Reduced levels of XPA, ERCC1 and XPF DNA repair proteins in testis tumor cell lines

Over 80% of patients with advanced metastatic testis tumors can be cured using cisplatin-based combination chemotherapy. This is unusual as metastatic cancer in adults is usually incurable. Cell lines derived from testis tumors retain sensitivity to cisplatin in vitro. We previously investigated 2 testis tumor cell lines with a low capacity to remove cisplatin-induced DNA damage and found that they had low levels of the DNA nucleotide excision repair proteins XPA, ERCC1 and XPF. To determine whether low levels of XPA, ERCC1 and XPF proteins are characteristic of testis tumor cell lines, we investigated 35 cell lines derived from cancers to determine whether groups of cell lines from diverse tissue origins differ from one another in constitutive levels of these NER proteins. Quantitative immunoblotting was used to compare groups of cell lines representing prostate, bladder, breast, lung, cervical, ovarian and testis cancers. Only the 6 testis tumor cell lines showed significantly lower mean levels of XPA (p = 0.001), XPF (p = 0.001) and ERCC1 (p = 0.004) proteins from the other groups. Our results encourage further investigation of the possibility that low levels of these nucleotide excision repair proteins could be related to the favorable response of testis tumors to cisplatin-based chemotherapy.     

Polymorphisms in DNA repair gene XRCC1 and increased genetic susceptibility to glioma

Background: The XRCC1 gene encodes the XRCC1 protein, which complexes with three other DNA repair enzymes involved in the base-excision repair (BER) pathways. Different XRCC1 polymorphisms may increase the risk of cancers by impairing interaction with other enzymatic proteins and consequently altering DNA repair activity, and result in carcinogenesis. Our study aimed to investigate any association between three polymorphisms of the XRCC1 gene at codon 194, 280 and 399 and potential glioma risk. Methods: We collected 127 patients with primary glioma and 249 controls who requested general health examinations from Union Hospital of Tongji Medical College hospital from March 2007 to September 2010. A total of 5 ml venous blood was drawn from each subject. The polymorphisms of XRCC1 gene at codons 194, 280 and 399 were analyzed based on duplex polymerase-chain-reactions with the confronting-two-pair primer (PCR-CTPP) method. Results: The homozygous Trp/Trp and heterozygotes Arg/Trp variants of codon 194 had a 2.12 fold and 1.46 fold increased risk of glioma compared to the homozygous Arg/Arg wide genotypes. The same effect was found in codon 399, the codon 399 Gln/Gln and Arg/Gln genotypes being associated with a 2.24 fold and 1.67 fold increased risk in glioma. When comparing the codon 194 Arg/Arg and 399 Arg/Arg genotypes, the combination of codon 194 Trp allele and 399 Gln allele had a heavy increase in glioma risk (OR=2.87, 95%CI=1.56-6.73). Conclusion: The present study provided evidence of a potential role for XRCC1 codon 194 and 399 polymorphisms in genetic predisposition to glioma among the Chinese population. This analysis of correlation of DNA repair genes and glioma may provide a deeper insight into the genetic and environment factors for cancer risk.     

Association of DNA repair gene XRCC1 polymorphisms with head and neck cancer in Korean population

Squamous cell carcinoma of the head and neck (SCCHN), which is relatively prevalent in Korea, is believed to be induced by environmental carcinogens and host genetic factors. Accumulating evidence has shown that genetic differences in DNA repair capacity resulting from genetic polymorphism influence the risk of environmental carcinogenesis. We therefore examined the associations of genetic polymorphisms in the DNA repair genes XRCC1 with the risk of SCCHN in a Korean population (hospital-based, case-control study; 147 cases and 168 controls). Three known polymorphisms in the XRCC1 gene were genotyped: R194W(C>T) in exon 6, R280H(G>A) in exon 9 and R399G(G>A) in exon 10. Although no significant associations were apparent with R280H(G>A) and R399G(G>A), a highly significant association (p = 0.0005) of R194W(C>T) with the increased risk (OR = 2.61; 95% CI 1.53-4.46) of SCCHN was detected among patients and normal controls under dominant model. The frequency of minor allele-containing genotypes (TT and CT) was much higher in SCCHN patients (51.8%) compared to that in normal controls (30.3%) (p = 0. 0005). When considering a relatively small number of cases (n = 147) and controls (n = 168) in our study, larger studies are needed to validate the genetic effects of XRCC1 polymorphisms in Asian populations. In conclusion, the result from our study provides additional evidence of an association of the XRCC1 polymorphism (Arg194Trp) with SCCHN as markers of genetic susceptibility in the Korean population.     

转录因子Sp1在DNA损伤修复中的作用及其与肿瘤治疗的研究进展

细胞受到外界刺激导致DNA损伤时,DNA修复蛋白被激活并发挥功能,受损DNA得到修复。近年来研究表明,转录因子特异性蛋白1(specificity protein 1,Sp1)在DNA损伤修复中起重要作用,是参与调控DNA损伤应答与修复的重要蛋白之一。Sp1在多种肿瘤中高表达,通过调节细胞增殖、迁移和侵袭促进肿瘤的发生和发展,不利于肿瘤治疗。本文首先介绍Sp1特有的结构及其生理功能,由此引入Sp1通过转录依赖方式调控DNA损伤应答,其次介绍Sp1通过非转录依赖方式参与DSB修复,以及Sp1在肿瘤治疗中的研究进展,最后展望研究Sp1的意义及可能具有的应用前景。     

Immune responses to DNA mismatch repair enzymes hMSH2 and hPMS1 in patients with pancreatic cancer, dermatomyositis and polymyositis

To identify tumor antigens useful for diagnosis and immunotherapy of patients with pancreatic ductal adenocarcinoma, we applied a SEREX approach with a cDNA library made from 5 pancreatic cancer cell lines and sera obtained from 8 patients with pancreatic cancer, and isolated total 32 genes, including 14 previously characterized genes and 18 genes with unknown functions. Among these isolated antigens, serum IgG antibodies for 2 isolated DNA mismatch repair enzymes, Homo sapiens mutS homolog 2 (hMSH2) and Homo sapiens postmeiotic segregation increased 1 (hPMS1), were detected in patients with pancreatic ductal adenocarcinoma and dermatomyositis (DM), and polymyositis (PM), but not in sera from healthy individuals. Immunohistochemical study demonstrated that hMSH2 and hPMS1 were over-expressed in pancreatic ductal adenocarcinoma compared to normal pancreatic ducts. These results suggested that hMSH2 and hPMS1 may be useful as CD4+ helper T cell antigens for immunotherapy of pancreatic cancer patients and that serum IgG antibodies may be useful for diagnosis of patients with pancreatic ductal adenocarcinoma and DM/PM.     

肌氨酰胺亚硝脲在荷神经元外单胺递质载体和DNA修复基因表达的人肺癌裸鼠中的抗肿瘤作用

目的 探讨抗癌新药肌氨酰胺亚硝脲（２－ｃｈｌｏｒｏｅｔｈｙｌ－３－ｓａｒｃｏｓｉｎａｍｉｄｅ－１－ｎｉｔｒｏｓｏｕｒｅａ,ＳａｒＣＮＵ）在体内对ＤＮＡ修复基因表达阳性肿瘤的抗肿瘤作用。方法 将人肺癌细胞株ＮＣＩ－Ｈ５２２接种于裸鼠皮下,制作肿瘤模型,观察ＳａｒＣＮＵ的抗肿瘤作用。同时,采用逆转录－聚合酶链反应（ｒｅｖｅｒｓｅ－ｔｒａｎｓｃｒｉｐｔｉｏｎ ｐｏｌｙｍｅｒａｓｅ ｃｈａｉｎ ｒｅａｃｔ     

Role of multifunctional transcription factor TFII-I and putative tumour suppressor DBC1 in cell cycle and DNA double strand damage repair

Background:

In multicellular organisms, precise control of cell cycle and the maintenance of genomic stability are crucial to prevent chromosomal alterations. The accurate function of the DNA damage pathway is maintained by DNA repair mechanisms including homologous recombination (HR). Herein, we show that both TFII-I and DBC1 mediate cellular mechanisms of cell-cycle regulation and DNA double strand damage repair.

Methods:

Regulation of cell cycle by TFII-I and DBC1 was investigated using Trypan blue dye exclusion test, luciferase assay, and flow cytometry analysis. We also analysed the role of TFII-I and DBC1 in DNA double strand damage repair after irradiation by immunofluorescence study, clonogenicity assay, and HR assay.

Results:

Flow cytometry analysis revealed a novel function that siRNA-mediated knockdown of endogenous DBC1 resulted in G2/M phase arrest. We also have shown that both endogenous TFII-I and DBC1 activate DNA repair mechanisms after irradiation because irradiation-induced foci formation of TFII-I-γH2AX was observed, and the depletion of endogenous TFII-I or DBC1 resulted in the inhibition of normal HR efficiency.

Conclusion:

These results reveal novel mechanisms by which TFII-I and DBC1 can modulate cellular fate by affecting cell-cycle control as well as HR pathway.     

Polymorphism of DNA repair gene XRCC1 and hepatocellular carcinoma risk in Chinese population

Aim: We conducted a case-control study in China to clarify the association between the XRCC1-Arg399Gln polymorphism and HCC risk. Methods: A total of 202 cases and 236 controls were selected from the the Affiliated Hospital of Qingdao University from May 2008 to May 2010. Assessment of the XRCC1-Arg399Gln polymorphism was based upon duplex polymerase-chain-reactions with the confronting-two-pair primer (PCR-CTPP) method. All analyses were performed using the STATA statistical package. Results: A significant increase in risk was associated with the Arg/Gln genotype (adjusted OR 1.55, 95%CI=1.03-2.57) compared with Arg/Arg. However, the Gln/Gln genotype had non-significant increased risk of HCC with adjusted OR (95%CI) of 1.34(0.67-2.38). There was also a significant increasewith the Arg/Gln genotype among HCC patients above 50 years old (OR=1.95, 95% CI=1.14-3.57). Additionally, the risk of HCC was moderately increased in drinkers with Arg/Gln genotype compared with never drinkers, and the adjusted OR (95% CI) was 1.89 (1.13-3.45). Conclusion: This study demonstrated that a polymorphism in a DNA repair gene may influence the risk of HCC. The XRCC1 codon Arg/Gln was thuis associated with an increased risk of HCC, especiallyin patients above 50 years old and/or with a drinking habit.     

DNA损伤修复基因XRCC和hOGG1多态性与肺癌易感性的关系

DNA损伤修复基因的多态性能够改变DNA修复功能和效率,影响肿瘤易感性.许多研究报道DNA损伤修复基因多态性可能与肿瘤易感性有关,其突变在多种肿瘤的发生、发展过程中起着重要作用.另外,DNA损伤修复基因可能与其他基因相互作用,共同影响肿瘤的发生、发展.肺癌是目前在这方面被研究得最多的肿瘤.文章就DNA损伤修复基因XRCC和hOGG1多态性的生物学特点以及这些基因单核苷酸多态性与肿瘤易感性等方面进行了综述,为该基因用于肿瘤的预防、诊治提供理论借鉴.     

Polymorphisms in the DNA repair gene XRCC1 and susceptibility to alcoholic liver cirrhosis in older Southeastern Brazilians

The population of Southeastern Brazil has a very high mortality rate from liver cirrhosis, a disease that is considered an irreversible pre-malignant condition. This is largely due to the high prevalence of alcohol abuse in the region. Chronic alcohol consumption is associated with the production of free radical intermediates that can cause several DNA lesions. Reduced repair of these DNA lesions would, therefore, constitute a significant risk factor for liver cirrhosis and subsequent cancer. Recently, a number of polymorphisms in several DNA repair genes have been discovered, and it is possible that these polymorphisms may affect DNA repair capacity and thus modulate susceptibility to the disease. In this study, we tested the hypothesis that polymorphisms in the DNA repair gene XRCC1 are associated with increased risk of liver cirrhosis in Southeastern Brazilians. We conducted a pilot case-control study of 97 liver cirrhosis cases and 96 controls (matched for age, sex, and ethnicity) to investigate the role of two allelic variants coding for amino acid changes in the XRCC1 gene (the Arg194Trp and the Arg399Gln polymorphisms). Overall, we observed a 1.8-fold increase in the relative risk of liver cirrhosis associated with the 399Gln allele (either the heterozygous Arg/Gln or the homozygous Gln/Gln genotypes). The adjusted odds ratio (OR) was 1.82 (95% confidence limit (CL) 1.10–3.30). The relative risk appears to be highest among the Mestiso ethnic group (OR 2.60, 95% CL 0.92–7.34). There was a significant association between the 399Gln polymorphism and the risk of liver cirrhosis in older individuals over the age of 45 years (OR 2.70 (95% CL 1.14–6.48) compared to an OR of 1.24 (95% CL 0.55–2.78) for those under 45 years of age. No association was observed between the XRCC1 194Trp polymorphism and risk of liver cirrhosis. These preliminary results suggest that the XRCC1 399Gln polymorphism may be a significant risk modifier for alcoholic liver cirrhosis and justifies additional studies in that direction.     

XRCC1单核苷酸多态性与结直肠癌风险的关系

背景与目的:X线交叉互补基因1(X-ray repair cross complementing group 1,XRCC1)编码蛋白在DNA单链断裂修复和DNA碱基修复过程中起重要作用.该基因外显子多态性的存在可影响编码蛋白的功能活性,最终使机体对癌症的易感性发生变化.本研究旨在探讨该基因外显子最常见的3处单核苷酸多态(single nucleotide polymorphism,SNP)--C26304T、G27466A和G28152A与结直肠癌风险的关系.方法:以聚合酶链反应(polymerase chain reaction,PCR)和限制性片段长度多态性(restrictive fragment length polymorphism,RFLP)分析方法,检测207例结直肠癌病例和621例成组匹配的正常对照XRCC1 C26304T、G27466A和G28152A基因型,并比较不同基因型与结直肠癌风险的关系.采用EH Linkage Software 1.2统计分析软件对研究对象的单体型分布进行预测.结果:年龄、性别、身体质量指数(body mass index,BMI)等个体特征,以及吸烟、饮酒等常见环境暴露因素的分布和/或构成比在结直肠癌病例组和对照组间差异均无显著性(P＞0.05).对XRCC1各多态基因型检测分型发现,结直肠癌病例组携带26304T、27466A和28152A变异等位基因的频率分别为29.95%、11.22%和28.22%,对照组分别为32.87%、12.34%和27.27%,各多态等位基因在两组间分布均没有显著性差异(P＞0.05).各多态基因型分布经x2拟合优度检验均符合Hardy-Weinberg平衡定律,且在两组间都没有显著性差异(P＞0.05).没有观察到各多态基因型与结直肠癌发病风险存在显著相关关系(P＞0.05).单体型分析发现,各变异等位基因在病例组和对照组内均存在遗传连锁不平衡现象,CGG、CGA、CAG和TGG是最常见的4类单体型,其在两组的分布频率总和分别为95.54%和96.64%,然而在两组间同样不存在显著性差异(P＞0.05).结论:我国浙江省嘉善县人群中,XRCC1 C26304T、G27466A和G28152A基因多态性与结直肠癌发病风险不存在相关性,然而各变异等位基因存在遗传连锁不平衡现象,CGG、CGA、CAG和TGG是最常见的4类单体型.     

DNA repair genes PAXIP1 and TP53BP1 expression is associated with breast cancer prognosis

Despite remarkable advances in diagnosis, prognosis and treatment, advanced or recurrent breast tumors have limited therapeutic approaches. Many treatment strategies try to explore the limitations of DNA damage response (DDR) in tumor cells to selectively eliminate them. BRCT (BRCA1 C-terminal) domains are present in a superfamily of proteins involved in cell cycle checkpoints and the DDR. Tandem BRCT domains (tBRCT) represent a distinct class of these domains. We investigated the expression profile of 7 tBRCT genes (BARD1, BRCA1, LIG4, ECT2, MDC1, PAXIP1/PTIP and TP53BP1) in breast cancer specimens and observed a high correlation between PAXIP1 and TP53BP1 gene expression in tumor samples. Tumors with worse prognosis (tumor grade 3 and triple negative) showed reduced expression of tBRCT genes, notably, PAXIP1 and TP53BP1. Survival analyses data indicated that tumor status of both genes may impact prognosis. PAXIP1 and 53BP1 protein levels followed gene expression results, i.e., are intrinsically correlated, and also reduced in more advanced tumors. Evaluation of both genes in triple negative breast tumor samples which were characterized for their BRCA1 status showed that PAXIP1 is overexpressed in BRCA1 mutant tumors. Taken together our findings indicate that PAXIP1 status correlates with breast cancer staging, in a manner similar to what has been characterized for TP53BP1.     

非小细胞肺癌NP方案化疗敏感性与DNA修复基因XRCC1多态性的关系

背景与目的:基因多态预测肿瘤化疗药物敏感性对肿瘤个体化治疗具有重要意义。本研究旨在探讨DNA修复基因XRCC1 codon194及399位点基因多态性与非小细胞肺癌长春瑞滨加顺铂(vinorelbine and cisplatin,NVB and DDP,NP)方案化疗敏感性的关系。方法:采用聚合酶链反应-限制性片段长度多态性技术检测164例非小细胞肺癌患者外周血DNAXRCC1194和399位点的多态性。选择NP方案化疗,化疗两周期后评价疗效,并分析化疗敏感性与基因多态性的关系。结果:携带XRCC1基因Codon194C/T+T/T基因型者化疗有效率(41.8%)是C/C基因型者(26.0%)的2.038倍(P=0.036,95%CI=1.044-3.976)。携带XRCC1基因Codon399G/G、A/G、A/A型的患者化疗有效率(37.1%,34.6%,14.3%)之间的差异无统计学意义(P>0.05)。应用分析软件SHEsis发现以     

HIV-1 Tat depresses DNA-PK(CS) expression and DNA repair, and sensitizes cells to ionizing radiation

PURPOSE: There is accumulating evidence that cancer patients with human immmunodeficiency virus-1/acquired immunodeficency syndrome (HIV-1/AIDS) have more severe tissue reactions and often develop cutaneous toxic effects when subjected to radiotherapy. Here we explored the effects of the HIV-1 Tat protein on cellular responses to ionizing radiation. METHODS AND MATERIALS: Two Tat-expressing cell lines, TT2 and TE671-Tat, were derived from human rhabdomyosarcoma cells by transfecting with the HIV-1 tat gene. Radiosensitivity was determined using colony-forming ability. Gene expression was assessed by cDNA microarray and immunohybridization. The Comet assay and gamma-H2AX foci were use to detect DNA double-strand breaks (DSBs) and repair. Radiation-induced cell cycle changes were detected by flow cytometry. RESULTS: The radiosensitivity of TT2 and TE671-Tat cells was significantly increased as compared with parental TE671 cells or the control TE671-pCI cells. Tat also increased proliferation activity. The comet assay and gammaH2AX foci detection revealed a decreased capacity to repair radiation-induced DNA DSBs in Tat-expressing cells. Microarray assay demonstrated that the DNA repair gene DNA-PKcs, and cell cycle-related genes Cdc20, Cdc25C, KIF2C and CTS1 were downregulated in Tat-expressing cells. Depression of DNA-PKcs in Tat-expressing cells was further confirmed by RT-PCR and immuno-hybridization analysis. Tat-expressing cells exhibited a prolonged S phase arrest after 4 Gy gamma-irradiation, and a noticeable delay in the initiation and elimination of radiation-induced G(2)/M arrest as compared with parental cells. In addition, the G(2)/M arrest was incomplete in TT2 cells. Moreover, HIV-1 Tat resulted in a constitutive overexpression of cyclin B1 protein. CONCLUSION: HIV-1 Tat protein sensitizes cells to ionizing radiation via depressing DNA repair and dysregulating cell cycle checkpoints. These observations provide new insight into the increased tissue reactions of AIDS cancer patients to radiotherapy.     

修复基因XRCC1 Arg194Trp位点多态性与肝癌易感性的关系

目的:探讨DNA损伤修复基因XRCC1多态与肝癌遗传易感性的关系。方法:本研究选取了130例肝癌患者及130例性别、年龄相匹配的正常对照者进行研究,采用限制性片段长度多态性方法,比较不同基因型与肝癌发病的关系。结果:变异型等位基因XRCC1 Arg/Trp及Trp/Trp的出现率在肝癌组和对照组中分别是27.69%和10.77%,(P<0.05);而野生基因型XRCC1 Arg/Arg出现率在肝癌组和对照组中分别是72.31和89.23%,(P>0.05)。结论:XRCC1基因Arg194Trp位点单核苷酸多态在肝癌的发生过程中起着至关重要的作用。