Journal Article

Nitric oxide synthase activity and expression in human colorectal cancer

Shabbir Moochhala, Vikram J.S. Chhatwal, Steven T.F. Chan, Sing Shang Ngoi, Yee Wen Chia and Abu Rauff

in Carcinogenesis

Volume 17, issue 5, pages 1171-1174
Published in print May 1996 | ISSN: 0143-3334
e-ISSN: 1460-2180 | DOI:
Nitric oxide synthase activity and expression in human colorectal cancer

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The present study investigated the activity and cellular localization of individual isoenzymes of nitric oxide synthase (NOS) using immunohistochemistry and the [3H]citrulline assay in normal colorectal epithelia and neoplastic tissue. Intracellular localization of isoenzymes of NOS was detectable by immunohistochemistry in normal epithelial cells. Colorectal adenocarcinomas had a marked eduction of both inducible NOS (iNOS) and constitutive NOS (cNOS)expression. Expression of iNOS was completely absent in tumour cells (p& 0.0001), while cNOS was reduced in 66% and absent in 34% of tumours studied when ompared with controls (p& 0.0001). NOS activity using the [3H]citrulline assay was detectable in normal epithelium and was found to be reduced in tumours (p& 0.001). In addition, colonic adenomas had reduced iNOS but not cNOS expression when compared with controls (p& 0.003 and p= 039 respectively). We conclude that NOS is present and active within the epithelium of the normal colon, with localization of the individual isoenzymes. Furthermore, there was loss of activity and expression of individual isoenzymes in colonic neoplasms.

Journal Article.  0 words. 

Subjects: Clinical Cytogenetics and Molecular Genetics

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