碱基切除修复基因APE和XRCC1表达与大肠癌发生相关性的探讨

目的:通过检测大肠癌、癌旁黏膜与正常黏膜中APE和XRCC1蛋白的表达,探讨大肠癌的发生机制.方法:选取大肠癌手术切除标本185例,其中32例标本取癌旁黏膜组织;正常黏膜组织36例.通过免疫组化方法检测APE和XRCC1蛋白在癌、癌旁黏膜和正常黏膜的表达.结果:大肠癌、癌旁黏膜组APE阳性表达率分别为78.9％(146/185)和81.2％(26/32),两者均明显高于正常黏膜组的61.1％(22/36),x2值分别为5.23和4.86,P值分别为0.024和0.03,但前两者APE表达差异无统计学意义.大肠癌中APE蛋白表达与患者性别、年龄、肿瘤部位、分化程度、浆膜浸润及淋巴结转移无明显相关关系.大肠癌与癌旁黏膜组XRCC1阳性表达率分别为94.6％(175/185)和87.5％(27/32),两者均明显高于正常黏膜组的27.7％(10/36),x2值分别为4.43和29.69,P值分别为0.036和0.002,但前两者间差异无统计学意义.大肠癌中XRCC1蛋白表达与患者性别、年龄、肿瘤部位、分化程度、浆膜浸润及淋巴结转移无明显相关关系.大肠癌XRCC1阳性组的APE阳性率为95.8％(136/142),显著高于大肠癌XRCC1阴性组的86.0％(37/43),XRCC1与APE两者表达呈明显正相关关系,r=0.354,P=0.02.大肠癌和癌旁黏膜组的APE和XRCC1蛋白同时表达的阳性率分别为75.8％(140/185)和65.6％(21/32),两组均明显高于正常黏膜组的16.7％(6/36),x2值分别为46.8和16.17,P值分别为0.001和0.001 5,但癌组与癌旁组间差异无统计学意义.结论:大肠癌和癌旁黏膜中存在APE和XRCC1表达上调.大肠癌发生可能与DNA复制时位点损伤及烷化剂等有毒物质损伤关系密切,同时检测大肠黏膜不同种类DNA修复基因的表达有助于大肠癌的早期诊断.     

碱基切除修复因子SmuG1与肿瘤的研究进展

肿瘤是严重威胁人类健康的疾病之一。随着研究的不断深入，人们发现DNA损伤在肿瘤发生发展中的作用不可忽视。DNA损伤发生后，机体识别损伤类型并启动相应的修复机制以维持机体的正常状态，其中DNA糖基化酶SmuG1作为碱基切除修复途径的关键启动蛋白，在保持真核生物的基因稳定性和遗传完整性中发挥重要作用。近年研究发现SmuG1在肿瘤组织中的异常表达，与肿瘤的病理类型、肿瘤细胞的侵袭转移以及患者生存率、药物耐药性均相关。SmuG1有望成为新的肿瘤标志物和潜在治疗靶点。     

人细胞色素P4502E1基因在胚胎鼻咽组织、鼻咽癌细胞和组织中的表达

背景与目的有研究表明,亚硝胺类化学物质能诱导体内外鼻咽细胞癌变,但作为间接致癌物,其活化主要依赖细胞色素P4502E1(CYP2E1)的代谢.本研究旨在探讨人细胞色素P4502E1(hCYP2E1)基因在化学物质二亚硝基哌嗪(N,N-dinitrosopiperazine,DNP)致鼻咽癌变中的可能作用,为鼻咽癌病因和发病学机制提供新的证据.方法采用RTPCR方法检测8例胚胎鼻咽组织,10例鼻咽癌活检组织,5株鼻咽癌细胞系(CNE1,CNE2,HNE1,HNE2,HNE3)和1株体外恶性转化的鼻咽细胞系(7429)CYP2E1mRNA水平的表达.用不同浓度(200,250,300μg/ml)化学致癌物DNP作用于体外培养的正常鼻咽细胞后,也用RTPCR检测其CYP2E1mRNA表达.结果(1)100%胚胎鼻咽组织(8/8)和鼻咽癌细胞系(6/6,含7429细胞系)、80%(8/10)的鼻咽癌活检组织均存在CYP2E1的表达;(2)经DNP处理的胚胎鼻咽细胞CYP2E1表达增高.结论鼻咽部存在可诱导的CYP2E1基因表达,提示该基因在亚硝胺类间接致癌物(如DNP)致鼻咽癌变过程中可能发挥重要作用.     

cerbB-2基因在鼻咽癌组织中的表达及其意义

目的：探讨cerbB-2基因在鼻咽癌中表达的生物学意义。方法：采用SP supervision^TM 2步免疫组化法检测60例鼻咽癌组织中cerbB-2基因表达的情况。结果：60例鼻咽癌组织cerbB-2表达的阳性率为58.3%（35/60）,cerbB-2表达在年龄≤40岁患者中阳性率为78.3%,在淋巴结分期为N2和N3患者中阳性率为71.0%,cerbB-2表达与年龄、局部转移淋巴结大小和部位有关（P〈0.05）,而与性别、临床分期和远处转移无关（P均〉0.05）。结论：cerbB-2基因在鼻咽癌组织中有高表达,它可能在鼻咽癌发生和发展过程中起重要作用。     

切除修复交叉互补基因1在乳腺癌中的表达及意义

目的 探讨切除修复交叉互补基因1（ERCC1）在乳腺癌组织中的表达与临床病理特征及预后的关系。方法 应用实时荧光定量PCR技术检测363例乳腺癌组织中ERCC1 mRNA的相对表达水平,分析其表达与乳腺癌临床病理特征及预后之间的关系。结果 363例乳腺癌组织标本中ERCC1 mRNA的中位表达水平为1.02×10-2,其中ERCC1 mRNA高表达者181例,ERCC1 mRNA低表达者182例。 ERCC1 mRNA表达水平与ER、PR表达有关（P＜0.05）,而与患者的年龄、肿瘤大小、腋窝淋巴结转移、病理类型、组织学分级、HER-2的表达均无关（P＞0.05）。ERCC1 mRNA高表达与低表达者的中位无病生存期（DFS）均为未达到,差异无统计学意义（P＞0.05）。ERCC1 mRNA高表达者的中位无进展生存期（PFS）为34.0个月（95%CI：32.004～35.996个月）,低表达者的中位PFS为未达到,两组差异有统计学意义（P=0.017）。结论 乳腺癌中ERCC1 mRNA的表达可能与患者的雌激素代谢相关,检测ERCC1 mRNA的表达水平可能有助于判断乳腺癌患者的生存和预后。     

乙醛脱氢酶1在鼻咽鳞状细胞癌中的表达及其临床意义

目的 研究乙醛脱氢酶1（ALDH1）在鼻咽鳞状细胞癌中的表达及其临床意义.方法 采用免疫组织化学方法检测确诊为鼻咽鳞状细胞癌未行放化疗的120例患者石蜡标本中ALDH1的表达情况.结果 ALDH1在40.0％（48/120）鼻咽鳞状细胞癌患者中呈中、高表达,在癌巢和间质的边缘,尤其在梭形细胞中呈高表达.ALDH1表达与鼻咽原发灶范围（P=0.011）、颈淋巴结转移（P=0.005）、临床分期（P=0.001）相关,而与年龄、性别无关（均P＞0.05）.Kaplan-Merier生存分析和Cox回归分析均表明ALDH1表达与鼻咽鳞状细胞癌患者的临床预后相关,并且ALDH1是鼻咽鳞状细胞癌患者临床预后的独立危险因素（HR=2.056,P＜0.05）.结论 鼻咽鳞状细胞癌ALDH1的表达与患者的临床预后密切相关,是影响其临床预后的危险因素之一.     

TRAF1在鼻咽癌及癌旁组织中的表达

目的：研究鼻咽癌组织ＥＢ病毒ＬＭＰ１与ＴＲＡＦ１（ｔｕｍｏｒ ｎｅｃｒｏｓｉｓ ｆａｃｔｏｒ ｒｅｃｅｐｔｏｒ－ａｓｓｏｃｉａｔｅｄ ｆａｃｔｏｒ１）表达的关系,以探讨ＬＭＰ１可能促进ＴＲＡＦ１表达的作用。方法：应用ＬＭＰ１和ＴＲＡＦ１抗体对３０例鼻咽癌和１２例慢性炎症鼻咽粘膜石蜡标本,以ＳＰ免疫组织化学技术检测ＬＭＰ１及ＴＲＡＦ１的表达。结果：３０例鼻咽癌中１６例是ＬＭＰ１阳性（５３．３％）,     

碱基切除修复基因多态性与晚期非小细胞肺癌铂类药物化疗敏感性

目的：探讨DNA碱基切除修复通路中XRCC1 Arg399Gln和ADPRT Val762Ala基因多态性与晚期非小细胞肺癌（NSCLC）铂类药物化疗敏感性的关联,并与先前报道的XRCC1 T-77C、Argl94Trp联合分析其预测作用。方法：收集接受铂类药物为基础化疗的晚期NSCLC患者107例,用PCR—RFLP法检测基因型,分析各基因型与铂类药物化疗有效率的关联,并以非条件Logistic回归模型对患者年龄、性别、病理类型、临床分期和治疗方案进行校正。结果：对XRCC1 Arg399Gln多态性进行单因素分析时,发现携带至少1个Gln等位基因的患者的化疗有效率是携带Arg／Arg基因型者的0．42倍（95％CI：0．19—0．93）,差异具有统计学意义;经多因素校正后发现携带至少1个Gln等位基因的患者的化疗有效率是携带Arg／Arg基因型者的0．52倍（95％CI：0．22—1．26）,但差异不再具有统计学意义。对ADPRT Val762Ala多态性进行多因素分析时,发现携带至少1个Ala等位基因的患者的化疗有效率是携带Val／Val基因型者的1．57倍（95％CI：0．67—3．66）。联合分析各患者4个多态性位点的铂类药物敏感基因型的总数目与铂类药物化疗有效率的关联,并经多因素分析校正后,发现携带3—4个铂类药物敏感基因型的患者的化疗有效率是具有0—2个铂类药物敏感基因型者的4．15倍（95％CI：1．54—11．19）,差异具有统计学意义。结论：XRCC1 Arg399Gln多态性与铂类药物化疗敏感性的关系需进一步确认,似乎携带野生型Arg／Arg者对铂类药物化疗更敏感;但未能发现ADPRT Val762Ala多态性与锥苑矧别眇德魄牲存在明显关联;4个多态性位点联合分析的预测效能高于单个位点。     

MTA1在鼻咽癌中的表达及意义

目的探讨MTA1在鼻咽癌中的表达及临床意义.方法应用逆转录-PCR（RT-PCR）技术,检测43例鼻咽癌组织和14例正常鼻咽部组织中MTA1 mRNA的表达. 结果 MTA1 mRNA 在鼻咽癌组织的平均表达水平明显高于鼻咽部正常组织（P〈0.05）.鼻咽癌组织中MTA1 mRNA高表达率与临床分期、T分期和N分期呈正相关关系.结论 MTA1基因过度表达与鼻咽癌浸润和转移密切相关.MTA1 mRNA的过度表达可能是评价鼻咽癌的恶性程度、转移的重要指标.     

p53和nm23-H1在鼻咽癌组织中的表达及其意义

目的 探讨p53和nm23-H1蛋白在鼻咽癌中的表达及其与临床的相关性.方法 应用免疫组织化学方法对鼻咽癌40例、慢性鼻咽炎22例组织中p53和nm23-H1蛋白的表达进行检测,同时与临床相关资料进行对比研究.结果 慢性鼻咽炎组p53及nm23-H1蛋白的阳性率分别为1.0％、27.2％,而鼻咽癌组为92.5％、55.0％.在nm23-H1蛋白表达阳性的22例鼻咽癌组织中p53阳性表达9例（40.9％）,在nm23-H1表达阴性的18例中p53蛋白阳性表达17例（94.4％）.鼻咽癌组织中p53和nm23-H1蛋白的表达明显高于慢性鼻咽炎组织.p53蛋白表达与鼻咽癌淋巴结转移、临床分期和病理学分级呈正相关,与肿瘤T分级无关;nm23-H1蛋白表达与鼻咽癌淋巴结转移及临床分期呈负相关,与肿瘤T分级无关.结论 抑癌基因p53和nm23-H1在鼻咽癌的发生、发展及转移过程中起着协同、调控作用,可成为临床诊断和评价预后的重要生物学标志.     

Polymorphisms in base excision repair genes: Breast cancer risk and individual radiosensitivity

Breast cancer (BC) is the most common cancer among women worldwide. The aetiology and carcinogenesis of BC are not clearly defined, although genetic, hormonal, lifestyle and environmental risk factors have been established. The most common treatment for BC includes breast-conserving surgery followed by a standard radiotherapy (RT) regimen. However, radiation hypersensitivity and the occurrence of RT-induced toxicity in normal tissue may affect patients’ treatment. The role of DNA repair in cancer has been extensively investigated, and an impaired DNA damage response may increase the risk of BC and individual radiosensitivity. Single nucleotide polymorphisms (SNPs) in DNA repair genes may alter protein function and modulate DNA repair efficiency, influencing the development of various cancers, including BC. SNPs in DNA repair genes have also been studied as potential predictive factors for the risk of RT-induced side effects. Here, we review the literature on the association between SNPs in base excision repair (BER) genes and BC risk. We focused on X-ray repair cross complementing group 1 (XRCC1), which plays a key role in BER, and on 8-oxoguanine DNA glycosylase 1, apurinic/apyrimidinic endonuclease 1 and poly (ADP-ribose) polymerase-1, which encode three important BER enzymes that interact with XRCC1. Although no association between SNPs and radiation toxicity has been validated thus far, we also report published studies on XRCC1 SNPs and variants in other BER genes and RT-induced side effects in BC patients, emphasising that large well-designed studies are needed to determine the genetic components of individual radiosensitivity.     

XRCC1 and hOGG1 genes and risk of nasopharyngeal carcinoma in North African countries

Although genetic susceptibility to nasopharyngeal carcinoma (NPC) has been recognized for a long time, little is known about the responsible genes. X-Ray repair cross-complementing protein 1 (XRCC1) and human 8-oxo-guanine glycosylase 1 (hOGG1) genes are involved in deoxyribonucleic acid (DNA) repair and were found associated with NPC risk in three Asian case-control studies. The objective of the present study was to test these genes in a sample from North Africa, one of the major NPC endemic regions in the world. Three single nucleotide polymorphisms (SNPs) in the XRCC1 gene and one SNP in the hOGG1 gene were genotyped in 598 NPC cases from Morocco, Algeria, and Tunisia and 545 controls frequency matched by recruitment center, age, sex, and urban/rural household. The genotype and allelic distributions for the hOGG1 (326)Ser/Cys SNP and for the XRCC1 (399)Arg/Trp, (280)Arg/His, and (194)Arg/Trp SNPs did not differ significantly among NPC cases and controls. The XRCC1 (194)Trp allele frequency was significantly lower in the North African population than in Asian population (f = 0.04 vs. 0.31 in Cantonese Chinese and 0.21 Han Chinese). The hOGG1 (326)Ser allele frequency was significantly higher in the North African population (f = 0.73) than in Asian populations (f = 0.39 in Taiwanese). The results of the present study obtained from a large sample indicate that the XRCC1 and hOGG1 genes are unlikely to play a role in the susceptibility to NPC in North Africans. Our results do not corroborate those found in Asian population on smaller samples.     

First evidence for digenic inheritance in hereditary colorectal cancer by mutations in the base excision repair genes

Biallelic mutations in the base excision repair gene Mut Y homologue (MUTYH) are responsible for variable recessively inherited phenotypes of polyposis. Beside MUTYH, the proteins 8-oxo-guanine DNA glycosylase (OGG1) and MTH1 (or NUDT1) are also involved in the repair of 7,8-dihydro-8-oxoguanine (8-oxo-G), previous studies, however, only found missense mutations of unclear pathogenicity in either MTH1 or OGG1. To investigate the role of a defective 8-oxo-G repair we performed a germline mutation screening in the genes OGG1, MTH1 and MUTYH, in 81 patients with a clinical phenotype ranging from attenuated or atypical adenomatous polyposis coli including hyperplastic polyps to hereditary non-polyposis colorectal cancer (HNPCC) type X syndrome without mono- or biallelic mutations in either APC, MUTYH or the DNA mismatch repair genes.We describe here the first pathogenic germline mutation in OGG1, a splice site mutation affecting exon 1, which was inherited from the father, in combination with a maternal MUTYH missense mutation p.Ile223Val in a female patient with advanced synchronous colon cancer and adenomas at the age of 36 years pointing towards digenic inheritance for colorectal cancer (CRC) predisposition.Monoallelic missense mutations in MTH1 (3x), OGG1 (2x), or MUTYH (3x) were identified in 10 patients (12%), three of them were novel.Our findings indicate that mutations in other genes of the 8-oxo-G repair beside MUTYH are involved in CRC predisposition. Oligogenic inheritance affecting genes of a certain repair pathway might therefore be the missing link between monogenic and polygenic traits.     

Base excision repair of both uracil and oxidatively damaged bases contribute to thymidine deprivation-induced radiosensitization

PURPOSE: Increased cellular sensitivity to ionizing radiation due to thymidine depletion is the basis of radiosensitization with fluoropyrimidine and methotrexate. The mechanism responsible for cytotoxicity has not been fully elucidated but appears to involve both the introduction of uracil into, and its removal from, DNA. The role of base excision repair of uracil and oxidatively damaged bases in creating the increased radiosensitization during thymidine depletion is examined. METHODS AND MATERIALS: Isogenic strains of S. cerevisiae differing only at loci involved in DNA repair functions were exposed to aminopterin and sulfanilamide to induce thymidine deprivation. Cultures were irradiated and survival determined by clonogenic survival assay. RESULTS: Strains lacking uracil base excision repair (BER) activities demonstrated less radiosensitization than the parental strain. Mutant strains continued to show partial radiosensitization with aminopterin treatment. Mutants deficient in BER of both uracil and oxidatively damaged bases did not demonstrate radiosensitization. A recombination deficient rad52 mutant strain was markedly sensitive to radiation; addition of aminopterin increased radiosensitivity only slightly. Radiosensitization observed in rad52 mutants was also abolished by deletion of the APN1, NTG1, and NTG2 genes. CONCLUSION: These data suggest radiosensitization during thymidine depletion is the result of BER activities directed at both uracil and oxidatively damaged bases.     

层粘连蛋白在鼻咽癌中的表达及临床意义

目的探讨鼻咽癌中癌细胞及癌周基底膜层粘连蛋白(laminin,LN)的表达情况及临床意义.方法应用免疫组化S-P法对66例鼻咽癌组织蜡块进行层粘连蛋白检测.结果癌细胞LN阳性表达率为45.5%(30/66),癌周基底膜LN阳性表达率为36.4%(24/66);癌细胞LN表达与鼻咽癌T分期相关,与预后呈负相关,而癌周基底膜LN表达与淋巴结转移呈负相关;癌细胞LN阴性癌周基底膜LN阳性病例预后最好.结论层粘连蛋白的表达与鼻咽癌细胞的浸润、淋巴结转移有关,联合监测癌细胞及癌周基底膜LN的表达情况有助于判断鼻咽癌的预后.     

周期蛋白D1在鼻咽癌细胞系中功能及意义的深入研究

目的 深入研究周期蛋白D1在鼻咽癌细胞中的表达特征及生物学功能。以Western blot方法确定D型周期蛋白在鼻咽癌细胞系中的表达谱及表达水平;利用流式细胞术双参数法,确定cyclin D1在鼻咽癌细胞中的表达分布模式;结合反义硫代磷酸化寡聚脱氧核苷酸和抗体剔除实验,分别从mRNA及蛋白质水平抑制、中和cyclinD1的表达,探讨其在鼻咽癌细胞中的生物学功能。结果 在鼻咽癌细胞中,D型周期蛋白的表达谱为D1、D2、D3均表达型,cyclinD1在两株鼻咽癌细胞均有过表达。cyclinD1在鼻咽癌细胞系中的表达呈细胞周期依赖性,在G0／G1期表达最高,S期及G2／M期下降,但仍可检测到。反义cyclinD1硫代磷酸化寡聚脱氧核苷酸和抗体剔除实验可以有效抑制蛋白质表达,抑制细胞进入S期。结论 鼻咽癌细胞系中,D型周期蛋白的表达谱为D1、D2、D3均表达型,cyclinD1在鼻咽癌细胞中有过表达,且表达呈细胞周期依赖性,cyclinD1可能是鼻咽癌细胞G1／S期进行中必不可少的细胞周期调节因子。     

显微切割鼻咽癌组织16号染色体杂合性缺失的研究

目的：研究鼻咽癌中１６号染色体的缺失情况。方法：采用显微切割的方法获取肿瘤组织,然后用ＰＣＲ的方法以１６号染色体上的８对引物对３８例鼻咽癌进行分析。结果：３８例鼻咽癌组织中所有标本至少有一个位点出现有杂合笥缺失,其中Ｄ１６Ｓ５３３出现杂合性缺失的频率最高,占８６．１％（３１／３３）,此外,杂合性缺失频率超过５０％的有引物Ｄ１６Ｓ３９８、Ｄ１６Ｓ３００和Ｄ１６Ｓ４２０。分别占７８．８％（２６／３３）