Downregulation of cyclooxygenase-1 is involved in gastric mucosal apoptosis via death signaling in portal hypertensive rats.
Portal hypertension (PHT) gastropathy is a frequent complication of liver cirrhosis and one of the leading causes of death from cirrhosis. Apoptosis is widely considered to be an active energy-dependent mode of cell death and a distinct entity from necrotic cell death. It is unclear whether gastric mucosal apoptosis is involved in PHT gastropathy. Prostaglandins (PGs) produced through cyclooxygenase (COX) are thought to play a key role in protection of the gastrointestinal mucosa from injury and apoptosis. However, the role of COX in PHT gastropathy is still not clearly understood. The aims of this study were to investigate whether (1) gastric mucosal apoptosis is involved in PHT gastropathy and (2) downregulation of COX contributes to this apoptosis. In this study, we show that gastric mucosal apoptosis was remarkably increased while mucosal proliferation was inhibited in PHT rats. Gastric mucosal COX-1 was significantly suppressed at both the mRNA and protein levels, and PGE(2) was reduced in PHT rats. Further, PGE(2) treatment suppressed gastric mucosal apoptosis in PHT rats. However, gastric mucosal COX-2 levels did not differ between sham-operated rats and PHT rats. Gastric mucosal levels of tumor necrosis factor-alpha (TNF-alpha) and Fas ligand, but not TNF-related apoptosis-inducing ligand, were increased, and activated caspase-8 and caspase-3 levels were upregulated in PHT rats. The release of cytochrome c from the mitochondria to the cytosol was not observed in PHT rats. Our data indicate that downregulation of COX-1 is involved in gastric mucosal apoptosis via death signaling-mediated type-I cell death in PHT rats.
Wu
Bin
B
Department of Gastroenterology, The Third Affiliated Hospital of Sun Yat-Sen University, 600 Tianhe Road, Guangzhou 510630, China. binwu001@hotmail.com
Zeng
Lixian
L
Lin
Ying
Y
Wen
Zhuofu
Z
Chen
Guihua
G
Iwakiri
Ryuichi
R
Fujimoto
Kazuma
K
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D049109:Cell Proliferation; D051545:Cyclooxygenase 1 / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D015536:Down-Regulation; D053222:Fas Ligand Protein / Q000378:metabolism; D005753:Gastric Mucosa / Q000201:enzymology* / Q000473:pathology*; D006975:Hypertension, Portal / Q000201:enzymology* / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000097:blood / Q000473:pathology / Q000628:therapy; D051381:Rats; D015398:Signal Transduction / Q000502:physiology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D053222:Fas Ligand Protein; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha; D045304:Cytochromes c; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C505410:Casp3 protein, rat; C505528:Casp8 protein, rat; D053148:Caspase 3; D053181:Caspase 8; D015232:Dinoprostone