CYP2A6 activity determined by caffeine phenotyping: association with colorectal cancer risk.
Cancer Epidemiol Biomarkers Prev
; 11(4): 377-83, 2002 Apr.
Article
en En
| MEDLINE
| ID: mdl-11927498
ABSTRACT
Cytochrome P450 2A6 (CYP2A6) catalyzes the metabolic activation of several procarcinogens including dietary and environmental nitrosamines, and the involvement of CYP2A6 in cancer development has been postulated. CYP2A6 phenotype was determined using caffeine as a probe drug in individuals participating in a case-control study of colorectal cancer (127 cases and 333 controls matched on age, gender, race, and geographic region). Conversion of the caffeine metabolite 1,7-dimethylxanthine (17X) to 1,7-dimethyl uric acid (17U) is catalyzed primarily by CYP2A6, and this activity can be assayed by comparison of urinary molar ratios of metabolites. Caffeine (200 mg) was administered to each participant, and a 4-5 h postadministration urine sample was collected. Urinary metabolites of caffeine were separated by high-performance liquid chromatography and quantified by comparison to authentic standards. We examined the distributions of the ratio, 17U17X, according to subject characteristics among controls. In case-control comparisons, subjects in the medium and high tertiles of CYP2A6 activity had an increased risk of colorectal cancer compared with subjects with low activity. Odds ratios from a conditional logistic regression model for medium and high 17U17X ratio were 2.0 (95% confidence interval, 1.1-3.7) and 2.6 (95% confidence interval, 1.5-4.5), respectively (P for trend = 0.001). CYP2A6 phenotype has not been compared previously between cancer cases and controls. We found a strong relationship between CYP2A6 activity, measured by urinary caffeine metabolite ratio, and colorectal cancer risk.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Ácido Úrico
/
Cafeína
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Hidrocarburo de Aril Hidroxilasas
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Neoplasias Colorrectales
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Sistema Enzimático del Citocromo P-450
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Oxigenasas de Función Mixta
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Estimulantes del Sistema Nervioso Central
Tipo de estudio:
Etiology_studies
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Observational_studies
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Prognostic_studies
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Risk_factors_studies
Límite:
Adult
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Aged
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Female
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Humans
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Male
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Middle aged
Idioma:
En
Revista:
Cancer Epidemiol Biomarkers Prev
Asunto de la revista:
BIOQUIMICA
/
EPIDEMIOLOGIA
/
NEOPLASIAS
Año:
2002
Tipo del documento:
Article
País de afiliación:
Estados Unidos