Synchronous manifestation of colorectal cancer and intraductal papillary mucinous neoplasms

High rates of extrapancreatic malignancies,in particular colorectal cancer(CRC),have been detected in patients with intraductal papillary mucinous neoplasm(IPMN).So far,there is no distinct explanation in the literature for the development of secondary or synchronous malignancies in patients with IPMN.In the past few years,some data related to common genetic alterations in IPMN and other affiliated cancers have been published.This review elucidated the association between IPMN and CRC,shedding light on the most relevant genetic alterations that may explain the possible relationship between these entities.In keeping with our findings,we suggested that once the diagnosis of IPMN is made,special consideration of CRC should be undertaken.Presently,there are no specific guidelines regarding colorectal screening programs for patients with IPMN.We recommend that patients with IPMNs are at high-risk for CRC,and a more rigorous colorectal surveillance program should be implemented.

Colorectal cancer vaccines: Tumor-associated antigens vs neoantigens

Therapeutic options for the treatment of colorectal cancer(CRC) are diverse but still not always satisfying. Recent success of immune checkpoint inhibition treatment for the subgroup of CRC patients suffering from hypermutated tumors suggests a permanent role of immune therapy in the clinical management of CRC. Substantial improvement in treatment outcome could be achieved by development of efficient patient-individual CRC vaccination strategies. This mini-review summarizes the current knowledge on the two general classes of targets: tumor-associated antigens(TAAs) and tumorspecific antigens. TAAs like carcinoembryonic antigen and melanoma associated antigen are present in and shared by a subgroup of patients and a variety of clinical studies examined the efficacy of different TAA-derived peptide vaccines. Combinations of several TAAs as the next step and the development of personalized TAA-based peptide vaccines are discussed. Improvements of peptidebased vaccines achievable by adjuvants and immunestimulatory chemotherapeutics are highlighted. Finally, we sum up clinical studies using tumor-specific antigens-in CRC almost exclusively neoantigens-which revealed promising results; particularly no severe adverse events were reported so far. Critical progress for clinical outcomes can be expected by individualizing neoantigen-based peptide vaccines and combining them with immunestimulatory chemotherapeutics and immune checkpoint inhibitors. In light of these data and latest developments, truly personalized neoantigen-based peptide vaccines can be expected to fulfill modern precision medicine's requirements and will manifest as treatment pillar for routine clinical management of CRC.

Specific CEA-producing colorectal carcinoma cell killing with recombinant adenoviral vector containing cytosine deaminase gene

AIM: To kill CEA positive colorectal carcinoma cells specifically using the E coli cytosine deaminase (CD) suicide gene, a new replication-deficient recombinant adenoviral vector was constructed in which CD gene was controlled under CEA promoter and its in vitro cytotoxic effects were evaluated. METHODS: Shuttle plasmid containing CD gene and regulatory sequence of the CEA gene was constructed and recombined with the right arm of adenovirus genome DNA in 293 cell strain. Dot blotting and PCR were used to identify positive plaques. The purification of adenovirus was performed with ultra-concentration in CsCl step gradients and the titration was measured with plaque formation assay. Cytotoxic effects were assayed with MTT method, The fifty percent inhibition concentration (IC(50)) of 5-FC was calculated using a curve-fitting parameter. The human colorectal carcinoma cell line, which was CEA-producing, and the CEA-nonproducing Hela cell line were applied in cytological tests. An established recombinant adenovirus vector AdCMVCD, in which the CD gene was controlled under CMV promoter, was used as virus control. Quantitative results were expressed as the mean +/- SD of the mean. Statistical analysis was performed using ANOVA test. RESULTS: The desired recombinant adenovirus vector was named AdCEACD. The results of dot blotting and PCR showed that the recombinant adenovirus contained CEA promoter and CD gene. Virus titer was about 5.0 X 10(14)pfu/L(-1) after purification. The CEA-producing Lovo cells were sensitive to 5-FC and had the same cytotoxic effect after infection with AdCEACD and AdCMVCD (The IC(50) values of 5-FC in parent Lovo cells, Lovo cells infected with 100 M.O.I AdCEACD and Lovo cells infected with 10 M.O.I AdCMVCD were 】15000, 216.5+/-38.1 and 128.8+/-25.4 micromol.L(-1), P【0.001, respectively), and the cytotoxicity of 5-FC increased accordingly when the m.o.i of adenoviruses were enhanced (The value of IC(50) of 5-FC was reduced to 27.9+/-4.2 micromol.L(-1) in 1000 M.O.I AdCEACD infected Lovo cells and 24.8+/-7.1 micromol.L(-1) in 100 M.O.I AdCMVCD infected Lovo cells, P【0.05, P【0.01, respectively). The CEA-nonproducing Hela cells had no effect after infection with AdCEACD, but Hela cells had the cytotoxic sensitivity to 5-FC after infection with AdCMVCD (The IC(50) of 5-FC in parent Hele cells and Hela cells infected with AdCMVCD at 10 M.O.I was 】15000 and 214.5+/-31.3 micromol.L(-1), P【0.001). AdCEACD/5-FC system also had bystander effect, and the viability was about 30 percent when the proportion of transfected cells was only 10 percent. CONCLUSION: The recombinant adenovirus vector AdCEACD has the character of cell type-specific gene delivery. The AdCEACD/5-FC system may become a new, potent and specific approach for the gene therapy of CEA-positive neoplasms, especially colon carcinoma.

p16 gene methylation in colorectal cancers associated with Duke's staging

AIM: To explore the association of methylation of the CpG island in the promotor of the p16 tumor suppressor gene with the clinicopathological characteristics of the colorectal cancers. METHODS: Methylation-specific PCR (MSP) was used to detect p16 methylation of 62 sporadic colorectal cancer specimens. RESULTS: p16 methylation was detected in 42% of the tumors.Dukes'staging was associated with p16 methylation status.p16 methylation occurred more frequently in Dukes'C and D patients (75.9%) than in Dukes'A and B patients (12.1%). CONCLUSION: p16 methylation plays a role in the carcinogenesis of a subset of colorectal cancer, and it might be linked to poor prognosis.

New genes emerging for colorectal cancer predisposition

Colorectal cancer(CRC)is one of the most frequent neoplasms and an important cause of mortality in the developed world.This cancer is caused by both genetic and environmental factors although 35%of the variation in CRC susceptibility involves inherited genetic differences.Mendelian syndromes account for about5%of the total burden of CRC,with Lynch syndrome and familial adenomatous polyposis the most common forms.Excluding hereditary forms,there is an important fraction of CRC cases that present familial aggregation for the disease with an unknown germline genetic cause.CRC can be also considered as a complex disease taking into account the common diseasecommom variant hypothesis with a polygenic model of inheritance where the genetic components of common complex diseases correspond mostly to variants of low/moderate effect.So far,30 common,low-penetrance susceptibility variants have been identified for CRC.Recently,new sequencing technologies including exomeand whole-genome sequencing have permitted to add a new approach to facilitate the identification of new genes responsible for human disease predisposition.By using whole-genome sequencing,germline mutations in the POLE and POLD1 genes have been found to be responsible for a new form of CRC genetic predisposition called polymerase proofreading-associated polyposis.

Construction and selection of the natural immune Fab antibody phage display library from patients with colorectal cancer

AIM: To construct the natural immune Fab antibody phage display libraries of colorectal cancer and to select antibodies related with colorectal cancer. METHODS: Extract total RNA from tissue of local cancer metastasis lymph nodes of patients with colorectal cancer. RT-PCR was used to amplify the heavy chain Fd and light chain kappa and the amplification products were inserted successively into the vector pComb3 to construct the human libraries of Fab antibodies. They were then panned by phage display technology. By means of Dot immunoblotting and ELISA, the libraries were identified and the Fab phage antibodies binding with antigens of colorectal cancer were selected. RESULTS: The amplified fragments of Fd and kappa gained by RT-PCR were about 650 bp. Fd and kappa PCR products were subsequently inserted into the vector pComb3, resulting in a recombination rate of 40% and the volume of Fab phage display library reached 1.48 x 10(6).The libraries were enriched about 120-fold by 3 cycles of adsorption-elution-multiplication (panning). Dot immunoblotting showed Fab expressions on the phage libraries and ELISA showed 5 clones of Fab phage antibodies which had binding activities with antigens of colorectal cancer. CONCLUSION: The natural immune Fab antibody phage display libraries of colorectal cancer were constructed. They could be used to select the relative antibodies of colorectal cancer.

Activity of boanmycin against colorectal cancer

INTRODUCTIONBoanmycin (Bleomycin A6, BAM ), a newantitumor antibiotic, was isolated from manycomponents of bleomycin (BLM) produced bystreptomyces pingyangensis which were obtainedfrom a soil sample collected in Pingyang County,Zhejiang Province, China. Boanmycin has a similarchemical structure to that of BLM, but the terminalamine moiety is different[ 1].

Studies on mechanism of Sialy Lewis-X antigen in liver metastases of human colorectal carcinoma

INTRODUCTIONSialyl Lewis-X antigen ,correlated with carcinoma, is a group of carbohydrate antigen containing oligosaccharide expressed of embryonic tisue and glycoproteins on cell surface of embryonic tissue[1].The SLeX antigen located on cell surface is synthesized principally by two enzymes ,al ,3fucosyltransfrease and a2, 3sialyctransferase.In adults ,SLeX antigen is expressed principally on the surfaces of granulocytic cells and some tumor cells .

Colorectal cancer in patients with inflammatory bowel disease:Can we predict risk?

The inflammatory bowel diseases(IBD),Crohn's disease(CD) and ulcerative colitis(UC),may be complicated by colorectal cancer(CRC).In a recent populationbased cohort study of 47 347 Danish patients with IBD by Tine Jess and colleagues 268 patients with UC and 70 patients with CD developed CRC during 30 years of observation.The overall risk of CRC among patients with UC and CD was comparable with that of the general population.However,patients diagnosed with UC during childhood or as adolescents,patients with long duration of disease and those with concomitant primary sclerosing cholangitis were at increased risk.In this commentary,we discuss the mechanisms underlying carcinogenesis in IBD and current investigations of genetic susceptibility in IBD patients.Further advances will depend on the cooperative work by epidemiologist and molecular geneticists in order to identify genetic polymorphisms involved in IBD-associated CRC.The ultimate goal is to incorporate genotypes and clinical parameters into a predictive model that will refine the prediction of risk for CRC in colonic IBD.The challenge will be to translate these new findings into clinical practice and to determine appropriate preventive strategies in order to avoid CRC in IBD patients.The achieved knowledge may also be relevant for other inflammation-associated cancers.

Molecular evaluation of glutathione S transferase family genes in patients with sporadic colorectal cancer

AIM To evaluate the association between polymorphismsin glutathione S transferases(GSTs) and the risk of sporadic colorectal cancer(SCRC), tumor progression and the survival of patients.METHODS A case-control study of 970 individuals from the Brazilian population was conducted(232 individuals from the case group with colorectal cancer and 738 individuals from the control group without a history of cancer). PCR multiplex and PCR-RFLP techniques were used to genotype the GST polymorphisms. The tumors were categorized according to the TNM classification: tumor extension(T), affected lymph nodes(N), and presence of metastasis(M). Logistic regression, multiple logistic regression and survival analysis were used to analyze the data. The results are presented in terms of odds ratio(OR) and 95% confidence interval(CI). The level of significance was set at 5%(P ≤ 0.05).RESULTS Age equal to or over 62 years(OR = 8.79; 95%CI: 5.90-13.09, P < 0.01) and female gender(OR = 2.91; 95%CI: 1.74-4.37; P < 0.01) were associated with increased risk of SCRC. Analysis of the polymorphisms revealed an association between the GSTM1 polymorphisms and a risk of SCRC(OR = 1.45; 95%CI: 1.06-2.00; P = 0.02), as well as between GSTT1 and a reduced risk of the disease(OR = 0.65; 95%CI: 0.43-0.98; P = 0.04). An interaction between the presence of the wild-type allele of GSTP1 Ile105 Val polymorphism and tobacco consumption on risk of SCRC(OR = 2.33; 95%CI: 1.34-4.05; P = 0.05) was observed. There was an association between the GSTM1 null genotype and the presence of advanced tumors(OR = 2.33; 95%CI: 1.23-4.41; P = 0.009), as well as increased risk of SCRC in the presence of a combination of GSTT1 non-null/GSTM1 null genotypes(OR = 1.50; 95%CI: 1.03-2.19; P = 0.03) and GSTT1 non-null/GSTM1 null/GSTP1 Val~*(OR = 1.85; 95%CI: 1.01-3.36, P = 0.04). Combined GSTT1 non-null/GSTM1 null genotypes(OR = 2.40; 95%CI: 1.19-4.85; P = 0.01) and GSTT1 non-null/GSTM1 null/GSTP1 Val~*(OR = 2.92; 95%CI: 1.05-8.12; P = 0.04) were associated with tumor progression. Polymorphisms were not associated with the survival of patients with SCRC.CONCLUSION Females aged 62 years or older are more susceptible to SCRC. Polymorphisms of GSTT1 and GSTM1 null genotypes modulated the susceptibility to SCRC in the population studied.

Differential expression of a novel colorectal cancer differentiation-related gene in colorectal cancer

AIM: To investigate SBA2 expression in CRC cell lines and surgical specimens of CRC and autologous healthy mucosa. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used for relative quantification of SBA2 mRNA levels in 4 human CRC cell lines with different grades of differentiation and 30 clinical samples. Normalization of the results was achieved by simultaneous amplification of beta-actin as an internal control. RESULTS: In the exponential range of amplification, fairly good linearity demonstrated identical amplification efficiency for SBA2 and beta-actin (82%). Markedly lower levels of SBA2 mRNA were detectable in tumors, as compared with the coupled normal counterparts P【0.01). SBA2 expression was significantly (0.01】P 【 0.05) correlated with the grade of differentiation in CRC, with relatively higher levels in well-differentiated samples and lower in poorly-differentiated cases. Of the 9 cases with lymph nodes affected, 78% (7/9) had reduced SBA2 mRNA expression in contrast to 24% (5/21) in non-metastasis samples 0.01】P【0.05). CONCLUSION: SBA2 gene might be a promising novel biomarker of cell differentiation in colorectal cancer and its biological features need further studies.

Multiple biomarkers of colorectal tumor in a differential diagnosis model:A quantitative study

AIM:To evaluate the multiple biomarkers of colorectal tumor and their potential usage in early diagnosis of colorectal cancers. METHODS:Multiple biomarkers (DNA contents,AgNOR, PCNA,p53,c-erbB-2) in 10 normal colorectal mucosae,37 colorectal adenomas and 55 colorectal cancers were analyzed quantitatively in the computed processing imaging system. Discrimination patterns were employed to evaluate the significance of single and multiple indices in diagnosis of colorectal cancers. RESULTS:The mean values of the analyzed parameters increased in order of the normal mucosa,adenoma and adenocarcinoma,and this tendency reflected the progression of colorectal malignancy.The parameters including DNA index,positive rates,densities of AgNOR,c-erbB-2,and p53, shape and density of nucleus were relatively valuable for diagnoses.Then a diagnostic discrimination model was established.The samples were confirmed with the model, the sensitivity rates in cancer group and adenoma group were 96.36% and 89.19%,respectively.The value of proliferating cell nuclear antigen (PCNA) in early diagnosis of colorectal cancers was uncertain. CONCLUSION:The quantitative evaluation of some parameters for colorectal tumor can provide reproducible data for differential diagnosis.The established diagnostic discrimination model may be of clinicopathological value, and can make the early diagnosis of colorectal cancer possible.

A systemic review of glutathione S-transferase P1 Ile105Val polymorphism and colorectal cancer risk

Objectives： To investigate the correlation between glutathione S-transferase P1 （GSTP1） Ilel05Val polymorphism and colorectal cancer （CRC） risk. Methods： Studies were identified to investigate the association between GSTP1 Ilel05Val polymorphism and CRC risk. Systematic computerized searches of the PubMed, Chinese National Knowledge Infrastructure, WANFANG and SinoMed were performed. Summary odds ratios （OR） and 95% confidence intervals （95 % CI） were used to measure GSTP 1 Ile 105Val polymorphisms and CRC risk. Results： A total of 23 retrospective studies were included in the meta-analysis. During all studies including 6,981 cases and 8,977 controls, sample sizes ranged from 146 to 2,144. Overall, the pooled results revealed that lie 105Val polymorphism was not associated with CRC risk and confused results were found in subgroup analyses. Further meta-analyses were conducted after excluding low-quality studies. GSTP1 Ilel05Val is associated with increased risk of CRC limited in studies with matched control. There was no significant heterogeneity in all genetic comparisons, but heterogeneity existed in subgroup analyses of heterozygous and dominant comparisons. The meta-regression analyses indicated that matched controls were the significant factor influencing between-study heterogeneity in all possible influential factors including published year, ethnicity, source of control, sample size, Hardy-Weinberg equilibrium （HWE） in control and matched controls. Sensitivity analysis revealed the pooled ORs were not changed before and after removal of each single study in all genetic comparisons, indicating the robustness of the results. Conclusions： GSTP1 Ilel05Val might be associated with increased risk of CRC. However, more high- quality case-control studies should be performed to confirm the authenticity of our conclusion.

Clinicopathological and molecular genetic analysis of 4 typical Chinese HNPCC families

AIM: To study the clinicopathological and molecular genetic characteristics of typical Chinese hereditary nonpolyposis cotorectal cancer (HNPCC) families. METHODS: Four typical Chinese HNPCC families were analyzed using microdissection, microsatellite instability analysis, immunostaining of hMSH2 and hMLH1 proteins and direct DNA sequencing of hMSH2 and hMLH1 genes. RESULTS: All five tumor tissues of 4 probands from the 4 typical Chinese HNPCC families showed microsatellite instability at more than two loci (MSI-H or RER+ phenotype). Three out of the 4 cases lost hMSH2 protein expression and the other case showed no hMLH1 protein expression. Three pathological germline mutations (2 in hMSH2 and 1 in hMLH1), which had not been reported previously, were identified. The same mutations were also found in other affected members of two HNPCC families,respectively. CONCLUSION: Typical Chinese HNPCC families showed relatively frequent germline mutation of mismatch repair genes. High-level microsatellite instability and loss of expression of mismatch repair genes correlated closely with germline mutation of mismatch repair genes. Microsatellite instability analysis and immunostaining of mismatch repair gene might serve as effective screening methods before direct DNA sequencing. It is necessary to establish clinical criteria and molecular diagnostic strategies more suitable for Chinese HNPCC families.

Cytochrome P450 2E1 genetic polymorphism and gastric cancer in Changle,Fujian Province

AIM: Genetic polymorphism in enzymes of carcinogen metabolism has been found to have the influence on the susceptibility to cancer. Cytochrome P450 2E1 (CYP2E1) is considered to play an important role in the metabolic activation of procarcinogens such as N-nitrosoamines and low molecular weight organic compounds. The purpose of this study is to determine whether CYP450 2E1 polymorphisms are associated with risks of gastric cancer. METHODS: We conducted a population based case-control study in Changle county, Fujian Province, a high-risk region of gastric cancer in China. Ninety-one incident gastric cancer patients and ninety-four healthy controls were included in our study. Datas including demographic characteristics, diet intake, and alcohol and tobacco consumption of individuals in our study were completed by a standardized questionnaire.PCR-RFLP revealed three genotypes:heterozygote (C1/C2) and two homozygotes (C1/C1 and C2/C2) in CYP2E1. RESULTS: The frequency of variant genotypes (C1/C2 and C2/C2) in gastric cancer cases and controls was 36.3% and 24.5%, respectively. The rare homozygous C2/C2 genotype was found in 6 individuals in gastric cancer group(6.6%), whereas there was only one in the control group (1.1%). However, there was no statistically significant difference between the two groups (two-tailed Fisher's exact test P=0.066). Individuals in gastric cancer group were more likely to carry genotype C1/C2 (odds ratio, OR=1.50) and C2/C2 (OR=7.34) than individuals in control group (chi(2) =4.597, for trend P=0.032). The frequencies of genotypes with the C2 allele (C1/C2 and C2/C2 genotypes) were compared with those of genotypes without C2 allele (C1/C1 genotype) among individuals in gastric cancer group and control group according to the pattern of gastric cancer risk factors. The results show that individuals who exposed to these gastric cancer risk factors and carry the C2 allele seemed to have a higher risk of developing gastric cancer. CONCLUSION: Polymorphism of CYP2E1 gene may have some effect in the development of gastric cancer in Changle county, Fujian Province.

GSTM1,GSTT1,GSTP1 and CYP1A1 genetic polymorphisms and susceptibility to esophageal cancer in a French population:Different pattern of squamous cell carcinoma and adenocarcinoma

AIM:To evaluate the association between CYP1A1 and GSTs genetic polymorphisms and susceptibility to esophageal squamous cell carcinoma(SCC)and esophageal adenocarcinoma(ADC)in a high risk area of northwest of France. METHODS:A case-control study was conducted to investigate the genetic polymorphisms of these enzymes (CYPIAI*2C and GSTP1 exon 7 Val alleles,GSTMI*2/*2 and GSTTl *2/*2 null genotypes).A total of 79 esophageal cancer cases and 130 controls were recruited. RESULTS:GSTMI*2/*2 and CYPIAI*IA/*2C genotype frequencies were higher among squamous cell carcinomas at a level dose to statistical significance(OR =1.83,95% CI 0.88-3.83,P=0.11;OR=3.03,95% CI 0.93-9.90,P=0.07, respectively).For GSTP1 polymorphism,no difference was found between controls and cases,whatever their histological status.Lower frequency of GSTT1 deletion was observed in ADC group compared to controls with a statistically significant difference(OR=13.31,95% CI 1.66-106.92,P<0.01). CONCLUSION:In SCC,our results are consistent with the strong association of this kind of tumour with tobacco exposure.In ADC,our results suggest 3 distinct hypotheses: (1)activation of exogenous procarcinogens,such as small halogenated compounds by GSTT1;(2)contribution of GSTT1 to the inflammatory response of esophageal mucosa,which is known to be a strong risk factor for ADC, possibly through leukotriene synthesis;(3)higher sensitivity to the inflammatory process associated with intracellular depletion of glutathione.

GSTT1,GSTM1 and CYP2E1 genetic polymorphisms in gastric cancer and chronic gastritis in a Brazilian population

AIM:To test the hypothesis that,in the Southeastern Brazilian population,the GSTT1,GSTM1 and CYP2E1 polymorphisms and putative risk factors are associated with an increased risk for gastric cancer. METHODS:We conducted a study on 100 cases of gastric cancer (GC),100 cases of chronic gastritis (CG),and 150 controls (C).Deletion of the GSTT1 and GSTM1 genes was assessed by multiplex PCR.CYP2E1/Pst1 genotyping was performed using a PCR-RFLP assay. RESULTS:No relationship between GSTT1/GSTM1 deletion and the c1/c2 genotype of CYP2E1 was observed among the three groups.However,a significant difference between CG and C was observed,due to a greater number of GSTT1/GSTM1 positive genotypes in the CG group.The GSTT1 null genotype occurred more frequently in Negroid subjects,and the GSTM1 null genotype in Caucasians,while the GSTM1 positive genotype was observed mainly in individuals with chronic gastritis infected with H pylori. CONCLUSION:Our findings indicate that there is no obvious relationship between the GSTT1,GSTM1 and CYP2E1 polymorphisms and gastric cancer.

大肠癌Fas、FasL表达、突变与肝转移关系的研究

探讨Fas、FasL系统表达、突变与大肠癌转移的关系。方法 :采用RT -PCR和PCR -SSCP方法检测大肠癌原发灶、肝转移灶、癌旁肠粘膜、门静脉血淋巴细胞中Fas、FasL表达、突变。结果 :在 86例大肠癌原发灶、肝转移灶、癌旁肠粘膜、门静脉血淋巴细胞中Fas表达阳性率分别为 67.4 % ,63 .2 % ,4 1.9% ,87.2 %。Fas突变率分别为 50 .0 % ,70 .8% ,2 5.% ,8.0 %。在大肠癌原发灶、肝转移灶中Fas突变率较高 (P <0 .0 1)。3 8例肝转移灶中全部有FasL表达 ,而在原发灶、癌旁肠粘膜、门静脉血淋巴细胞中FasL表达阳性率分别为2 5.6% ,14 .0 % ,50 .0 %。肝转移灶中FasL表达高于其它组织 (P <0 .0 1)。结论 :Fas突变和FasL增强表达是大肠癌细胞逃避免疫监视和杀伤并发生肝转移的机制之一。

重庆地区人群GSTT1和GSTM1基因多态性与结直肠癌易感性研究

目的 了解谷胱苷肽转硫酶GSTT1和GSTT1基因多态性与结直肠癌易感性的关系。方法 采用多重PCR技术对 82例病例和 82例对照GSTT1、GSTM1基因型进行了检测和分析。结果 GSTM1基因缺失频率在病例组和对照组之间有显著差异 (P <0 .0 1,OR =2 .464 ,95 %CI =1.3 11～ 4.63 3 )。GSTM1和GSTT1基因同时缺失的个体在病例组和对照组之间有差异 (P <0 .0 5 ,OR =2 .476,95 %CI =1.0 46～ 5 .861)。结论 GSTM1基因缺失可能是结直肠癌发生的易感基因型。GSTT1基因单独缺失与结直肠癌发生的危险性不相关 ,但在GSTM1缺失基础上再伴有GSTT1基因缺失的个体 。

硒蛋白S基因多态性与结直肠癌遗传易感性的相关性

目的探讨硒蛋白S（SelS）基因rs34713741位点多态性与结直肠癌遗传易感性的相关性。方法用聚合酶链反应-限制性片断长度多态性（PCR-RFLP）检测119例结直肠癌患者及144例体检健康者SelS基因型和等位基因频率,并经测序验证,分析体检健康者与结直肠癌患者SelS基因rs34713741位点基因型频率、等位基因频率的差异,并对结直肠癌进行分层分析。结果 SelS基因rs34713741位点CC、CT和TT基因型及C、T等位基因在结直肠癌患者和健康对照者间差异有统计学意义（χ^2分别为7.598,7.134,P均〈0.05）,中国人群中CT基因型患结直肠癌的风险是CC基因型的1.597倍（OR=1.597,95%CI：1.096-2.326）。对结直肠癌组分层分析发现,与CC基因型比较,CT基因型和TT基因型在〈55岁组（OR=1.870,95%CI：1.123-3.313,P〈0.05）,女性组（OR=1.953,95%CI：1.076-3.545,P〈0.05）,远侧结直肠癌组（OR=1.617,95%CI：1.060-2.466,P〈0.05）,中分化腺癌组（OR=2.070,95%CI：1.274-3.361,P〈0.05）分布频率明显升高。结论 SelS基因rs34713741位点多态性与结直肠癌的发病有关,T等位基因可能是中国人群结直肠癌发病的危险因素之一。