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)

Single-chain Fv proteins containing a COOH-terminal cysteine (sFv') were constructed by using an antidigoxin 26.10 sFv and an anti-c-erbB-2 741F8 sFv. The fully active sFv' proteins were prepared by expression in Escherichia coli as insoluble inclusion bodies, followed by in vitro refolding using glutathione redox buffers and purification. The COOH-terminal cysteines of the refolded sFv' proteins were protected by a blocking group presumed to be the glutathionyl peptide, which was easily and selectively removed by gentle reduction. Air oxidation of the reduced sFv' monomers resulted in the efficient formation of disulfide-linked sFv' homodimers, designated (sFv')2, which were stable under oxidizing conditions and relatively slow to be disrupted under reducing conditions. The (26-10-1 sFv')-(741F8-1 sFv') heterodimer was prepared and possessed dual-antigen specificity; the active bispecific (sFv')2 dimerized under native conditions, apparently as a manifestation of self-association by the 741F8 sFv' subunit. Biodistribution and imaging studies that were performed on mice bearing human SK-OV-3 tumor xenografts that express the c-erbB-2 as a cell surface antigen were reviewed. Radioiodinated 741F8-2 (sFv')2 homodimer localized to the tumors with high specificity, as evidenced by excellent tumor:normal tissue ratios. Sagittal section autoradiography of whole animals 24 h after administration of antibody species revealed that 741F8 (sFv')2 produced a stronger tumor image than comparable doses of the 741F8 Fab, monomeric sFv', and the 26-10 (sFv')2 control without the high nonspecific background distribution of the 741F8 IgG.
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PMID:Targeting c-erbB-2 expressing tumors using single-chain Fv monomers and dimers. 749 81

The group of subtype I transmembrane tyrosine kinases includes the epidermal growth factor (EGF) receptor (ErbB-1), an orphan receptor (ErbB-2), and two receptors for the Neu differentiation factor (NDF/heregulin), namely: ErbB-3 and ErbB-4. Here we addressed the distinct functions of the two NDF receptors by using an immunological approach. Two sets of monoclonal antibodies (mAbs) to ErbB-3 and ErbB-4 were generated through immunization with recombinant ectodomains of the corresponding receptors that were fused to immunoglobulin. We found that the shared ligand binds to highly immunogenic, but immunologically distinct sites of ErbB-3 and ErbB-4. NDF receptors differed also in their kinase activities; whereas the catalytic activity of ErbB-4 was activable by mAbs, ErbB-3 underwent no activation by mAbs in living cells. Likewise, down-regulation of ErbB-4, but not ErbB-3, was induced by certain mAbs. By using the generated mAbs, we found that the major NDF receptor on mammary epithelial cells is a heterodimer of ErbB-3 with ErbB-2, whereas an ErbB-1/ErbB-2 heterodimer, or an ErbB-1 homodimer, is the predominant species that binds EGF. Consistent with ErbB-2 being a shared receptor subunit, its tyrosine phosphorylation was increased by both heterologous ligands and it mediated a trans-inhibitory effect of NDF on EGF binding. Last, we show that the effect of NDF on differentiation of breast tumor cells can be mimicked by anti-ErbB-4 antibodies, but not by mAbs to ErbB-3. Nevertheless, an ErbB-3-specific mAb partially inhibited the effect of NDF on cellular differentiation. These results suggest that homodimers of ErbB-4 are biologically active, but heterodimerization of the kinase-defective ErbB-3, probably with ErbB-2, is essential for transmission of NDF signals through ErbB-3.
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PMID:An immunological approach reveals biological differences between the two NDF/heregulin receptors, ErbB-3 and ErbB-4. 863 97

The trefoil peptide intestinal trefoil factor (ITF) plays a critical role in the protection of colonic mucosa and is essential to restitution after epithelial damage. These functional properties are accomplished through coordinated promotion of cell migration and inhibition of apoptosis. ITF contains a unique three-looped trefoil motif formed by intrachain disulfide bonds among six conserved cysteine residues, which is thought to contribute to its marked protease resistance. ITF also has a seventh cysteine residue, which permits homodimer formation. A series of cysteine-to-serine substitutions and a C-terminally truncated ITF were made by PCR site-directed mutagenesis. Any alteration of the trefoil motif or truncation resulted in loss of protease resistance. However, neither an intact trefoil domain nor dimerization was required to promote cell migration. This pro-restitution activity correlated with the ability of the ITF mutants to activate mitogen-activated protein (MAP) kinase independent of phosphorylation of the epidermal growth factor (EGF) receptor. In contrast, only intact ITF retained both phosphatidylinositol 3-kinase and the EGF receptor-dependent antiapoptotic effect in HCT116 and IEC-6 cells. The inability to block apoptosis correlated with a loss of trefoil peptide-induced transactivation of the EGF receptor or Akt kinase in HT-29 cells. In addition to defining structural requirements for the functional properties of ITF, these findings demonstrate that distinct intracellular signaling pathways mediate the effects of ITF on cell migration and apoptosis.
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PMID:Distinct pathways of cell migration and antiapoptotic response to epithelial injury: structure-function analysis of human intestinal trefoil factor. 1084 94

The c-erbB-2 proto-oncogene encodes a 185kDa protein p185, which belongs to epidermal growth factor receptor family. Amplification of this gene has been shown to correlate with poor clinical prognosis for certain cancer patients. The monoclonal antibody A21 which directed against p185 specifically inhibits proliferation of tumor cells overexpressing p185, hence allows it to be a candidate for targeted therapy. In order to overcome several drawbacks of murine MAb, we cloned its VH and VL genes and constructed the single-chain Fv (scFv) through a peptide linker. The recombinant scFvA21 was expressed in Escherichia coli and purified by the affinity column. Subsequently it was characterized by ELISA, Western blot, cell immunohistochemistry and FACS. All these assays showed the binding activity to extracellular domain (ECD) of p185. Based on those properties of scFvA21, we further constructed the scFv-Fc fusion molecule with a homodimer form and the recombinant product was expressed in mammalian cells. In a series of subsequent analysis this fusion protein showed identical antigen binding site and activity with the parent antibody. These anti-p185 engineered antibodies have promised to be further modified as a tumor targeting drugs, with a view of application in the diagnosis and treatment of human breast cancer.
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PMID:Construction, expression and characterization of the engineered antibody against tumor surface antigen, p185(c-erbB-2). 1264 48

The epidermal growth factor receptor (EGFR) family plays an important role in breast carcinogenesis. Much interest has been focused recently on its members because of their potential role as prognostic indicators in breast cancer and their involvement in cancer therapy. We have evaluated more than 1500 cases of invasive breast carcinoma immunohistochemically using tissue microarray technology to examine the expression of EGFR family receptor proteins. We have found that 20.1 and 31.8% of cases were positive for EGFR and c-erbB-2, respectively, and 45 and 45.1% of tumours overexpressed for c-erbB-3 and c-erbB-4, respectively. The expression of either EGFR or c-erbB-2 was associated with other bad prognostic features and with poor outcome. Neither c-erbB-3 nor c-erbB-4 had any association with survival. c-erbB-2 had an independent prognostic effect on overall and disease-free survival (DFS) in all cases, as well as in the subset of breast carcinoma patients with nodal metastases. Several hetero- and homodimeric combinations have been reported between the EGFR members. Those dimers can evoke diverse signal transduction pathways with variable cellular responses. We stratified cases according to their co-expression of receptors into distinct groups with different receptor-positive combinations. Patients whose tumours co-expressed c-erbB-2 and c-erbB-3, as well as those whose tumours co-expressed EGFR, c-erbB-2 and c-erbB-4 showed an unfavourable outcome compared with other groups, while combined c-erbB-3 and c-erbB-4 expression was associated with a better outcome. In cases showing expression of one family member only (homodimers), we found a significant association between c-erbB-4 homodimer-expressing tumours and better DFS. In contrast, patients with c-erbB-2 homodimer-expressing tumours had a significant poorer DFS compared with other cases. These data imply that the combined profile expression patterns of the four receptor family members together provide more accurate information on the tumour behaviour than studying the expression of each receptor individually.
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PMID:Expression and co-expression of the members of the epidermal growth factor receptor (EGFR) family in invasive breast carcinoma. 1548 Apr 34

(-)-Epigallocatechin-3-gallate (EGCG), the principal polyphenol in green tea, has been shown to inhibit the growth of many cancer cell lines and to suppress the phosphorylation of epidermal growth factor receptor (EGFR). We observed similar effects of EGCG in esophageal squamous cell carcinoma KYSE 150 cells and epidermoid squamous cell carcinoma A431 cells. Pretreatment of KYSE 150 cells with EGCG (20 micromol/L) for 0.5 to 24 hours in HAM's F12 and RPMI 1640 mixed medium at 37 degrees C, before the addition of EGF, resulted in a decreased level of phosphorylated EGFR (by 32-85%). Prolonged treatment with EGCG (8 or 24 hours) also decreased EGFR protein level (both by 80%). EGCG treatment for 24 hours also caused decreased signals of HER-2/neu in esophageal adenocarcinoma OE19 cells. These effects of EGCG were prevented or diminished by the addition of superoxide dismutase (SOD, 5 units/mL), or SOD plus catalase (30 units/mL), to the cell culture medium. A similar phenomenon on inactivation of EGFR was observed in A431 cells as well. Under culture conditions for KYSE 150 cells, EGCG was unstable, with a half-life of approximately 30 minutes; EGCG dimers and other oxidative products were formed. The presence of SOD in the culture medium stabilized EGCG and increased its half-life to longer than 24 hours and some EGCG epimerized to (+)-gallocatechin-3-gallate. A mechanism of superoxide radical-mediated dimerization of EGCG and H2O2 formation is proposed. The stabilization of EGCG by SOD in the culture medium potentiated the activity of EGCG in inhibiting KYSE 150 cell growth. The results suggest that in cell culture conditions, the auto-oxidation of EGCG leads to EGFR inactivation, but the inhibition of cell growth is due to other mechanisms. It remains to be determined whether the presently observed auto-oxidation of EGCG occurs in vivo. In future studies of EGCG and other polyphenolic compounds in cell culture, SOD may be added to stabilize EGCG and to avoid possible artifacts.
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PMID:Mechanism of action of (-)-epigallocatechin-3-gallate: auto-oxidation-dependent inactivation of epidermal growth factor receptor and direct effects on growth inhibition in human esophageal cancer KYSE 150 cells. 1614 Sep 80

All four members of the human epidermal growth factor (EGF) receptor (HER) family are implicated in human cancers. Although efficacious in a subset of patients, resistance to single-targeted anti-HER therapy [i.e., cetuximab (Erbitux) and trastuzumab (Herceptin)] is often associated with coexpression of other HER family members. This may be overcome by a HER ligand binding molecule that sequesters multiple EGF-like ligands, preventing ligand-dependent receptor activation. Toward this end, we have combined the HER-1/EGFR and HER-3 ligand binding domains, dimerized with fusion of an Fc fragment of human IgG1. This resulted in a mixture of HER-1/Fc homodimer (HFD100), HER-3/Fc homodimer (HFD300), and HER-1/Fc:HER-3/Fc heterodimer (RB200), also termed Hermodulins. The purified first-generation RB200 bound EGF and neuregulin 1 (NRG1)-beta1 ligands, determined by cross-linking and direct binding studies. The binding affinity for both was approximately 10 nmol/L by dissociation-enhanced lanthanide fluorescence immunoassay using europium (Eu)-labeled ligands. Competition studies with RB200 using Eu-EGF or Eu-NRG1-beta1 revealed that RB200 bound HER-1 ligands, including transforming growth factor-alpha and heparin-binding EGF, and HER-3 ligands NRG1-alpha and NRG1-beta3. RB200 inhibited EGF- and NRG1-beta1-stimulated tyrosine phosphorylation of HER family proteins, proliferation of a diverse range of tumor cells in monolayer cell growth assays, tumor cell proliferation as a single agent and in synergy with tyrosine kinase inhibitors, lysophosphatidic acid-stimulated cell proliferation, and tumor growth in two human tumor xenograft nude mouse models. Taken together, the data reveal that RB200 has the potential to sequester multiple HER ligands and interfere with signaling by HER-1, HER-2, and HER-3.
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PMID:Human epidermal growth factor receptor (HER-1:HER-3) Fc-mediated heterodimer has broad antiproliferative activity in vitro and in human tumor xenografts. 1885 26

The epidermal growth factor (EGF) receptor is a member of the ErbB family of receptors that also includes ErbB2, ErbB3, and ErbB4. These receptors form homo- and heterodimers in response to ligand with ErbB2 being the preferred dimerization partner. Here we use (125)I-EGF binding to quantitate the interaction of the EGF receptor with ErbB2. We show that the EGFR/ErbB2 heterodimer binds EGF with a 7-fold higher affinity than the EGFR homodimer. Because it cannot bind a second ligand, the EGFR/ErbB2 heterodimer is not subject to ligand-induced dissociation caused by the negatively cooperative binding of EGF to the second site on the EGFR homodimer. This increases the stability of the heterodimer relative to the homodimer and is associated with enhanced and prolonged EGF receptor autophosphorylation. These effects are independent of the kinase activity of ErbB2 but require back-to-back dimerization of the EGF receptor with ErbB2. Back-to-back dimerization is also required for phosphorylation of ErbB2. These findings provide a molecular explanation for the apparent preference of the EGF receptor for dimerizing with ErbB2 and suggest that the phosphorylation of ErbB2 occurs largely in the context of the EGFR/ErbB2 heterodimer, rather than through lateral phosphorylation of isolated ErbB2 subunits.
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PMID:Quantitation of the effect of ErbB2 on epidermal growth factor receptor binding and dimerization. 2282 73

Preeclampsia is a complication of pregnancy manifested as hypertension-in-pregnancy (HTN-Preg) and often intrauterine growth restriction (IUGR). Placental ischemia could be an initiating event, but the molecular mechanisms are unclear. To test the hypothesis that dimerization of matrix metalloproteinases (MMPs) plays a role in HTN-Preg and IUGR, the levels/activity of MMP-9, tissue inhibitor of metalloproteinase (TIMP-1), and their dimerization forms were measured in the placenta, uterus, and uterine artery of normal pregnant (Preg) rats and a rat model of reduced uteroplacental perfusion pressure (RUPP). Consistent with our previous report, blood pressure (BP) was higher, pup weight was lower, and gelatin zymography showed different gelatinolytic activity for pro-MMP-9, MMP-9, pro-MMP-2 and MMP-2 in RUPP vs Preg rats. Careful examination of the zymograms showed additional bands at 200 and 135kDa. Western blots with MMP-9 antibody suggested that the 200kDa band was a MMP-9 homodimer. Western blots with TIMP-1 antibody as well as reverse zymography suggested that the 135kDa band was a MMP-9/TIMP-1 complex. The protein levels and gelatinase activity of MMP-9 homodimer were decreased while MMP-9/TIMP-1 complex was increased in placenta, uterus and uterine artery of RUPP vs Preg rats. The epidermal growth factor (EGF) receptor blocker erlotinib and protein kinase C (PKC) inhibitor bisindolylmaleimide decreased MMP-9 homodimer and increased MMP-9/TIMP-1 complex in placenta, uterus and uterine artery of Preg rats. EGF and the PKC activator phorbol-12,13-dibutyrate (PDBu) reversed the decreases in MMP-9 homodimer and the increases in MMP-9/TIMP-1 complex in tissues of RUPP rats. Thus, the increased BP and decreased pup weight in placental ischemia model of HTN-Preg are associated with a decrease in MMP-9 homodimer and an increase in MMP-9/TIMP-1 complex in placenta, uterus, and uterine artery, which together would cause a net decrease in MMP-9 activity and reduce uteroplacental and vascular remodeling in the setting of HTN-Preg and IUGR. Enhancing EGFR/PKC signaling may reverse the MMP-9 unfavorable dimerization patterns and thereby promote uteroplacental and vascular remodeling in preeclampsia.
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PMID:Decreased homodimerization and increased TIMP-1 complexation of uteroplacental and uterine arterial matrix metalloproteinase-9 during hypertension-in-pregnancy. 2850 58