Folate status, genomic DNA hypomethylation, and risk of colorectal adenoma and cancer: a case control study.
OBJECTIVE
Low folate intake may increase risk for colorectal cancer by inducing DNA hypomethylation. This study reports the influence of folate status, DNA methylation, and polymorphisms of methylenetetrahydrofolate reductase (MTHFR 677C-->T and 1298A-->C), methionine synthase (MS 2756A-->G), and cystathionine-beta-synthase (CBS 844ins68) on risk for developing colorectal neoplasia.


METHODS
Thirty-five patients with adenoma, 28 patients with cancer, and 76 controls were recruited for a case control study. Recruitment consent rate was 98%. Blood samples were obtained for determination of blood folates, vitamin B(12), homocysteine, DNA methylation, and genotypes. Tissue biopsy samples were obtained at colonoscopy for determination of DNA methylation in colonic mucosa. Folate status was assessed by constructing a score from estimates of dietary intake and serum and erythrocyte folate.


RESULTS
Cancer patients had 26% lower folate status (95% confidence interval [CI]: 6% to 44%, P = 0.01) and 21% lower serum vitamin B(12) concentration (95% CI: -38% to 1%, P = 0.06) compared with controls. [(3)H] methyl incorporation into colonic DNA was 26% higher in patients with adenoma (95% CI: 8% to 56%, P = 0.009) and 30% higher in patients with cancer (95% CI: -3% to 48%, P = 0.08) compared with controls. High folate status was associated with decreased risk for cancer (P = 0.01 for trend). Colonic and leukocyte DNA hypomethylation were associated with increased risk for adenoma (P = 0.02 and P = 0.01 for trend, respectively) and a nonsignificantly increased risk for cancer (P = 0.09 and P = 0.08 for trend, respectively).


CONCLUSIONS
Low folate status and DNA hypomethylation are associated with colorectal neoplasia.
Pufulete
Maria
M
Nutrition Food and Health Research Centre, Department of Nutrition and Dietetics, King's College London, United Kingdom. maria.pufulete@kcl.ac.uk
Al-Ghnaniem
Reyad
R
Leather
Andrew J M
AJ
Appleby
Paul
P
Gout
Sally
S
Terry
Catherine
C
Emery
Peter W
PW
Sanders
Thomas A B
TA
D000236:Adenoma / Q000097:blood / Q000453:epidemiology* / Q000235:genetics; D000368:Aged; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000235:genetics; D019175:DNA Methylation; D005260:Female; D005492:Folic Acid / Q000097:blood*; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D005838:Genotype; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D008875:Middle Aged; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics; D011110:Polymorphism, Genetic; D012307:Risk Factors
D005492:Folic Acid; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2)