Gene Summary

Gene:LIG4; DNA ligase 4
Aliases: LIG4S
Summary:The protein encoded by this gene is a DNA ligase that joins single-strand breaks in a double-stranded polydeoxynucleotide in an ATP-dependent reaction. This protein is essential for V(D)J recombination and DNA double-strand break (DSB) repair through nonhomologous end joining (NHEJ). This protein forms a complex with the X-ray repair cross complementing protein 4 (XRCC4), and further interacts with the DNA-dependent protein kinase (DNA-PK). Both XRCC4 and DNA-PK are known to be required for NHEJ. The crystal structure of the complex formed by this protein and XRCC4 has been resolved. Defects in this gene are the cause of LIG4 syndrome. Alternatively spliced transcript variants encoding the same protein have been observed. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:DNA ligase 4
Source:NCBIAccessed: 11 March, 2017


What does this gene/protein do?
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Cancer Overview

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Publications Per Year (1992-2017)
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Literature Analysis

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Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Latest Publications: LIG4 (cancer-related)

Sanie-Jahromi F, Saadat I, Saadat M
Effects of extremely low frequency electromagnetic field and cisplatin on mRNA levels of some DNA repair genes.
Life Sci. 2016; 166:41-45 [PubMed] Related Publications
AIMS: It has been shown that exposure to extremely-low frequency (˂300Hz) oscillating electromagnetic field (EMF) can affect gene expression. The effects of different exposure patterns of 50-Hz EMF and co-treatment of EMF plus cisplatin (CDDP) on mRNA levels of seven genes involved in DNA repair pathways (GADD45A, XRCC1, XRCC4, Ku70, Ku80, DNA-PKcs and LIG4) were evaluated.
MAIN METHODS: Two 50-Hz EMF intensities (0.25 and 0.50mT), three exposure patterns (5min field-on/5min field-off, 15min field-on/15min field-off, 30min field-on continuously) and two cell lines (MCF-7 and SH-SY5Y) were used. The mRNA levels were measured using quantitative real-time PCR.
KEY FINDINGS: The examined genes had tendency to be down-regulated in MCF-7 cells treated with EMF. In the pattern of 15min field-on/15min field-off of the 0.50mT EMF, no increase in mRNA levels were observed, but the mRNA levels of GADD45A, XRCC1, XRCC4, Ku80, Ku70, and LIG4 were down-regulated. A significant elevation in IC50 of CDDP was observed when MCF-7 and SH-SY5Y cells were co-treated with CDDP+EMF in comparison with the cells treated with CDDP alone. GADD45A mRNA levels in MCF-7 and SH-SY5Y cells co-treated with CDDP+EMF were increased and at the same time the mRNA levels of XRCC4, Ku80, Ku70 and DNA-PKcs were down-regulated.
SIGNIFICANCE: Present study provides evidence that co-treatment of CDDP+EMF can enhance down-regulation of the genes involved in non-homologous end-joining pathway. It might be suggested that co-treatment of CDDP+EMF could be more promising for sensitizing cancer cells to DNA double strand breaks.

Jun S, Jung YS, Suh HN, et al.
LIG4 mediates Wnt signalling-induced radioresistance.
Nat Commun. 2016; 7:10994 [PubMed] Free Access to Full Article Related Publications
Despite the implication of Wnt signalling in radioresistance, the underlying mechanisms are unknown. Here we find that high Wnt signalling is associated with radioresistance in colorectal cancer (CRC) cells and intestinal stem cells (ISCs). We find that LIG4, a DNA ligase in DNA double-strand break repair, is a direct target of β-catenin. Wnt signalling enhances non-homologous end-joining repair in CRC, which is mediated by LIG4 transactivated by β-catenin. During radiation-induced intestinal regeneration, LIG4 mainly expressed in the crypts is conditionally upregulated in ISCs, accompanied by Wnt/β-catenin signalling activation. Importantly, among the DNA repair genes, LIG4 is highly upregulated in human CRC cells, in correlation with β-catenin hyperactivation. Furthermore, blocking LIG4 sensitizes CRC cells to radiation. Our results reveal the molecular mechanism of Wnt signalling-induced radioresistance in CRC and ISCs, and further unveils the unexpected convergence between Wnt signalling and DNA repair pathways in tumorigenesis and tissue regeneration.

Sharapova SO, Chang EY, Guryanova IE, et al.
Next generation sequencing revealed DNA ligase IV deficiency in a "developmentally normal" patient with massive brain Epstein-Barr virus-positive diffuse large B-cell lymphoma.
Clin Immunol. 2016; 163:108-10 [PubMed] Related Publications
INTRODUCTION: Here we present an unusual case of DNA ligase IV deficiency syndrome without dysmorphic facial findings and microcephaly complicated with Epstein-Barr virus-associated large B-cell lymphoma with the right lung involvement and a massive brain tumor lesion in a two-year-old female.
METHODS: PID panel was used for sequencing 55 genes. Most genes have >98% exon coverage including splicing sites. LIG4 gene has 100% exon and splicing site coverage. This was used in Ion Torrent PGM system, the library kit was made by Agilent with Haloplex technology. The sequence analysis software was Alamut, direct sequencing of LIG4 gene was performed after NGS results.
RESULT: We identified three heterozygous mutations in LIG4 gene c.2736+3delC and c.8 C>T (p.A3V) inherited from mother and c.26C>T (p.T9I) - from father after PID panel sequencing and some additional polymorphisms in ATM, NOD2 and NLRP3 genes.
CONCLUSION: This case broadens the clinical spectrum of DNA ligase IV deficiency.

Ma H, Takahashi A, Yoshida Y, et al.
Combining carbon ion irradiation and non-homologous end-joining repair inhibitor NU7026 efficiently kills cancer cells.
Radiat Oncol. 2015; 10:225 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Our previous data demonstrated that targeting non-homologous end-joining repair (NHEJR) yields a higher radiosensitivity than targeting homologous recombination repair (HRR) to heavy ions using DNA repair gene knockouts (KO) in mouse embryonic fibroblast (MEF). In this study, we determined if combining the use of an NHEJR inhibitor with carbon (C) ion irradiation was more efficient in killing human cancer cells compared with only targeting a HRR inhibitor.
METHODS: The TP53-null human non-small cell lung cancer cell line H1299 was used for testing the radiosensitizing effect of NHEJR-related DNA-dependent protein kinase (DNA-PK) inhibitor NU7026, HRR-related Rad51 inhibitor B02, or both to C ion irradiation using colony forming assays. The mechanism underlying the inhibitor radiosensitization was determined by flow cytometry after H2AX phosphorylation staining. HRR-related Rad54-KO, NHEJR-related Lig4-KO, and wild-type TP53-KO MEF were also included to confirm the suppressing effect specificity of these inhibitors.
RESULTS: NU7026 showed significant sensitizing effect to C ion irradiation in a concentration-dependent manner. In contrast, B02 showed a slight sensitizing effect to C ion irradiation. The addition of NU7026 significantly increased H2AX phosphorylation after C ion and x-ray irradiations in H1299 cells, but not B02. NU7026 had no effect on radiosensitivity to Lig4-KO MEF and B02 had no effect on radiosensitivity to Rad54-KO MEF in both irradiations.
CONCLUSION: These results suggest that inhibitors targeting the NHEJR pathway could significantly enhance radiosensitivity of human cancer cells to C ion irradiation, rather than targeting the HRR pathway.

Zhou C, Tang H, Yu J, et al.
Blood-based DNA methylation of DNA repair genes in the non-homologous end-joining (NEHJ) pathway in patient with glioma.
Int J Clin Exp Pathol. 2015; 8(8):9463-7 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: To investigate the blood-based DNA methylation of repair genes including LIG4, XRCC4, XRCC5, XRCC6 and XRCC7 that involved in non-homologous end-joining (NEHJ) DNA repair pathway in patients with glioma. Blood samples were obtained from 114 glioma patients, 96 normal controls, and 81 glioma patients after radiotherapy and chemotherapy. Blood-based DNA methylation of the five NHEJ repair genes was assayed by methylation-specific polymerase chain reaction (MSP). The DNA methylation level of XRCC5 and XRCC7 in glioma group are significantly higher than those of normal group (P<0.001). Moreover, radiotherapy treatment significantly increased methylation level of XRCC5 and XRCC7 compared to glioma group. No significant difference for the methylation of the other three genes, LIG4, XRCC4 and XRCC6 were detected among three groups.
IN CONCLUSION: our findings indicate that DNA methylation modification plays an important role to regulate the gene expression of XRCC5 and XRCC7, from the results that the gene methylation level of the glioma group is higher than that of the normal group. Increased methylation of XRCC5 and XRCC7 in blood samples of glioma patients and patients with radiotherapy and chemotherapy suggests that blood-based methylation level of XRCC5 and XRCC7 could be a potential indicator for evaluating of the effect of radiotherapy and chemotherapy for glioma patient.

Gan W, Liu P, Wei W
Akt promotes tumorigenesis in part through modulating genomic instability via phosphorylating XLF.
Nucleus. 2015; 6(4):261-5 [PubMed] Free Access to Full Article Related Publications
To maintain genome stability, mammalian cells have developed a delicate, yet efficient, system to sense and repair damaged DNA, including two evolutionarily conserved DNA damage repair (DDR) pathways: homologous recombination (HR) and non-homologous-end-joining (NHEJ). Deregulation in these repair pathways may lead to genomic instability and subsequent human diseases, including cancer. On the other hand, hyper-activation of the oncogenic Akt signaling pathway has been observed in almost all solid tumors. Emerging evidence has begun to reveal a possible role of active Akt in regulating DDR, possibly through suppression of HR. However, whether and how Akt regulates NHEJ remains largely undefined. To this end, we recently reported that Akt impairs NHEJ by phosphorylating XLF at T181, to trigger its dissociation from the functional DNA ligase IV (LIG4)/XRCC4 complex. Here, we provide an additional perspective discussing how Akt is activated upon DNA damage to regulate DNA repair pathways as well as the cellular apoptotic responses.

Wagner W, Ciszewski WM, Kania KD
L- and D-lactate enhance DNA repair and modulate the resistance of cervical carcinoma cells to anticancer drugs via histone deacetylase inhibition and hydroxycarboxylic acid receptor 1 activation.
Cell Commun Signal. 2015; 13:36 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The consideration of lactate as an active metabolite is a newly emerging and attractive concept. Recently, lactate has been reported to regulate gene transcription via the inhibition of histone deacetylases (HDACs) and survival of cancer cells via hydroxycarboxylic acid receptor 1 (HCAR1). This study examined the role of L- and D-lactate in the DNA damage response in cervical cancer cells.
METHODS: Three cervical cancer cell lines were examined: HeLa, Ca Ski and C33A. The inhibitory activity of lactate on HDACs was analysed using Western blot and biochemical methods. The lactate-mediated stimulation of DNA repair and cellular resistance to neocarzinostatin, doxorubicin and cisplatin were studied using γ-H2AX, comet and clonogenic assays. HCAR1 and DNA repair gene expression was quantified by real-time PCR. DNA-PKcs activity and HCAR1 protein expression were evaluated via immunocytochemistry and Western blot, respectively. HCAR1 activation was investigated by measuring intracellular cAMP accumulation and Erk phosphorylation. HCAR1 expression was silenced using shRNA.
RESULTS: L- and D-lactate inhibited HDACs, induced histone H3 and H4 hyperacetylation, and decreased chromatin compactness in HeLa cells. Treating cells with lactate increased LIG4, NBS1, and APTX expression by nearly 2-fold and enhanced DNA-PKcs activity. Based on γ-H2AX and comet assays, incubation of cells in lactate-containing medium increased the DNA repair rate. Furthermore, clonogenic assays demonstrated that lactate mediates cellular resistance to clinically used chemotherapeutics. Western blot and immunocytochemistry showed that all studied cell lines express HCAR1 on the cellular surface. Inhibiting HCAR1 function via pertussis toxin pretreatment partially abolished the effects of lactate on DNA repair. Down-regulating HCAR1 decreased the efficiency of DNA repair, abolished the cellular response to L-lactate and decreased the effect of D-lactate. Moreover, HCAR1 shRNA-expressing cells produced significantly lower mRNA levels of monocarboxylate transporter 4. Finally, the enhancement of DNA repair and cell survival by lactate was suppressed by pharmacologically inhibiting monocarboxylate transporters using the inhibitor α-cyano-4-hydroxycinnamic acid (α-CHCA).
CONCLUSIONS: Our data indicate that L- and D-lactate present in the uterine cervix may participate in the modulation of cellular DNA damage repair processes and in the resistance of cervical carcinoma cells to anticancer therapy.

Su Y, Qi S, Dou C, et al.
Association of LIG4 and XRCC4 gene polymorphisms with the risk of human glioma in a Chinese population.
Int J Clin Exp Pathol. 2015; 8(2):2057-62 [PubMed] Free Access to Full Article Related Publications
We conducted a case-control study to assess the LIG4 and XRCC4 genes polymorphisms and development of glioma. A case-control study including 162 glioma cases and 324 controls was conducted in a Chinese population. Genotypes of rs10131 and rs1805388 in LIG4 and rs2075685 and rs1805377 in XRCC4 were conducted by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assay. Conditional logistic regression analysis showed that subjects carrying AA genotype of LIG4 rs10131 was associated with increased risk of glioma when compared with GG genotype, and the OR (95% CI) was 3.26 (1.50-7.23). We found that GA+AA of LIG4 rs10131 was associated with increased risk of glioma in those without family history of cancer, and the OR (95% CI) was 1.78 (1.12-2.83). However, no association was found between variants of LIG4 rs1805388, XRCC4 rs2075685 and XRCC4 rs1805377 and development of glioma. In conclusion, our results suggest that LIG4 rs10131 polymorphism in the DNA repair pathways plays an important role in the risk of glioma in a Chinese population.

Xu F, Han JC, Zhang YJ, et al.
Associations of LIG4 and HSPB1 genetic polymorphisms with risk of radiation-induced lung injury in lung cancer patients treated with radiotherapy.
Biomed Res Int. 2015; 2015:860373 [PubMed] Free Access to Full Article Related Publications
OBJECTIVE: This study aims to explore the correlations of genetic polymorphisms in LIG4 and HSPB1 genes with the radiation-induced lung injury (RILI), especially radiation pneumonitis (RP), in lung cancer patients.
METHODS: A total of 160 lung cancer patients, who were diagnosed with inoperable lung cancer and received radiotherapy, were included in the present study from September 2009 to December 2011. TaqMan Real-Time PCR (RT-PCR) was used to verify the SNPs of LIG4 and HSPB1 genes. Chi-square criterion was used to compare the differences in demographic characteristics, exposure to risk factors, and SNPs genotypes. Crude odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated by logistic regression analysis. All statistical analyses were conducted in SPSS 18.0.
RESULTS: A total of 32 (20.0%) lung cancer patients had RP after receiving radiotherapy. Of the 32 cases, 4 cases were of grade 2, 24 cases were of grade 3, and 4 cases were of grade 4. However, our results indicated that the general condition and treatment of all patients had no significant difference with RP risk (P > 0.05). Meanwhile, our results revealed that there was no significant association between the frequencies of LIG4 rs1805388 and HSPB1 rs2868371 genotype distribution and the risk of RP (P > 0.05).
CONCLUSION: In conclusion, we demonstrated that the genetic polymorphisms in LIG4 rs1805388 and HSPB1 rs2868371 were not obviously correlated with the risk of RP and RILI of lung cancer.

Kim DH, Oh SY, Kim SY, et al.
DNA ligase4 as a prognostic marker in nasopharyngeal cancer patients treated with radiotherapy.
Asian Pac J Cancer Prev. 2014; 15(24):10985-9 [PubMed] Related Publications
BACKGROUND: The capability for DNA double-strand breaks (DSBs) repair is crucial for inherent radiosensitivity of tumor and normal cells. We have investigated the clinicopathologic significance of DNA repair gene expression in nasopharyngeal (NP) carcinoma.
MATERIALS AND METHODS: A total of 65 NP cancer patients who received radiotherapy were included. The immunopositivity to Ku 70, DNA-PKcs, MRN, RAD50, XRCC4, and LIG4 were examined in all tumor tissues.
RESULTS: The patients comprised 42 males and 23 females, with a median age of 56 years (range, 18-84). The expression levels of RAD50 (0,+1,+2,+3) were 27.7%, 32.3%, 21.5%, and 18.5%. LIG4 (±) were 43.1% and 56.9% respectively. The 5-year OS rate of patients with LIG4 (±) were 90% and 67.9%, respectively (p=0.035). The 5-year TTP rate of patients with LIG4 (±) were 75.9%, 55.5%, respectively (P=0.039).
CONCLUSIONS: Our results suggest the possibility of predicting the radiosensitivity of NP cancer by performing immunohistochemical analysis of LIG4.

Newman EA, Lu F, Bashllari D, et al.
Alternative NHEJ Pathway Components Are Therapeutic Targets in High-Risk Neuroblastoma.
Mol Cancer Res. 2015; 13(3):470-82 [PubMed] Related Publications
UNLABELLED: In neuroblastoma, MYCN genomic amplification and segmental chromosomal alterations including 1p or 11q loss of heterozygocity and/or 17q gain are associated with progression and poor clinical outcome. Segmental alterations are the strongest predictor of relapse and result from unbalanced translocations attributable to erroneous repair of chromosomal breaks. Although sequence analysis of affected genomic regions suggests that these errors arise by nonhomologous end-joining (NHEJ) of DNA double-strand breaks (DSB), abnormalities in NHEJ have not been implicated in neuroblastoma pathogenesis. On this basis, the hypothesis that an error-prone mechanism of NHEJ is critical for neuroblastoma cell survival was tested. Plasmid-based DSB repair assays demonstrated efficient NHEJ activity in human neuroblastoma cells with repair products that were error-prone relative to nontransformed cells. Neuroblastoma cells derived from tumorigenic neuroblastic phenotypes had differential DNA repair protein expression patterns compared with nontumorigenic cells. Tumorigenic neuroblastoma cells were deficient in DNA ligase IV (Lig4) and Artemis (DCLRE1C), mediators of canonical NHEJ. Conversely, enzymes required for an error-prone alternative NHEJ pathway (alt-NHEJ), DNA Ligase IIIα (Lig3), DNA Ligase I (Lig1), and PARP1 protein were upregulated. Inhibition of Lig3 and Lig1 led to DSB accumulation and cell death, linking alt-NHEJ to cell survival in neuroblastoma. Neuroblastoma cells demonstrated sensitivity to PARP1 inhibition (PARPi) that paralleled PARP1 expression. In a dataset of human neuroblastoma patient tumors, overexpression of genes encoding alt-NHEJ proteins associated with poor survival.
IMPLICATIONS: These findings provide an insight into DNA repair fidelity in neuroblastoma and identify components of the alt-NHEJ pathway as promising therapeutic targets.

Henríquez-Hernández LA, Valenciano A, Foro-Arnalot P, et al.
Single nucleotide polymorphisms in DNA repair genes as risk factors associated to prostate cancer progression.
BMC Med Genet. 2014; 15:143 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Besides serum levels of PSA, there is a lack of prostate cancer specific biomarkers. It is need to develop new biological markers associated with the tumor behavior which would be valuable to better individualize treatment. The aim of this study was to elucidate the relationship between single nucleotide polymorphisms (SNPs) in genes involved in DNA repair and prostate cancer progression.
METHODS: A total of 494 prostate cancer patients from a Spanish multicenter study were genotyped for 10 SNPs in XRCC1, ERCC2, ERCC1, LIG4, ATM and TP53 genes. The SNP genotyping was made in a Biotrove OpenArray® NT Cycler. Clinical tumor stage, diagnostic PSA serum levels, and Gleason score at diagnosis were obtained for all participants. Genotypic and allelic frequencies were determined using the web-based environment SNPator.
RESULTS: SNPs rs11615 (ERCC1) and rs17503908 (ATM) appeared as risk factors for prostate cancer aggressiveness. Patients wild homozygous for these SNPs (AA and TT, respectively) were at higher risk for developing cT2b - cT4 (OR = 2.21 (confidence interval (CI) 95% 1.47 - 3.31), p < 0.001) and Gleason scores ≥ 7 (OR = 2.22 (CI 95% 1.38 - 3.57), p < 0.001), respectively. Moreover, those patients wild homozygous for both SNPs had the greatest risk of presenting D'Amico high-risk tumors (OR = 2.57 (CI 95% 1.28 - 5.16)).
CONCLUSIONS: Genetic variants at DNA repair genes are associated with prostate cancer progression, and would be taken into account when assessing the malignancy of prostate cancer.

Xie S, Shan XF, Shang K, et al.
Relevance of LIG4 gene polymorphisms with cancer susceptibility: evidence from a meta-analysis.
Sci Rep. 2014; 4:6630 [PubMed] Free Access to Full Article Related Publications
Polymorphisms of LIG4 gene may influence DNA repair ability, thus altering the genetic stability and resulting in carcinogenesis. A growing number of studies have investigated the relevance of LIG4 T9I (rs1805388) and D501D (rs1805386) polymorphisms with cancer risk, however, the results are conflicting. To obtain a comprehensive conclusion, we searched relevant literatures from PubMed, Web of Science, Ovid and Embase databases on May 15, 2014 and performed a meta-analysis. In this meta-analysis, a total of 17 articles were included. Of them, there were 15 studies with 5873 cases and 5771 controls for rs1805388 and 6 studies with 4161 cases and 4881 controls for rs1805386. Overall, our results suggested that there was no obvious relevance of LIG4 T9I polymorphism with cancer susceptibility. However, in subgroup analysis, we found the LIG4 T9I was associated with a slightly decreased cancer risk among Caucasians. As to the rs1805386, the genetic variant had no significant association with cancer risk. In conclusion, despite several limitations, this meta-analysis suggested that LIG4 T9I genetic variant is associated with a decreased risk of cancer among Caucasians, however, the rs1805386 gene polymorphism is not a risk factor of cancer.

Zhang MY, Keel SB, Walsh T, et al.
Genomic analysis of bone marrow failure and myelodysplastic syndromes reveals phenotypic and diagnostic complexity.
Haematologica. 2015; 100(1):42-8 [PubMed] Free Access to Full Article Related Publications
Accurate and timely diagnosis of inherited bone marrow failure and inherited myelodysplastic syndromes is essential to guide clinical management. Distinguishing inherited from acquired bone marrow failure/myelodysplastic syndrome poses a significant clinical challenge. At present, diagnostic genetic testing for inherited bone marrow failure/myelodysplastic syndrome is performed gene-by-gene, guided by clinical and laboratory evaluation. We hypothesized that standard clinically-directed genetic testing misses patients with cryptic or atypical presentations of inherited bone marrow failure/myelodysplastic syndrome. In order to screen simultaneously for mutations of all classes in bone marrow failure/myelodysplastic syndrome genes, we developed and validated a panel of 85 genes for targeted capture and multiplexed massively parallel sequencing. In patients with clinical diagnoses of Fanconi anemia, genomic analysis resolved subtype assignment, including those of patients with inconclusive complementation test results. Eight out of 71 patients with idiopathic bone marrow failure or myelodysplastic syndrome were found to harbor damaging germline mutations in GATA2, RUNX1, DKC1, or LIG4. All 8 of these patients lacked classical clinical stigmata or laboratory findings of these syndromes and only 4 had a family history suggestive of inherited disease. These results reflect the extensive genetic heterogeneity and phenotypic complexity of bone marrow failure/myelodysplastic syndrome phenotypes. This study supports the integration of broad unbiased genetic screening into the diagnostic workup of children and young adults with bone marrow failure and myelodysplastic syndromes.

Ciszewski WM, Wagner W, Kania KD, Dastych J
Interleukin-4 enhances PARP-dependent DNA repair activity in vitro.
J Interferon Cytokine Res. 2014; 34(9):734-40 [PubMed] Free Access to Full Article Related Publications
Eukaryotic cells possess several DNA repair mechanisms, including homologous recombination and the non-homologous end-joining (NHEJ) system. There are two known NHEJ systems. The major mechanism depends on the catalytic unit of DNA-dependent protein kinase (DNA-PKcs) and DNA ligase IV, and an alternative mechanism (B-NHEJ) depends on poly(ADP-ribose) polymerase (PARP). These systems are upregulated by genotoxic agents. Interleukin 4 (IL-4) is an immunoregulatory cytokine that is secreted by immune cells upon contact with certain genotoxic compounds and is known to regulate several genes encoding components of DNA repair systems in human monocytes. We have investigated the possible effects of IL-4 on the DNA repair process within murine and human cells exposed to selected genotoxic compounds. In a series of experiments, including the comet assay, cell surface annexin V staining, analysis of histone H2AX phosphorylation, and a DNA end-joining assay, we observed that IL-4 decreased DNA damage in murine fibroblasts and human glioblastoma cells exposed to genotoxic agents and increased DNA ligation activity in the nuclei of these cells in a process that depended on PARP. These observations suggest that IL-4 is capable of upregulating the alternative NHEJ DNA repair mechanism in murine and human cells.

Jiang YH, Xu XL, Ruan HH, et al.
The impact of functional LIG4 polymorphism on platinum-based chemotherapy response and survival in non-small cell lung cancer.
Med Oncol. 2014; 31(5):959 [PubMed] Related Publications
DNA repair capacity is correlated with the sensitivity of cancer cells toward platinum-based chemotherapy. The aim of this study was to investigate whether single-nucleotide polymorphisms (SNPs) in DNA repair genes NBS1, LIG4, and RAD51 were correlated with tumor response in advanced non-small cell lung cancer (NSCLC) patients in a Chinese population who received platinum-based chemotherapy. The treatment outcomes of 146 advanced NSCLC patients who were treated with platinum-based chemotherapy were evaluated. The polymorphic status of three SNPs was determined by genotyping via the polymerase chain reaction-restriction fragment length polymorphism method. Forty-five patients in the group with the CC genotype (45/90) showed a good response to treatment, while only 18 patients in the CT+TT group (18/55) showed a good response, indicating a substantial differences in the chemotherapy response rate based on the LIG4 Thr9Ile polymorphism (P = 0.042). Patients with the GG genotype for the NSB1 Glu185Gln polymorphism were more sensitive to platinum-based chemotherapy compared with patients with either the CG or CC genotype (P = 0.001). Kaplan-Meier analysis of all patients showed a significant association between the LIG4 Thr9Ile CC polymorphism and superior progression-free survival and overall survival (log-rank P = 0.045 and 0.031, respectively). However, there were no significant differences in survival based on the LIG4 Thr9Ile or the RAD51 135G>C polymorphisms. Polymorphisms in the NSB1 and LIG4 genes may be a predictive marker for treatment response and for advanced NSCLC patients in stage IIIB + IV. The CC genotype of the LIG4 Thr9Ile polymorphism may also serve as an independent prognosis factor.

Usmani N, Leong N, Martell K, et al.
Single-nucleotide polymorphisms studied for associations with urinary toxicity from (125)I prostate brachytherapy implants.
Brachytherapy. 2014 May-Jun; 13(3):285-91 [PubMed] Related Publications
PURPOSE: To identify clinical, dosimetric, and genetic factors that are associated with late urinary toxicity after a (125)I prostate brachytherapy implant.
METHODS AND MATERIALS: Genomic DNA from 296 men treated with (125)I prostate brachytherapy monotherapy was extracted from saliva samples for this study. A retrospective database was compiled including clinical, dosimetric, and toxicity data for this cohort of patients. Fourteen candidate single-nucleotide polymorphism (SNPs) from 13 genes (TP53, ERCC2, GSTP1, NOS, TGFβ1, MSH6, RAD51, ATM, LIG4, XRCC1, XRCC3, GSTA1, and SOD2) were tested in this cohort for correlations with toxicity.
RESULTS: This study identified 217 men with at least 2 years of followup. Of these, 39 patients developed Grade ≥2 late urinary complications with a transurethral resection of prostate, urethral stricture, gross hematuria, or a sustained increase in their International Prostate Symptom Score. The only clinical or dosimetric factor that was associated with late urinary toxicity was age (p = 0.02). None of the 14 SNPs tested in this study were associated with late urinary toxicity in the univariate analysis.
CONCLUSIONS: This study identified age as the only variable being associated with late urinary toxicity. However, the small sample size and the candidate gene approach used in this study mean that further investigations are essential. Genome-wide association studies are emerging as the preferred approach for future radiogenomic studies to overcome the limitations from a candidate gene approach.

Nishida Y, Mizutani N, Inoue M, et al.
Phosphorylated Sp1 is the regulator of DNA-PKcs and DNA ligase IV transcription of daunorubicin-resistant leukemia cell lines.
Biochim Biophys Acta. 2014; 1839(4):265-74 [PubMed] Related Publications
Multidrug resistance (MDR) is a serious problem faced in the treatment of malignant tumors. In this study, we characterized the expression of non-homologous DNA end joining (NHEJ) components, a major DNA double strand break (DSB) repair mechanism in mammals, in K562 cell and its daunorubicin (DNR)-resistant subclone (K562/DNR). K562/DNR overexpressed major enzymes of NHEJ, DNA-PKcs and DNA ligase IV, and K562/DNR repaired DSB more rapidly than K562 after DNA damage by neocarzinostatin (MDR1-independent radiation-mimetic). Overexpressed DNA-PKcs and DNA ligase IV were also observed in DNR-resistant HL60 (HL60/DNR) cells as compared with parental HL60 cells. Expression level of DNA-PKcs mRNA paralleled its protein level, and the promoter activity of DNA-PKcs of K562/DNR was higher than that of K562, and the 5'-region between -49bp and the first exon was important for its activity. Because this region is GC-rich, we tried to suppress Sp1 family transcription factor using mithramycin A (MMA), a specific Sp1 family inhibitor, and siRNAs for Sp1 and Sp3. Both MMA and siRNAs suppressed DNA-PKcs expression. Higher serine-phosphorylated Sp1 but not total Sp1 of both K562/DNR and HL60/DNR was observed compared with their parental K562 and HL60 cells. DNA ligase IV expression of K562/DNR was also suppressed significantly with Sp1 family protein inhibition. EMSA and ChIP assay confirmed higher binding of Sp1 and Sp3 with DNA-PKcs 5'-promoter region of DNA-PKcs of K562/DNR than that of K562. Thus, the Sp1 family transcription factor affects important NHEJ component expressions in anti-cancer drug-resistant malignant cells, leading to the more aggressive MDR phenotype.

Kuhmann C, Li C, Kloor M, et al.
Altered regulation of DNA ligase IV activity by aberrant promoter DNA methylation and gene amplification in colorectal cancer.
Hum Mol Genet. 2014; 23(8):2043-54 [PubMed] Related Publications
Colorectal cancer (CRC) presents as a very heterogeneous disease which cannot sufficiently be characterized with the currently known genetic and epigenetic markers. To identify new markers for CRC we scrutinized the methylation status of 231 DNA repair-related genes by methyl-CpG immunoprecipitation followed by global methylation profiling on a CpG island microarray, as altered expression of these genes could drive genomic and chromosomal instability observed in these tumors. We show for the first time hypermethylation of MMP9, DNMT3A and LIG4 in CRC which was confirmed in two CRC patient groups with different ethnicity. DNA ligase IV (LIG4) showed strong differential promoter methylation (up to 60%) which coincided with downregulation of mRNA in 51% of cases. This functional association of LIG4 methylation and gene expression was supported by LIG4 re-expression in 5-aza-2'-deoxycytidine-treated colon cancer cell lines, and reduced ligase IV amounts and end-joining activity in extracts of tumors with hypermethylation. Methylation of LIG4 was not associated with other genetic and epigenetic markers of CRC in our study. As LIG4 is located on chromosome 13 which is frequently amplified in CRC, two loci were tested for gene amplification in a subset of 47 cases. Comparison of amplification, methylation and expression data revealed that, in 30% of samples, the LIG4 gene was amplified and methylated, but expression was not changed. In conclusion, hypermethylation of the LIG4 promoter is a new mechanism to control ligase IV expression. It may represent a new epigenetic marker for CRC independent of known markers.

Henríquez-Hernández LA, Valenciano A, Foro-Arnalot P, et al.
Polymorphisms in DNA-repair genes in a cohort of prostate cancer patients from different areas in Spain: heterogeneity between populations as a confounding factor in association studies.
PLoS One. 2013; 8(7):e69735 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Differences in the distribution of genotypes between individuals of the same ethnicity are an important confounder factor commonly undervalued in typical association studies conducted in radiogenomics.
OBJECTIVE: To evaluate the genotypic distribution of SNPs in a wide set of Spanish prostate cancer patients for determine the homogeneity of the population and to disclose potential bias.
DESIGN SETTING AND PARTICIPANTS: A total of 601 prostate cancer patients from Andalusia, Basque Country, Canary and Catalonia were genotyped for 10 SNPs located in 6 different genes associated to DNA repair: XRCC1 (rs25487, rs25489, rs1799782), ERCC2 (rs13181), ERCC1 (rs11615), LIG4 (rs1805388, rs1805386), ATM (rs17503908, rs1800057) and P53 (rs1042522). The SNP genotyping was made in a Biotrove OpenArray® NT Cycler.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Comparisons of genotypic and allelic frequencies among populations, as well as haplotype analyses were determined using the web-based environment SNPator. Principal component analysis was made using the SnpMatrix and XSnpMatrix classes and methods implemented as an R package. Non-supervised hierarchical cluster of SNP was made using MultiExperiment Viewer.
RESULTS AND LIMITATIONS: We observed that genotype distribution of 4 out 10 SNPs was statistically different among the studied populations, showing the greatest differences between Andalusia and Catalonia. These observations were confirmed in cluster analysis, principal component analysis and in the differential distribution of haplotypes among the populations. Because tumor characteristics have not been taken into account, it is possible that some polymorphisms may influence tumor characteristics in the same way that it may pose a risk factor for other disease characteristics.
CONCLUSION: Differences in distribution of genotypes within different populations of the same ethnicity could be an important confounding factor responsible for the lack of validation of SNPs associated with radiation-induced toxicity, especially when extensive meta-analysis with subjects from different countries are carried out.

Alsbeih G, El-Sebaie M, Al-Harbi N, et al.
SNPs in genes implicated in radiation response are associated with radiotoxicity and evoke roles as predictive and prognostic biomarkers.
Radiat Oncol. 2013; 8:125 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Biomarkers are needed to individualize cancer radiation treatment. Therefore, we have investigated the association between various risk factors, including single nucleotide polymorphisms (SNPs) in candidate genes and late complications to radiotherapy in our nasopharyngeal cancer patients.
METHODS: A cohort of 155 patients was included. Normal tissue fibrosis was scored using RTOG/EORTC grading system. A total of 45 SNPs in 11 candidate genes (ATM, XRCC1, XRCC3, XRCC4, XRCC5, PRKDC, LIG4, TP53, HDM2, CDKN1A, TGFB1) were genotyped by direct genomic DNA sequencing. Patients with severe fibrosis (cases, G3-4, n = 48) were compared to controls (G0-2, n = 107).
RESULTS: Univariate analysis showed significant association (P < 0.05) with radiation complications for 6 SNPs (ATM G/A rs1801516, HDM2 promoter T/G rs2279744 and T/A rs1196333, XRCC1 G/A rs25487, XRCC5 T/C rs1051677 and TGFB1 C/T rs1800469). In addition, Kaplan-Meier analyses have also highlighted significant association between genotypes and length of patients' follow-up after radiotherapy. Multivariate logistic regression has further sustained these results suggesting predictive and prognostic roles of SNPs.
CONCLUSIONS: Univariate and multivariate analysis suggest that radiation toxicity in radiotherapy patients are associated with certain SNPs, in genes including HDM2 promoter studied for the 1st time. These results support the use of SNPs as genetic predictive markers for clinical radiosensitivity and evoke a prognostic role for length of patients' follow-up after radiotherapy.

Zhao P, Zou P, Zhao L, et al.
Genetic polymorphisms of DNA double-strand break repair pathway genes and glioma susceptibility.
BMC Cancer. 2013; 13:234 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Genetic variations in DNA double-strand break repair genes can influence the ability of a cell to repair damaged DNA and alter an individual's susceptibility to cancer. We studied whether polymorphisms in DNA double-strand break repair genes are associated with an increased risk of glioma development.
METHODS: We genotyped 10 potentially functional single nucleotide polymorphisms (SNPs) in 7 DNA double-strand break repair pathway genes (XRCC3, BRCA2, RAG1, XRCC5, LIG4, XRCC4 and ATM) in a case-control study including 384 glioma patients and 384 cancer-free controls in a Chinese Han population. Genotypes were determined using the OpenArray platform.
RESULTS: In the single-locus analysis there was a significant association between gliomas and the LIG4 rs1805388 (Ex2 +54C>T, Thr9Ile) TT genotype (adjusted OR, 3.27; 95% CI, 1.87-5.71), as well as the TC genotype (adjusted OR, 1.62; 95% CI, 1.20-2.18). We also found that the homozygous variant genotype (GG) of XRCC4 rs1805377 (IVS7-1A>G, splice-site) was associated with a significantly increased risk of gliomas (OR, 1.77; 95% CI, 1.12-2.80). Interestingly, we detected a significant additive and multiplicative interaction effect between the LIG4 rs1805388 and XRCC4 rs1805377 polymorphisms with an increasing risk of gliomas. When we stratified our analysis by smoking status, LIG4 rs1805388 was associated with an increased glioma risk among smokers.
CONCLUSIONS: These results indicate for the first time that LIG4 rs1805388 and XRCC4 rs1805377, alone or in combination, are associated with a risk of gliomas.

Mahaney BL, Hammel M, Meek K, et al.
XRCC4 and XLF form long helical protein filaments suitable for DNA end protection and alignment to facilitate DNA double strand break repair.
Biochem Cell Biol. 2013; 91(1):31-41 [PubMed] Free Access to Full Article Related Publications
DNA double strand breaks (DSBs), induced by ionizing radiation (IR) and endogenous stress including replication failure, are the most cytotoxic form of DNA damage. In human cells, most IR-induced DSBs are repaired by the nonhomologous end joining (NHEJ) pathway. One of the most critical steps in NHEJ is ligation of DNA ends by DNA ligase IV (LIG4), which interacts with, and is stabilized by, the scaffolding protein X-ray cross-complementing gene 4 (XRCC4). XRCC4 also interacts with XRCC4-like factor (XLF, also called Cernunnos); yet, XLF has been one of the least mechanistically understood proteins and precisely how XLF functions in NHEJ has been enigmatic. Here, we examine current combined structural and mutational findings that uncover integrated functions of XRCC4 and XLF and reveal their interactions to form long, helical protein filaments suitable to protect and align DSB ends. XLF-XRCC4 provides a global structural scaffold for ligating DSBs without requiring long DNA ends, thus ensuring accurate and efficient ligation and repair. The assembly of these XRCC4-XLF filaments, providing both DNA end protection and alignment, may commit cells to NHEJ with general biological implications for NHEJ and DSB repair processes and their links to cancer predispositions and interventions.

Guo Q, Guo P, Mao Q, et al.
ID1 affects the efficacy of radiotherapy in glioblastoma through inhibition of DNA repair pathways.
Med Oncol. 2013; 30(1):325 [PubMed] Related Publications
Glioblastoma multiforme (GBM) is characterized by poor therapeutic response and poor overall survival. It is crucial that more effective therapies be developed for the treatment of GBM. Inhibitor of DNA binding protein-1 (ID1) has been shown to maintain the self-renewal capacity of neural stem cells and might be involved in the therapeutic resistance of GBM. In the present study, we explored survival data from the The Cancer Genome Atalas database that were based on ID1 expression for patients diagnosed with primary GBMs. Interestingly, patients with high ID1 expression had better survival than patients with low ID1 expression, and a strong correlation was found between radiotherapy efficacy, ID1 expression, and overall survival. We further investigated the relationship between ID1 expression and the radiosensitivity of glioblastoma using glioblastoma cell lines. The clonogenic formation assay showed that U87 ID1-shRNA cells were much less sensitive to radiation. Moreover, both the results of the γH2AX foci staining assay and the comet assay further revealed that ID1 negatively regulates DNA repair processes by downregulating the expression of genes such as DNA ligase IV (LIG4) and ataxia-telangiectasia-mutated. Additionally, ID1 induces G2/M arrest in U87 cells. Taken together, these results suggest that ID1 may be a new prognostic marker for GBM and have important implications for the therapeutic strategies used to treat GBM patients.

Fachal L, Gómez-Caamaño A, Peleteiro P, et al.
Association of a XRCC3 polymorphism and rectum mean dose with the risk of acute radio-induced gastrointestinal toxicity in prostate cancer patients.
Radiother Oncol. 2012; 105(3):321-8 [PubMed] Related Publications
BACKGROUND AND PURPOSE: We have performed a case-control study among prostate cancer patients treated with three-dimensional conformational radiotherapy (3D-CRT) in order to investigate the association between single nucleotide polymorphisms (SNPs), treatment and patient features with gastrointestinal and genitourinary acute toxicity.
MATERIAL AND METHODS: A total of 698 patients were screened for 14 SNPs located in the ATM, ERCC2, LIG4, MLH1 and XRCC3 genes. Gastrointestinal and genitourinary toxicities were recorded prospectively using the Common Terminology Criteria for Adverse Events v3.0.
RESULTS: The XRCC3 SNP rs1799794 (G/G OR=5.65; 95% CI: 1.95-16.38; G/A OR=2.75; 95% CI: 1.25-6.05; uncorrected p-value=2.8×10(-03); corrected p-value=0.03; FDR q-value=0.06) as well as the mean dose received by the rectum (OR=1.06; 95% CI: 1.02-1.1; uncorrected p-value=2.49×10(-03); corrected p-value=0.03; FDR q-value=0.06) were significantly associated with gastrointestinal toxicity after correction for multiple testing. Those patients who undergone previous prostatectomy were less prone to develop genitourinary toxicity (OR=0.38; 95% CI: 0.18-0.71; uncorrected p-value=4.95×10(-03); corrected p-value=0.03; FDR q-value=0.08). Our study excludes the possibility of a >2-fold risk increase in genitourinary acute toxicity being due to rs1801516 ATM SNP, the rs1805386 and rs1805388 LIG4 markers, as well as all the SNPs evaluated in the ERCC2, MLH1 and XRCC3 genes.
CONCLUSIONS: The XRCC3 rs1799794 SNP and the mean dose received by the rectum are associated with the development of gastrointestinal toxicity after 3D-CRT.

Zhou LP, Luan H, Dong XH, et al.
Lack of association between LIG4 gene polymorphisms and the risk of breast cancer: a HuGE review and meta-analysis.
Asian Pac J Cancer Prev. 2012; 13(7):3417-22 [PubMed] Related Publications
OBJECTIVE: Non-homologous end joining (NHEJ) is one of the pathways of repair of DNA double-strand breaks. A number of genes involved in NHEJ have been implicated as breast cancer susceptibility genes such as LIG4. However, some studies have generated conflicting results. The aim of this Human Genome Epidemiology (HuGE) review and meta-analysis was to investigate association between LIG4 gene polymorphisms in the NHEJ pathway and breast cancer risk.
METHODS: Studies focusing on the relationship between LIG4 gene polymorphisms and susceptibility to breast cancer were selected from the Pubmed, Cochrane library, Embase, Web of Science, Springerlink, CNKI and CBM databases. Data were extracted by two independent reviewers and the meta-analysis was performed with Review Manager Version 5.1.6 and STATA Version 12.0 software, calculating odds ratios (ORs) with 95% confidence intervals (95%CIs).
RESULTS: According to the inclusion criteria, we final included seven studies with a total of 10,321 breast cancer cases and 10,160 healthy controls in the meta-analysis. The results showed no association between LIG4 gene polymorphisms (rs1805386 T>C, rs1805389 C>T, rs1805388 C>T and rs2232641 A>G) and breast cancer risk, suggesting that the mutant situation of these SNPs neither increased nor decreased the risk for breast cancer. In the subgroup analysis by Hardy-Weinberg equilibrium (HWE) and ethnicity, we also found no associations between the variants of LIG4 gene and breast cancer risk among HWE, non-HWE, Caucasians, Asians and Africans.
CONCLUSION: This meta-analysis suggests that there is a lack of any association between LIG4 gene polymorphisms and the risk of breast cancer.

Chrzanowska KH, Gregorek H, Dembowska-Bagińska B, et al.
Nijmegen breakage syndrome (NBS).
Orphanet J Rare Dis. 2012; 7:13 [PubMed] Free Access to Full Article Related Publications
Nijmegen breakage syndrome (NBS) is a rare autosomal recessive syndrome of chromosomal instability mainly characterized by microcephaly at birth, combined immunodeficiency and predisposition to malignancies. Due to a founder mutation in the underlying NBN gene (c.657_661del5) the disease is encountered most frequently among Slavic populations. The principal clinical manifestations of the syndrome are: microcephaly, present at birth and progressive with age, dysmorphic facial features, mild growth retardation, mild-to-moderate intellectual disability, and, in females, hypergonadotropic hypogonadism. Combined cellular and humoral immunodeficiency with recurrent sinopulmonary infections, a strong predisposition to develop malignancies (predominantly of lymphoid origin) and radiosensitivity are other integral manifestations of the syndrome. The NBN gene codes for nibrin which, as part of a DNA repair complex, plays a critical nuclear role wherever double-stranded DNA ends occur, either physiologically or as a result of mutagenic exposure. Laboratory findings include: (1) spontaneous chromosomal breakage in peripheral T lymphocytes with rearrangements preferentially involving chromosomes 7 and 14, (2) sensitivity to ionizing radiation or radiomimetics as demonstrated in vitro by cytogenetic methods or by colony survival assay, (3) radioresistant DNA synthesis, (4) biallelic hypomorphic mutations in the NBN gene, and (5) absence of full-length nibrin protein. Microcephaly and immunodeficiency are common to DNA ligase IV deficiency (LIG4 syndrome) and severe combined immunodeficiency with microcephaly, growth retardation, and sensitivity to ionizing radiation due to NHEJ1 deficiency (NHEJ1 syndrome). In fact, NBS was most commonly confused with Fanconi anaemia and LIG4 syndrome. Genetic counselling should inform parents of an affected child of the 25% risk for further children to be affected. Prenatal molecular genetic diagnosis is possible if disease-causing mutations in both alleles of the NBN gene are known. No specific therapy is available for NBS, however, hematopoietic stem cell transplantation may be one option for some patients. Prognosis is generally poor due to the extremely high rate of malignancies.

Reeves SG, Meldrum C, Groombridge C, et al.
DNA repair gene polymorphisms and risk of early onset colorectal cancer in Lynch syndrome.
Cancer Epidemiol. 2012; 36(2):183-9 [PubMed] Related Publications
DNA repair plays a pivotal role in maintaining genomic integrity with over 130 genes involved in various repair pathways that include base excision repair, nucleotide excision repair, double strand break repair and DNA mismatch repair. Polymorphisms within genes that are involved in these processes have been widely reported to be associated with cancer susceptibility in an extensive range of malignancies that include colorectal cancer (CRC). Lynch syndrome is caused by inherited germline mutations in DNA mismatch repair genes, predominantly in MLH1 and MSH2, that predispose to a variety of epithelial malignancies, most notably CRC. Despite being a relatively well understood hereditary cancer syndrome there remain several questions in relation to genetic influences on disease expression. Since Lynch syndrome is associated with a breakdown in DNA mismatch repair variation in other DNA repair genes may influence disease expression. In this report we have genotyped 424 Australian and Polish Lynch syndrome participants for eight common DNA repair gene polymorphisms to assess any association with the age of CRC onset. The DNA repair gene SNPs included in the study were: BRCA2 (rs11571653), MSH3 (rs26279), Lig4 (rs1805386), OGG1 (rs1052133), XRCC1 (rs25487), XRCC2 (rs3218536 and rs1799793) and XRCC3 (rs861539). Cox multi-variant regression modelling failed to provide any convincing evidence of an effect in any of the polymorphisms analysed. The data suggest that polymorphisms in DNA repair genes do not contribute to cancer risk in a population of CRC patients who are at increased risk of disease as a result in a deficiency of DNA mismatch repair.

Yin M, Liao Z, Liu Z, et al.
Genetic variants of the nonhomologous end joining gene LIG4 and severe radiation pneumonitis in nonsmall cell lung cancer patients treated with definitive radiotherapy.
Cancer. 2012; 118(2):528-35 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Nonhomologous end joining (NHEJ) is a pathway that repairs DNA double-strand breaks (DSBs) to maintain genomic stability in response to irradiation. The authors hypothesized that single nucleotide polymorphisms (SNPs) in NHEJ repair genes may affect clinical outcomes in patients with nonsmall cell lung cancer (NSCLC) who receive definitive radio(chemo)therapy.
METHODS: The authors genotyped 5 potentially functional SNPs-x-ray repair complementing defective repair in Chinese hamster cells 4 (XRCC4) reference SNP (rs) number rs6869366 (-1394 guanine to thymine [-1394G→T] change) and rs28360071 (intron 3, deletion/insertion), XRCC5 rs3835 (guanine to adenine [G→A] change at nucleotide 2408), XRCC6 rs2267437 (-1310 cytosine to guanine [C→G) change], and DNA ligase IV (LIG4) rs1805388 (threonine-to-isoleucine change at codon 9 [T9I])-and estimated their associations with severe radiation pneumonitis (RP) (grade ≥3) in 195 patients with NSCLC.
RESULTS: A predictive role in radiation pneumonitis (RP) development was observed for the LIG4 SNP rs1805388 (adjusted hazard ratio, 2.08; 95% confidence interval, 1.04-4.12; P = .037 for the CT/TT genotype vs the CC genotype). In addition, men with the TT genotype of the XRCC4 rs6869366 SNP and women with AG + AA genotypes of the XRCC5 rs3835 SNP also were at increased risk of developing severe RP.
CONCLUSIONS: The current results indicated that NHEJ genetic polymorphisms, particularly LIG4 rs1805388, may modulate the risk of RP in patients with NSCLC who receive definitive radio(chemo)therapy. Large studies will be needed to confirm these findings.

Salagovič J, Klimčáková L, Ilenčíková D, Kafková A
Association of follicular lymphoma risk with BRCA2 N372H polymorphism in Slovak population.
Med Oncol. 2012; 29(2):1173-8 [PubMed] Related Publications
Follicular lymphoma (FL) is one of the most common Non-Hodgkin lymphoma (NHL) subtype. Only small number of studies concerning NHL and DNA reparation gene polymorphisms has been performed so far. Hence, we have assessed the effect of 4 selected polymorphisms with possible influence on risk of FL development in a case-control study in Slovak population. We have genotyped polymorphisms in the RAG1 (K820R), LIG4 (T9I), BRCA2 (N372H), and WRN (V114I) genes in 108 patients with histologically proven FL diagnosis and 127 healthy controls. For discrimination between the allelic variants, we have established the genotyping by real-time melting analysis of an unlabeled probe. The most notable finding was related to polymorphism N372H in the BRCA2 gene. Compared with the wild-type genotype (NN), the homozygous variant genotype (HH) was associated with an increased FL risk (OR = 2.91, 95% CI: 0.96-8.81), although on the borderline of statistical significance (P = 0.050). However, after stratification by gender and age, the FL risk was significantly increased in men with variant-containing genotypes (OR = 2.79, 95% CI: 1.20-6.45) and even severalfold significantly increased among men with homozygous variant BRCA2 genotype (OR = 21.18, 95% CI: 2.46-182.2). No significant associations with FL risk were identified for other polymorphisms.

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