Sera from cancer patients contain two oscillating ECTO-NOX activities with different period lengths.
ECTO-NOX protein's are cell surface-associated and growth-related hydroquinone oxidases with both protein disulfide-thiol interchange activity and the capacity to oxidize NAD(P)H. The activities of these ECTO-NOX proteins are not steady state but fluctuate to create a repeating pattern of oscillations. Two forms of ECTO-NOX activities have been distinguished. The constitutive ECTO-NOX (CNOX), is hormone responsive and refractory to quinone-site inhibitors. A tumor-associated NOX (tNOX) is unregulated, refractory to hormones and growth factors and responds to quinone-site inhibitors. CNOX proteins are widely distributed and exhibit oscillations in enzymatic activity with a period length of 24 min. tNOX proteins are cancer specific and exhibit oscillations with a period length of about 22 min. Our findings now demonstrate the presence of the novel oscillating tNOX activity in sera of patients with cancer whereas the constitutive NOX of non-cancer cells is present in sera of both cancer patients and healthy volunteers. We conclude that ECTO-NOX proteins in sera exhibit oscillatory characteristics similar to those of ECTO-NOX forms of the cell surface.
Wang
Sui
S
Department of Foods and Nutrition, Purdue University, West Lafayette, IN, USA.
Morré
Dorothy M
DM
Morré
D James
DJ
D002211:Capsaicin / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000097:blood; D007700:Kinetics; D008565:Membrane Proteins / Q000097:blood*; D009097:Multienzyme Complexes / Q000097:blood*; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000097:blood*; D009369:Neoplasms / Q000097:blood* / Q000201:enzymology*; D013997:Time Factors
D007527:Isoenzymes; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D009243:NAD; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D002211:Capsaicin