Antizyme delays the restoration by spermine of growth of polyamine-deficient cells through its negative regulation of polyamine transport.
Effects of antizyme on polyamine transport and spermine restoration of the growth of polyamine-deficient cells were examined by using mouse FM3A cells transfected with pMAMneoZ1 possessing rat antizyme cDNA under the control of glucocorticoid-inducible promoter. Treatments of the transfected cells with alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase (ODC), and dexamethasone, an inducer of antizyme, both caused a decrease in ODC activity and polyamine contents and inhibition of cell growth. However, spermine uptake of the transfected cells was repressed by dexamethasone but stimulated by DFMO. The decrease in the rate of spermine uptake in dexamethasone-treated cells was attributed to an increase in Km value and a slight decrease in Vmax value. Accordingly, restoration of cell growth by spermine was less effective in dexamethasone-treated cells than DFMO-treated cells. These results clearly indicate that antizyme has dual functions: one for ODC degradation and the other for negative regulation of polyamine transport.
He
Y
Y
Faculty of Pharmaceutical Sciences, Chiba University, Japan.
Suzuki
T
T
Kashiwagi
K
K
Igarashi
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K
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology; D000518:Eflornithine / Q000494:pharmacology*; D007700:Kinetics; D008325:Mammary Neoplasms, Experimental; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D051379:Mice; D009955:Ornithine Decarboxylase / Q000378:metabolism; D065108:Ornithine Decarboxylase Inhibitors; D010957:Plasmids; D011073:Polyamines / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011506:Proteins; D051381:Rats; D012091:Repetitive Sequences, Nucleic Acid; D013096:Spermine / Q000378:metabolism / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured
D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines; D011506:Proteins; C031017:ornithine decarboxylase antizyme; D013096:Spermine; D003907:Dexamethasone; D009955:Ornithine Decarboxylase; D000518:Eflornithine