|Budget Amount *help
¥3,600,000 (Direct Cost : ¥3,600,000)
Fiscal Year 2003 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 2002 : ¥2,600,000 (Direct Cost : ¥2,600,000)
Cancer cell specific growth inhibition by antioxidants and NAD(P)H oxidase inhibitors.
First we investigated the growth-inhibitory effects of five sulfur-containing antioxidants on oncogene-transformed rat fibroblast cells, 3Y1-ras and its counterpart, 3Y1 cells. All five antioxidants tested showed 3Y1-ras selective growth inhibition but those antioxidants didn't show cytotoxicity at 1 mM. In contrast to antioxidants, NAD(P)H oxidase inhibitors showed growth inhibition and induced cell death in 3Y1-ras cells at μM level.
Induction of apoptosis by lipoic acid in HL-60 cells.
In another approach to investigate the effects of antioxidants on cellular functions, we tested the effect of lipoic acid(LA), a sulfur containing antioxidant, on human leukemia cell line, HL-60. LA induced apoptosis in HL-60 cells through caspase dependent pathway. However, DNA ladder formation, a typical marker of apoptosis, was found prior caspase 3 activation, suggesting the involvement of capase independent pathwa
y in LA induced apoptosis. To demonstrate the involvement of caspase independent pathway, we used caspase inhibitor and analyzed various kinds of apoptosis regulating proteins. We found that DNA ladder formation by LA in the presence of caspse inhibitor. In addition, nuclear localization of apoptosis inducing factor(AIF)and inhibition of DNA ladder formation by a Ca^<2+> chelator were observed at the early stage of apoptosis. Thus, we showed that LA induced apoptosis of HL-60 cells through both caspase dependent and independent pathways.
Antioxidant metabolism by sulfation.
In mammals, sulfation is known to be a major pathway for the detoxification of xenobiotics as well as the biotransformation of endogenous compounds such as steroid and thyroid hormones, catecholamines. In these compounds steroids and catecholamines are relevant antioxidants in the body. We explored the sulfation of these antioxidative hormones with respect to substrate specificities, structure-function relationship of sulfotransferase and effect of divalent metal cations on the enzyme activity. Less