Metabolic polymorphisms and the cancer risk: the evaluation of epidemiological studies]

Genetic modulation of environmental exposures associated with common malignancies is an attractive mechanism to explain differential susceptibility to tobacco or occupation-related carcinogens in the population. The paper reviews the evidence for an association between three genetically based metabolic polymorphisms (N-acetyltransferase, Debrisoquine, hydroxylase, aryl hydrocarbon hydroxylase), which have been implicated in the modulation of lung or bladder cancer risks. Fair to good support emerged for both an association of the acetylation phenotype with occupationally related bladder cancer and for an association of the debrisoquine metabolic phenotype with lung cancer, although in neither case was the evidence completely convincing. Epidemiologic evidence for an association between aryl hydrocarbon hydroxylase and lung cancer is presently problematic because of the difficulties in the assay and subsequent confounding factors.     

A review of genetic polymorphisms and prostate cancer risk

In this study, we review a variety of genetic polymorphisms that may have an etiologic role in prostate cancer. We include associations identified in molecular epidemiology studies and the consistency of findings reported to date. Suggestions for further research are also offered. For the purposes of this review, we identified relevant articles through a MEDLINE search for the period of January 1987 through March 2001. The searches were limited to articles published in English. Medical subject headings were used to scan titles, abstracts, and subject headings in the databases using the keywords "prostate neoplasms," "genetics," and "polymorphisms."     

Molecular biomarkers in cancer: implications for epidemiological research and public health

Identification of molecular biomarkers is a common result of current cancer epidemiological research. Both genetic and molecular epidemiology have enjoyed impressive developments in recent decades, with important repercussions on traditional epidemiological approaches. In this paper we evaluate the new frontiers of cancer epidemiology, incorporating both genetic and molecular biology approaches. We examine the current knowledge of molecular biomarkers for exposure and susceptibility to cancer, the role of gene mutations in carcinogenesis, and their application to epidemiological studies. By exploring the status of relevant biomarkers, these approaches become effective in evaluating exposure and susceptibility and show enormous potential for elucidating mechanisms of carcinogenesis and the effect of risk factors in cancer. However, these approaches are necessarily more invasive and raise several ethical issues for consideration by both researchers in public health and society as a whole.     

N-乙酰转移酶基因多态性与胃癌易感性

目的探讨N-乙酰转移酶2（NAT2）基因多态性与胃癌易感性的关系.方法采用1：1配对病例-对照研究方法和PCR技术,检测121例原发性胃癌患者和相应对照的NAT2基因型,分析其NAT2基因突变位点及表型与胃癌遗传易感性的关系.结果 NAT2 M1位点的突变增加胃癌的发病危险,OR=11.111（95%CI=4.510～27.377）.NAT2 M2、NAT2 M3、NAT2表型在胃癌发生中的作用差异均无统计学意义.结论 NAT2 M位点的突变与胃癌易感性增加有关.     

着色性干皮病基因多态性及单体型与肺癌遗传易感的关联

目的探讨DNA的修复基因着色性干皮病基因B(XPB)、XPD、XPG的单核苷酸多态性和单体型与肺癌遗传易感的关联。方法用病例-对照研究的方法,选择海南省有吸烟暴露史、诊断明确的肺癌患者100例为病例组,与其有相近吸烟暴露史、胸外科其他疾病(如胸外伤、支气管扩张、肺结核等)患者100例为对照组。采用质谱法检测XPB基因rs4150441和rs4150434,XPD基因rs171140和rs11878544,XPG基因rs4771436、rs2094258、rs17655位点的多态性,采用Halopview软件进行单体型构建,探讨XP基因多态性及单体型与肺癌遗传易感性的关联。结果 XPB基因的rs4150434位点,携带GA基因型个体患肺癌的易感性是携带GG基因型个体的2. 071倍(OR=2. 071,95%CI 1. 055～4. 067),携带AA基因型个体患肺癌的易感性是携带GG基因型个体的2. 535倍(OR=2. 535,95%CI 1. 063～6. 044)。XPG基因的rs4771436位点,携带GG基因型个体患肺癌的风险是携带TT基因型个体的2. 494倍(OR=2. 494,95%CI 1. 038～5. 992)。XPG基因的rs2094258位点,携带AA基因型个体对肺癌的易感性是携带GG基因型个体的3. 020倍(OR=3. 020,95%CI1. 015～8. 980)。单体型结果显示,XPB基因rs4150441位点(G> A)和XPB rs4150434位点(G>A)所构成的单体型中,GA单体型的肺癌易感性是GG单体型的3. 643倍(OR=3. 643,95%CI 1. 113～11. 921)。XPG基因rs2094258位点(G>A)、rs4771436位点(T>G)和rs17655位点(C>G)所构成的单体型中,ATC单体型的肺癌易感性是GTC单体型的3. 800倍(OR=3. 800,95%CI 1. 073～13. 459)。结论XPB rs4150434、XPG rs4771436、XPG rs2094258位点多态性与肺癌的遗传易感性相关联,XPB基因的GA单体型和XPG基因的ATC单体型可能增加肺癌的发病风险。     

基因多态性与膀胱癌易感性的研究进展

膀胱癌是泌尿系统常见的恶性肿瘤之一,其发生和发展与环境因素、遗传因素及其交互作用等密切相关。本文综述了Ⅰ、Ⅱ相代谢酶基因和DNA修复基因多态性与膀胱癌易感性的关系,重点讨论了CYP1A1、CYP1A2、CYP2C19、CYP2D6、CYP2E1、NAT1、NAT2、GSTM1和XRCC1基因多态性与膀胱癌的相关性。     

尿苷二磷酸葡萄糖转移酶基因多态性与肿瘤遗传易感性研究进展

尿苷二磷酸葡萄糖转移酶是生物体内重要的Ⅱ相代谢酶,它催化多种内源性和外源性化学物的代谢。根据基因结构、组织表达和底物特异性可将尿苷二磷酸葡萄糖醛酸转移酶分为肝外和肝内表达酶。研究表明尿苷二磷酸葡萄糖醛酸转移酶基因存在大量多态性位点,一些位点改变将影响酶的活性,进而影响酶对化学致癌物的代谢。因此,尿苷二磷酸葡萄糖醛酸转移酶基因多态性最终影响机体发生肿瘤的危险性,如结肠癌、乳腺癌、肺癌、近端消化道肿瘤、肝癌和前列腺癌。本文就尿苷二磷酸葡萄糖醛酸转移酶基因多态性与肿瘤遗传易感性关系作一综述。     

亚甲基四氢叶酸还原酶与肺癌的关联性研究

目的研究中国大陆人群亚甲基四氢叶酸还原酶（MTHFR）基因遗传位点C677T和A1298C多态性与肺癌的关联性。方法通过PubMed和CNKI等数据库检索有关MTHFR基因与肺癌的文献,收集和整理中国大陆人群MTHFR基因遗传位点C677T和A1298C与肺癌有关4 781例数据,进行Meta分析和关联性研究。结果 MTHFR基因遗传位点C677T的等位基因分布和基因型分布对应的假设检验的概率分别为2.6×10-3、9.4×10-3,表明病例对照差异有统计学意义（P〈0.05）;Meta分析对等位基因T的优势比OR值（95%CI）为1.28（1.16～1.41）。遗传位点A1298C的等位基因分布对应的假设检验概率分别为0.713和0.944,说明假设检验差异无统计学意义（P〉0.05）,Meta分析对等位基因A的优势比OR值（95%CI）为1.04（0.85～1.27）。结论 MTHFR基因的单核苷酸C677T多态性是中国大陆人群肺癌的遗传变异位点,A1298C多态性不是中国大陆人群肺癌的风险因素。     

谷胱甘肽过氧化物酶1和硫氧还蛋白还原酶2遗传变异与胃癌易感性的相关性

目的 探讨谷胱甘肽过氧化物酶1(GPX1)第198位氨基酸Pro→Leu和硫氧还蛋白还原酶2(TXNRD2)第370位氨基酸Lys→Arg遗传变异单独或联合与胃癌易感性的关系.方法 采用聚合酶链式反应-限制性片段长度多态性方法,检测361例胃癌患者和363例无肿瘤正常对照的基因型,用logistic多因素分析计算各基因型以及基因-基因交互作用与胃癌易感性的相关性.结果 GPXl 198Pro→Leu和TXNRD2 370Lys→Arg变异单独与胃癌易感性无关.但GPX1和TXNR2基因型存在基因一基因交互作用,携带GPX1 198Pro/Pro和TXNRD2 370Arg/Arg这种保护基因型者患胃癌的风险比携带其他危险基因型者低62%(OR=0.38,95%C/:0.26～0.55,P＜0.001).结论 GPX1198Pro→Leu和TXNRD2 370Lys→Arg基因型可能与胃癌的易感性相关.     

代谢酶基因多态性与结直肠癌的易感性

目的研究代谢酶细胞色素P450（cytochrome P450s,CYP）1A1、谷胱甘肽转移酶（glutathione—S-transferase,GST）M1和T1、尿苷二磷酸葡萄糖醛酸转移酶（UDPglucumnosyltransferase,UGT）1A7基因多态性与结直肠癌的易感性及其交互作用。方法2002年5月在浙江省嘉善县开展的现场病例对照研究及单纯病例研究,获得140例结直肠癌患者和343名健康对照,用PCR-限制性片段长度多态性等方法检测CYP1A1、GSTM1、GSTT1和UGT1A7的基因多态,并应用非条件logistic回归方法进行数据分析。结果CYPIA1 MspI多态（非编码区T6235C）C／C基因型、T／C和C／C基因型者相对于T／T基因型者的OR值分别为0．493（95％CI：0．254—0．956）和0．638（95％CI：0．427—0．952）,具有统计学意义;GSTM1、GSTT1非缺陷型与缺陷型的分布频率对照组和病例组比较差异无统计学意义;对照组和病例组UGT1A7变异／变异型基因与野生纯合型基因比较差异有统计学意义（OR=2．501,95％CI：1．456—4．296）。单纯病例研究分析,CYP1A1与GSTT1、GSTM1与GSTT1对结直肠癌的发生存在交互作用,COR值分别为2．617（95％CI：1．015—6．752）和3．935（95％CI：1．323—11．706）;而CYPlAl与GSTM1、CYP1A1与UGT1A7之间无交互作用。结论CYP1A1 MspI变异型可降低机体对结直肠癌的易感性,而UGT1A7的变异／变异基因型可增加结直肠癌的罹患风险,CYP1A1与GSTT1、GSTM1与GSTT1对结直肠癌的发生存在交互作用。     

Family environment and child's cognitive development: an epidemiological approach

OBJECTIVE: To assess the association between quality of stimulation in the family environment and child's cognitive development considering the impact of mother's schooling on the quality of stimulation. METHODS: A cross-sectional study comprising 350 children aged 17-42 months was carried out in central and peripheral areas of Salvador, Northeastern Brazil, in 1999. A socio-economic questionnaire was used, along with the Home Observation for Measurement of the Environment Scale (HOME Inventory), and the Bayley Scale for Infant Development. Bivariate and multivariate analyses were carried out through linear regression at 5% level of significance. RESULTS: There was a positive (beta=0.66) and statistically significant association between quality of stimulation in the family environment and child's cognitive development. Part of the effect was mediated by the mother's working circumstances and educational level. It was verified that a better quality of stimulation is provided for those who come early in the birth order in family, and live with only a few others under five years of age. This pattern of stimulation is better among children who live with their parents and whose mothers have better education, have a job and a partner involved in the family environment. CONCLUSIONS: Quality of stimulation in the family environment is crucial for child's cognitive development, besides the significant role of the available resources and family dynamics. The study findings show the pertinence to cognitive development of interventions which improve the quality of the environment and the child-caregiver relationship.     

DAT13’端VNTR区多态性与异常体液型癌症的相关性研究

目的探讨多巴胺转运体基因1(DAT1)3’端40bp VNTR多态性与新疆省维吾尔族异常体液型癌症的相关性。方法按维吾尔医将癌症患者分为4种体液型,采用聚合酶链式反应(PCR)和VNTR多态性分析技术对新疆省维吾尔族47例异常黑胆质型癌症患者、26例其它异常体液型癌症患者和57例正常对照组DAT1多态性进行检测,比较各组间等位基因和基因型频率分布的差异。结果(1)所测人群中,DAT1 VNTR多态性表现出6～11倍重复的6种等位基因,其中最为常见的等位基因为10倍重复的480bp片段,其基因频率为90.4%。共检出6种基因型,其中最常见的基因型为480bp/480bp,占80.7%。(2)DAT1 VNTR10倍重复等位基因及10/10基因型个体患异常黑胆质型癌症的发病风险与非10倍重复等位基因和非10/10基因型个体差异无统计学意义(P=0.158,OR=1.994,95%CI为0.754～5.275;P=0.138,OR=2.143,95%CI为0.772～5.947);异常黑胆质型癌症患者和其它异常体液型癌症患者的DAT1 VNTR等位基因及基因型频率的差异均无显著性(P=0.729;P=0.782)。结论DAT13’端40bp可变串联重复多态性可能与维吾尔医异常体液型癌症易感性无关。     

Significance of genetic polymorphisms in glutathione S-transferase multigene family and lung cancer risk

A vast number of studies are focused on investigating genetic polymorphism in order to estimate genetic contribution to the development of cancer. Possible cancer susceptibility genes have been sought among oncogenes, tumor suppressor genes, DNA repair genes and genes encoding phase I and phase II enzymes. Large individual differences in the biotransformation of xenobiotics have been explained on the basis of genetic polymorphisms in some detoxifying enzymes, regardless of environmental and occupational exposure. Among these enzymes, glutathione S-transferases (GST) constitute a large multigene family of phase II enzymes involved in detoxification of potentially genotoxic chemicals. Five genetic polymorphisms of GST have been well documented. Total or partial deletions and (or) single nucleotide polymorphisms in alleles encoding GSTM1, GSTM3, GSTPI, GSTT1, GSTZ1 are associated with reduction of enzymatic activity toward several substrates of different GST isoenzymes. In addition, molecular epidemiology studies indicate that a single genetic polymorphism of glutathione S-transferase appears to be a moderate lung cancer risk factor. However, the risk is higher when interactions with more GST polymorphisms and other risk factors (e.g. cigarette smoking) occur. Individuals with decreased rate of detoxification, with "high risk" glutathione S-transferase genotypes have a slightly higher level of carcinogen-DNA adducts and more cytogenetic damages.