title: Superoxide generation from Kupffer cells contributes to hepatocarcinogenesis: studies on NADPH oxidase knockout mice.
abstract: We hypothesized that superoxide from Kupffer cells (KC) contributes to hepatocarcinogenesis. p47phox(-/-) mice, deficient in phagocyte NADPH oxidase and superoxide generation, received a single dose of the hepatocarcinogen diethylnitrosamine (DEN). The following hepatic effects were observed at time points between 30 min and 35 days. Liver damage after DEN was manifested by loss of body and liver mass and of liver DNA and by an increase in apoptosis, necrosis and signs of inflammation. These effects were massive in wild-type (wt) male mice, but only very mild in p47phox(-/-) mice. Regenerative DNA synthesis subsequent to liver damage was high in wt male mice, but weak in p47phox(-/-) mice. In females the apparent protection by p47phox(-/-) was less pronounced than in males. Therefore, further experiments were performed with males. In KC isolated from wt mice superoxide production was enhanced by DEN pretreatment in vivo. Also, in vitro addition of DEN to KC cultures induced superoxide release, similarly to lipopolysaccharide, a standard KC activator. Thus, DEN directly activates wt KC to produce superoxide. KC from p47phox(-/-) mice did not release superoxide. TNFalpha production by isolated KC was transiently depressed 0.5 h after DEN treatment in vivo, but recovered rapidly. In blood serum TNFalpha levels of wt mice were elevated for the initial 6 h. TNFalpha in KC cultures and in serum of p47phox(-/-) mice was reduced. DEN in vivo induced DNA damage ('comets') in hepatocytes. This damage was extensive in wt mice but much less in p47phox(-/-) mice. These studies suggest two conclusions: (i) superoxide generation by phagocytes during liver damage and inflammation aggravates genotoxic and cytotoxic effects in hepatocytes and may thus contribute to tumor initiation and promotion; (ii) DEN has a direct stimulatory effect on KC to release superoxide and TNFalpha.
authors.affiliation: Institut für Krebsforschung, Universität Wien, Borschkegasse 8a, A-1090 Wien, Austria.
authors.forename: Olga
authors.initials: O
authors.lastname: Teufelhofer
authors.forename: Wolfram
authors.initials: W
authors.lastname: Parzefall
authors.forename: Eveline
authors.initials: E
authors.lastname: Kainzbauer
authors.forename: Franziska
authors.initials: F
authors.lastname: Ferk
authors.forename: Constanze
authors.initials: C
authors.lastname: Freiler
authors.forename: Siegfried
authors.initials: S
authors.lastname: Knasmüller
authors.forename: Leonilla
authors.initials: L
authors.lastname: Elbling
authors.forename: Ronald
authors.initials: R
authors.lastname: Thurman
authors.forename: Rolf
authors.initials: R
authors.lastname: Schulte-Hermann
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000633:toxicity; D002478:Cells, Cultured; D004052:Diethylnitrosamine / Q000633:toxicity; D005260:Female; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D007728:Kupffer Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008113:Liver Neoplasms / Q000139:chemically induced / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D010586:Phagocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D013481:Superoxides / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D002273:Carcinogens; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D004052:Diethylnitrosamine; D019255:NADPH Oxidases