Anti-apoptotic effects of arachidonic acid and prostaglandin E2 in pancreatic beta-cells.
OBJECTIVE
The polyunsaturated fatty acid arachidonic acid (AA) has been implicated in beta-cell defence mechanisms and prostaglandin (PG) products of cyclooxygenase (COX) 2 action confer resistance to alloxan-induced apoptosis in insulin-secreting RIN cells. We have now investigated the anti-apoptotic effects of AA and its metabolite, PGE(2), in the MIN6 mouse insulin-secreting beta-cell line and mouse islets.


METHODS
Apoptosis was determined in MIN6 beta-cell and mouse islet extracts by measurement of capase-3 activity, and COX2 mRNA levels were quantified by real-time RT-PCR.


RESULTS
Exposure of MIN6 cells to AA (3.1-12.5 microM) caused concentration-dependent reductions in apoptosis, and similar results were obtained when endogenous AA levels were elevated in cytosolic phospholipase A(2)-overexpressing MIN6 cells. 25mM glucose caused both a significant up-regulation of MIN6 cell COX2 mRNA levels and a decrease in apoptosis. Inhibition of MIN6 cell COX2 activity with a selective inhibitor, NS-398 (10-100 microM), increased apoptosis and exogenous PGE(2) (0.2-5 microM) reduced NS-398-induced apoptosis in a concentration-dependent manner. The protective effects of AA and PGE(2) were also observed in primary mouse islets.


CONCLUSIONS
These data show that AA and its COX2-generated metabolite, PGE(2), can protect beta-cells from apoptosis.
Papadimitriou
Alexandros
A
Beta Cell Development and Function Group, School of Biomedical and Health Sciences, King's College London, London, UK.
King
Aileen J F
AJ
Jones
Peter M
PM
Persaud
Shanta J
SJ
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001092:Arachidonate 12-Lipoxygenase / Q000235:genetics / Q000378:metabolism; D001094:Arachidonate 5-Lipoxygenase / Q000235:genetics / Q000378:metabolism; D016718:Arachidonic Acid / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D016859:Lipoxygenase Inhibitors; D051379:Mice; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics
D052246:Cyclooxygenase 2 Inhibitors; D016859:Lipoxygenase Inhibitors; D012333:RNA, Messenger; D016718:Arachidonic Acid; D001092:Arachidonate 12-Lipoxygenase; D001094:Arachidonate 5-Lipoxygenase; D051546:Cyclooxygenase 2; D010741:Phospholipases A; D053148:Caspase 3; D005947:Glucose; D015232:Dinoprostone