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)

The neu protooncogene (also known as c-erbB2, NGL, and HER2) encodes a 185-kDa transmembrane glycoprotein with intrinsic tyrosine kinase activity that resembles the receptor for epidermal growth factor. The p185 gene and protein were originally identified in the brain and are thought to play a critical role in neurogenesis. Aberrant c-erbB2 protein overexpression also occurs in several human adenocarcinomas. A ligand for p185, neu-activating factor (NAF), specifically binds to neu receptor and increases the p185c-neu tyrosine phosphorylation in vitro and in vivo in a dose-dependent manner. We now show that NAF specifically binds to purified p185 expressed in baculovirus. Direct binding analysis showed that NAF binds with high affinity (Kd = 1.3 nM). We have investigated changes in the structure and association state of baculovirus-produced neu holoreceptor that are induced by ligand binding. In this study, we used sucrose gradients to show that purified p185c-neu exists mainly in the monomeric form at low concentrations, whereas at higher concentrations p185c-neu exists as dimers or multimers. At low concentrations, but in the presence of ligand, p185c-neu sediments as a dimeric or multimeric form. Monomer-oligomer interconversion is absolutely ligand dependent at low receptor concentrations. The high molecular weight form of the receptor is enzymatically more active, as a consequence of ligand-driven activation of the receptor kinase. Oncogenic p185neu receptors sediment predominantly as high molecular weight forms and have constitutively active kinases.
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PMID:Ligand and p185c-neu density govern receptor interactions and tyrosine kinase activation. 790 21

Phenotypic biochemical markers of oncogenesis and differentiation were mapped in bladder biopsies to investigate changes that occur in bladder tumorigenesis and to identify markers for increased bladder cancer risk. Touch preparations from biopsy specimens from 30 patients were obtained from tumors, the adjacent bladder epithelium, and random distant bladder epithelium. Markers, including DNA ploidy, epidermal growth factor receptor (EGFR), and oncoproteins, were quantified in individual cells by using quantitative fluorescence image analysis. Cluster analysis revealed the markers fell into three independent groups: (i) G-actin and EGFR; (ii) ploidy, cytology, and p185 (HER-2/neu oncoprotein) (ERBB2); and (iii) p300, a low-grade tumor antigen. Each marker displayed a gradient of abnormality from distant field to adjacent field to tumor. Different patterns for each marker suggested a developmental sequence of bladder cancer oncogenesis; G-actin was altered in 58% of distant biopsies (vs. 0/6 normals, P < 0.001), ploidy and cytology were altered in < 20% of distant fields and approximately 80% of tumors, and the other markers were intermediate. Patterns of EGFR and p185 suggest low-and high-grade tracks diverge early (P < 0.05 by Mann-Whitney U test for EGFR and ANOVA for p185). In conclusion, this study shows that a sequence of phenotypic changes accompanies development and progression of bladder cancers. Biochemical alterations in cells of the bladder field are often detectable before abnormal pathology, and markers previously thought to be limited to tumors were found in the field. The hierarchy of expression may be useful in identifying high-risk patients, assessing completeness of response to therapy, and monitoring and predicting recurrence.
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PMID:Alterations in phenotypic biochemical markers in bladder epithelium during tumorigenesis. 836 95

The HER2/neu protooncogene encodes a transmembrane receptor tyrosine kinase of Mr185 kDa (called p185) which is structurally and functionally homologous to the epidermal growth factor receptor. Shc proteins are important downstream signal transducers of receptor tyrosine kinases. We reported here a novel finding that p66Sch was absent or nearly absent in p185-overexpressing breast cancer cells. This inverse correlation of p185 overexpression and p66Shc expression is probably specific to breast cancer cells because this phenomenon was not observed in p185-overexpressing human ovarian, lung, or oral cancer cells, or mouse fibroblast cells. In contrast, the p52Shc and p46Shc isoforms were expressed at similar levels in both p185-overexpressing and p185 basal level breast cancer cell lines. Furthermore, tyrosine phosphorylation of p52Shc and p46Shc and subsequent formation of Shc/Grb2 complex were detected in breast cancer cells in which the p185 tyrosine kinase is activated, indicating that p66Shc is not required for mediating the HER-2/neu signaling pathway in breast cancer cells.
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PMID:p66Shc isoform down-regulated and not required for HER-2/neu signaling pathway in human breast cancer cell lines with HER-2/neu overexpression. 866 Mar 24

Ovarian cancer is the leading cause of death in gynecological cancers. To date, there are no prognostic factors in ovarian cancer that adequately account for tumor biology and the course of the disease. In recent years, some reports have described the prognostic significance of the amplification and overexpression of the oncogene c-erbB-2 (HER2/neu) in various human cancers, including ovarian cancer. The c-erbB-2 proto-oncogene is located on the long arm of chromosome 17. It encodes a 185 kD transmembrane glycoprotein receptor (p185HER2) that has sequence similarities with the epidermal growth factor receptor (EGF-R). In ovarian cancer, the percentage of c-erbB-2 positive cases varies from 9 to 32%. Correlation with tumor stage and the degree of histological differentiation was not observed. The overexpression of c-erbB-2 is a new and statistically independent prognostic factor. The overexpression of oncogene c-erbB-2 in ovarian cancer can-be detected by immunohistochemistry staining for the protein p185 and characterizes a group with unfavorable tumor biology and a significantly worse prognosis. Elevated serum levels of the c-erbB-2 oncoprotein have been identified in patients with various cancers known to overexpress the c-erbB-2 oncogene. The detection of a p185 oncoprotein fragment in the sera of ovarian cancer patients was recently published by our group. Antiproliferative effects of monoclonal antibodies directed against p185 have been demonstrated in breast cancer patients. This may lead to a new approach in ovarian carcinoma therapy, too, over and above the diagnostic aspects.
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PMID:Overexpression of the oncogene c-erbB-2 (HER2/neu) in ovarian cancer: a new prognostic factor. 913 62

The c-erbB-2-encoded oncoprotein p185 (HER2) is overexpressed in the fetal epithelium, the placenta and several carcinomas. Elevated serum levels of the released ectodomain (p105) were found in cancer patients and pregnant women at term. In cultured breast cancer cells estradiol inhibited p185 expression and induced growth arrest. These results prompted us to investigate the in vivo influence of serum estradiol and estriol on c-erbB-2 protein levels in pregnancy. We examined chorionic villous tissue extracts and maternal sera obtained from six legal abortions in the first trimester and 20 vaginal deliveries at term. For quantification of c-erbB-2 protein we employed an ELISA. In the first trimester maternal p105 serum levels were significantly (p < 0.0001) lower and p185 tissue levels significantly (p < 0.05) higher than in the third trimester. The highest p105 values were found in additionally examined cord blood. Interindividual regression analyses yielded inverse correlation between estradiol concentrations and placental p185 expression in the first (r = -0.58) and third trimester (r = -0.38) as well as p105 serum levels in the first trimester (r = -0.83). Estriol was correlated positively with p105 values in maternal and umbilical serum but not with placental p185 expression. We conclude that estradiol down-regulates p185 expression in pregnancy whereas the level of maternal p105 depends on the total amount of fetoplacental p185.
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PMID:In vivo effects of estrogens on c-erbB-2 oncoprotein levels in chorionic villous tissue and maternal serum. 927 19

In this study we have examined the interaction between CD44s (the standard form) and the p185(HER2) proto-oncogene in the ovarian carcinoma cell line. Surface biotinylation followed by wheat germ agglutinin column chromatography and anti-CD44-mediated immunoprecipitation indicate that both CD44s and p185(HER2) are expressed on the cell surface and most importantly, that these two molecules are physically linked to each other via interchain disulfide bonds. We have also determined that hyaluronic acid stimulates CD44s-associated p185(HER2) tyrosine kinase activity, leading to an increase in the ovarian carcinoma cell growth. After transfection of the ovarian carcinoma cell line with the adenovirus 5 E1A gene, which is known to repress p185(HER2) expression, we observed that both surface CD44s expression and CD44s-mediated cell adhesion to hyaluronic acid are significantly reduced in the transfectant cells compared with the control cells. These data suggest that down-regulation of p185(HER2) blocks CD44s expression and subsequent adhesion function. Our findings also indicate that the CD44s-p185(HER2) interaction is both functionally coupled and biosynthetically regulated. We believe that direct "cross-talk" between these two surface molecules (i.e. CD44s and the p185(HER2)) may be one of the most important signaling events in human ovarian carcinoma development.
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PMID:Interaction between the adhesion receptor, CD44, and the oncogene product, p185HER2, promotes human ovarian tumor cell activation. 934 40

Peptides are flexible molecules and can adopt local structural features of protein, such as secondary structure, hydrophobicity, and distribution of electrostatic charges, and so forth, and mimic their functions. Therapeutic peptidomimetics that are immunologically relevant are developed by engineering the surface loop structures in the proteins and receptors. The class of molecules targeted include immunoglobulin fold-containing molecules: antibody, cell-surface CD4 receptors and cystine-knot-containing receptor family members: tumor necrosis factor (TNF), CD40, and p185/Neu receptors. We have used the loops involved in the molecular recognition as a template and developed peptidomimetics that interfere with the functions of the target molecules. In this article, two molecular targets are discussed: (1) immunoglobulin fold-containing CD4 receptor and (2) cystine-knot-containing TNF receptor (TNFR).
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PMID:Structure-based design of immunologically active therapeutic peptides. 947 78

The HER2/neu oncogene encodes a cell surface protein which plays a role in growth factor-stimulated mitogenic signaling. HER2/neu is overexpressed in 30-40% of human breast carcinomas. This study tested the hypothesis that inhibiting HER2/neu expression using a phosphorothioate antisense (AS) oligonucleotide would inhibit the growth of breast cancer cells that overexpress this gene. A human breast carcinoma cell line, BT474, which overexpresses the HER2/neu oncogene was exposed to AS, sense (S), or scrambled antisense (SC) phosphorothioate oligonucleotides in tissue culture. Treatment with AS oligonucleotides specifically downregulated HER2/neu mRNA expression and resulted in lower levels of the HER2/neu protein product, p185; control oligonucleotides had no such effect. AS oligonucleotide treatment significantly inhibited the in vitro growth of BT474 cells, whereas S and SC controls had little effect on BT474 growth. HER2/neu AS oligonucleotide treatment had no effect on the growth of a distinct breast cancer line, MCF7, which expresses low levels of the HER2/neu oncogene. Breast carcinoma cells which overexpress the HER2/neu gene appear to be dependent on continued expression of this oncogene for cell growth. AS oligonucleotide pharmaceuticals which interfere with the expression of the HER2/neu oncogene may be of use in the therapy of some patients with breast carcinoma.
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PMID:Antisense oligonucleotides specific for the HER2/neu oncogene inhibit the growth of human breast carcinoma cells that overexpress HER2/neu. 969 39

Receptor dimerization is a crucial intermediate step in activation of signaling by receptor tyrosine kinases (RTKs). However, dimerization of the RTK Neu (also designated ErbB-2, HER-2, and p185(neu)), while necessary, is not sufficient for signaling. Earlier work in our laboratory had shown that introduction of an ectopic cysteine into the Neu juxtamembrane domain induces Neu dimerization but not signaling. Since Neu signaling does require dimerization, we hypothesized that there are additional constraints that govern signaling ability. With the importance of the interreceptor cross-phosphorylation reaction, a likely constraint was the relative geometry of receptors within the dimer. We have tested this possibility by constructing a consecutive series of cysteine substitutions in the Neu juxtamembrane domain in order to force dimerization along a series of interreceptor faces. Within the group that dimerized constitutively, a subset had transforming activity. The substitutions in this subset all mapped to the same face of a predicted alpha helix, the most likely conformation for the intramembrane domain. Furthermore, this face of interaction aligns with the projected Neu* V664E substitution and with a predicted amphipathic interface in the Neu juxtamembrane domain. We propose that these results identify an RTK dimer interface and that dimerization of this RTK induces an extended contact between juxtamembrane and intramembrane alpha helices.
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PMID:Activation of Neu (ErbB-2) mediated by disulfide bond-induced dimerization reveals a receptor tyrosine kinase dimer interface. 971 Jun 21

Approximately 30% of ovarian and breast cancers overexpress p185(c-erbB-2) with as many as 10(6) receptors/cell. Normal cells have as few as 10(4) receptors/cell. We have examined the susceptibility of SKOv3 human ovarian cancer cells to anti-c-erbB2 antibodies and immunotoxins as a function of c-erbB-2 density on the cell surface. A panel of SKOv3 clones that expressed different densities of p185(c-erbB-2) receptor were generated through transfection with the c-erbB-2 gene. A significant correlation was found between p185(c-erbB-2) density and susceptibility to killing by anti-p185(c-erbB-2)-ricin A chain (anti-p185(c-erbB-2)-RTA) immunotoxins. With 10(5) copies/cell of p185(c-erbB-2), <10% of clonogenic ovarian cancer cells could be eliminated, whereas in clones that expressed 10(6) copies/cell of p185(c-erbB-2), 99.9% of clonogenic tumor cells were killed. In cell lines that overexpressed p185(c-erbB-2) and also expressed p170(EGFR), anti-p185(cerbB-2)-RTA and anti-p170(EGFR)-RTA immunotoxins exerted synergistic cytotoxicity. Treatment with the two immunotoxins could eliminate 99.99% of clonogenic cells. Importantly, tumor cells that had survived first treatment with anti-p185(c-erbB2)-RTA alone still retained sensitivity to repeat treatment with the same immunotoxin and also proved susceptible to the synergistic cytotoxicity of anti-p185(cerbB-2)-RTA in combination with anti-p170(EGFR)-RTA. Growth characteristics of the clones expressing various levels of p185(c-erbB-2) were also studied. No correlation was found between p185(c-erbB-2) expression levels and the rate of anchorage-dependent growth, anchorage-independent growth, or in vivo growth in nude mice.
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PMID:Cell surface density of p185(c-erbB-2) determines susceptibility to anti-p185(c-erbB-2)-ricin A chain (RTA) immunotoxin therapy alone and in combination with anti-p170(EGFR)-RTA in ovarian cancer cells. 979 89


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