Journal Article

NAD(P)H:quinone oxidoreductase-dependent risk for colorectal cancer and its association with the presence of K-<i>ras</i> mutations in tumors

M.J. Lafuente, X. Casterad, M. Trias, C. Ascaso, R. Molina, A. Ballesta, S. Zheng, J.K. Wiencke and A. Lafuente

in Carcinogenesis

Volume 21, issue 10, pages 1813-1819
Published in print October 2000 | ISSN: 0143-3334
Published online October 2000 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/21.10.1813
NAD(P)H:quinone oxidoreductase-dependent risk for colorectal cancer and its association with the presence of K-ras mutations in tumors

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NAD(P)H:quinone oxidoreductase (NQO1) is a polymorphic enzyme involved in the detoxification of potentially mutagenic and carcinogenic quinones. The homozygous C609T NQO1 genotype resulting in loss of reductase activity is found in 2–20% of individuals. In the present study, the NQO1-dependent risk for sporadic colorectal cancer (CRC) was studied in 247 incident CRC cases and 296 hospital-based controls recruited during 1996–1997. Four subgroups of cases were studied: (i) all CRCs; (ii) a molecular CRC subgroup (n = 117, cases with molecular tumor analyses); (iii) within the molecular subgroup those tumors with K-ras mutations in codon 12 (CRC K12); (iv) within the molecular subgroup those tumors with K-ras mutations in codon 13 (CRC K13). The C609T NQO1 genotype was found to be twice as prevalent in all CRC patients (6.8%) compared with controls (3%) and six times more common in the subset CRC K12 (20%). Multivariant analyses in the overall population of 247 cases and 296 controls showed a significant age and gender adjusted risk for CRC associated with the C609T NQO1 genotype (OR 2.9, 95% CI 1.19–6.97; P = 0.01) or with any variant genotype (the low activity allele frequency, i.e. heterozygotes plus homozygotes) (OR 1.41, 95% CI 1.02–1.92; P = 0.03). Within cases of the molecular subgroup (n = 117) the C609T NQO1 genotype was associated with the presence of K-ras codon 12 mutation (OR 6.5 95%, CI 1.39–34.9; P = 0.003). Logistic regression showed an age and gender adjusted risk for K-ras codon 12 mutant CRC associated with the C609T NQO1 genotype (OR 10.5, 95% CI 2.99–36.7; P = 0.0002) or with any variant NQO1 genotype (OR 2.23, 95% CI 1.23–4.00; P = 0.007) compared with the control group. Genetically determined variations in NQO1 may modify the risk for CRC and these risks may be greatest for tumors containing K-ras codon 12 mutations. CRC with K-ras codon 12 mutations may represent a distinct and etiologically more homogeneous subtype of the disease, which may be associated with toxicants that are metabolized via a NQO1-dependent pathway.

Keywords: BP, benzo[a]pyrene; BPQ, quinone metabolites of benzo[a] pyrene; C609T NQO1 genotype, homozygous C609T NQO1 genotype; CE, catechol estrogens; CI, confidence interval; CRC, colorectal cancer; CRCK12, colorectal tumors with a mutation in K-ras codon 12; CRCK13, colorectal tumors with a mutation in K-ras codon 13; NQO1, NAD(P)H:quinone oxidoreductase; OR, odds ratio.

Journal Article.  6758 words. 

Subjects: Clinical Cytogenetics and Molecular Genetics

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