Overexpression of regucalcin suppresses cell death in cloned rat hepatoma H4-II-E cells induced by tumor necrosis factor-alpha or thapsigargin.
The role of regucalcin, which is a regulatory protein in intracellular signaling pathway, in the regulation of cell death was investigated by using the cloned rat hepatoma H4-II-E cells overexpressing regucalcin. The hepatoma cells (wild-type) and stable regucalcin (RC)/pCXN2 transfectants were cultured for 72 h in medium containing 10% fetal bovine serum (FBS) to obtain subconfluent monolayers. The proliferation of the cells was significantly suppressed in transfectants cultured for 72 h, as shown previously (Tsurusaki and Yamaguchi [2003]: J Cell Biochem 90:619-626). After culture for 72 h, cells were further cultured for 24-72 h in medium without FBS containing either vehicle, tumor necrosis factor-alpha (TNF-alpha; 0.1, 1, or 10 ng/ml) or thapsigargin (10(-7)-10(-5) M). The number of wild-type cells was significantly decreased by culture for 42 or 72 h in the presence of TNF-alpha (0.1, 1, or 10 ng/ml) or thapsigargin (10(-7)-10(-5) M). The effect of TNF-alpha (0.1 or 1 ng/ml) or thapsigargin (10(-7) or 10(-6) M) in decreasing the number of hepatoma cells was significantly prevented in transfectants overexpressing regucalcin. The presence of TNF-alpha (10 ng/ml) or thapsigargin (10(-5) M) caused a significant decrease in cell number of transfectants. Ca(2+)/calmodulin-dependent nitric oxide (NO) synthase activity in wild-type cells was significantly increased by culture with TNF-alpha (10 ng/ml) for 48 or 72 h. This increase was significantly prevented in transfectants. Culture with thapsigargin (10(-5) M) caused a significant increase in Ca(2+)/calmodulin-dependent NO synthase activity in wild-type cells or transfectants. TNF-alpha-induced decrease in the number of wild-type cells was significantly prevented by culture with N omega-nitro-L-arginine (10(-4) M), an inhibitor of caspase. Agarose gel electrophoresis showed the presence of low-molecular-weight deoxyribonucleic acid (DNA) fragments of adherent wild-type cells cultured with thapsigargin (10(-6) M), and this DNA fragmentation was not suppressed by culture with caspase inhibitor. Thapsigargin-induced DNA fragmentation was significantly suppressed in transfectants cultured with or without caspase inhibitor. This study demonstrates that overexpression of regucalcin has a suppressive effect on cell death induced by TNF-alpha or thapsigargin.
Izumi
Takako
T
Laboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan.
Yamaguchi
Masayoshi
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D047908:Intracellular Signaling Peptides and Proteins; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D051381:Rats; D015238:Sulfotransferases; D019284:Thapsigargin / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002135:Calcium-Binding Proteins; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D014409:Tumor Necrosis Factor-alpha; D019284:Thapsigargin; D019001:Nitric Oxide Synthase; D015238:Sulfotransferases; C028152:alcohol sulfotransferase; D002265:Carboxylic Ester Hydrolases; C513325:Rgn protein, rat; D020169:Caspases