Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:O76050 (neu)
 3,969 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to obtain further information on the biological role of the HER2/neu oncoprotein monoclonal antibodies (MAbs) were produced against the p185 extracellular domain. To immunize the mice and screen the hybridoma supernatants we selected a lung adenocarcinoma cell line (Calu-3), which demonstrated an over-expression of p185HER2 measured as the reactivity with polyclonal rabbit serum to the 14-amino-acid carboxy-terminal-HER2/neu. Two MAbs, designated MGR2 (IgG1) and MGR3 (IgG2), selected for reactivity on Calu-3 and negativity on A43I live cells, the reference target cell for EGF receptor expression, were found to immunoprecipitate a 185-kDa molecule. Immunodepletion experiments with the polyclonal antiserum and cross-competition experiments indicated that the 2 reagents recognized 2 different epitopes located on the p185HER2 molecule. One of the 2 MAbs, MGR3, was found to internalize, induce p185HER2 phosphorylation and inhibit tumor cell growth in vitro. These results indicate that MGR3 is directed against a determinant located in the p185HER2 ligand binding site and may compete with the p185HER2 ligand, but is incapable of inducing a complete mitotic signal.
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PMID:Selection of monoclonal antibodies which induce internalization and phosphorylation of p185HER2 and growth inhibition of cells with HER2/NEU gene amplification. 167 68

Oncogene amplification has been observed in various primary tumors and tumor-derived cell lines. In several types of cancer, amplification of specific oncogenes is correlated with the stage of tumor progression. To estimate the frequency of gene amplification in other tumor types and to determine whether the ability to grow in vivo is associated with gene amplification in tumor cell lines, we have developed a modified version of the in-gel renaturation assay that detects human DNA sequences of unknown nature amplified as little as 7- to 8-fold. This assay was used to screen 16 cell lines derived from various solid tumors and leukemias. Amplified DNA sequences were detected in only one cell line, Calu-3 lung adenocarcinoma. This cell line was found to contain coamplified NGL (formerly termed neu) and ERBA1 oncogenes. However, when one of the amplification-negative cell lines, PC-3 prostatic carcinoma, was selected for in vivo growth in nude mice, amplified DNA sequences became detectable in these cells. The amplified sequences included the MYC oncogene, which showed no amplification in the parental cell line but was amplified 10- to 12-fold in the in vivo-selected cells. MYC amplification may, therefore, provide tumor cells with a selective advantage specific for in vivo growth.
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PMID:Analysis of gene amplification in human tumor cell lines. 341 26

Anti-p185HER2 monoclonal antibodies often show intense reactivity with the basement membrane of tumor cells that overexpress the HER2/neu gene product (p185HER2). To evaluate a possible interaction between p185HER2 and adhesion molecules or their receptors, the polarity of p185HER2 was tested in lung carcinoma cell line Calu-3, which overexpresses this protein, in cultures grown as confluent monolayers or as aggregates. MAb immunostaining patterns indicated that p185HER2 is concentrated on the baso-lateral membrane of cells and that it colocalizes with the integrin alpha 6 beta 4 at the cell-cell junctions where laminin is also found. The same membrane region showed intense reactivity with antiphosphotyrosine antibodies. Furthermore, integrin clustering induced by the specific antibody was accompanied by the clustering of p185HER2, as indicated by immunoelectron microscopy, and by a subsequent increase in p185HER2 tyrosine phosphorylation. Treatment with exogenous laminin also resulted in increased basal levels of p185HER2 phosphorylation. These data suggest a physical interaction between the integrin and the oncoprotein that might be functionally relevant in directly controlling the tyrosine phosphorylation of the catalytic domain of p185HER2.
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PMID:Colocalization of the p185HER2 oncoprotein and integrin alpha 6 beta 4 in Calu-3 lung carcinoma cells. 796 74

In the present study we utilized two previously described monoclonal antibodies (mAb), and their respective Fab portions, directed against the extracellular domain of p185HER2, a transmembrane glycoprotein with intrinsic tyrosine kinase activity coded by the HER2/neu oncogene, to study the mechanism of mAb-induced receptor internalization and phosphorylation. Fluorescence scan analysis and direct binding of radiolabelled mAb and their Fab fragments showed that entire MGR2 and MGR3 mAb were reactive with similar binding affinity on two cell lines (Calu-3 and Sk-Br-3) overexpressing the p185HER2 receptor, and unreactive on unrelated cells. The corresponding Fab fragments were positive on the related cells, but bound with diminished intensity and affinity. Entire MGR2 and MGR3 induced internalization in both Calu-3 and Sk-Br-3 cells, whereas their Fab portions were not internalized. When the bivalency of the MGR2 Fab fragment was artificially reconstituted by incubation with rabbit anti-(mouse IgG), internalization was obtained. Monovalent binding of the entire labelled antibodies, obtained in the presence of a saturating amont of unlabelled antibody, decreased both the rate and the final amount of internalized antibody. Metabolic labelling and immunoblotting experiments showed that incubation with entire MGR3 amplified the basal phosphorylation of the p185HER2 receptor in Calu-3 and Sk-Br-3 cells, whereas MGR3 Fab decreased the signal. Taken together, our data indicate that antibody-mediated activation of p185HER2 in Calu-3 and Sk-Br-3 cells occurs through the dimerization of receptor molecules and that bivalency of the activating antibody is mandatory for induction of internalization and phosphorylation of the receptor. Our data support an allosteric model of activation for the p185HER2 receptor.
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PMID:Antibody-induced activation of p185HER2 in the human lung adenocarcinoma cell line Calu-3 requires bivalency. 809 92