[A case-control study on the association between genetic polymorphisms of metabolic enzymes and the risk of colorectal cancer].
OBJECTIVE
To investigate the association between metabolic enzymes polymorphisms and the risk of colorectal cancer(CRC).


METHODS
Methods of detection used were based on polymerase chain reaction(PCR) including PCR-restriction fragment length polymorphism (PCR-RFLP), allele specific-PCR (AS-PCR) and multiple-PCR to identify the polymorphisms of CYP1A1 6235T/C, CYP1A2 734C/A, CYP2E1 -1259G/C, CYP2E1 -1019C/T, GSTM1 and T1 null type, NAT1 and NAT2 alleles among 140 cases and 343 cancer-free controls.


RESULTS
The allele frequencies of CYP1A1 6235C, CYP1A2 734A, CYP2E1 -1259C, CYP2E1 -1019T, GSTM1 and T1 null type, NAT1* 10 and NAT2 Mx (x = 1,2,3) alleles were 31.65%, 63.77%, 23.02%, 32.61%, 57.25%, 17.39%, 26.45% and 39.21% in the case group and 39.85%, 66.62%, 20.27%, 28.61%, 55.46%, 20.35%, 25.22% and 39.36% in control group, respectively. The frequencies were in Hardy-Weinberg equilibrium. Data on single genetic polymorphism and stratification analysis of multi-genetic polymorphisms indicated that CYP1A1 6235CC homozygote was associated with the significant reduction of CRC risk (OR = 0.79, 95% CI: 0.63-0.99) and in individuals with CYP1A2 734A allele. CYP1A1 62345C allele had the same effect (OR = 0.53, 95% CI: 0.34-0.83). However, individuals with GSTT1 null genotype, GSTM1 null genotype could significantly increase the risk (OR = 4.41, 95% CI: 1.21-16.10).


CONCLUSIONS
CYP1A1 6235C allele might play an important role in fighting against colorectal carcinogenesis. However, GSTM1 and T1 null genotype might serve as risk factors genetically. Larger scale population-based studies were needed to confirm the current findings.
Chen
Kun
K
Departent of Epidemiology and Health Statistics, Zhejiang University School of Public Health, Hangzhou 310031, China.
Jin
Ming-juan
MJ
Fan
Chun-hong
CH
Song
Liang
L
Jiang
Qin-ting
QT
Yu
Wei-ping
WP
Ma
Xin-yuan
XY
Yao
Kai-yan
KY
D000483:Alleles; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic