Ethanol inhibits insulin-like growth factor-1-mediated signalling and proliferation of C6 rat glioblastoma cells.
BACKGROUND
Alcohol consumption during pregnancy often results in disorders of fetal development (Fetal Alcohol Syndrome). The brain appears to be particularly vulnerable, and alcohol abuse during pregnancy is probably the most common cause of acquired mental retardation. We therefore studied the in vitro effects of ethanol on insulin-like growth factor-1 (IGF-1)-mediated proliferation of rat C6 glioblastoma cells.


METHODS
The proliferation of C6 rat glioblastoma cells was measured in serum-free medium supplemented with specific growth factors in the presence or absence of ethanol. The effect of ethanol on IGF-1 receptor and insulin receptor substrate 1 (IRS-1) tyrosine phosphorylation was determined by immunoprecipitation and Western blotting, as was the phosphatidylinositol 3-kinase content within IRS-1 immunoprecipitates.


RESULTS
C6 cells grew slowly in serum-free medium and proliferated in response to IGF-1. Ethanol, at physiologically tolerated concentrations, markedly inhibited the growth of C6 cells in response to IGF-1, but had no effect on the proliferative rate in the presence of platelet-derived growth factor or 1% fetal bovine serum. Inhibition of cell proliferation was evident when ethanol was only present during a 1-hour pulse of IGF-1. Cell growth in the presence of IGF-2 was also prevented by ethanol. The inhibition of IGF-1-mediated cell proliferation was accompanied by abrogation of IGF-1 receptor tyrosine autophosphorylation. Ethanol also interfered with the IGF-1-induced tyrosine phosphorylation of IRS-1, and the association of phosphatidylinositol-3 kinase with IRS-1.


CONCLUSIONS
The data indicate that physiologically relevant concentrations of ethanol inhibit the responses of glial cells to IGF-1, including IGF-1 receptor autophosphorylation, IRS-1 and phosphatidylinositol-3 kinase activation, and cell growth.
Resnicoff
M
M
Department of Pathology and Cell Biology, Jefferson Medical College, Philadelphia, Pennsylvania.
Rubini
M
M
Baserga
R
R
Rubin
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002455:Cell Division / Q000187:drug effects; D017931:DNA Primers / Q000737:chemistry; D000431:Ethanol / Q000494:pharmacology*; D005909:Glioblastoma / Q000473:pathology; D066298:In Vitro Techniques; D055504:Insulin Receptor Substrate Proteins; D007334:Insulin-Like Growth Factor I / Q000037:antagonists & inhibitors*; D008969:Molecular Sequence Data; D009457:Neuroglia / Q000166:cytology*; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D010750:Phosphoproteins / Q000378:metabolism; D019000:Phosphotyrosine; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D017931:DNA Primers; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D010455:Peptides; D010750:Phosphoproteins; D019000:Phosphotyrosine; D000431:Ethanol; D014443:Tyrosine; D007334:Insulin-Like Growth Factor I; D020794:Receptor Protein-Tyrosine Kinases; D017526:Receptor, IGF Type 1