Low-protein diet promotes sodium chloride-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in Wistar rats.
Sodium chloride (NaCl) initiates and promotes experimental carcinogenesis in rats. We recently found that a high-protein diet attenuates NaCl-enhanced gastric carcinogenesis in Wistar rats. To investigate the effect of a purified low-protein diet on NaCl-enhanced gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Wistar rats, rats were fed a purified diet with an equalized caloric content containing 1% or 2% NaCl and 25% casein (normal-protein diet) or 10% casein (low-protein diet) after oral treatment with MNNG for 25 weeks. In week 52, neither 1% nor 2% NaCl had a significant effect on gastric carcinogenesis in rats fed a normal-protein diet. However, oral administration of 2%, but not 1%, NaCl significantly increased the incidence of gastric cancers in rats fed a low-protein diet. Oral administration of 2% NaCl also significantly increased the bromodeoxyuridine (BrdU)-labeling index and the ornithine decarboxylase (ODC) activity and decreased apoptosis of gastric cancers in rats fed a low-protein diet. However, 2% NaCl had no significant effect on these three parameters in rats fed a normal-protein diet. These findings indicate that a low-protein diet enhances the effect of NaCl in gastric carcinogenesis and that this enhancement may be mediated by increased cell proliferation and reduced apoptosis of gastric cancers.
Iishi
H
H
Department of Gastrointestinal Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Japan. hiroyasu@mbox2.inet-osaka.or.jp
Tatsuta
M
M
Baba
M
M
Hirasawa
R
R
Sakai
N
N
Yano
H
H
Uehara
H
H
Nakaizumi
A
A
D000230:Adenocarcinoma / Q000139:chemically induced / Q000201:enzymology / Q000209:etiology* / Q000473:pathology; D000818:Animals; D017209:Apoptosis; D015197:Carcinogenicity Tests; D018753:Diet, Protein-Restricted / Q000009:adverse effects*; D007150:Immunohistochemistry; D008297:Male; D008769:Methylnitronitrosoguanidine; D008940:Mitotic Index; D009955:Ornithine Decarboxylase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride / Q000633:toxicity*; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000201:enzymology / Q000209:etiology* / Q000473:pathology
D008769:Methylnitronitrosoguanidine; D012965:Sodium Chloride; D009955:Ornithine Decarboxylase