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)

The major site of phosphorylation of the epidermal growth factor (EGF) receptor after treatment of cells with EGF is threonine 669. Phosphorylation of this site is also associated with the transmodulation of the EGF receptor caused by platelet-derived growth factor and phorbol ester. A distinctive feature of the primary sequence surrounding threonine 669 is the proximity of 2 proline residues (-Pro-Leu-Thr669-Pro-). This site is not a substrate for phosphorylation by protein kinase C. To investigate the mechanism of the increased phosphorylation of the EGF receptor at threonine 669, in vitro assays were used to measure protein kinase and protein phosphatase activities present in homogenates prepared from cells treated with and without EGF. No evidence for the regulation of protein phosphatase activity was obtained in experiments using the [32P]phosphate-labeled EGF receptor as a substrate. A synthetic peptide corresponding to residues 663-681 of the EGF receptor was used as a substrate for protein kinase assays. Incubation of murine 3T3 L1 pre-adipocytes and human WI-38 fibroblasts with EGF caused a rapid increase (3-10-fold) in the level of threonine protein kinase activity detected in cell homogenates. Similar results were obtained after EGF treatment of Chinese hamster ovary cells expressing wild-type (Thr669) and mutated (Ala669) human EGF receptors. Activation of the threonine protein kinase activity was also observed in cells treated with platelet-derived growth factor, serum, and phorbol ester. Insulin-like growth factor-1 caused no significant change in protein kinase activity. Together these data indicate a role for the regulation of the activity of a threonine protein kinase in the control of the phosphorylation state of the EGF receptor at threonine 669. The significance of the identification of a growth factor-stimulated threonine protein kinase to the mechanism of signal transduction is discussed.
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PMID:Mechanism of phosphorylation of the epidermal growth factor receptor at threonine 669. 254 83

Monoclonal antibodies (MAbs) to the human epidermal growth factor (EGF) receptor, the type I insulin-like growth factor (IGF) receptor, and the nerve growth factor (NGF) receptor were used to study the growth regulation of malignant cells. Anti-EGF receptor MAb 425 inhibited the growth of A 431 squamous carcinoma cells which express high numbers of EGF receptors on their surfaces. Growth inhibition induced by MAb 425 was accompanied by alterations of the cell-cycle distribution of these cells, indicating the ability of a monoclonal antibody to act as a biologically active ligand. Growth stimulation of melanoma cells by EGF was unrelated to EGF receptor expression on the cell surface. Insulin- and IGF-I-induced growth stimulation of melanoma cells was inhibited by MAb alpha IR-3 which reacts with the type I IGF receptor. This result indicates that the type I IGF receptor mediated growth stimulation not only by IGF-I but also by insulin. Normal melanocytes and cells of all stages of tumor progression expressed in tissue culture the receptor for NGF, but no effect on the growth of these cells has been observed.
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PMID:Interactions between growth factor receptors and corresponding monoclonal antibodies in human tumors. 283 Dec 41

Autocrine activation of the epidermal growth factor (EGF) receptor on keratinocytes has been recognized as an important growth regulatory mechanism involved in epithelial homeostasis, and, possibly, hyperproliferative diseases. Insulin-like growth factor (IGF)-1 and insulin have been shown to be paracrine keratinocyte mitogens that bind to the type I IGF receptor which is expressed on actively proliferating keratinocytes in situ. In this report, we demonstrate that IGF-1/insulin induced production of keratinocyte-derived autocrine growth factors that bind to the EGF receptor. Increased steady-state mRNA levels for transforming growth factor alpha (TGF-alpha) and for amphiregulin (AR) were observed upon incubation of keratinocytes with mitogenic concentrations of IGF-1. IGF-1 also induced production and secretion of TGF-alpha and AR proteins as detected by immunoassays. An EGF receptor antagonistic monoclonal antibody abolished the mitogenic effect of IGF-1 on cultured keratinocytes. These results suggest that stimulation of keratinocyte growth of IGF-1 requires activation of an EGF receptor-mediated autocrine loop.
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PMID:Induction of autocrine epidermal growth factor receptor ligands in human keratinocytes by insulin/insulin-like growth factor-1. 770 70

Insulin-stimulated glucose transport in adipocytes is mediated by the insulin receptor. To ascertain whether a related receptor could also trigger this response, the epidermal growth factor (EGF) receptor (EGFR) was introduced into adipocytes. 3T3-L1 fibroblasts were infected by a retroviral construct encoding either the full-length (WT) or a carboxy-terminal truncated (c'973) human EGFR; truncation of the amino acids distal to 973 removes all autophosphorylation motifs. After selection and conversion to adipocytes, the level of EGFR expression was retained in infectant adipocytes (150,000 and 250,000/cell, respectively), but not in the parental 3T3-L1 adipocytes (< 5000/cell). WT and c'973 EGFR exhibited ligand-dependent tyrosine kinase activity and stimulated mitogen-activated protein kinase activity equivalently; neither phosphorylated insulin receptor substrate-1. WT EGFR, but not c'973 EGFR, underwent ligand-induced autophosphorylation. EGF did not stimulate tyrosine phosphorylation of the insulin receptor or insulin receptor substrate-1. EGF had a minimal effect on glucose transport by parental 3T3-L1 adipocytes. Glucose transport in the WT EGFR adipocytes was stimulated equivalently by insulin and EGF; exposure to insulin and EGF in combination did not result in augmented transport. Glucose transport in the c'973 EGFR adipocytes was stimulated by insulin, but not by EGF. GLUT4 was translocated to the plasma membrane to a similar extent in response to insulin or EGF in the WT EGFR adipocytes; only insulin caused a significant GLUT4 translocation in the parental or c'973 EGFR adipocytes. These data suggest that the insulin and EGF signaling pathways that lead to glucose transport converge in these adipocytes down-stream of the insulin receptor, and that activation of this pathway requires signaling motifs in the carboxy-terminus of the EGFR. This model system represents a novel approach with which to dissect signal transduction pathways in terminally differentiated adipocytes.
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PMID:Epidermal growth factor (EGF) receptor carboxy-terminal domains are required for EGF-induced glucose transport in transgenic 3T3-L1 adipocytes. 783 73

Insulin-like growth factors I and II (IGF-I and IGF-II) are potent mitogens for some human breast cancer cell lines, and expression of IGF-II mRNA in the oestrogen receptor-positive (ER+) and oestradiol (E2) stimulated human breast cancer cell line T47D is increased by E2, suggesting a role for IGF-II in the mitogenic response to E2. Very little information is available from the literature on the relation between growth inhibition by endocrine therapy and cellular production of IGF-II. Here we report on the effect of E2 and tamoxifen (TAM) on IGF-II mRNA and protein expression in the ER+T61 human breast cancer xenograft. Growth of the T61 tumour is inhibited by treatment with E2 and TAM. Ribonuclease (RNAse) protection assays with human- and mouse-specific IGF-II antisense probes were used to study the regulation of IGF-II mRNA by E2 and TAM in the tumour. IGF-II protein expression was studied by radioimmunoassay. Untreated T61 tumours have a high baseline expression of IGF-II mRNA. TAM treatment of T61 tumours, which results in inhibition of tumour growth without tumour regression, reduced IGF-II mRNA expression approximately 10-fold after 48 h of treatment. E2 treatment of T61 tumours, which results in tumour regression, was accompanied by a more pronounced decrease in IGF-II mRNA expression in the tumour cells; 96 h after initiation of E2 treatment, there was almost no detectable IGF-II mRNA. Analyses of IGF-II protein showed that both treatments significantly reduced the concentration of IGF-II protein in the tumours. This down-regulation was found to be specific for IGF-II, since analyses of the effect of E2 on the expression of IGF-I mRNA, 36B4 mRNA, transforming growth factor alpha(TGF-alpha) mRNA, and epidermal growth factor (EGF) receptor mRNA in T61 tumours did not reveal any down-regulation. To further study the relation between inhibition of tumour growth and down-regulation of IGF-II, we exposed T61 tumours to a monoclonal antibody, alpha-IR3, which abolishes the physiological effect of IGF-I and IGF-II by blocking the binding of both growth factors to the type I IGF receptor. Treatment with alpha-IR3 resulted in inhibition of tumour growth during treatment.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Effect of endocrine therapy on growth of T61 human breast cancer xenografts is directly correlated to a specific down-regulation of insulin-like growth factor II (IGF-II). 843 11

Shc has two distinct domains, amino-terminal and SH2 domain, which can interact with activated growth factor receptors. Shc interacts with insulin receptor via Shc-amino-terminal (N) domain, whereas Shc associates with epidermal growth factor (EGF) receptor through both Shc-N and -SH2 domains. In accordance with the different functional roles between insulin and EGF receptors, EGF stimulated tyrosine phosphorylation of Shc faster than insulin. To clarify the functional importance of three distinct Shc domains on insulin and EGF signaling, we microinjected glutathione S-transferase (GST) fusion proteins containing the amino terminus plus collagen homology domain (NCH), collagen homology domain (CH), and Src homology 2 domain (SH2) into Rat1 fibroblasts expressing insulin receptors (HIRc). Bromodeoxyuridine (BrdUrd) incorporation into newly synthesized DNA was subsequently studied to assess the importance of the three distinct domains of Shc. Microinjection of the NCH-GST fusion protein inhibited BrdUrd incorporation induced by both EGF and insulin, whereas microinjection of the SH2-GST fusion protein inhibited EGF, but not insulin stimulation of DNA synthesis. Neither EGF- nor insulin-induced BrdUrd incorporation was inhibited by the CH-GST fusion protein. Following EGF or insulin stimulation, Shc is phosphorylated on single Tyr-317 residue serving as a docking site for Grb2. Microinjection of Shc-N+CH GST fusion protein with Tyr-317 --> Phe replacement (Y317F) also inhibited insulin stimulation of DNA synthesis. Next, we stably overexpressed wild-type Shc or Y317F mutant Shc into HIRc cells. Insulin-induced tyrosine phosphorylation of IRS-1 was compared among the transfected cell lines, since IRS-1 and Shc could competitively interact with insulin receptor. Insulin-stimulated tyrosine phosphorylation of IRS-1 was decreased in both WT-Shc and Y317F-Shc cells compared with that in HIRc cells. Furthermore, overexpression of the Shc-SH2 domain or Shc-N+CH domain with Y317F mutation interfered with EGF-stimulated endogenous Shc phosphorylation. These results suggest that the amino terminus domain of Shc is functionally important in insulin- and EGF-induced cell cycle progression and that the phosphorylation of Shc Tyr-317 residue is independent of Shc interaction with these receptors.
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PMID:Functional importance of amino-terminal domain of Shc for interaction with insulin and epidermal growth factor receptors in phosphorylation-independent manner. 870 28

Malignant insulinoma is an rare form of cancer with poor prognosis and a reported 5-year survival of 35%. Relatively little is known about the etiology of this disease or of the oncogenes and tumor suppressor genes that participate in its genesis and progression. To address this issue, several protooncogenes, including K-ras, N-ras, erbB-2, erbB-3,c-myc, c-fos, c-jun were examined. Also analyzed was the expression of the growth factors TGF-alpha, EGF, and insulin as well as the EGF receptor (EGF-R), p53 and the putative anti-metastasis gene nm23-H1. These were examined in malignant insulinomas, benign insulinomas, pancreatic B cell hyperplasias and in normal endocrine pancreas. Normal endocrine pancreas showed moderate immunoreaction for c-myc and a strong reaction for insulin. All other parameters were negative. Benign pancreatic B cell hyperplasias were slightly or moderately positive for N-ras and TGF-alpha, and were weakly positive for EGF-R. They were strongly positive for c-myc and insulin. In malignant insulinomas there was strong immunoreaction for c-myc, TGF-alpha, N-ras, K-ras and p53. Insulin reaction was moderate or strong. Molecular genetic studies have been performed for the presence of activating point mutations in codon 12 of the c-K-ras oncogene. Mutations were detected using primer-mediated, mutant-enriched, polymerase chain reaction-restriction fragment length polymorphism analysis and were further characterized by allele-specific oligonucleotide hybridization. Four out of six patients with malignant insulinoma and two out of eight patients with benign insulinoma harbored K-ras point mutations at codon 12. All patients with mutated K-ras oncogene also had elevated levels of p53 protein as well as c-myc and TGF-alpha. In one extremely malignant case we found concomitant mutation at codon 12 of K-ras and codon 61 of the N-ras gene. Our data are consistent with the idea that malignant progression is accompanied by the progressive accumulation of multiple genetic lesions and suggest that activation of myc, TGF-alpha and ras genes may be early events in the development of insulinoma.
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PMID:Molecular genetics of malignant insulinoma. 871 89

In many cellular systems, activation with more than one ligand can produce a cellular response that is greater than the sum of the individual responses to the ligands. This synergy is sometimes referred to as coactivation. In Swiss 3T3 fibroblasts, activation of the epidermal growth factor (EGF) receptor produces a weak induction of DNA synthesis. Insulin has no stimulatory effect on this response. However, in combination, EGF and insulin synergize to cause a large induction of S phase. The underlying cellular biochemistry of this effect has been examined. The data indicate that phospholipase C activation is a major component of agonist-induced DNA synthesis. In contrast, activation of p70 S6 kinase by single agonists was inversely related to their ability to stimulate DNA synthesis. Therefore, it was examined whether stimulation of Swiss 3T3 cells with insulin causes changes in the subcellular distribution of EGF receptors and phospholipase Cgamma1 that could potentially explain the observed synergy or costimulation. It was found that insulin effectively induced the accumulation of EGF receptors on the actin arc of cells without activation of the EGF receptor. In contrast, EGF, when added for several hours, did not cause accumulation of the EGF receptor at this site. However, both EGF and insulin stimulated the accumulation of phospholipase Cgamma1 at the actin arc, which was coincident with the EGF receptor in the case of insulin- stimulated cells. Therefore, it is suggested that the insulin-induced coclustering of the EGF receptor with phospholipase Cgamma1 at the actin arc may allow for greater efficiency of signal transduction, resulting in the synergy observed for these two hormones in stimulation of DNA synthesis.
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PMID:Insulin induces epidermal growth factor (EGF) receptor clustering and potentiates EGF-stimulated DNA synthesis in swiss 3T3 cells: a mechanism for costimulation in mitogenic synergy. 1094 66

Thirty-two normal LEW/Sea rats were transplanted a piece of syngeneic pancreas between the peritoneum and abdominal muscle. Among them, 17 (68%) of the 25 rats that received pancreatic transplantation at 41-50 days of age had a surviving beta-cell mass at 5.5-7.1 months after transplantation. Among the 25 rats, 12 rats injected with interleukin-1 receptor (IL-1R) and IL-2Rbeta peptides at post-transplantation showed better surviving grafts at 5.5 months' observation. Only 2 (25%) of the other 7 young rats that received a pancreatic graft at 20 days of age had a small mass at 21 days post-transplantation. Flow cytometer (FCM) analyses showed that thymus OX40(+) (CD134(+)) T-cells were increased up to 37+/-4% at the graft rejection in the 13 old rats without the IL-R peptide injections. The 7 young rats had 99% of thymus OX40(+) T-cells. However, the 12 old rats injected with the IL-R peptides showed suppressed numbers of thymus OX40(+) T-cells (8-13+/-3%). The long-term surviving, but apoptotic, grafted beta-cells were stained positively both with anti-insulin monoclonal antibody (mAb) and with anti-c-erbB-2/human epidermal growth factor receptor (HER)-2/neu mAb. Expression of a c-erb family oncogene was shown on the pancreatic graft surviving for 7.1 months. Electron microscopic analysis of the grafted beta-cells showed abnormally large beta granules and loss of functioning mitochondria in the cytoplasm. In 18 (56%) of the 32 rats, the 220-bp and 380-bp specific products of insulin-degrading enzyme (IDE) gene were amplified using the polymerase chain reaction (PCR) of the liver DNA. Among the 18 rats, 6 rats expressed 2 extra hands of 280-bp and 700-bp in a correlation with the high levels of the transforming growth factor-alpha (TGF-alpha) cDNA of 120-bp which was amplified in the quantitative reverse-transcriptase (RT)-PCR of the liver cDNA. Among the selected 11 rats, 5 rats showed large amounts of the 120-bp TGF-alpha cDNA. Host pancreatic RT-PCR showed 235-bp or 250-bp bcl-2 and 181-bp bcl-xS gene products. The bcl-2 cDNA of the host pancreas was amplified actively when the pancreatic graft was being rejected. Exceptionally, the one female injected with the IL-R peptides showed a low level of the liver TGF-alpha cDNA together with the pancreatic expressions of Bax (140-bp), bcl-2 and like interleukin converting enzyme (LICE) (318-bp) cDNA. Insulin secretion from the grafted beta-cells and IL-1beta-induced Fas-mediated apoptosis of the beta-cells were suspected to be present at the same time in the female with the best graft survival.
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PMID:Oncogene expression on the syngeneic beta-cells of long-term surviving pancreatic grafts and better effects of interleukin-1 receptor (IL-1R) and IL-2Rbeta on the grafted beta-cells in LEW/Sea strain rats. 1272 75

Studies in mammals have led to the suggestion that hyperglycemia and hyperinsulinemia are important factors both in aging and in the development of cancer. Insulin/insulin-like growth factor 1 (IGF-1) signaling molecules that have been linked to longevity include DAF-2 and InR and their homologues in mammals, and inactivation of the corresponding genes is followed by increased life span in nematodes, fruit flies and mice. It is possible that the life-prolonging effects of calorie restriction are due to decreasing IGF-1 levels. A search of pharmacological modulators of insulin/IGF-1 signaling pathway (which mimetic effects of life span extending mutations or calorie restriction) could be a perspective direction in regulation of longevity. The chronic treatment of female transgenic HER-2/neu mice with metformin (100 mg/kg in drinking water) slightly decreased the food consumption but failed in reducing the body weight or temperature, slowed down the age-related rise in blood glucose and triglycerides level, as well as the age-related switch-off of estrous function, prolonged the mean life span by 8% (p < 0.05), the mean life span of last 10% survivors by 13.1%, and the maximum life span by 1 month in comparison with control mice. The demographic aging rate represented by the estimate of respective Gompertz's parameter was decreased 2.26 times. The metformin-treatment significantly decreased the incidence and size of mammary adenocarcinomas in mice and increased the mean latency of the tumors.
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PMID:Effect of metformin on life span and on the development of spontaneous mammary tumors in HER-2/neu transgenic mice. 1612 52


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