Colorectal carcinoma development in inducible nitric oxide synthase-deficient mice with dextran sulfate sodium-induced ulcerative colitis

Darren N. Seril, Jie Liao, Guang Yu Yang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

The overproduction of reactive oxygen and nitrogen species (RONS) may play an important role in ulcerative colitis (UC)-associated carcinogenesis. In order to study the role of nitric oxide (NO) in UC-associated colorectal carcinogenesis, the development of colorectal carcinoma was studied using the DSS-induced and iron-enhanced model of chronic UC in inducible nitric oxide synthase (iNOS)-deficient mice. Female wild-type C57BL/6 (iNOS+/+) and iNOS-/- mice were administered 1% DSS (w/v) through the drinking fluid for 15 DSS cycles and fed twofold iron-enriched diet. Colorectal inflammation and mucosal ulceration of moderate severity were observed in both iNOS+/+ and iNOS-/- mice. Similar tumor incidence and multiplicity in the colon were observed that 15 out of 23 (65.2%) iNOS +/+ mice developed colorectal tumors with a tumor multiplicity of 1.47 ± 0.17 (mean ± SE) after 15 DSS cycles, and 13 out of 19 (68.4%) iNOS-/- mice developed colorectal tumors with a tumor multiplicity of 2.08 ± 0.21. Histopathologically, the tumors were confirmed to be well-differentiated adenocarcinomas. Nitrotyrosine, an indicator of peroxynitrite-caused protein modification, was detectable by immunohistochemistry in inflammatory cells and epithelial cells of the colon in iNOS+/+ and iNOS-/- mice, and no difference in staining intensity was observed between the two groups. Immunostaining for endothelial NOS (eNOS) was observed in lamina propria macrophages and colonic blood vessels, and eNOS protein levels were increased in the inflamed colon. These results show that there is no difference in UC-associated cancer development in iNOS+/+ and iNOS-/- mice, and suggest that in the absence of iNOS, other factors, such as eNOS, may play a role in nitrosative stress and UC-associated carcinogenesis in this model system.

Original languageEnglish (US)
Pages (from-to)341-353
Number of pages13
JournalMolecular Carcinogenesis
Volume46
Issue number5
DOIs
StatePublished - May 2007

Keywords

  • Carcinogenesis
  • Nitrotyrosine
  • Ulcerative colitis
  • eNOS
  • iNOS

ASJC Scopus subject areas

  • Molecular Biology
  • Cancer Research

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