Differential thioredoxin reductase activity from human normal hepatic and hepatoma cell lines.
Thioredoxin reductase (TrxR), a component of the thioredoxin system, including thioredoxin (Trx) and NADPH, catalyzes the transfer of electrons from NADPH to Trx, acts as a reductant of disulfide-containing proteins and participates in the defense system against oxidative stresses. In this study, the regulation pattern of TrxR in the presence of various stressful reagents was compared between Chang (human normal hepatic cell) and HepG2 (human hepatoma cell) cell lines. Aluminum chloride (0.5 mM) and zinc chloride (0.5 mM) enhanced the TrxR activity in the Chang cell line to a higher degree than in the HepG2 cell line, but cupric chloride (0.2 mM) and cadmium chloride (0.1 mM) enhanced the TrxR activity in the HepG2 cell line to a greater degree. The TrxR activities in both Chang and HepG2 cell lines were similarly induced by treatment with sodium selenite (0.02 mM) and menadione (0.5 and 1.0 mM). Lipopolysaccharide (2 micro g/m1) increased the TrxR activity upto 4.02- and 2.2-fold in the Chang and HepG2 cell lines, respectively, in time-dependent manners. Hydrogen peroxide (5 mM) markedly enhanced the TrxR activity in the HepG2 cell line, but not in the Chang cell line. NO-generating sodium nitroprusside (3.0 and 6.0 mM) induced TrxR activities in both human liver cell lines. The TrxR activity was also induced in human liver cells under limited growth conditions by serum deprivation. These results imply that the TrxR activities in normal hepatic and hepatoma cell lines are subject to different regulatory responses to various stresses.
Jung
Haeng-Im
HI
Division of Life Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Korea.
Lim
Hye-Won
HW
Kim
Byung-Chul
BC
Park
Eun-Hee
EH
Lim
Chang-Jin
CJ
D045744:Cell Line, Tumor; D022781:Hepatocytes / Q000166:cytology / Q000201:enzymology*; D006801:Humans; D018384:Oxidative Stress / Q000502:physiology*; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism*
D013880:Thioredoxin-Disulfide Reductase