DNA repair gene ERCC2 polymorphisms and risk of squamous cell carcinoma of the head and neck

Introduction

Genetic aberrations of DNA repair enzymes are known to be common events and to be associated with different cancer entities. Aim of the following study was to analyze the genetic association of single nucleotide polymorphisms (SNP) of the DNA repair genes with the risk of squamous cell carcinoma of the head and neck (HNSCC).

Materials and methods

Genetic variants ERCC2 Lys751Gln (rs13181), ERCC2 Asp312Asn (rs1799793), XRCC1 Arg194Trp (rs1799782); XRCC1 Gln399Arg (rs25487), XRCC1 Arg280His (rs25489) and XRCC3 Thr241Met (rs861539) were analyzed in a primary study group comprising 169 patients with histologically confirmed HNSCC and 463 healthy control subjects. Polymorphisms associated with HNSCC were furthermore analyzed in an independent replication study including 125 HNSCC.

Results

Only the ERCC2 751 Gln/Gln genotype was associated with HNSCC in the primary study (p = 0.033) and in the replication study (p = 0.023), resulting in an overall odds ratio of 0.54 (95% confidence interval 0.35–0.92; p = 0.006).

Conclusion

Carriers of the homozygous ERCC2 751 Gln/Gln genotype may be at lower risk for HNSCC.     

中国辽宁汉族群体DNA修复基因: ERCC2/XPD A35931C 遗传多态性

DNA修复基因在保护维持基因组整体性及抗癌发生过程中起着重要作用，DNA修复基因的产物:ERCC2/XPD参与核苷酸切除修复过程。单核苷酸多态的群体遗传学信息对于遗传疾病的研究是非常重要的。我们调查了中国辽宁汉族群体DNA修复基因: ERCC2 A35931C 遗传多态性。ERCC2 A35931C基因型频率：AA=0.95; AC=0.05; CC=0, 基因型分布符合Hardy-Weinberg遗传平衡定律(P=0.77)；ERCC2 A35931C等位基因频率：A=0.98; C=0.02。研究结果与前期所报道的其他群体的该等位基因频率分布进行比较。     

Polymorphism in the nuclear excision repair gene ERCC2/XPD: association between an exon 6-exon 10 haplotype and susceptibility to cutaneous basal cell carcinoma

Cutaneous basal cell carcinoma (BCC) risk is mediated by interactions between ultraviolet radiation (UVR) and host factors, including DNA repair efficiency. We investigated the association between BCC risk and SNPs in exon 6 (c.466C > A, dbSNP238406:g.C > A; designated C/A156), exon 10 (c.932G > A, dbSNP1799793:g.G > A; designated G/A312), and exon 23 (c.2251A > C, dbSNP13181:g.A > C; designated A/C751) of the nucleotide excision repair gene, XPD (ERCC2; excision repair cross-complementing repair deficiency, complementation 2 [xeroderma pigmentosum D]). XPD genotype frequencies were not significantly different in 509 cases and 379 controls, although AA156 (odds ratio [OR]=0.61, 95% confidence interval [CI]=0.37-1.01, P=0.052) and AA312 (OR=0.65, 95% CI=0.40-1.05, P=0.08) were linked with reduced risk. A156-A312 and A156-A312-A751 haplotype frequencies however, were significantly lower in cases than controls (OR=0.12, 95% CI=0.05-0.31, P < 0.001; OR=0.10, 95% CI=0.03-0.33, P < 0.001). We confirmed the robustness of these findings by showing significant associations of the haplotypes with risk in two randomly selected equal sized groups of cases and controls and, using the false positive report probability (FPRP) approach (FPRP values < 0.001 and < 0.004, respectively). A156-A312 was similarly associated with reduced risk in subgroups, including cases with no family history of skin cancer, with only BCC on the head/neck, and those with a high rate of increase in BCC numbers. The association was not dependent on gender, age, or extent of UVR exposure. A156-A312 was found in 6.3% of controls and the corresponding risk haplotype, C156-G312 (OR=1.65, 95% CI=1.21-2.26, P=0.002) in 35.4% of controls. We interpret these data as showing that XPD SNP mediate susceptibility to BCC.     

A summary of mutations in the UV‐sensitive disorders: Xeroderma pigmentosum,Cockayne syndrome,and trichothiodystrophy

The human diseases xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy are caused by mutations in a set of interacting gene products, which carry out the process of nucleotide excision repair. The majority of the genes have now been cloned and many mutations in the genes identified. The relationships between the distribution of mutations in the genes and the clinical presentations can be used for diagnosis and for understanding the functions and the modes of interaction among the gene products. The summary presented here represents currently known mutations that can be used as the basis for future studies of the structure, function, and biochemical properties of the proteins involved in this set of complex disorders, and may allow determination of the critical sites for mutations leading to different clinical manifestations. The summary indicates where more data are needed for some complementation groups that have few reported mutations, and for the groups for which the gene(s) are not yet cloned. These include the Xeroderma pigmentosum (XP) variant, the trichothiodystrophy group A (TTDA), and ultraviolet sensitive syndrome (UV^s) groups. We also recommend that the XP‐group E should be defined explicitly through molecular terms, because assignment by complementation in culture has been difficult. XP‐E by this definition contains only those cell lines and patients that have mutations in the small subunit, DDB2, of a damage‐specific DNA binding protein. Hum Mutat 14:9–22, 1999. © 1999 Wiley‐Liss, Inc.     

Temperature-sensitive DNA repair mutations in the cellular slime mould Dictyostelium discoideum

The flowering dogwood trees and green lawns of Cold Spring Harbor provided the setting for a meeting devoted to Mitochondrial Genes from May 13-17th, 1981. Dedicated to the memory of Boris Ephrussi, who pioneered mitochondrial genetics at a time when the only kinds of genetics were nuclear or unclear, the meeting showed that the study of mtDNA has had impact on many areas of molecular biology including the genetic code and decoding, tRNA function, mechanisms of splicing and molecular evolution. Curiously, as Herschel Roman pointed out in his opening address, Ephrussi took great pains to avoid any mention of mitochondrial DNA in connection with his observations on cytoplasmic inheritance, preferring instead to refer to cytoplasmic particles, endowed with genetic continuity (Ephrussi 1953). This reticence was not shared by participants at the meeting, as the following, brief report will show.     

Polymorphisms in DNA repair genes, chromosome aberrations, and lung cancer

We have previously investigated the role of polymorphic chemical metabolizing genes in the susceptibility to the development of lung cancer using 110 primary lung cancer patients and 119 matched smoker controls. Together with data from the present study on DNA repair genes, we did not observe significant associations between any single variant genotype for several DNA-repair and chemical-metabolizing genes (XPD [or ERCC2], XRCC1, XRCC3, GSTM1, GSTT1, MPO, and mEH [or EPHX1]) and lung cancer. In the present study, we have further evaluated a nested group of 79 patients and 69 matched controls, and observed that increased chromosome aberrations (CAs) were associated with variant DNA-repair genotypes among both the patient and the control groups, with a significant increase for individuals having the XPD Lys/Gln + Gln/Gln genotypes (P = 0.046). Patients often had significantly increased CAs compared with controls with the same DNA-repair genotype and with similar cigarette smoking habits (< or =40 pack-years or >40 pack-years). Analyses of interactions between the DNA-repair and chemical-metabolizing genes indicated that the most significant interactions were between the repair genotypes and the GSTM1/T1 null genotypes. Significant increases in CA from the interactions were often observed among patients with < or =40 pack-years, but not among those with >40 pack-years. Since some variant DNA-repair genotypes have functional deficits for DNA repair, the association between variant DNA-repair genotypes and increased CAs suggests a risk mechanism for the development of lung cancer, with the DNA-repair genotypes interacting with variant chemical metabolizing genotypes to further increase the risk. The observation that patients had significantly increased CA frequencies compared with controls, irrespective of genotype, suggests that patients have additional factors that contribute to the development of lung cancer.     

Lynch syndrome‐associated mutations in MSH2 alter DNA repair and checkpoint response functions in vivo

The DNA mismatch repair (MMR) pathway is essential in maintaining genomic stability through its role in DNA repair and the checkpoint response. Loss of DNA MMR underlies the hereditary cancer disease Lynch Syndrome (LS). Germline mutations in MSH2 account for approximately 40% of LS patients and of these, 18% are missense variants. One important clinical challenge has been discriminating between missense variants that are pathogenic and those that are not. Current analysis of missense mutations in MSH2 is performed using a combination of clinical, biochemical, and functional data; however, suitable cell culture models to test the various functions of the DNA MMR proteins are lacking. Here, we have generated human cell lines stably expressing a subset of MSH2 missense mutants and tested their effect on DNA repair and checkpoint response functions. We have expanded on previous biochemical and functional analyses performed in non‐human systems to further understand defects conferred by this subset of single amino acid alterations. The functional characterization of MSH2 missense mutants combined with clinical and biochemical data is essential for appropriate patient management and genetic counseling decisions. ©2010 Wiley‐Liss, Inc.     

肺癌组织中DNA修复基因ERCC1的表达与多环芳烃-DNA加合物的关系

目的:探讨核苷酸切除修复基因ERCC1在肺癌中的表达及其与多环芳烃(PAH)-DNA加合物的关系。方法: 用RT-PCR技术检测150例肺癌、120例癌旁肺组织、40例肺良性病变和40例正常肺组织中ERCC1基因mRNA的表达;用免疫法检测PAH-DNA加合物;分析有关暴露因素对修复基因ERCC1的表达和PAH-DNA加合物的影响,并探讨ERCC1与PAH-DNA加合物的关系。结果:30.7%(46/150)的肺癌组织和2.5%(1/40)的正常肺组织存在ERCC1基因的表达低下;吸烟可抑制ERCC1基因的表达。肺组织中PAH-DNA加合物的水平与ERCC1基因表达呈显著负相关,Spearman相关系数为-0.648,P<0.01。结论:ERCC1是参与修复DNA加合物等损伤的一个重要的核苷酸切除修复基因,其表达低下在肺癌发生中起着重要作用。     

Intermittent hair loss in a child with PIBI(D)S syndrome and trichothiodystrophy with defective DNA repair-xeroderma pigmentosum group D

We describe a girl with photosensitivity (P), ichthyosis (I), brittle hair (B), impaired intelligence (I), possibly decreased fertility (D), and short stature (S). The clinical findings fit into the PIBI(D)S syndrome and trichothiodystrophy. A remarkable and probably unique observation for this disorder was the intermittent character of the scalp hair loss during infectious periods in this patient. Easy suntanning suggested photosensitivity and prompted DNA repair studies which demonstrated reduced UV-induced DNA repair synthesis. Subsequent studies have assigned this patient to xeroderma pigmentosum group D and suggested a specific deficiency of 6–4 photoproduct repair. An unaffected child was diagnosed in the next pregnancy of the mother. © 1994 Wiley-Liss, Inc.     

Influence of DNA repair gene polymorphisms on the yield of chromosomal aberrations

We evaluated the influence of several DNA repair gene polymorphisms on the frequency of chromosomal aberrations (CAs) analyzed in peripheral lymphocytes, using the fluorescence in situ hybridization technique. The CA data were obtained from an earlier study of 84 healthy nonsmokers (48 women and 36 men) carefully characterized for indoor radon exposure. The frequency of translocations showed a wide interindividual variability, which was only partly explained by age. To investigate the potential role of DNA repair polymorphisms in this variation, genotypes of DNA repair genes OGG1 (codon 326), XPD (codon 751), XRCC1 (X-ray repair cross-complementing group 1) (codons 194, 280, and 399), and XRCC3 (X-ray repair cross-complementing group 3) (codon 241) were determined from leukocyte DNA using polymerase chain reaction-based methods. Negative binomial regression models were applied to evaluate the effect of the polymorphisms and other factors (age, gender, radon exposure, and medical exposure) on the frequency of CAs. No interactions between genotypes and radon, medical exposure, or gender were found. Carriers of the XRCC1 codon 280His variant allele had a two-fold increase (frequency ratio [FR] = 2.01, 95% confidence interval [CI] = 1.01-3.98; P = 0.046) in unstable exchanges (dicentrics and ring chromosomes). In addition, the XRCC3 codon 241 homozygous variant genotype (Met/Met) was associated with an increase (FR = 1.70, 95% CI = 1.06-2.74; P = 0.028) in two-way translocations when age was taken into account in the analysis. Our data suggest that the XRCC1 280His and XRCC3 241Met alleles affect individual CA levels, most probably via influencing the DNA repair phenotype.     

Exome sequencing revealed a novel deletion in the ERCC8 gene in an Iranian family with Cockayne syndrome

Cockayne syndrome (CS) is one the rare DNA‐repair deficiency disorders with autosomal recessive inheritance. Failure to thrive and microcephaly are the major criteria of diagnosis. Owing to genetic heterogeneity of CS, whole exome sequencing is promising way to determine the genetic basis of the disease. Here, we present c.1053delT in ERCC8 gene in an Iranian family with symptom of CS using whole exome sequencing. The deletion was novel and was not previously reported elsewhere.     

Extensive gene conversion at the PMS2 DNA mismatch repair locus

Mutations of the PMS2 DNA repair gene predispose to a characteristic range of malignancies, with either childhood onset (when both alleles are mutated) or a partially penetrant adult onset (if heterozygous). These mutations have been difficult to detect, due to interference from a family of pseudogenes located on chromosome 7. One of these, the PMS2CL pseudogene, lies within a 100-kb inverted duplication (inv dup), 700 kb centromeric to PMS2 itself on 7p22. Here, we show that the reference genomic sequences cannot be relied upon to distinguish PMS2 from PMS2CL, because of sequence transfer between the two loci. The 7p22 inv dup occurred prior to the divergence of modern ape species (15 million years ago [Mya]), but has undergone extensive sequence homogenization. This process appears to be ongoing, since there is considerable allelic diversity within the duplicated region, much of it derived from sequence exchange between PMS2 and PMS2CL. This sequence diversity can result in both false-positive and false-negative mutation analysis at this locus. Great caution is still needed in the design and interpretation of PMS2 mutation screens.