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 ErbB receptor tyrosine kinase family consists of the epidermal growth factor (EGF) receptor (ErbB1) and three related receptors (ErbB2, ErbB3, ErbB4). Their intrinsic tyrosine kinases can be activated by receptor-dimerization induced by numerous ligands or overexpression. ErbB receptors are frequently overexpressed in breast cancer, and their overexpression is associated with protection from apoptosis. To directly assess their role in apoptosis sensitivity of breast cancer cells, we established MCF-7 breast carcinoma cell lines overexpressing each ErbB receptor alone or in all possible pairs. Overexpression of ErbB1, ErbB2 and ErbB4 receptors was enough to activate them as judged by their phosphorylation, whereas co-expression of other ErbB receptors was necessary for the phosphorylation of the ErbB3. Surprisingly, overexpression of the ErbB receptors even when combined with treatment with their ligands (EGF, transforming growth factor alpha, betacellulin, neuregulins) failed to protect the MCF-7 cells from cell death induced by either tumor necrosis factor (TNF) or serum starvation. During starvation TGF-alpha, however, increased the cell size of the ErbB1 overexpressing cell line, and neuregulin1-beta1 increased that of all cell lines. In conclusion, our data does not support the role of ErbB receptors in the regulation of cell death induced by TNF or serum starvation, and the observed association in breast cancer may be due to other concomitant changes.
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PMID:Cell death induced by TNF or serum starvation is independent of ErbB receptor signaling in MCF-7 breast carcinoma cells. 1079 81

Evidence suggests that there is an association between the abnormal expression of members of the c-erbB receptor tyrosine kinase family and poor prognosis in head and neck squamous cell carcinomas (HNSCC). Until now, the relative contributions of different c-erbB ligands to HNSCC progression have not been clearly defined. In this paper we examined the effects of ligands with different c-erbB receptor specificities in terms of their stimulation of HNSCC proliferation, expression of matrix metalloproteinases (MMPs) and invasion. Heregulin-beta1 (HRG-beta1; selective c-erbB3/B4 ligand) was found to stimulate proliferation in the majority of cell lines, whereas epidermal growth factor (EGF; EGFR ligand) and betacellulin (BTC; EGFR/B4 ligand) induced variable responses. All three ligands up-regulated multiple MMPs including collagenases, stromelysins, matrilysin and gelatinase B (MMP-9) but had minimal or no effects on gelatinase A (MMP-2), MT1-MMP and tissue inhibitors of MMPs (TIMPs). MMP-9 mRNA was induced to a higher level than other MMPs, although with slower kinetics. HRG-beta1 was less active than EGF and BTC at the optimal concentration (relative potency of EGF:BTC:HRG = 3:4:1). In vitro invasion through Matrigel was also increased by all three ligands in proportion to their MMP up-regulation. A specific anti-EGFR monoclonal antibody (mAb ICR62) inhibited MMP up-regulation, migration and invasion induced by all three ligands, whereas an anti-c-erbB-2 mAb ICR12 inhibited mitogenic and motogenic responses following ligand stimulation but had no effect on MMP expression. These results suggest that c-erbB ligands may differentially potentiate the invasive phenotype of HNSCC via co-operative induction of cell proliferation, migration and proteolysis. The EGFR signalling pathway appears to be the dominant component controlling the proteolytic and invasive phenotype in HNSCC, whereas the c-erbB-2 signalling pathway is responsible, in part, for the mitogenic and motogenic effects of ligands.
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PMID:Differential modulation of proliferation, matrix metalloproteinase expression and invasion of human head and neck squamous carcinoma cells by c-erbB ligands. 1084 63

Aberrant expression of tyrosine kinases such as c-erbB and EGFR contributes to the progression of head and neck squamous cell carcinomas (HNSCCs). One mechanism may be potentiation of angiogenesis, since upregulation of vascular endothelial growth factor (VEGF) expression by activation of epidermal growth factor receptor (EGFR) and/or c-erbB-2 has been described. Firstly, we demonstrated expression of all 4 members of the VEGF family in a panel of 15 HNSCC cell lines which over-express one or more c-erbB receptors. We then explored the regulatory roles of three major ligands with different selectivity of binding to c-erbB receptors (namely transforming growth factor-alpha (TGF-alpha), betacellulin (BTC) and heregulin-beta1 (HRG-beta1)) on VEGF-A, B, C and D expression in selected HNSCC lines. Using semi-quantitative reverse transcription-PCR, we showed that all three c-erbB ligands up-regulated VEGF-A mRNA (all isoforms) and VEGF-C (BTC max at 1-10 nM; TGF-alpha and HRG-beta1 max at 10-100 nM) but had no effect on VEGF-B. Interestingly, all ligands simultaneously down-regulated the expression of VEGF-D mRNA. A monoclonal antibody (mAb) which blocks EGFR ligand binding (ICR62) down-regulated the basal levels of VEGF-A (all isoforms) and VEGF-C, had no detectable effects on VEGF-B and increased VEGF-D. ICR62 also reversed the effects of all three erbB ligands (TGF-alpha, BTC and HRG-beta1) on VEGF-A, VEGF-C and VEGF-D expression. An anti-c-erbB-2 mAb (ICR12) showed similar effects on basal or ligand-modulated expression of VEGF in these cell lines, although to a lesser extent. Our results reveal that the four VEGF genes are regulated by c-erbB signaling pathways in a strikingly different manner, suggesting that they serve distinct, although perhaps complimentary (VEGF-A and VEGF-C) or antagonistic (VEGF-D) functions. The EGFR and c-erbB-2 signaling pathway(s) plays a role in VEGF regulation in HNSCC, although EGFR would appear to be dominant in this cell type.
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PMID:Vascular endothelial growth factor family members are differentially regulated by c-erbB signaling in head and neck squamous carcinoma cells. 1123 91

The neuregulin (NRG)/epidermal growth factor (EGF) family of growth factors consists of several ligands that specifically activate four erbB receptor-tyrosine kinases, namely erbB-1 (EGF-R), erbB-2 (neu), erbB-3, and erbB-4. We have previously shown that islet morphogenesis is impaired and beta-cell differentiation delayed in mice lacking functional EGF-R [EGF-R (-/-)]. The present study aims to clarify which erbB ligands are important for islet development. Pancreatic expression of EGF, TGF-alpha, heparin-binding EGF, betacellulin (BTC), and NRG-4 was detected as early as embryonic d 13 (E13). Effects of these ligands were studied in E12.5 pancreatic explant cultures grown for 5 d ex vivo. None of the growth factors affected the ratio of endocrine to exocrine cells. However, significant effects within the endocrine cell populations were induced by EGF, BTC, and NRG-4. beta-Cell development was augmented by BTC, whereas the development of somatostatin-expressing delta-cells was stimulated by NRG-4. Both ligands decreased the numbers of glucagon-containing alpha-cells. The effect of BTC was abolished in the EGF-R (-/-) mice. A soluble erbB-4 binding fusion protein totally inhibited the effects of NRG-4 but not of BTC. Neutralization of endogenous NRG-4 activity in the model system effectively inhibited delta-cell development, indicating that this erbB4-ligand is an essential factor for delineation of the somatostatin-producing delta-cells. Our results suggest that ligands of the EGF-R/erbB-1 and erbB-4 receptors regulate the lineage determination of islet cells during pancreatic development. BTC, acting through EGF-R/erbB-1, is important for the differentiation of beta-cells. This could be applied in the targeted differentiation of stem cells into insulin-producing cells.
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PMID:ErbB signaling regulates lineage determination of developing pancreatic islet cells in embryonic organ culture. 1239 41

We previously provided evidence that glucagon-like peptide 1 (GLP-1) induces pancreatic beta-cell growth nonadditively with glucose in a phosphatidylinositol (PI) 3-kinase- and protein kinase C zeta-dependent manner. However, the exact mechanism by which the GLP-1 receptor (GLP-1R), a member of the G protein-coupled receptor (GPCR) superfamily, activates the PI 3-kinase signaling pathway to promote beta-cell growth remains unknown. We hypothesized that the GLP-1R could activate PI 3-kinase and promote beta-cell proliferation through transactivation of the epidermal growth factor (EGF) receptor (EGFR), an event possibly linked to GPCRs via activation of c-Src and the production of putative endogenous EGF-like ligands. Both the c-Src inhibitor PP1 and the EGFR-specific inhibitor AG1478 blocked GLP-1-induced [(3)H]thymidine incorporation in INS(832/13) cells as well as in isolated rat islets, while only AG1478 inhibited the proliferative action of betacellulin (BTC), an EGFR agonist. Both compounds also suppressed GLP-1-induced PI 3-kinase activation. A time-dependent increase in tyrosine phosphorylation of the EGFR in response to GLP-1 was observed in INS(832/13) cells. This transactivation of the EGFR was sensitive to both the pharmacological agents PP1 and AG1478. The action of GLP-1 and BTC on INS cell proliferation was found to be not additive. Overexpression of a dominant-negative EGFR in INS cells with a retroviral expression vector curtailed GLP-1-induced beta-cell proliferation. GLP-1 treatment of INS cells caused a decrease in cell surface-associated BTC, as shown by FACS analysis. Also, the metalloproteinase inhibitor GM6001 and an anti-BTC neutralizing antibody suppressed the GLP-1 proliferative effect. Finally, coculturing the prostatic cancer cell line LNCaP that lacks GLP-1 responsiveness with INS cells increased LNCaP cell proliferation in the presence of GLP-1, thus revealing that INS cells secrete a growth factor in response to GLP-1. GM6001 and an anti-BTC neutralizing antibody suppressed increased LNCaP cell proliferation in the presence of GLP-1 in the coculture experiments. The results are consistent with a model in which GLP-1 increases PI 3-kinase activity and enhances beta-cell proliferation via transactivation of the EGFR that would require the proteolytic processing of membrane-anchored BTC or other EGF-like ligands.
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PMID:Glucagon-like peptide 1 induces pancreatic beta-cell proliferation via transactivation of the epidermal growth factor receptor. 1250 2

The epidermal growth factor (EGF) receptor and its various ligands (EGF, TGF-alpha, amphiregulin, heparin-binding (HB)-EGF, heregulin, betacellulin) seem to be involved in the growth regulation of intestinal mucosa and might be related to the development and progression of gastrointestinal tumors. However, few quantitative data investigating the impact of tumor-EGF receptor levels in gastrointestinal carcinomas on tumor stage and prognosis are available. Therefore, EGF receptors were quantitatively determined in colorectal carcinomas in comparison to adjacent normal mucosa by 125I[EGF]-binding studies. EGFR capacity was increased in advanced invasive colorectal carcinomas (T1/2 vs. T3/4 tumors, p<0.001) and advanced UICC stages (UICC I vs. UICC II/III, p<0.001). These findings were confirmed with quantitative 125[I]EGF autoradiography performed on frozen tissue slides and analyzed by laser densitometry (p=0.020). EGF receptor analysis with immunohistochemistry with EGFR antibodies directed against the extracellular domain of the receptor was not correlated with tumor invasion or prognosis. mRNA-expression of EGFR ligands was investigated using semiquantitative RT-PCR amplification using specific primers. RT-PCR transcripts of EGFR ligands (EGF, TGF-alpha, HB-EGF, and amphiregulin) were detected in both carcinomas and normal mucosa, indicating that autocrine growth stimulation of colorectal carcinomas is mediated by coexpression of EGF receptor ligands and upregulation of EGF receptors. Survival of colorectal cancer patients with increased tumor EGF receptor levels was significantly reduced in comparison to patients with low/unchanged tumor EGF receptor levels (mean survival+/-SD, 36.2+/-4.0 vs. 46.8+/-4.3 months; p=0.017). Further studies investigating EGF receptor levels in gastric cancer patients have shown that increased tumor EGF receptor levels were associated with poor prognosis in gastric cancer patients with tumors localized distal from the cardia. Several specific EGF receptor tyrosine kinase inhibitors have recently entered clinical phase I-III studies, with promising antitumor effects in several tumors, including gastrointestinal cancer. Therefore, patients with invasive gastric or colorectal carcinomas might benefit from therapies specifically blocking EGFR-mediated signal transduction.
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PMID:Clinical implications of the EGF receptor/ligand system for tumor progression and survival in gastrointestinal carcinomas: evidence for new therapeutic options. 1279 Mar 26

Antagonism of voltage-dependent K+ (Kv) currents in pancreatic beta-cells may contribute to the ability of glucagon-like peptide-1 (GLP-1) to stimulate insulin secretion. The mechanism and signaling pathway regulating these currents in rat beta-cells were investigated using the GLP-1 receptor agonist exendin 4. Inhibition of Kv currents resulted from a 20-mV leftward shift in the voltage dependence of steady-state inactivation. Blocking cAMP or protein kinase A (PKA) signaling (Rp-cAMP and H-89, respectively) prevented the inhibition of currents by exendin 4. However, direct activation of this pathway alone by intracellular dialysis of cAMP or the PKA catalytic subunit (cPKA) could not inhibit currents, implicating a role for alternative signaling pathways. A number of phosphorylation sites associated with phosphatidylinositol 3 (PI3)-kinase activation were up-regulated in GLP-1-treated MIN6 insulinoma cells, and the PI3 kinase inhibitor wortmannin could prevent antagonism of beta-cell currents by exendin 4. Antagonists of Src family kinases (PP1) and the epidermal growth factor (EGF) receptor (AG1478) also prevented current inhibition by exendin 4, demonstrating a role for Src kinase-mediated trans-activation of the EGF tyrosine kinase receptor. Accordingly, the EGF receptor agonist betacellulin could replicate the effects of exendin 4 in the presence of elevated intracellular cAMP. Downstream, the PKCzeta pseudosubstrate inhibitor could prevent current inhibition by exendin 4. Therefore, antagonism of beta-cell Kv currents by GLP-1 receptor activation requires both cAMP/PKA and PI3 kinase/PKCzeta signaling via trans-activation of the EGF receptor. This represents a novel dual pathway for the control of Kv currents by G protein-coupled receptors.
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PMID:Antagonism of rat beta-cell voltage-dependent K+ currents by exendin 4 requires dual activation of the cAMP/protein kinase A and phosphatidylinositol 3-kinase signaling pathways. 1456 57

Human pancreatic ductal adenocarcinomas overexpress the epidermal growth factor (EGF) receptor. Betacellulin is a mitogenic polypeptide that binds and activates this receptor. To determine whether betacellulin has a role in human pancreatic cancer, we studied its expression in cultured human pancreatic cancer cell lines and in normal and cancerous pancreatic tissues. Five of 6 pancreatic cancer cell lines expressed the 3 kb betacellulin mRNA moiety, T3M4, MiaPaCa-2 and COLO-357 cells exhibiting the highest expression levels. EGF, heparin-binding EGF-like growth factor (HB-EGF), and basic fibroblast growth factor (bFGF) increased betacelullin mRNA levels. Only 2 of 15 normal samples and 1 of 10 cancer samples failed to exhibit the betacellulin transcript. Densitometric analysis of the autoradiographs revealed a 7.5-fold increase in betacellulin mRNA levels in the cancer tissues by comparison with the normal tissues. By in situ hybridization, the duct-like cancer cells exhibited many betacellulin mRNA in situ hybridization grains. These findings indicate that human pancreatic cancer cells express betacellulin in culture and in vivo, and suggest that this EGF-like ligand may participate in aberrant autocrine and paracrine activation of the EGF receptor in human pancreatic cancer.
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PMID:Betacellulin, a member of the epidermal growth-factor family, is overexpressed in human pancreatic-cancer. 2155 10

Diabetes mellitus is a disease with considerable morbidity and mortality worldwide. Breakdown of the blood-retinal barrier and leakage from the retinal vasculature leads to diabetic macular edema, an important cause of vision loss in patients with diabetes. Although epidemiologic studies and randomized clinical trials suggest that glycemic control plays a major role in the development of vascular complications of diabetes, insulin therapies for control of glucose metabolism cannot prevent long-term retinal complications. The phenomenon of temporary paradoxical worsening of diabetic macular edema after insulin treatment has been observed in a number of studies. In prospective studies on non-insulin-dependent (type 2) diabetes mellitus patients, a change in treatment from oral drugs to insulin was often associated with a significant increased risk of retinopathy progression and visual impairment. Although insulin therapies are critical for regulation of the metabolic disease, their role in the retina is controversial. In this study with diabetic mice, insulin treatment resulted in increased vascular leakage apparently mediated by betacellulin and signaling via the epidermal growth factor (EGF) receptor. In addition, treatment with EGF receptor inhibitors reduced retinal vascular leakage in diabetic mice on insulin. These findings provide unique insight into the role of insulin signaling in mediating retinal effects in diabetes and open new avenues for therapeutics to treat the retinal complications of diabetes mellitus.
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PMID:Inhibition of EGF signaling protects the diabetic retina from insulin-induced vascular leakage. 2383 29

Seven ligands bind to and activate the mammalian epidermal growth factor (EGF) receptor (EGFR/ERBB1/HER1): EGF, transforming growth factor-alpha (TGFA), heparin-binding EGF-like growth factor (HBEGF), betacellulin (BTC), amphiregulin (AREG), epiregulin (EREG), and epigen (EPGN). Of these, EGF, TGFA, HBEGF, and BTC are thought to be high-affinity ligands, whereas AREG, EREG, and EPGN constitute low-affinity ligands. This focused review is meant to highlight recent studies related to actions of the individual EGFR ligands, the interesting biology that has been uncovered, and relevant advances related to ligand interactions with the EGFR.
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PMID:EGF receptor ligands: recent advances. 2763 38


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