Human colon cancer cell lines show a diverse pattern of nitric oxide synthase gene expression and nitric oxide generation

Jenkins, D. C.; Charles, IG; Baylis, S.A.; Lelchuk, Rosalia; Radomski, M. W.; Moncada, Salvador

doi:10.1038/bjc.1994.409

Cited by 125 publications

(82 citation statements)

References 16 publications

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“…29) Positive staining for iNOS was clearly observed in the carcinoma epithelial cells, 37) predominantly at the luminal surfaces of carcinoma cells forming glandular patterns, but not in moderately differentiated adenocarcinoma cells not forming clear glandular patterns, implying the involvement of factors other than alteration of β-catenin alone. Since some colon cancer cell lines are known to express iNOS on cytokine treatment, 38) cytokine receptors and/or subcellular components present in well-differentiated cells might be contributing to the iNOS expression. The results therefore suggest that increased expression of iNOS could be related to the altered localization of β-catenin in the presence of other factors.…”

Section: Inosmentioning

confidence: 99%

Gene mutations and altered gene expression in azoxymethane‐induced colon carcinogenesis in rodents

2004

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Studies of colon carcinogenesis in animal models are very useful to elucidate mechanisms and provide pointers to potential prevention approaches in the human situation. In the rat colon carcinogenesis model induced by azoxymethane (AOM), we have documented frequent mutations of specific genes. K-ras mutations at codon 12 were found to be frequent in hyperplastic aberrant crypt foci (ACF) and large adenocarcinomas. In addition, mutations of the β β β β-catenin gene in its GSK-3β β β β phosphorylation consensus motif could also be identified in many adenomas and adenocarcinomas, and altered cellular localization of β β β β-catenin protein was observed in all of the dysplastic ACF, adenomas and adenocarcinomas examined, indicating that activation of Wnt signaling by accumulation of β β β β-catenin is a major mechanism in the AOM-induced colon carcinogenesis model. Frequent gene mutations of β β β β-catenin and altered cellular localization of the protein are also features of AOM-induced colon tumors in mice. Expression of enzymes associated with inflammation, such as inducible nitric oxide synthase (iNOS) and the inducible type of cyclooxygenase (COX), COX-2, is increased in AOM-induced rat colon carcinogenesis, and overproduction of nitric oxide (NO) and prostaglandins is considered to be involved in colon tumor development. We have demonstrated that increased expression of iNOS is an early and important event occurring in step with β β β β-catenin alteration in rat colon carcinogenesis. Activation of K-ras was also found to be involved in up-regulation of iNOS in the presence of inflammatory stimuli. In addition, expression levels of prostaglandin E 2 (PGE 2 ) receptors may be altered in colon cancers. For example, the EP 1 and EP 2 subtypes have been shown to be up-regulated and EP 3 down-regulated in AOM-induced colon cancers in rats and mice. EP 1 and EP 4 appear to be involved in ACF formation, while alteration in EP 2 and EP 3 is considered to contribute to later steps in colon carcinogenesis. n recent years, colorectal cancer has increasingly become a major cause of cancer mortality in Japan. Therefore, elucidation of the mechanisms of colon carcinogenesis and the search for chemopreventive agents are important and urgent tasks. Screening of colon cancer preventive agents has been carried out using several in vivo animal models, the majority using azoxymethane (AOM), a very potent carcinogen which induces colorectal cancers at high incidence in rats and mice. In relatively short-term experiments, aberrant crypt foci (ACF) induced by treatment with AOM in rats and mice can be used as biomarkers, since the formation and growth of these putative preneoplastic lesions are thought to be useful indices of the effects of carcinogens and agents promoting or preventing carcinogenesis in the colon.1, 2) Recently, other pre-neoplastic lesions such as β-catenin-accumulated crypts and mucin-depleted foci have also been reported as specific biomarkers for colon carcinogenesis. [3][4][5] Compounds which appear to be effec...

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Section: Inosmentioning

confidence: 99%

Gene mutations and altered gene expression in azoxymethane‐induced colon carcinogenesis in rodents

2004

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“…Certain miRNAs are expressed in solid organ cancers and have been shown to correlate with survival (25)(26)(27). The hiNOS gene is expressed in many cancers, and NO has been shown to exert a complex role during inflammation-associated carcinogenesis (28)(29)(30)(31)(32). However, no information exists as to a direct role for miRNA in regulating hiNOS gene expression.…”

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confidence: 99%

miRNA-939 regulates human inducible nitric oxide synthase posttranscriptional gene expression in human hepatocytes

Guo¹,

Shao²,

Zheng

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Human inducible nitric oxide synthase (hiNOS) gene expression is regulated by transcriptional and posttranscriptional mechanisms. The purpose of this study was to determine whether specific microRNA (miRNA) directly regulate hiNOS gene expression. Sequence analysis of the 496-bp hiNOS 3′-untranslated region (3′-UTR) revealed five putative miR-939 binding sites. The hiNOS 3′-UTR conferred significant posttranscriptional blockade of luciferase activity in human A549, HCT8, and HeLa cells. The hiNOS 3′-UTR also exerted basal and cytokine-stimulated posttranscriptional repression in an orientation-dependent manner. Functional studies demonstrated that transfection of miR-939 into primary human hepatocytes (HCs) significantly inhibited cytokine-induced NO synthesis in a dose-dependent manner that was abrogated by a specific miR-939 inhibitor. MiR-939 (but not other miRNAs) abolished cytokine-stimulated hiNOS protein in human HC, but had no effect on hiNOS mRNA levels. Site-directed mutagenesis of miR-939 bindings sites at +99 or +112 bp in the hiNOS 3′-UTR increased reporter gene expression. Furthermore, intact miR-939 binding sites at +99 or +112 positions were required for posttranscriptional suppression by miR-939. Cytokine stimulation directly increased miR-939 levels in human HC. Transfection of miR-939 inhibitor (antisense miR-939) enhanced cytokine-induced hiNOS protein and increased NO synthesis in vitro in human HC. Finally, cytokine or LPS injection in vivo in mice increased hepatic miR-939 levels. Taken together, these data identify that miR-939 directly regulates hiNOS gene expression by binding in the 3′-UTR to produce a translational blockade. These findings suggest dual regulation of iNOS gene expression where cytokines induce iNOS transcription and also increase miR-939, leading to translational inhibition in a checkand-balance system. nitric oxide | miRNA regulation

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“…NOS II has been highlighted as the predominant isoenzyme that facilitates tumor progression (25), prompting the search for novel therapies based on highly selective NOS-II inhibitors (26). However, this strategy can offer only limited therapeutic benefit where constitutive isoforms are the major, or perhaps the only, source of NO (27).…”

Section: Introductionmentioning

confidence: 99%

Antitumor Actions of Ruthenium(III)-Based Nitric Oxide Scavengers and Nitric Oxide Synthase Inhibitors

Flitney

Pritchard²,

Kennovin³

et al. 2011

Molecular Cancer Therapeutics

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The role of endogenous nitric oxide (NO) in the growth and vascularization of a rat carcinosarcoma (P22) has been investigated. Tumor-bearing animals were treated with (i) nitric oxide synthase (NOS) inhibitors, administered via the drinking water, including N G -nitro-L-arginine methyl ester (L-NAME), a nonisoform-selective inhibitor, and 2 others that target the inducible (NOS II) enzyme preferentially, namely 1-amino-2-hydroxyguanidine or N-[3-(aminomethyl)benzyl]acetamidine hydrochloride; or (ii) daily injections (intraperitoneally) of 2 Ru(III) polyaminocarboxylates, AMD6221 and AMD6245, both of which are effective NO scavengers. L-NAME, AMD6221, and AMD6245 reduced tumor growth by approximately 60% to 75% of control rates. Tumor sections stained with abs to CD-31/platelet endothelial cell adhesion molecule-1 or NOS III showed that this was associated with a marked reduction (60%-77%) of tumor microvascular densitiy (MVD). Tumors resumed growing promptly when treatment was discontinued, accompanied by partial or complete restoration of MVDs. In contrast, NOS-II selective inhibitors had no effect on tumor growth or vascularization, indicating that both responses require complete blockade of NO production. The results corroborate the view that endogenous NO facilitates tumor development. We suggest that NO deprivation causes tumor feeder vessels to constrict, reducing tumor blood flow. The delivery of oxygen and essential nutrients to the developing tumor is impaired as a consequence, hampering further growth. Normalizing NO levels by withholding treatment causes tumor feeder vessels to dilate, increasing tumor perfusion and reestablishing conditions that allow tumors to begin growing again.

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Human colon cancer cell lines show a diverse pattern of nitric oxide synthase gene expression and nitric oxide generation

Cited by 125 publications

References 16 publications

Gene mutations and altered gene expression in azoxymethane‐induced colon carcinogenesis in rodents

Gene mutations and altered gene expression in azoxymethane‐induced colon carcinogenesis in rodents

miRNA-939 regulates human inducible nitric oxide synthase posttranscriptional gene expression in human hepatocytes

Antitumor Actions of Ruthenium(III)-Based Nitric Oxide Scavengers and Nitric Oxide Synthase Inhibitors

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