scholarly journals Endocytosis Deficiency of Epidermal Growth Factor (EGF) Receptor–ErbB2 Heterodimers in Response to EGF Stimulation

1999 ◽  
Vol 10 (5) ◽  
pp. 1621-1636 ◽  
Author(s):  
Zhixiang Wang ◽  
Lianfeng Zhang ◽  
Tai K. Yeung ◽  
Xinmei Chen
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Subcellular Fractionation ◽  
Breast Cancer Cell Lines ◽  
Expression Plasmid ◽  
Intracellular Domain ◽  
Egfr Expression ◽  
Epidermal Growth ◽  
Very High

Epidermal growth factor (EGF) stimulates the homodimerization of EGF receptor (EGFR) and the heterodimerization of EGFR and ErbB2. The EGFR homodimers are quickly endocytosed after EGF stimulation as a means of down-regulation. However, the results from experiments on the ability of ErbB2 to undergo ligand-induced endocytosis are very controversial. It is unclear how the EGFR–ErbB2 heterodimers might behave. In this research, we showed by subcellular fractionation, immunoprecipitation, Western blotting, indirect immunofluorescence, and microinjection that, in the four breast cancer cell lines MDA453, SKBR3, BT474, and BT20, the EGFR–ErbB2 heterodimerization levels were positively correlated with the ratio of ErbB2/EGFR expression levels. ErbB2 was not endocytosed in response to EGF stimulation. Moreover, in MDA453, SKBR3, and BT474 cells, which have very high levels of EGFR–ErbB2 heterodimerization, EGF-induced EGFR endocytosis was greatly inhibited compared with that in BT20 cells, which have a very low level of EGFR–ErbB2 heterodimerization. Microinjection of an ErbB2 expression plasmid into BT20 cells significantly inhibited EGF-stimulated EGFR endocytosis. Coexpression of ErbB2 with EGFR in 293T cells also significantly inhibited EGF-stimulated EGFR endocytosis. EGF did not stimulate the endocytosis of ectopically expressed ErbB2 in BT20 and 293T cells. These results indicate that ErbB2 and the EGFR–ErbB2 heterodimers are impaired in EGF-induced endocytosis. Moreover, when expressed in BT20 cells by microinjection, a chimeric receptor composed of the ErbB2 extracellular domain and the EGFR intracellular domain underwent normal endocytosis in response to EGF, and this chimera did not block EGF-induced EGFR endocytosis. Thus, the endocytosis deficiency of ErbB2 is due to the sequence of its intracellular domain.

scholarly journals Localization dynamics of endogenous fluorescently labeled RAF1 in EGF-stimulated cells

2019 ◽  
Vol 30 (4) ◽  
pp. 506-523
Author(s):  
Sachin V. Surve ◽  
Paul J. Myers ◽  
Samantha A. Clayton ◽  
Simon C. Watkins ◽  
Matthew J. Lazzara ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cell Surface ◽  
Gene Editing ◽  
Egf Receptor ◽  
Subcellular Fractionation ◽  
Receptor Endocytosis ◽  
Downstream Effectors ◽  
Epidermal Growth

Activation of the epidermal growth factor (EGF) receptor (EGFR) at the cell surface initiates signaling through the RAS-RAF-MAPK/ERK1/2 pathway and receptor endocytosis. Whether this signaling continues from endosomes remains unclear, because RAS is predominantly located on the plasma membrane, and the localization of endogenous RAF kinases, downstream effectors of RAS, is not defined. To examine RAF localization, we labeled endogenous RAF1 with mVenus using gene editing. From 10 to 15% of RAF1-mVenus (<2000 molecules/cell), which was initially entirely cytosolic, transiently translocated to the plasma membrane after EGF stimulation. Following an early burst of translocation, the membrane-associated RAF1-mVenus was undetectable by microscopy or subcellular fractionation, and this pool was estimated to be <200 molecules per cell. In contrast, persistent EGF-dependent translocation of RAF1-mVenus to the plasma membrane was driven by the RAF inhibitor sorafenib, which increases the affinity of Ras-GTP:RAF1 interactions. RAF1-mVenus was not found in EGFR-containing endosomes under any conditions. Computational modeling of RAF1 dynamics revealed that RAF1 membrane abundance is controlled most prominently by association and dissociation rates from RAS-GTP and by RAS-GTP concentration. The model further suggested that the relatively protracted activation of the RAF-MEK1/2-ERK1/2 module, in comparison with RAF1 membrane localization, may involve multiple rounds of cytosolic RAF1 rebinding to active RAS at the membrane.

scholarly journals Argonaute-2 Expression Is Regulated by Epidermal Growth Factor Receptor and Mitogen-Activated Protein Kinase Signaling and Correlates with a Transformed Phenotype in Breast Cancer Cells

Endocrinology ◽  
2008 ◽  
Vol 150 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Brian D. Adams ◽  
Kevin P. Claffey ◽  
Bruce A. White
Keyword(s):  
Breast Cancer ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Growth Factor Receptor ◽  
Mapk Signaling ◽  
Full Length ◽  
Breast Cancer Cell Lines ◽  
Epidermal Growth ◽  
Mcf 7

Argonaute (Ago) 2 is the catalytic engine of mammalian RNA interference, but little is known concerning the regulation of Ago2 by cell-signaling pathways. In this study we show that expression of Ago2, but not Ago1, Ago3, or Ago4, is elevated in estrogen receptor (ER) α-negative (ERα−) vs. ERα-positive (ERα+) breast cancer cell lines, and in ERα− breast tumors. In MCF-7 cells the low level of Ago2 was found to be dependent upon active ERα/estrogen signaling. Interestingly, the high expression of Ago2 in ERα− cells was severely blunted by inhibition of the epidermal growth factor (EGF) receptor/MAPK signaling pathway, using either a pharmacological MAPK kinase inhibitor, U0126, or a small interfering RNA directed against EGF receptor. Half-life studies using cycloheximide indicated that EGF enhanced, whereas U0126 decreased, Ago2 protein stability. Furthermore, a proteosome inhibitor, MG132, blocked Ago2 protein turnover. The functional consequences of elevated Ago2 levels were examined by stable transfection of ERα+ MCF-7 cells with full-length and truncated forms of Ago2. The full-length Ago2 transfectants displayed enhanced proliferation, reduced cell-cell adhesion, and increased migratory ability, as shown by proliferation, homotypic aggregation, and wound healing assays, respectively. Overexpression of full-length Ago2, but not truncated forms of Ago2 or an empty vector control, reduced the levels of E-cadherin, β-catenin, and β-actin, as well as enhanced endogenous miR-206 activity. These data indicate that Ago2 is regulated at both the transcriptional and posttranslational level, and also implicate Ago2 and enhanced micro-RNA activity in the tumorigenic progression of breast cancer cell lines. Argonaute-2 is elevated in ERα- breast cancer cells due to epidermal growth factor receptor/MAPK signaling, and overexpression of this gene induces a more transformed phenotype in ERα+ MCF-7 cells.

Epidermal growth factor receptor (EGFR) expression in colorectal cancer in Slovakia

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 20103-20103
Author(s):  
T. Salek ◽  
J. Mardiak ◽  
F. Ondrias ◽  
J. Bodnar ◽  
L. Klimcakova
Keyword(s):  
Colorectal Cancer ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Growth Factor Receptor ◽  
Cellular Processes ◽  
Egfr Expression ◽  
Promising Therapeutic Target ◽  
Epidermal Growth ◽  
Improve Clinical Outcome

20103 Background: EGFR is involved in the epidermal growth factor pathway that regulates cellular processes and is associated with the development of malignancy.EGFR targeted therapy could be an alternative option to improve clinical outcome in tumors with EGFR expression. Methods: From 09/2004 till 12/2005 we evaluated histologic specimens of 130 patients (89 male, 41 female) with colorectal cancer. EGFR expression was examined by immunohistochemistry using theEGFR Detection Kit (Dako Corporation) in paraffin-embedded colon/rectum tumors and graded as percentage of cells stained. Results: EGFR positivity (1% and more) was observed in 106 pts (81.5%) and EGFR negativity in 24 pts (18.5%). Median of positivity in percentage is 40 (1–95). Conclusions: The EGF receptor is overexpressed in many human tumors and is a promising therapeutic target. No significant financial relationships to disclose.

scholarly journals Expression of epidermal growth factor receptor in neoplastic pituitary cells: evidence for a role in corticotropinoma cells

2004 ◽  
Vol 183 (2) ◽  
pp. 385-394 ◽  
Author(s):  
M Theodoropoulou ◽  
T Arzberger ◽  
Y Gruebler ◽  
M L Jaffrain-Rea ◽  
J Schlegel ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Pituitary Adenomas ◽  
Egf Receptor ◽  
Pituitary Tumors ◽  
Tumor Formation ◽  
Pituitary Cells ◽  
Egfr Expression ◽  
Epidermal Growth ◽  
P27 Kip1

The oncogenic effects of epidermal growth factor (EGF) have long been established. EGF receptor (EGFr) is overexpressed in many types of tumors and constitutes a target for cancer treatment. The pituitary gland is a target of EGF action and it is very likely that EGFr plays a role in pituitary tumor formation and progression. However, there is a controversy in the literature concerning EGFr expression in the different types of pituitary adenomas. In the present study we investigated the expression pattern of the wild type EGFr (EGFrWT) and the constitutively active variant III (EGFrvIII) at the mRNA and protein levels in a large series of pituitary tumors. EGFrWT was found in a high percentage of hormone-secreting tumors, but only in a small fraction of non-functioning pituitary adenomas, while no expression of the EGFrvIII could be detected by nested RT-PCR in any tumor. Among the hormone-secreting adenomas, the highest incidence of EGFr expression was found in Cushing’s pituitary adenomas. Furthermore, immunohistochemistry for the phosphorylated EGFr revealed the presence of activated EGFr in most Cushing’s adenomas, compared with most pituitary adenomas. Taking into account that downregulation of p27/Kip1 plays a significant role in corticotrope tumorigenesis and that EGFr mitogenic signaling results in decreased p27/Kip1, we searched for a correlation between EGFr expression and p27/Kip1 levels in corticotropinomas. Low p27/Kip1 immunoreactivity was observed in corticotropinomas expressing EGFr. On the other hand, somatotropinomas expressing EGFr had high p27/Kip1 immunoreactivity. These data suggest a corticotrope-specific phenomenon and indicate that EGFr may have a role in the unbalanced growth of corticotrope tumoral cells.

Pharmacogenetic Profiling for Cetuximab Plus Irinotecan Therapy in Patients With Refractory Advanced Colorectal Cancer

2008 ◽  
Vol 26 (9) ◽  
pp. 1427-1434 ◽  
Author(s):  
Francesco Graziano ◽  
Annamaria Ruzzo ◽  
Fotios Loupakis ◽  
Emanuele Canestrari ◽  
Daniele Santini ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Salvage Therapy ◽  
Egf Receptor ◽  
Growth Factor Receptor ◽  
Skin Toxicity ◽  
Egfr Expression ◽  
Intron 1 ◽  
Epidermal Growth

PurposeRegulation of epidermal growth factor receptor (EGFR) signaling pathways may play a relevant role in determining the activity of cetuximab therapy in patients with metastatic colorectal cancer (MCRC). We investigated possible associations between genetic variants and clinical outcomes of MCRC patients treated with cetuximab-irinotecan salvage therapy.Patients and MethodsPatients who underwent cetuximab-irinotecan salvage therapy after disease progression during or after first-line bolus/infusional fluorouracil, leucovorin, and oxaliplatin chemotherapy and a second-line irinotecan-based regimen were considered eligible for analysis of polymorphisms with putative influence on cetuximab-related pathways. Epidermal growth factor (EGF) 61A>G, EGF receptor (EGFR) 216G>T, EGFR 497G>A, EGFR intron-1 (CA)ndinucleotide short (S)/long (L) variant, cyclin-D1 870A>G, immunoglobulin-G fragment-C receptors RIIIa 158G>T, and RIIa 131G>A were studied for a possible association with overall survival (OS) as the primary end point. Additional analyses were addressed at possible associations among polymorphisms and EGFR expression, toxicity, and response.ResultsIn 110 assessable patients, significant association with favorable OS was observed for EGFR intron-1 S/S and EGF 61 G/G genotypes. In the multivariate model, EGFR intron-1 S/S and EGF 61 G/G genotypes showed a hazard ratio of 0.41 (95% CI, 0.21 to 0.78; P = .006) and 0.44 (95% CI, 0.23 to 0.84; P = .01), respectively. EGFR intron-1 S/S carriers showed more frequent G2-G3 skin toxicity (χ2test = 12.7; P = .001) and treatment response (χ2test = 9.45; P = .008) than EGFR intron-1 L/L carriers.ConclusionAlthough additional studies are required for confirmation, our findings could optimize the use of cetuximab in MCRC patients.

947: Chemopreventive Effects of COX-2 Inhibitor and Epidermal Growth Factor (EGF)-Receptor Kinase Inhibitor on Rat Urinary Bladder Tumorigenesis

2004 ◽  
Vol 171 (4S) ◽  
pp. 251-251
Author(s):  
Kazunori Hattori ◽  
Katsuyuki Iida ◽  
Akira Johraku ◽  
Sadamu Tsukamoto ◽  
Taeko Asano ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Urinary Bladder ◽  
Egf Receptor ◽  
Kinase Inhibitor ◽  
Receptor Kinase ◽  
Rat Urinary Bladder ◽  
Epidermal Growth ◽  
Cox 2

scholarly journals EGF induces increased ligand binding affinity and dimerization of soluble epidermal growth factor (EGF) receptor extracellular domain.

1991 ◽  
Vol 266 (32) ◽  
pp. 22035-22043
Author(s):  
D.R. Hurwitz ◽  
S.L. Emanuel ◽  
M.H. Nathan ◽  
N. Sarver ◽  
A. Ullrich ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Ligand Binding ◽  
Binding Affinity ◽  
Egf Receptor ◽  
Extracellular Domain ◽  
Epidermal Growth
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