Partial rescue of ethanol-induced neuronal apoptosis by growth factor activation of phosphoinositol-3-kinase.
BACKGROUND
Ethanol inhibition of insulin signaling pathways may contribute to impaired central nervous system (CNS) development in the fetal alcohol syndrome and brain atrophy associated with alcoholic neurodegeneration. Previous studies demonstrated ethanol inhibition of insulin-stimulated growth in PNET2 CNS-derived proliferative (immature) neuronal cells. We now provide evidence that the growth-inhibitory effect of ethanol in insulin-stimulated PNET2 cells is partly due to apoptosis.


METHODS
Control and ethanol-treated PNET2 cells were stimulated with insulin and analyzed for viability, apoptosis, activation of pro-apoptosis and survival gene expression and signaling pathways, and evidence of caspase activation.


RESULTS
Ethanol-treated PNET2 neuronal cells exhibited increased apoptosis mediated by increased levels of p53 and phospho-amino-terminal c-jun kinase (phospho-JNK), and reduced levels of Bcl-2, phosphoinositol 3-kinase (PI3 K), and intact (approximately 116 kD) poly (ADP ribose) polymerase (PARP), a deoxyribonucleic acid repair enzyme and important substrate for caspase 3. Partial rescue from ethanol-induced neuronal cell death was effected by culturing the cells in medium that contained 2% fetal calf serum instead of insulin, or insulin plus either insulin-like growth factor type 1 or nerve growth factor. The resulting enhanced viability was associated with reduced levels of p53 and phospho-JNK and increased levels of PI3 K and intact PARP.


CONCLUSIONS
The findings suggest that ethanol-induced apoptosis of insulin-stimulated neuronal cells can be reduced by activating PI3 K and inhibiting pro-apoptosis gene expression and intracellular signaling through non-insulin-dependent pathways.
de la Monte
S M
SM
MGH East Cancer Center and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, USA. delamonte@hotmail.com
Ganju
N
N
Banerjee
K
K
Brown
N V
NV
Luong
T
T
Wands
J R
JR
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002460:Cell Line / Q000187:drug effects; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D004789:Enzyme Activation; D000431:Ethanol / Q000494:pharmacology*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology* / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects* / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000187:drug effects / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000187:drug effects / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000187:drug effects / Q000378:metabolism
D002492:Central Nervous System Depressants; D007004:Hypoglycemic Agents; D007328:Insulin; D018809:Proliferating Cell Nuclear Antigen; D019253:Proto-Oncogene Proteins c-bcl-2; D016755:Proto-Oncogene Proteins c-jun; D016159:Tumor Suppressor Protein p53; D000431:Ethanol; D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases