title: Nitric oxide and p53 in cancer-prone chronic inflammation and oxyradical overload disease.
abstract: Nitric oxide (NO(.)), which is generated under chronic inflammatory conditions that predispose individuals to cancer, has paradoxical effects. NO(.) can activate p53, which can result in anti-carcinogenic effects, or it can be mutagenic and increase cancer risk. We explored the mechanisms by which NO(.) induced p53 activation in vitro and found that NO(.) induced p53 accumulation and phosphorylation, particularly at ser-15, via ATM and ATR kinases, which then led to cell cycle arrest at G(2)/M. We next examined proteins in these pathways in both inflamed and normal human colon tissue. Inducible nitric oxide synthase (iNOS) levels and p53-P-ser15 levels were positively correlated with the degree of inflammation and with each other. Additionally, the p53 targets, HDM-2 and p21 (WAF1), were present in ulcerative colitis (UC) colon, but undetectable in normal colon, consistent with activated p53. We also found higher p53 mutant frequencies of both G:C --> A:T transitions at the CpG site of codon 248 and C:G --> T:A transitions at codon 247 in lesional colon tissue from UC cases versus nonlesional tissue from these cases or colon tissue from normal adult controls. Consistent with nitrosative stress and the deamination of 5-methylcytosine, p53 mutations were also detected in sporadic colon cancer tissue and were associated with iNOS activity in these tissues. These studies identified a potential mechanistic link between NO(.) and p53 in UC and sporadic colon cancer.
authors.affiliation: Cancer Prevention Fellowship Program, Division of Cancer Prevention, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Julie E
authors.initials: JE
authors.lastname: Goodman
authors.forename: Lorne J
authors.initials: LJ
authors.lastname: Hofseth
authors.forename: S Perwez
authors.initials: SP
authors.lastname: Hussain
authors.forename: Curtis C
authors.initials: CC
authors.lastname: Harris
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism; D003093:Colitis, Ulcerative / Q000378:metabolism / Q000503:physiopathology*; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000503:physiopathology; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004268:DNA-Binding Proteins; D006801:Humans; D009154:Mutation / Q000235:genetics; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins
chemical_list: C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases