Search PubMed⌕ Search

Biomedical subjects

M I Greene

Publications and source records attributed to M I Greene.

At least 163 records · Page 9Linked to original sources
PubMed1988

Phosphorylation process induced by epidermal growth factor alters the oncogenic and cellular neu (NGL) gene products.

The rat neu oncogene encodes a cell surface glycoprotein, p185, that possesses tyrosine kinase activity. The p185 polypeptide exhibits structural similarity to the epidermal growth factor receptor (EGFR) at both the deduced amino acid and nucleic acid level. However, the neu oncogene and the gene encoding the EGFR have been shown to reside on distinct chromosomes. Comparative analysis of the sequences of the normal neu cDNA and of the neu cDNA from neuroblastomas has revealed a single point mutation leading to a valine-to-glutamic acid substitution in the transmembrane anchoring domain. This mutation converts the neu gene to a transforming gene in rodents. In humans, the gene is called ERBB2 (also NGL and HER2), and amplification and over-expression of its products have been detected in certain tumors. The rat embryonal fibroblast cell line (Rat-1) appears to express both EGFR and cellular p185 polypeptides. We have found that EGF stimulates the phosphorylation of p185 in these cells at tyrosine as well as serine and threonine residues in a specific and dose-dependent manner. This activity occurs even though radiolabeled EGF cannot bind to immunopurified p185. The EGF effect is apparently unique since platelet-derived growth factor, insulin, and transforming growth factor beta all fail to phosphorylate p185 at tyrosine. The EGF-induced effect requires interaction of the EGFR and its cognate ligand because cell lines that lack EGFR cannot be shown to phosphorylate p185, even when exposed to large amounts of EGF. Oncogenic rodent p185 and the human p185 homologue ERBB2 that is overexpressed in human breast tumor cells also can be shown to become phosphorylated on tyrosine residues by the action of EGF. Collectively, these data demonstrate that EGF mediates phosphorylation of p185 at tyrosine as well as serine/threonine through cellular kinases by a receptor-specific mechanism.

Amino Acids↗
PubMed1988

CD3-associated heterodimeric polypeptides on suppressor hybridomas define biologically active inhibitory cells.

We have investigated the relationship between CD3 expression and the suppressor T-cell function. We have isolated stable clonal cell lines of the F12.23 suppressor T-cell hybridoma that are either CD3+ or CD3-. These lines were subjected to functional assays including inhibition of in vivo hapten-specific delayed-type hypersensitivity responses, in vitro hapten-specific interleukin 2 responses, as well as hapten-specific cytotoxic T-lymphocyte assays. In all assays, the functional suppressor phenotype absolutely correlated with CD3 surface expression. Furthermore, we have immunoprecipitated heterodimeric proteins that share molecular features with some receptor polypeptides previously described. CD3 polypeptides found on the surface of suppressor T cells are phosphorylated after phorbol ester stimulation. Collectively these studies unambiguously define the suppressive supernatant function as a product of CD3+ receptor-bearing T cells.

Animals↗
PubMed1988

Sequences of the cell-attachment sites of reovirus type 3 and its anti-idiotypic/antireceptor antibody: modeling of their three-dimensional structures.

Previous studies have identified an area of amino acid sequence similarity shared by the reovirus type 3 cell-attachment protein sigma 1 and an anti-idiotypic/antireceptor monoclonal antibody (mAb) 87.92.6 that mimics reovirus type 3 by attaching to the same cell-surface receptor. We found that synthetic peptides corresponding to this area of primary sequence similarity bind a neutralizing mAb 9BG5 against which the mAb 87.92.6 is directed. The synthetic peptides compete with mAb 87.92.6 and reovirus type 3 for binding by mAb 9BG5 and displace mAb 87.92.6 and reovirus type 3 from binding to the cell-surface reovirus type 3 receptor. Such observations show that the shared primary structure between reovirus type 3 sigma 1 polypeptide and antireceptor mAb 87.92.6 defines the oligopeptide neutralizing/cell-attachment epitope of reovirus type 3. Computer modeling of this epitope, by use of sequence similarities of known immunoglobulin hypervariable loop conformations, permits an examination of the rudimentary three-dimensional structure of this epitope.

Amino Acid Sequence↗
PubMed1988

Monoclonal antibodies reactive with distinct domains of the neu oncogene-encoded p185 molecule exert synergistic anti-tumor effects in vivo.

The neu oncogene encodes a 185,000 dalton transmembrane glycoprotein, p185. The current study examined the effects of p185-specific monoclonal antibody administration on the tumorigenic growth of neu-transformed NIH3T3 cells implanted into nude mice. Treatment with anti-p185 monoclonal antibodies of the IgG1, IgG2a, IgG2b subclasses was able to profoundly inhibit the growth of neu-transformed cells. Furthermore, while none of these antibodies individually was able to cause complete eradication of tumors, the administration of mixtures of antibodies reactive with two distinct regions on the p185 molecule resulted in synergistic anti-tumor effects and complete eradication of tumors in a substantial fraction of the treated animals. The effect was oncogene specific, since the growth of ras transformed cells was not influenced by anti p185 antibodies. These results demonstrate that antibodies reactive with multiple domains of a tumor antigen can exert synergistic anti-tumor effects, and suggest that therapy with monoclonal antibodies specific for the neu oncogene product may play a role in cancer treatment.

Animals↗
PubMed1988

Monoclonal antibodies specific for the neu oncogene product directly mediate anti-tumor effects in vivo.

We have produced a panel of monoclonal antibodies which bind cell surface domains of the 185 Kd tumor antigen (p185) encoded by the neu oncogene. All of these antibodies stain neu-transformed cells in immunofluorescence assays and immunoprecipitate p185 from metabolically labeled cell lysates. All of the anti-p185 monoclonal antibodies, regardless of isotype, exert a selective cytostatic effect on the growth of neu-transformed cells suspended in soft agar, demonstrating their ability to directly inhibit the transformed phenotype. Anti-p185 antibodies of the IgM, IgG2a, and IgG2b isotypes exert a cytolytic effect on neu-transformed cells in the presence of complement. Only one IgG2a monoclonal antibody is also able to mediate minimal levels of antibody-dependent cellular cytotoxicity (ADCC) (Roussel et al., 1984) in the presence of non-immune spleen cells. In vivo administration of anti-p185 antibodies of the IgG1, IgG2a, and IgG2b isotypes exerts a profound inhibitory effect on the tumorigenic growth of neu-transformed cells. This tumor inhibitory effect is unaffected by depleting tumor bearing animals of complement, and is only minimally affected by depleting tumor bearing animals of macrophages. This suggests that neither complement-mediated killing nor ADCC are necessary for the anti-tumor effects of p185-specific monoclonal antibodies. The results presented here demonstrate that monoclonal antibodies reactive with cell surface domains of an oncogene-encoded protein can directly inhibit tumor growth in vitro and in vivo. Such antibodies may prove useful in the therapy of certain malignancies.

Animals↗
PubMed1988

The role of the neu oncogene product in cell transformation and normal development.

p185neu, the protein product of the neu gene, is a tyrosine kinase receptor with structural similarity to the epidermal growth factor (EGF) receptor. The cognate ligand for the p185neu receptor remains unknown. We have defined: 1) stage and tissue-specific expression patterns of the neu gene product in developing tissues; 2) p185neu phosphorylation and the regulation of p185neu tyrosine kinase activity by EGF. 3) Synergistic interactions of cellular rat p185neu and EGF receptor leading to cell transformation; 4) structural and functional differences of normal and oncogenic p185neu. These observations explain some features of how p185neu is involved in normal development and neoplastic transformation.

Animals↗
PubMed1988

Molecular aspects of reovirus-host cell interaction.

Reovirus biology is defined, in the main, by the sigma 1 cell attachment protein located in the virion outer capsid. Interaction of the sigma 1 protein with serotype-specific receptor molecules located on the surface of target cells determines the tropism and virulence of the virus and mediates viral inhibition of target cell growth.

Amino Acid Sequence↗
PubMed1987

Characterization of Lyt-2-, L3T4- class I-specific cytolytic clones in C3H-gld/gld mice. Implications for functions of accessory molecules and programmed development.

We report the first demonstration of Thy-1+, Lyt-2-, L3T4- MHC-specific CTL clones derived from the Lyt-2-, L3T4- subset of lymph node cells of C3H-gld/gld mice. These clones express alpha/beta heterodimeric TCRs on the cell surface and specifically recognize class I molecules on target cells. Lyt-2 and L3T4 molecules are therefore not essential for the induction, recognition, and killing of antigen-specific CTL. In addition, these studies suggest that antigen specificity development for class I structures may occur before Lyt-2 gene activation in the differentiation of T cells.

Animals↗
PubMed1987

Localization of beta-adrenergic receptors on differentiated cells of the central nervous system in culture.

Hypothalamic neurons and cortical protoplasmic (type 1) astrocytes in dissociated cultures of rat brain express binding sites for antibodies specific for epitopes related to the beta-adrenergic receptor. Undifferentiated glial progenitor cells of the rat optic nerve do not detectably bind these antibodies, but both of the progeny [oligodendroglia and process-bearing (type 2) astrocytes] express immunologically identified beta-adrenergic receptors. Levels of receptor expression are variable: not all cells of each type express receptors nor is expression uniform on a given cell. The data suggest that cells of the central nervous system express beta-adrenergic receptors but that levels of expression may be determined by the differentiated state of the cells.

Animals↗
PubMed1987

T-cell receptor genes in autoimmune mice: T-cell subsets have unexpected T-cell receptor gene programs.

Two unique cell subsets have been identified in the autoimmune-prone MRL/MP lpr/lpr and C3H/HeJ gld/gld murine strains that have the Lyt-2-,L3T4-,Thy-1+, and Lyt-2-,L3T4-,Ia-,Thy-1- phenotypes, respectively. We have now found that these cells express T-cell receptor proteins on their surface. Our observations further indicate that the expression of the Thy-1 antigen does not correlate with the expression of alpha-chain and beta-chain T-cell receptor polypeptides. Interestingly, T-cell receptor gamma-chain RNA expression may be influenced or correlate with Thy-1 molecular expression. These studies indicate unusual relationships of different cell-surface structures that may reflect unexpected developmental programs.

Animals↗
PubMed1987

Stage- and tissue-specific expression of the neu oncogene in rat development.

The neu oncogene (also referred to as c-erbB-2 and HER2) encodes a 185-kDa transmembrane glycoprotein with tyrosine kinase activity termed p185. The p185 glycoprotein is structurally related to the epidermal growth factor receptor. It is thought that p185 is the receptor for an as yet unidentified growth factor. In the present study, RNA blot analyses and immunohistochemical studies were performed on rat tissues obtained from a variety of prenatal and postnatal stages to examine the expression of the neu oncogene and its product, p185, during normal development. Expression of the neu gene was detected in mid-gestation embryos in a variety of tissues including nervous system, connective tissue, and secretory epithelium, but not in lymphoid tissue. In adult animals, secretory epithelial tissues and basal cells of the skin expressed neu. These studies demonstrate that the neu gene is expressed in a tissue- and developmental stage-specific manner. We suggest that the p185 molecule plays an important role in the growth and development of a variety of tissues, and, in particular, in epithelial tissue.

Animals↗
PubMed1987

Transport of infectious reovirus into bile: class II major histocompatibility antigen-bearing cells determine reovirus transport.

We have previously demonstrated that mammalian reovirus type 1 enters the bile and gut lumen after systemic administration. In the present study, we showed that Kupffer cell uptake is essential for the transport of reovirus into the bile. Furthermore, class II major histocompatibility antigen (I-A)-bearing cells are a major determinant for the transit of reovirus from the hepatic environment, as well as from the intestine, during the course of systemic infection. These findings may provide an approach to the control of viral pathogens that cause systemic disease by selective utilization or modification of I-A-bearing cells.

Animals↗
PubMed1987

The role of an anti-idiotype antibody in regulating hapten (azobenzenearsonate)-specific granuloma formation.

Antibody regulation of hapten-specific granulomas was studied in mice in order to assess the relationship between an anti-idiotypic antibody and granuloma formation. An anti-idiotypic antibody was raised against the idiotype of an azobenzenearsonate (ABA)-specific antibody of A/J mice. The anti-idiotypic antibody was subcutaneously (s.c.) administered to syngeneic mice prior to challenge with ABA-coupled polyacrylamide beads injected into the intestinal wall. The results of such a challenge were assessed histologically for granuloma formation at 24-h intervals. Mice primed with anti-Id antibody and challenged with ABA-linked beads developed epithelioid granulomas at 72 and 96 hr post-challenge. Unprimed mice or mice primed with control antibodies did not develop granulomas when challenged with ABA-linked beads. Moreover, we found that priming with anti-Id antibody intravenously (i.v.) resulted in suppression of intestinal granuloma formation that was similar to that observed previously after priming mice i.v. with ABA-coupled spleen cells (Ginsburg et al., 1982). This study demonstrates the induction and suppression of hapten-specific granuloma formation in the intestine by an anti-Id antibody. The observations indicate a role for the idiotype-anti-idiotype interaction in regulation of hapten-specific granuloma formation, and may have implications for the manner in which the host reacts against self in the autoimmune inflammatory process.

Animals↗