title: Gastric pit cell hyperplasia and glandular atrophy in carbonic anhydrase IX knockout mice: studies on two strains C57/BL6 and BALB/C.
abstract: Carbonic anhydrase (CA) isoenzyme IX is a hypoxia-inducible enzyme, which is expressed in the human and rodent gastrointestinal tract and overexpressed in several different tumors. Functionally, it has probably an effect on proliferation and differentiation of gastrointestinal epithelial cells. It may also participate in gastric morphogenesis, since a recent study has shown gastric pit cell hyperplasia and glandular atrophy in CA IX-knockout mice. However, it is not known whether CA IX produces morphological changes in the gastric mucosa, which can turn into a dysplasia or malignancy in the presence of some carcinogenic factors. High-salt diet is considered such a factor which has been shown to modulate Helicobacter pylori-associated carcinogenesis. We produced two strains of CA IX-knockout mice, C57/BL6 and BALB/c, and the mice ate either standard or high-salt feed for 20 weeks. Stomach samples were collected from 40 Car 9(-/-) knockout mice and 37 wildtype littermates, and the tissue sections were examined for histology. CA IX-deficiency caused gastric pit cell hyperplasia and glandular atrophy in both BALB/c and C57/BL6 strains. Excess dietary salt had no significant effect on the severity of pit cell hyperplasia. No dysplasia was found in any of the groups. In C57/BL6 mice, CA IX-deficiency was associated with gastric submucosal inflammation. The results indicate that CA IX-deficiency provides a useful model to study the mechanisms of gastric morphogenesis and epithelial integrity. Further studies are needed to see whether CA IX has a role in the regulation of immune response. The findings suggest that although CA IX-deficiency is not a tumor-promoting factor per se, it induces glandular atrophy in the body mucosa, a lesion which is considered to be a preneoplastic alteration in the stomach.
authors.affiliation: Department of Clinical Chemistry, University of Oulu, P.O. Box 5000, FIN-90014 Oulu, Finland. mari.leppilampi@oulu.fi
authors.forename: Mari
authors.initials: M
authors.lastname: Leppilampi
authors.forename: Tuomo J
authors.initials: TJ
authors.lastname: Karttunen
authors.forename: Jyrki
authors.initials: J
authors.lastname: Kivelä
authors.forename: Marta Ortova
authors.initials: MO
authors.lastname: Gut
authors.forename: Silvia
authors.initials: S
authors.lastname: Pastoreková
authors.forename: Jaromir
authors.initials: J
authors.lastname: Pastorek
authors.forename: Seppo
authors.initials: S
authors.lastname: Parkkila
mesh_terms: D000818:Animals; D001284:Atrophy; D001483:Base Sequence; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases / Q000172:deficiency* / Q000235:genetics; D004247:DNA / Q000235:genetics; D004847:Epithelial Cells / Q000473:pathology; D005753:Gastric Mucosa / Q000201:enzymology* / Q000473:pathology*; D006801:Humans; D006965:Hyperplasia; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011230:Precancerous Conditions / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D012982:Sodium, Dietary / Q000008:administration & dosage; D013045:Species Specificity; D013274:Stomach Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology
chemical_list: D012982:Sodium, Dietary; D004247:DNA; D000071231:Carbonic Anhydrase IX; D002256:Carbonic Anhydrases; C492796:Car9 protein, mouse