a strong positive correlation between increased ERBB-2, but not MET, and COX-2 immunoreactivity measured in the tumors and risk conditions. Enhanced immunoreactivity for ERBB-2 and COX-2 also correlated directly with tumor differentiation and was highest in well-differentiated tumors. Interestingly, some but not all cases of hepatolithiasis and most cases of PSC showed increased ERBB-2 and COX-2 immunostaining in the large but not small HBDs, whereas strong MET immunostaining was detected in both the large and small ducts. In conclusion, overexpression of ERBB-2 and COX-2 may herald an early carcinogenic event in the human hepatic biliary tract and one that is consistent with a frequent anatomic site of origin of the tumors. The results also suggest ERBB-2 and COX-2 as potentially important targets relevant to chemoprevention or adjunct therapy of ChC.
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PMID:ERBB-2 overexpression and cyclooxygenase-2 up-regulation in human cholangiocarcinoma and risk conditions. 1214 54

Breast cancer is associated with increased glucose consumption and can therefore be visualised with the glucose analogue [(18)F]2-deoxy-2-fluoro-D-glucose (FDG) and positron emission tomography (PET). FDG uptake in the primary tumour can vary substantially, and specific tumour characteristics have been demonstrated to determine the degree of glucose metabolism. Factors with a major influence on FDG uptake in breast cancer comprise expression of glucose transporter Glut-1 and hexokinase I, number of viable tumour cells per volume, histological subtype, tumour grading, microvessel density and proliferative activity. Recently, an association between high FDG uptake and a worse prognosis was suggested. Several studies have been performed correlating FDG uptake with a variety of prognostic and molecular biomarkers as well as parameters predicting tumour response to therapy. However, a correlation with important clinical prognostic markers such as axillary lymph node status and size of the primary tumour, expression of oestrogen and progesterone receptors, proto-oncogene c-erbB-2 or VEGF could not be demonstrated. The lack of correlation with important markers of prognosis does not suggest that FDG uptake might be used as a prognostic criterion in breast cancer. Innovative radiotracers for specific imaging of tumoural perfusion ([(15)O]H(2)O), hormone receptor expression ([(18)F]FES), protein synthesis ([(11)C]methionine), proliferation rate ([(18)F]FLT) or bone mineralisation ([(18)F]fluoride) may provide additional information compared with that provided by FDG PET.
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PMID:Biological characterisation of breast cancer by means of PET. 1512 40


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