scholarly journals Bradykinin-induced growth inhibition of normal rat kidney (NRK) cells is paralleled by a decrease in epidermal-growth-factor receptor expression

1994 ◽  
Vol 298 (2) ◽  
pp. 335-340 ◽  
Author(s):  
E J J Van Zoelen ◽  
P H J Peters ◽  
G B Afink ◽  
S Van Genesen ◽  
A D G De Roos ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Rat Kidney ◽  
Receptor Expression ◽  
Binding Studies ◽  
Normal Rat ◽  
Epidermal Growth

Normal rat kidney fibroblasts, grown to density arrest in the presence of epidermal growth factor (EGF), can be induced to undergo phenotypic transformation by treatment with transforming growth factor beta or retinoic acid. Here we show that bradykinin blocks this growth-stimulus-induced loss of density-dependent growth arrest by a specific receptor-mediated mechanism. The effects of bradykinin are specific, and are not mimicked by other phosphoinositide-mobilizing agents such as prostaglandin F2 alpha. Northern-blot analysis and receptor-binding studies demonstrate that bradykinin also inhibits the retinoic acid-induced increase in EGF receptor levels in these cells. These studies provide additional evidence that EGF receptor levels modulate EGF-induced expression of the transformed phenotype in these cells.

scholarly journals Asbestos-induced phosphorylation of epidermal growth factor receptor is linked to c-fos and apoptosis

1999 ◽  
Vol 277 (4) ◽  
pp. L684-L693 ◽  
Author(s):  
Christine L. Zanella ◽  
Cynthia R. Timblin ◽  
Andrew Cummins ◽  
Michael Jung ◽  
Jonathan Goldberg ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Growth Factor Receptor ◽  
Direct Interaction ◽  
Mrna Levels ◽  
Binding Studies ◽  
Therapeutic Implications ◽  
Asbestos Fibers ◽  
Epidermal Growth

We examined the mechanisms of interaction of crocidolite asbestos fibers with the epidermal growth factor (EGF) receptor (EGFR) and the role of the EGFR-extracellular signal-regulated kinase (ERK) signaling pathway in early-response protooncogene (c- fos/c- jun) expression and apoptosis induced by asbestos in rat pleural mesothelial (RPM) cells. Asbestos fibers, but not the nonfibrous analog riebeckite, abolished binding of EGF to the EGFR. This was not due to a direct interaction of fibers with ligand, inasmuch as binding studies using fibers and EGF in the absence of membranes showed that EGF did not adsorb to the surface of asbestos fibers. Exposure of RPM cells to asbestos caused a greater than twofold increase in steady-state message and protein levels of EGFR ( P < 0.05). The tyrphostin AG-1478, which inhibits the tyrosine kinase activity of the EGFR, but not the tyrphostin A-10, which does not affect EGFR activity, significantly ameliorated asbestos-induced increases in mRNA levels of c- fos but not of c- jun. Pretreatment of RPM cells with AG-1478 significantly reduced apoptosis in cells exposed to asbestos. Our findings suggest that asbestos-induced binding to EGFR initiates signaling pathways responsible for increased expression of the protooncogene c- fos and the development of apoptosis. The ability to block asbestos-induced elevations in c- fos mRNA levels and apoptosis by small-molecule inhibitors of EGFR phosphorylation may have therapeutic implications in asbestos-related diseases.

scholarly journals Transforming growth factor-alpha (TGF-alpha) in human bone marrow: demonstration of TGF-alpha in erythroblasts and eosinophilic precursor cells and of epidermal growth factor receptors in blastlike cells of myelomonocytic origin

Blood ◽  
1995 ◽  
Vol 85 (9) ◽  
pp. 2385-2392 ◽  
Author(s):  
TM Walz ◽  
C Malm ◽  
BK Nishikawa ◽  
A Wasteson
Keyword(s):  
Monoclonal Antibody ◽  
Bone Marrow ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Precursor Cells ◽  
Transforming Growth Factor Alpha ◽  
Epidermal Growth ◽  
Factor Alpha

The expression of transforming growth factor-alpha (TGF-alpha) in human differentiating leukemic cell lines and in circulating human eosinophils prompted the search for an analogous function in normal human bone marrow (BM) cells. Immunohistochemistry, using a monoclonal antibody directed to the mature form of the TGF-alpha molecule, showed TGF-alpha on the erythroblasts of normal donors. This novel property of erythroid cells was found on cells at all stages of maturation, most clearly on nucleated forms but to some extent also on erythrocytes within the BM. The presence of membrane-bound TGF-alpha on erythroblasts was confirmed by immunomagnetic cell sorting with polyclonal TGF-alpha antibodies; the recovered cells consisted almost entirely of erythroblasts. Using another monoclonal antibody directed to TGF-alpha, immunohistochemistry showed a different pattern of positive cells including eosinophilic precursor cells, in accordance with earlier findings in blood eosinophils. In addition, the TGF-alpha immunoreactivity was shown in promyelocytes and neutrophilic myelocytes. The presence of epidermal growth factor (EGF) receptor mRNA in BM cells was demonstrated by reverse transcription polymerase chain reaction, whereas EGF receptor-carrying cells were recognized by immunohistochemistry, using polyclonal antibodies directed to the cytoplasmic part of the EGF receptor. The EGF receptor-positive cell constituted about 3% of the nucleated BM cell population. It was classified as a blastlike cell of myelomonocytic origin by morphologic criteria and CD68 positivity. Our results may indicate a novel function of TGF-alpha in erythrocytic differentiation.

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