ROR1-AS1调控Notch1信号通路对乳腺癌MCF-7细胞增殖和凋亡影响

摘 要：［目的］ 研究酪氨酸蛋白激酶跨膜受体 1 反义 RNA 1（tyrosine protein kinase transmembrane receptor 1 antisense RNA 1，ROR1-AS1）调控Notch1信号通路对乳腺癌MCF-7细胞增殖、凋亡及上皮-间质转化(epithelial-mesenchymal transition，EMT)的影响。［方法］ 实时荧光定量PCR方法检测乳腺癌MCF-7、MDA-MB-231、MDA-MB-361细胞和正常乳腺上皮MCF10A细胞中ROR1-AS1表达变化。乳腺癌MCF-7细胞分成对照、sh-NC（转染shRNA 对照）、sh-ROR1-AS1（转染ROR1-AS1 shRNA）、sh-ROR1-AS1+Jagged1组（转染ROR1-AS1 shRNA，Notch1通路激活剂Jagged1处理）。CCK-8实验检测细胞增殖，流式细胞术检测细胞凋亡，Transwell小室检测细胞迁移和侵袭，Western blot方法检测细胞中活化的半胱氨酰天冬氨酸特异性蛋白酶9（cleaved cysteinyl aspartate-specific protease-9，C-Caspase-9）、上皮型钙黏蛋白（E-cadherin）、活化的半胱氨酰天冬氨酸特异性蛋白酶3（cleaved cysteinyl aspartate-specific protease-3，C-Caspase-3）、神经型钙黏蛋白（N-cadherin）、Notch1、Hes1蛋白表达。 ［结果］ 乳腺癌MCF-7、MDA-MB-231、MDA-MB-361细胞中ROR1-AS1水平明显高于正常乳腺上皮MCF10A细胞（P<0.05）。与对照组、sh-NC组比较，sh-ROR1-AS1组乳腺癌MCF-7细胞存活率降低(100.00%±9.82%，99.74%±12.05%，58.91%±6.33%)，细胞凋亡率升高(4.81%±0.26%，4.93%±0.34%，20.58%±2.11%），细胞迁移数目( 225.36±12.84个，224.89±19.56个，140.89±13.64个）和侵袭数目(180.47±16.32个，177.54±16.92个，110.44±10.87个)减少，细胞中C-Caspase-9、E-cadherin、C-Caspase-3蛋白表达水平增加，N-cadherin、Notch1、Hes1蛋白表达水平降低（P<0.05）。与sh-ROR1-AS1组比较，sh-ROR1-AS1+Jagged1组乳腺癌MCF-7细胞存活率升高(100.00%±11.58% vs 147.36%±12.05%），细胞凋亡率降低(19.54%±1.74% vs 8.36%±0.75%)，细胞迁移数目(139.58±12.78个 vs 175.26±16.94个)和侵袭数目（107.45±9.35个 vs 162.04±13.67个）均升高，C-Caspase-9、E-cadherin、C-Caspase-3蛋白水平降低，N-cadherin、Notch1、Hes1蛋白水平升高（P<0.05）。［结论］ 下调ROR1-AS1通过抑制Notch1信号减弱乳腺癌MCF-7细胞增殖、迁移、侵袭和EMT能力，激活细胞凋亡。     

敲低性别决定区Y-box蛋白5对胃癌细胞增殖、侵袭和上皮间质转化的影响

摘 要：［目的］ 探讨敲低性别决定区Y-box蛋白5（Sox-5）的表达水平及对胃癌细胞增殖、侵袭和上皮间质转化（EMT）的影响。［方法］ 实时荧光定量聚合酶链反应（qRT-PCR）检测胃癌细胞和正常人胃黏膜上皮细胞中Sox-5 mRNA的相对表达水平；sh-NC和sh-Sox-5质粒转染BGC823细胞，蛋白免疫印迹实验检测Sox-5蛋白表达水平；MTT实验、划痕实验和Transwell实验分别检测BGC823细胞增殖活性、迁移能力和侵袭能力；蛋白免疫印迹实验检测扭曲蛋白（Twist）、波形蛋白（Vimentin）、E-钙黏蛋白（E-cadherin）的表达。［结果］ 胃癌细胞中Sox-5 mRNA的相对表达水平高于正常人胃黏膜上皮细胞（P<0.01）；与转染sh-NC组相比，转染sh-Sox5质粒组中Sox-5蛋白的相对表达水平降低（1.120±0.142 vs 0.124±0.010，t=9.032，P<0.001）；与转染sh-NC组相比，转染sh-Sox-5组细胞增殖活性显著降低（1.32±0.10 vs 0.74±0.06，t=3.514，P=0.005），迁移率能力减弱（46.2%±4.7% vs 17.6%±2.5%，t=9.625，P<0.001），侵袭能力减弱（93.7±9.1 vs 113.7±6.5，t=3.103，P=0.036）；敲低Sox-5蛋白表达后Twist和Vimentin蛋白表达减弱，E-cadherin蛋白表达增强（P均<0.001）。［结论］ 敲低胃癌细胞中Sox-5的表达，可抑制胃癌细胞的增殖、迁移、侵袭和EMT。     

过表达miR-497靶向细胞周期蛋白E1抑制肺癌A549细胞的上皮间质转化

目的：探讨过表达 miR-497 靶向细胞周期蛋白 E1（cyclin E1,CCNE1）对肺癌 A549 细胞上皮间质转化（epithelialmesenchymal transition,EMT）的影响。方法：常规培养人肺癌A549细胞,细胞实验分为正常组（不加干预）、对照组（转染miR497 mimics-NC）、实验组（转染miR-497 mimics）。采用Transwell小室实验、免疫荧光染色、qPCR、Western blotting法分别检测各组细胞迁移和侵袭能力、蛋白间质标志物α-SMA和上皮标志物E-cadherin的表达、miR-497和CCNE1的表达水平,荧光素酶基因基因报告实验验证miR-497和CCNE1的靶向关系。结果：与对照组和正常组相比,实验组A549细胞迁移和侵袭的数量明显减少（均P<0.05）,细胞的间质标志物α-SMA的绿色荧光强度明显减弱（[ 36.95±5.81）vs（98.69±2.36）、（97.94±2.63）,均P<0.05],上皮标志物E-cadherin的绿色荧光强度明显增强（[ 388.41±10.93）vs（100.95±6.37）、（102.55±3.18）,均P<0.05],miR-497 的表达明显升高（均P<0.05）,CCNE1的表达均明显下降（均P<0.05）。miR-497能够靶向调控CCNE1的表达。结论：在肺癌A549细胞中miR-497能够靶向调控CCNE1的表达,上调miR-497的表达后能明显抑制A549细胞迁移和侵袭能力,影响EMT相关蛋白的表达。     

miR-640通过抑制SLIT1介导Wnt/β-catenin通路促进脑胶质瘤对替莫唑胺的耐药

摘 要：［目的］评价miR-640介导Wnt/β-catenin通路对脑胶质瘤耐药细胞增殖、侵袭及替莫唑胺(temazolamide,TMZ)敏感性的影响。［方法］ 利用实时荧光定量聚合酶链反应（RT-qPCR）测定脑胶质瘤细胞内miR-640的表达。U87/TMZ细胞分为NC inhibitor组、 miR-640 inhibitor组和miR-640 inhibitor+si-SLIT1组。用不同浓度（15、30、60、120、240 、480和960 μmol/L）TMZ处理细胞,检测细胞对TMZ的耐药性;运用细胞计数试剂盒8（CCK-8）、Transwell实验检测U87/TMZ细胞增殖活力和侵袭力;用双荧光素酶报告基因实验验证miR-640与SLIT1的靶向关系。采用Western blot检测Wnt/β-Catenin信号通路相关蛋白表达水平。［结果］ miR-640在脑胶质瘤细胞中高表达,转染后miR-640 inhibitor组的miR-640表达水平、侵袭细胞数目（57±23 vs 153±31）、IC50值（131.61±8.97 vs 293.33±11.28）、增殖率（18.48±4.23 vs 43.84±8.94）均比NC inhibitor组低（P<0.05）。miR-640靶向调控SLIT1的表达,miR-640 inhibitor+si-SLIT1组β-catenin、c-myc、Cyclin D1蛋白表达水平均高于miR-640 inhibitor组（P<0.05）。［结论］miR-640通过SLIT1介导Wnt/β-catenin通路促进脑胶质瘤增殖、侵袭及对替莫唑胺的耐药性。     

干扰TBL1XR1表达调控c-Met/PI3K/Akt通路对胰腺癌细胞生物学行为影响的实验研究

目的 探讨干扰TBL1XR1表达对胰腺癌细胞增殖、迁移、侵袭和上皮间质转化(EMT)的影响,及其可能分子机制.方法 体外培养胰腺癌细胞AsPC-1,分为空白对照组、阴性对照组(转染scramble shRNA),si-TBL1XR1组(转染TBL1XR1 shRNA),AMG-458组(加入c-Met抑制剂AMG-45...     

LASP1在鼻咽癌组织中的表达及其临床预后价值分析

摘 要：［目的］ 探讨LASP1在鼻咽癌组织中的表达与预后的关系,及其在鼻咽癌中的功能。［方法］ 免疫组化法检测79例鼻咽癌患者组织标本中LASP1蛋白的表达。Western Blot和Real-time PCR检测鼻咽癌细胞株中LASP1表达。Transwell小室实验明确体外LASP1对细胞迁移和侵袭能力的影响。Kaplan-Meier法分析LASP1表达与患者预后的关系,Cox比例风险回归模型分析LASP1表达在鼻咽癌患者预后预测中的价值。［结果］ LASP1在鼻咽癌组织（0.087±0.103）表达显著高于癌旁组织（0.016±0.010）（t=2.154,P=0.034）。LASP1在N2~3期（χ2=38.406,P<0.001）与Ⅳ期（χ2=4.595,P=0.043）患者表达较N0~1和Ⅱ~Ⅲ期患者更高。LASP1高表达与低表达两组患者总生存（overall survival,OS）、无远处转移生存（distant metastasis free survival,DMFS）和无局部复发生存（relapse free survival,RFS）分别为(114.5±8.5)个月 vs (137.5±4.6)个月(P=0.038）、(112.3±9.1)个月vs (140.3±3.8)个月（P=0.009）和(108.6±9.4)个月 vs (134.6±5.3)个月（P=0.029）。LASP1高表达（HR=4.437,95%CI：1.148~17.415,P=0.031）和TNM分期（HR=5.512,95%CI：1.075~28.254,P=0.041)是患者生存的独立预测因素。LASP1在鼻咽癌细胞株中表达（1.47±0.35）较正常鼻咽上皮细胞株（0.90±0.11）也显著升高（t=4.488,P<0.001）。过表达LASP1的鼻咽癌细胞株与对照组相比,Transwell小室细胞侵袭［（238.7±36.2） vs （48.7±11.6）］、迁移［（571.0±15.7） vs （91.6±20.3）］能力显著增强（P<0.01）。采用特异性shRNA敲低LASP1表达,鼻咽癌细胞体外侵袭［（168.7±14.6） vs （64.3±7.4）］和迁移［（205.0±9.8） vs （79.0±10.5）］能力受到抑制（P<0.01）。［结论］ LASP1在鼻咽癌组织和细胞中过表达,与鼻咽癌患者分期相关,且LASP1高表达是患者预后不良因素。体外功能实验表明LASP1发挥促进肿瘤侵袭和迁移功能。提示LASP1在鼻咽癌进展中发挥重要作用,可作为鼻咽癌诊治新的分子靶点。     

STC1诱导上皮-间质转化促进肺癌细胞的侵袭和迁移

背景与目的：斯钙素1（stanniocalcin 1,STC1）与癌症的发展和不良预后相关,但STC1对肺癌细胞转移的影响及其作用机制目前还未完全阐明。探讨STC1对肺癌细胞侵袭和迁移的影响及其可能的内在分子机制。方法：构建STC1过表达的细胞系HLEC-STC1及对照细胞系HLEC-EV,STC1沉默的细胞系A549-STC1 siRNA及对照细胞系A549-EV;采用Transwell和划痕实验检测细胞的侵袭和迁移能力;采用实时荧光定量聚合酶链反应（real-time fluorescence quantitative polymerase chain reaction,RTFQ-PCR）和蛋白质印迹法（Western blot）检测上皮-间质转化（epithelial-mesenchymal transition,EMT）标志物的mRNA和蛋白质水平变化;并使用细胞免疫荧光技术进一步验证细胞EMT标志物的表达和定位;采用Western blot检测EMT相关信号通路蛋白和转录因子的水平。结果：与对照细胞相比,过表达STC1的HLEC-STC1细胞的侵袭和迁移能力增强,STC1沉默的A549-STC1 siRNA细胞的侵袭和迁移能力减弱（P＜0.05）;过表达STC1的HLEC-STC1细胞中上皮标志物上皮型钙黏蛋白（E-cadherin）的表达下调,间质标志物神经型钙黏蛋白（N-cadherin）、波形蛋白（vimentin）及肿瘤干细胞标志物上皮细胞黏附分子（epithelial cell adhesion molecule,EpCAM）表达上调（P＜0.05）;低表达STC1的A549-STC1 siRNA细胞中E-cadherin的表达上调,N-cadherin、vimentin及EpCAM的表达下调（P＜0.05）;同时,HLEC-STC1细胞中细胞外调节蛋白激酶信号通路（extracellular signal-regulated protein kinase,ERK）及Wnt/β-连环蛋白（β-catenin）信号通路激活相关的磷酸化（p）-ERK和β-catenin的水平升高,转录因子E盒结合锌指蛋白1（zinc finger E-box-binding homeobox 1,ZEB1）和锌指转录因子1（Snail1）的表达水平上调,A549-STC1 siRNA细胞中的结果则相反（P＜0.05）。结论：STC1可能通过激活ERK和Wnt/β-catenin信号通路上调转录因子ZEB1和Snail1的表达水平,从而诱导EMT促进肺癌细胞的侵袭和迁移。     

WP1130通过下调β-catenin增强鼻咽癌细胞化疗敏感性

摘 要：［目的］探讨WP1130与顺铂联合用药对鼻咽癌细胞增殖和转移的影响及其可能机制。［方法］ CCK-8法检测鼻咽癌顺铂敏感细胞系HNE1和顺铂耐药细胞系HNE1/DDP的顺铂药物半抑制浓度（IC50）,以及不同浓度WP1130对鼻咽癌细胞活力的影响;选取适当药物浓度处理细胞,两种鼻咽癌细胞系分别分为4组：空白对照组（DMSO）、DDP单药组（6 ?滋mol/L顺铂）、WP1130单药组（1.25 ?滋mol/L WP1130）以及DDP+WP1130联合用药组（6 ?滋mol/L顺铂+1.25 ?滋mol/L WP1130）。MTT法检测鼻咽癌细胞增殖能力;细胞划痕实验检测鼻咽癌细胞迁移能力;Transwell侵袭实验检测鼻咽癌细胞侵袭能力;RT-PCR和Western blot实验检测顺铂耐药HNE1/DDP与亲本HNE1鼻咽癌细胞中β-catenin的表达情况以及不同药物处理对β-catenin的表达的影响。［结果］ 耐药HNE1/DDP细胞比亲本HNE1细胞对顺铂的耐受性提高了近5.7倍（5.17±0.33 vs 29.44±2.62,P＜0.01）。β-catenin在HNE1/DDP细胞中的mRNA表达上调约3.4倍（1.00±0.26 vs 3.44±0.39,P＜0.01）。与空白对照组和单药组相比,顺铂+WP1130联合用药组细胞中β-catenin的表达显著下调（HNE1：1.00±0.06 vs 0.78±0.07 vs 0.32±0.05,P＜0.05;HNE1/DDP：1.01±0.05 vs 0.57±0.07 vs 0.39±0.07,P＜0.05）,顺铂+WP1130联合用药组细胞增殖、迁移和侵袭能力均显著下降（P均＜0.01）。［结论］ WP1130与顺铂联合用药可以通过下调β-catenin的表达增强顺铂对细胞增殖、迁移和侵袭的抑制作用,从而增强鼻咽癌细胞的化疗敏感性。     

Rap1GAP对胃癌细胞侵袭、迁移及上皮细胞-间充质转化的作用

摘 要：［目的］ 分析Rap1GAP对胃癌细胞增殖、侵袭及迁移能力的影响。［方法］ 运用qRT-PCR及Western blo法检测Rap1GAP在胃癌细胞中的表达。Rap1GAP载体慢病毒感染MGC803及MKN-45两个细胞系,构建出Rap1GAP高表达胃癌细胞系。MTT、细胞克隆形成实验、Transwell实验及划痕实验检测Rap1GAP 对胃癌细胞增殖、侵袭及迁移能力的影响。运用qRT-PCR及Western blot法检测上皮化标志物E-cadherin、Snail和N-cadherin的表达。［结果］正常细胞株GES-1中Rap1GAP表达量为1.02±0.08,而SGC7901、AGS、MGC803、HGC-27、MKN-45中表达量分别为0.66±0.10、0.51±0.10、0.20±0.08、0.31±0.07、0.26±0.11（P均<0.01）。体外实验显示Rap1GAP能抑制胃癌细胞的增殖（酶标仪检测波长为570 nm时的吸光度）、侵袭及迁移能力;且Rap1GAP能抑制胃癌细胞的EMT。［结论］ Rap1GAP在胃癌进展中起到抑癌作用,具有成为胃癌治疗靶点的潜力。     

甲基化修饰抑癌基因MSX1抑制黑色素瘤细胞迁移和侵袭的研究

目的 探讨MSX1在黑色素瘤细胞系和组织中表达和甲基化及对黑色素瘤细胞A375迁移/侵袭的影响和机制。方法 qRT-PCR和免疫组织化学法分别检测MSX1在黑色素瘤细胞系和组织中的表达;甲基化PCR分析MSX1在黑色素瘤组织中甲基化;分别转染pcDNA3.1(+)-Flag-MSX1质粒(实验组)和pcDNA3.1(+)-Flag-Vector质粒(对照组)至A375细胞;Transwell迁移和侵袭实验检测MSX1对细胞迁移和侵袭的影响;RT-PCR验证MSX1对上皮间质转化及下游相关标志物的影响,免疫蛋白印迹实验验证MSX1对WNT/β-catenin信号通路的影响。结果 与色素痣组织和细胞相比,MSX1 mRNA和蛋白在黑色素瘤细胞和组织中表达下调(P＜0.001);MSX1甲基化水平表达上调,其甲基化程度明显高于癌旁组织和正常色素痣组织。过表达MSX1后抑制细胞迁移和侵袭(P＜0.001),而上皮间质转化及下游相关标志物表达受到抑制。过表达MSX1能抑制WNT/β-catenin信号通路及其下游细胞因子的表达。结论 MSX1在黑色素瘤组织中表达下调,能抑制Wnt/β-catenin信号通路参与黑色素瘤的进展。     

Polymorphisms in GSTM1, GSTT1 and CYP1A1 and risk of pancreatic adenocarcinoma

A prospective study of 149 unselected incident cases of pancreatic adenocarcinoma and 146 ethnically-matched controls found no associations between GSTM1 (adjusted odds ratio (AOR) 1.14), GSTT1 (AOR: 1.19) and CYP1A1 (AOR: 1.08) polymorphisms and pancreatic cancer susceptibility. Smoking and drinking status did not affect results. These polymorphisms do not appear to be important gene modifiers in pancreatic cancer.     

GSTM1, GSTT1 and GSTP1 polymorphisms and lung cancer risk

Previous studies have suggested that GST genotypes may play a role in determining susceptibility to lung cancer, though the data are often conflicting. In this study we investigated GSTM1, GSTT1 and GSTP1 status in relation to lung cancer risk in patients attending a Manchester bronchoscopy clinic. Cases were all patients (n=94) currently with, or with a history of, tumours of the lung, trachea or bronchus. The control group were all other patients (n=165) who were free of benign and malignant tumours both at the time of, or prior to, diagnosis. All patients were interviewed for information on lifestyle risk factors, and DNA extracted from bronchial lavage and blood samples was used for genotyping. GSTM1 null genotype was associated with decreased lung cancer risk (odds ratio (OR) 0.50, 95% confidence interval (CI) 0.29–0.87), particularly among men (OR 0.43, 95% CI 0.21–0.87) and those above the median age (OR 0.33, 95% CI 0.15–0.70). No difference in GSTT1 and GSTP1 genotype distribution was seen between cases and controls. The GSTM1 null genotype was associated with a decreased risk of squamous cell carcinoma: the OR, adjusted for age, sex and pack years was 0.32 (95% CI 0.12–0.82). As previous studies have reported that the GSTM1 null genotype is associated with an increased lung cancer risk, further work is required to determine whether the observed association is true, or whether it arises from bias or confounding factors.     

Polymorphisms in CYP1B1, GSTM1, GSTT1 and GSTP1, and susceptibility to breast cancer

Polymorphisms in the cytochrome P450 1B1 (CYP1B1) and glutathione S-transferase (GST) drug metabolic enzymes, which are responsible for metabolic activation/detoxification of estrogen and environmental carcinogens, were analyzed for their association with breast cancer risk in 541 cases and 635 controls from a North Carolina population. Each polymorphism, altering the catalytic function of their respective enzymes, was analyzed in Caucasian and African-American women. As reported in previous studies, individual polymorphisms did not significantly impact breast cancer risk in either Caucasian or African-American women. However, African-American women exhibited a trend towards a protective effect when they had at least one CYP1B1 119S allele (OR=0.53; 95% CI=0.20-1.40) and increased risk for those women harboring at least one CYP1B1 432V allele (OR=5.52; 95% CI=0.50-61.37). Stratified analyses demonstrated significant interactions in younger (age < or =60) Caucasian women with the CYP1B1 119SS genotype (OR=3.09; 95% CI=1.22-7.84) and younger African-American women with the GSTT1 null genotype (OR=4.07; 95% CI=1.12-14.80). A notable trend was also found in Caucasian women with a history of smoking and at least one valine allele at GSTP1 114 (OR=2.12; 95% CI=1.02-4.41). In Caucasian women, the combined GSTP1 105IV/VV and CYP1B1 119AA genotypes resulted in a near 2-fold increase in risk (OR=1.96; 95% CI=1.04-3.72) and the three way combination of GSTP1 105IV/VV, CYP1B1 119AS/SS and GSTT1 null genotypes resulted in an almost 4-fold increase in risk (OR=3.97; 95% CI=1.27-12.40). These results suggest the importance of estrogen/carcinogen metabolic enzymes in the etiology of breast cancer, especially in women before the age of 60, as well as preventative measures such as smoking cessation.     

CYP1B1 and hormone-induced cancer

Cancers in hormone-responsive tissues (e.g., breast, ovary, endometrium, prostate) occur at high incidence rates worldwide. However, their genetic basis remains poorly understood. Studies to date suggest that endogenous/exogenous oestrogen and environmental carcinogens may play a role in development and/or progression of hormone-induced cancers via oxidative oestrogen metabolism. Cytochrome P450 1B1 is a key enzyme in its oestrogen metabolism pathway, giving rise to hydroxylation and conjugation. Although CYP1B1 is expressed in many cancers, particularly high levels of expression are observed in oestrogen-mediated disease. CYP1B1 is more readily found in tumour tissue compared to normal. Given the role of CYP1B1 in pro-carcinogen and oestrogen metabolism, polymorphisms in CYP1B1 could result in modifications in its enzyme activity and subsequently lead to hormone-mediated carcinogenesis. CYP1B1 may also be involved in progression of the disease by altering the tissue response to hormones and clinical response to chemotherapy. The exact mechanism behind these events is complex and unclear. Only a few functional single nucleotide polymorphisms of CYP1B1 are known to result in amino acid substitutions and have been extensively investigated. Studies examining the contribution of different CYP1B1 alleles to hormone-mediated cancer risks are inconsistent. The main focus of this review is to appraise the available studies linking the pathogenesis of the hormone-induced cancers to various CYP1B1 polymorphisms. Additionally, we explore the role of a neuronal protein, γ-synuclein, in CYP1B1-mediated pathogenesis.     

Genetic polymorphisms of CYP1A1, GSTM1 and GSTT1 genes and lung cancer risk

Genetic polymorphisms of the genes encoding for the xenobiotic metabolizing enzymes result in individual variations in the efficiency of detoxification of environmental carcinogens, and have been extensively associated with variable risk for lung neoplasms in different ethnic and environmental backgrounds. In this study, using PCR-RFLP based assays, we investigated the distribution of genetic polymorphisms in CYP1A1, GSTM1 and GSTT1 genes in Greek lung cancer patients (N=122) and healthy controls (N=178). The frequency of CYP1A1 m1 homozygous genotype was 0.04 in patients and 0.02 in controls (detected in 4.10% of patients and in 1.69% of controls, respectively), that of GSTM1 null genotype was 0.52 in patients and 0.54 in controls, whereas those of GSTT1 null genotype was 0.17 and 0.11, in patients and controls, respectively. The GSTM1 null genotype was more frequent in adenocarcinoma, as well as in lung cancer patients with history of chronic obstructive pulmonary disease (COPD). The GSTT1 null genotype correlated with advanced age of the patients at the time of diagnosis. Three combinations of rare genotypes - in subjects carrying simultaneously deviations from the common genotype in more than one gene - were over-represented in lung cancer patients, compared to control population, and were furthermore significantly associated with history of heavy tobacco consumption in lung cancer patients. The results imply involvement of specific genotype combinations of CYP1A1, GSTM1 and GSTT1 alleles in the development of lung cancer in heavy smokers.     

Genetic polymorphisms of SULT1A1 and SULT1E1 and the risk and survival of breast cancer.

We examined whether common single nucleotide polymorphisms (SNP) in SULT1A1 (c.779G>A, *14A>G, and *85C>T) and SULT1E1 (IVS1-447C>A, IVS4-1653T>C, and *959G>A) genes influenced the risk and survival of breast cancer. Our study population consisted of 989 histologically confirmed sporadic breast cancer patients and 1,054 controls without history of cancer recruited from three teaching hospitals in Seoul. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by logistic regression model. In the survival analysis for 529 breast cancer patients with completed treatments, the hazard ratios (HR) were calculated with Cox proportional hazard model. Women with the SULT1E1 *959 GA/AA genotype had a moderately decreased breast cancer risk compared with those with the GG genotypes (OR, 0.8; 95% CI, 0.70-1.00). When the haplotypes were considered, the homozygous *959 AA genotype together with the IVS4-1653 T>C base change (CTA-CCA haplotype) was associated with halved breast cancer risk (OR, 0.5; 95% CI, 0.24-0.88) compared with the wild type CTG-CTG haplotype. No other significant overall association was observed between the SULT1A1 and SULT1E1 SNPs nor haplotypes and breast cancer risk. When stratified by survival, patients with the SULT1E1 IVS4-1653 TC/CC genotypes showed a >3-fold risk of recurrence (HR, 3.2; 95% CI, 1.39-7.48) compared with those with the TT genotype. Moreover, when the haplotypes were considered, the SULT1E1 *959 G>A base change together with the IVS4-1653 T>C base change (CTG-CCA haplotype) was associated with a >4-fold risk of breast cancer (OR, 4.2; 95% CI, 1.15-15.15). These findings suggest that genetic polymorphisms of SULT1E1 are associated with increased risk and a disease free survival of breast cancer in Korean women.     

CYP1A1, GSTM1, and GSTP1 genetic polymorphisms and urinary 1-hydroxypyrene excretion in non-occupationally exposed individuals.

The CYP1A1 and glutathione S-transferase enzymes (e.g., GSTM1 and GSTP1) are involved in the activation and conjugation of polycyclic aromatic hydrocarbons (PAHs), respectively, and are controlled by genes that are polymorphic. The CYP1A1*2 allelic variant has been associated with elevated urinary 1-hydroxypyrene (1-OHP), a proposed marker for internal dose of activated PAHs, in coke-oven workers. We investigated whether this association could be observed at low exposure levels, such as those experienced by the general population. We conducted a cross-sectional study among 188 individuals (106 Japanese, 60 Caucasians, and 22 Hawaiians) who were selected as controls in a population-based case-control study and provided lifestyle information, a 12-h urine specimen, and a blood sample. 1-OHP was analyzed by high-performance liquid chromatography after enzymatic hydrolysis. Lymphocyte DNA was used for PCR-based genotyping. Smokers excreted twice as much 1-OHP (geometric mean, 0.51 nmol/12 h) as nonsmokers (geometric mean, 0.27 nmol/12 h; P = 0.006). Overall and among nonsmokers, 1-OHP urinary levels did not differ by CYP1A1, GSTM1, or GSTP1 genotypes. However, after adjusting for age, ethnicity, and number of cigarettes per day, smokers with at least one CYP1A1*2 variant allele excreted 2.0-fold more 1-OHP than smokers with the wild-type genotype (P = 0.02). Similar results were obtained for the CYP1A1*3 variant allele. The present data add to the growing evidence suggesting that individuals with the (linked) CYP1A1*2 or *3 variant alleles have a greater capacity to activate PAHs from tobacco smoke and occupational exposure and, as a result, are at greater risk for PAH-related cancers, especially certain respiratory cancers.     

CYP1A1, GSTM1, and GSTT1 polymorphisms and breast cancer risk in Brazilian women

The frequency of CYP1A1 (CYP1A1*2A), GSTM1, and GSTT1 polymorphisms, as well as the main risk factors associated with breast cancer were studied in Brazilian women, with malignant breast cancer (n=128), or age-matched controls (n=256). Only a family history of breast cancer presented a significant risk (OR=3.00, CI=1.27-7.06). Among non-whites, the CYP1A1*2A allele was underrepresented among patients. Statistical analysis indicated that this polymorphism may decrease the risk of breast cancer among these individuals, particularly after adjusting for the risk presented by selected risk factors (OR=0.30, 95% CI=0.12-0.76).     

Methoxyestrogens exert feedback inhibition on cytochrome P450 1A1 and 1B1

Cytochrome P450 1A1 (CYP1A1) and 1B1 (CYP1B1) catalyze the oxidative metabolism of 17 beta-estradiol (E2) to catechol estrogens (2-OHE2 and 4-OHE2) and estrogen quinones, which may lead to DNA damage. Catechol-O-methyltransferase catalyzes the methylation of catechol estrogens to methoxyestrogens (2-MeOE2, 2-OH-3-MeOE2, and 4-MeOE2), which simultaneously lowers the potential for DNA damage and increases the concentration of 2-MeOE2, an antiproliferative metabolite. In this study, we showed that CYP1A1 and CYP1B1 recognized as substrates both the parent hormone E2 and the methoxyestrogens. Using purified recombinant enzymes, we demonstrated that CYP1A1 and CYP1B1 O-demethylated the methoxyestrogens to catechol estrogens according to Michaelis-Menten kinetics. Both CYP1A1 and CYP1B1 demethylated 2-MeOE2 and 2-OH-3-MeOE2 to 2-OHE2, whereas CYP1B1 additionally demethylated 4-MeOE2 to 4-OHE2. Because the P450-mediated oxidation of E2 and the O-demethylation of methoxyestrogens both yielded identical catechol estrogens as products, we used deuterated E2 (E2-d4), unlabeled methoxyestrogens, and gas chromatography/mass spectrometry to examine both reactions simultaneously. Kinetic analysis revealed that methoxyestrogens acted as noncompetitive inhibitors of E2 oxidation with K(i) ranging from 27 to 153 micro M. For both enzymes, the order of inhibition by methoxyestrogens was 2-OH-3-MeOE2 > or = 2-MeOE2 > 4-MeOE2. Thus, methoxyestrogens exert feedback inhibition on CYP1A1- and CYP1B1-mediated oxidative estrogen metabolism, thereby reducing the potential for estrogen-induced DNA damage.     

Meta- and pooled analyses of GSTM1, GSTT1, GSTP1, and CYP1A1 genotypes and risk of head and neck cancer.

Sequence variation in the GSTM1, GSTT1, GSTP1, and CYP1A1 genes may potentially alter susceptibility to head and neck cancers, although evidence from previous studies has not been consistent. To explore these associations, we conducted a meta-analysis of 31 published case-control studies (4635 cases and 5770 controls) and a pooled analysis of original data from nine published and two unpublished case-control studies (2334 cases and 2766 controls). In the meta-analysis, the summary odds ratios (ORs) for head and neck cancer were 1.23 [95% confidence interval (95% CI), 1.06-1.42] for the GSTM1 null genotype, 1.17 (95% CI, 0.98-1.40) for the GSTT1 null genotype, 1.10 (95% CI, 0.92-1.31) for carrying the GSTP1 Val105 allele, and 1.35 (95% CI, 0.95-1.82) for carrying the CYP1A1 Val462 allele. The pooled analysis ORs were 1.32 (95% CI, 1.07-1.62) for the GSTM1 null genotype, 1.25 (95% CI, 1.00-1.57) for the GSTT1 null genotype, 1.15 (95% CI, 0.86-1.53) for carrying the GSTP1 Val105 allele, and 0.98 (95% CI, 0.75-1.29) for carrying the CYP1A1 Val462 allele. Increasing risk of head and neck cancer was observed with inheritance of increasing numbers of modest risk genotypes at the three GST loci (P for trend = 0.04), with the combination of carrying the GSTM1 null, GSTT1 null, and GSTP1 Val105 alleles conferring an OR of 2.06 (95% CI, 1.11-3.81). In conclusion, both the meta- and pooled analysis support modest associations of GSTM1 and GSTT1 genotypes with head and neck cancer risk, and our pooled analysis supports the notion of greater risk when genotypes at multiple GST loci are considered in a multigenic model.