Effect of active hexose correlated compound on the production of nitric oxide in hepatocytes.
BACKGROUND
Active hexose correlated compound (AHCC) is a "complex compound" containing polysaccharides. AHCC has been reported to improve the prognosis of postoperative hepatocellular carcinoma patients. However, the molecular mechanism of this improvement is not fully understood. In the diseased liver, nitric oxide (NO) generated by inducible nitric oxide synthase (iNOS) is considered to be a causal factor for various hepatopathies. In this study, the possibility of AHCC regulation of NO production by iNOS was pursued as a potential liver-protecting mechanism.


METHODS
Primary cultured rat hepatocytes were treated with interleukin-1beta (IL-1beta) in the presence or absence of AHCC. NO production, iNOS induction, and iNOS signal were analyzed.


RESULTS
IL-1beta stimulated iNOS induction through the activation of nuclear factor kappaB (NFkappaB), leading to NO production. The addition of AHCC inhibited NO production, showing >80% inhibition at 8 mg/mL. AHCC also decreased the levels of iNOS protein and mRNA. However, AHCC influenced neither the degradation of inhibitory protein kappaB (IkappaB) nor the activation of NFkappaB stimulated by IL-1beta. Transfection experiments with an iNOS promoter-luciferase construct (iNOS-Luc) revealed that AHCC had no effect on the transactivation activity of the iNOS promoter. By contrast, AHCC inhibited the activity of iNOS-Luc containing a 3'untranslated region (UTR) with adenosine and uridine (AU)-rich elements, which shows the stabilizing activity of iNOS mRNA.


CONCLUSIONS
Results indicated that AHCC inhibits the induction of iNOS at the level of transcription, causing a decrease in NO production in hepatocytes. AHCC seems to decrease the levels of iNOS mRNA by reducing mRNA stabilization rather than inhibiting its synthesis.
Matsui
Kosuke
K
Department of Surgery, Kansai Medical University, Moriguchi, Osaka, Japan.
Kawaguchi
Yusai
Y
Ozaki
Takashi
T
Tokuhara
Katsuji
K
Tanaka
Hironori
H
Kaibori
Masaki
M
Matsui
Yoichi
Y
Kamiyama
Yasuo
Y
Wakame
Koji
K
Miura
Takehito
T
Nishizawa
Mikio
M
Okumura
Tadayoshi
T
D020413:3' Untranslated Regions; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D022781:Hepatocytes / Q000201:enzymology / Q000378:metabolism*; D006601:Hexoses / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000494:pharmacology; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015533:Transcriptional Activation
D020413:3' Untranslated Regions; D006601:Hexoses; D053583:Interleukin-1beta; D016328:NF-kappa B; D012333:RNA, Messenger; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II