Genotype And Phenotype Study On Cancer Related Genes In Relation To Esophageal Squamous Cell Carcinoma In Yangzhong County, Jiangsu Province, China

[Objective]This study aimed to investigate the role of environmental factors, genetic polymorphisms and protein expressions of XRCC1 and MGMT genes,and their interactions in the risk of esophageal squamous cell carcinoma(ESCC) in a Chinese population.[Methods]A population-based case-control study was conducted in Yangzhong County,Jiangsu Province,China.ESCC cases were diagnosed between 1^st January 2004 and 14^th May 2008 and histologically confirmed,while controls were randomly selected from the local healthy and cancer-free population.Face-to-face interviews were carried out by trained interviewers using a standard structured questionnaire and blood samples were collected after informed consent.Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism(RFLP) methods were used to detect polymorphisms of XRCC1 and MGMT gene.Histologically confirmed ESCC cases from January 2005 to August 2007 were also collected with paraffin-embedded slides and cancer-free controls were selected with paraffin-embedded slides. Immunohistochemistry assay was conducted with these samples.Epidata 3.0.SPSS 11.0 and STATA 9.2 statistical softwares were used to input and analyze data,and x² test and unconditional logistic regression were occupied to measure the relationship between environmental factors,genetic polymorphisms,protein expression and the possible gene-environment and gene-gene interactions in the risk of esophageal cancer by calculating odds ratio(OR),adjusted OR(aOR) and 95%confidence interval(95%CI).[Results]Totally,432 cases(men 61.8%,women 37.2%) were enrolled in this study with the average age of 61.5±7.8 years old and then 915 controls were recruited(men 49.3%,women 50.7%,age in mean of 57.1±9.1 years old).After stratified by sex and adjusted by age and education years,the results from unconditional logistic regression suggested that river water drinking and alcohol drinking could increase the risk of esophageal cancer with aOR of 4.20(95%CI:2.90-6.07) and 2.03(95%CI:1.43-2.89) in men,respectively,as well as river water drinking and old stocked rice intake with aOR of 8.37(95%CI:5.09-13.75) and 12.78(95%CI:2.69-60.69) in women, respectively. The allele frequencies of XRCC1 Arg194Trp 194T were 33.0%and 31.3%in cases and controls,respectively.Compared with CC genotype,subjects with CT,TT and CT/TTgenotypes got ORs of 1.18(95%CI:0.80-1.73),1.06(95%CI:0.84-1.36) and 1.09(95%CI:0.86-1.37),respectively.After adjusted by sex,age,education years, river water drinking,old stocked rice intake,tobacco smoking and alcohol drinking, subjects with CT,TT and CT/TT genotypes had aORs of 1.19(95%CI:0.76-1.84). 1.06(95%CI:0.81-1.39) and 1.08(95%CI:0.84-1.40),respectively.The allele frequencies of XRCC1 Arg280His 280A were 11.0%and 14.4%in cases and controls, respectively.Compared with GG genotype,subjects with GA,AA and GA/AA genotypes got ORs of 0.76(95%CI:0.31-1.83),0.70(95%CI:0.52-0.92) and 0.70 (95%CI:0.53-0.92),respectively..After adjusted by those factors,individuals with GA,AA and GA/AA genotypes had aORs of 0.94(95%CI:0.36-2.48),0.80(95%CI: 0.58-1.10) and 0.81(95%CI:0.60-1.11),respectively.The allele frequencies of XRCC1 Arg399Gln 399A were 27.1%and 23.3%in cases and controls,respectively. Compared with GG genotype,subjects with GA,AA and GA/AA genotypes had ORs of 1.84(95%CI:1.17-2.88) and 1.07(95%CI:0.84-1.36) and 1.16(95%CI:0.92-1.47). respectively..After adjusted by those factors,individuals with GA,AA and GA/AA genotypes had aORs of 1.48(95%CI:0.89-2.48),1.16(95%CI:0.88-1.53) and 1.21 (95%CI:0.93-1.56),respectively.Old stocked rice intake had a positive multiple interaction with XRCC1 Arg399Gln polymorphisms(for interaction,OR=6.58, 95%CI:1.60-27.11,P=0.009).and subjectls with variant genotypes(GA or AA) had a significant higher risk of ESCC if they took old stocked rice.Compared with wild genotypes of Arg194Trp and Arg280His.subjects with Arg194Trp CC genotype and Arg280His variant genotype(GA or AA) had a significant higher risk of ESCC(for interaction.OR=1.87,95%CI:1.10-3.18,P=0.020).There was a complete consistency between MGMT Ile143Val and Lys178Arg loci. The allele frequencies of MGMT 143G(178G) were 0.6%and 0.4%in cases and controls,respectively.Compared with AA genotype,subjects with AG genotype got OR of 1.33(95%CI:0.43-4.08).After adjusted by related factors,subjects with GA genotype got OR of 0.79(95%CI:0.23-2.69).Tobacco smoking and river water drinking had negative multiple interactions with MGMT polymorphisms,and their ORs were 0.06(95%CI:0.01-0.85,P=0.038) and 0.03(95%CI:0.01-0.51,P=0.014). respectively,subjects with AA genotype who smoked or drank river water had a significant higher risk of ESCC. Immunohistochemistry analysis detected the XRCC1 positive rates were 44.3% (62/140) and 33.3%(27/81) in cases and controls,respectively,and no significant difference was found(x²=2.559,P =0.110).The MGMT positive rates were 70.0% (98/140) and 51.7%(45/87) in cases and controls,respectively,and a significant difference was observed(x²=7.688,P=0.006).There was a weak association between low MGMT protein expression and distant metastasis(P=0.081),and as also,a weak association between high MGMT protein expression and old stocked rice intake was found(P=0.072).There were no associations between XRCC1 protein expression and sex,age,tobacco smoking,alcohol drinking,old stocked rice intake,river water drinking and clinical pathological characteristics.Also,there was no association between XRCC1 polymorphisms and XRCC1 protein expression,neither did MGMT polymorphisms and MGMT protein expression.[Conclusions]Common environmental factors like river water drinking,old stocked rice intake,alcohol drinking and genetic factors might contribute to the occurance of ESCC.Tobacco smoking might also play a role in increasing the incidence of ESCC. Drinking tap water,taking fresh rice,smoking cessation and controlling alcohol drinking are important to the prevention of ESCC.There could be modification effects between old stocked rice intake and XRCC1 Arg399Gln,tobacco smoking and MGMT.river water drinking and MGMT,as well as XRCC1 Arg280His and Arg194Trp.High MGMT protein expression might be associated with the risk of ESCC.There might also be a weak association between low MGMT protein expression and distant metastasis as well as a weak association between high MGMT protein expression and old stocked rice intake.