Functional polymorphisms in the NBS1 gene and acute lymphoblastic leukemia susceptibility in a Chinese population

Association of DNA repair genes polymorphisms with childhood acute lymphoblastic leukemia: a high-resolution melting analysis

Objective

Acute lymphoblastic leukemia (ALL) is one of the most common cancers in children for which the exact pathogenesis is not yet known. Single-nucleotide variants (SNVs) in different DNA repair genes are reported to be associated with ALL risk. This study aimed to determine the association between XRCC1 (rs1799782) and NBN (rs1805794, rs709816) SNVs and childhood ALL risk in a sample of the Iranian population. Fifty children with ALL and 50 age- and sex-matched healthy children were included in this case–control study. Genotyping of the mentioned SNVs was done by high-resolution melting (HRM) analysis.

Results

The prevalence of all three SNVs in XRCC1 and NBN genes did not differ between the patient and control groups, and these polymorphisms were not associated with childhood ALL risk (P > 0.05). HRM was a practical method for the detection of SNVs in XRCC1 and NBN genes. We found no significant association between XRCC1 (rs1799782) and NBN (rs1805794, rs709816) SNVs and childhood ALL risk.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-05918-3.

DNA repair pathways as guardians of the genome: Therapeutic potential and possible prognostic role in hematologic neoplasms

DNA repair pathways, which are also identified as guardians of the genome, protect cells from frequent damage that can lead to DNA breaks. The most deleterious types of damage are double-strand breaks (DSBs), which are repaired by homologous recombination (HR) and non-homologous end joining (NHEJ). Single strand breaks (SSBs) can be corrected through base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Failure to restore DNA lesions or inappropriately repaired DNA damage culminates in genomic instability and changes in the regulation of cellular functions. Intriguingly, particular mutations and translocations are accompanied by special types of leukemia. Besides, expression patterns of certain repair genes are altered in different hematologic malignancies. Moreover, analysis of mutations in key mediators of DNA damage repair (DDR) pathways, as well as investigation of their expression and function, may provide us with emerging biomarkers of response/resistance to treatment. Therefore, defective DDR pathways can offer a rational starting point for developing DNA repair-targeted drugs. In this review, we address genetic alterations and gene/protein expression changes, as well as provide an overview of DNA repair pathways.

A non-synonymous polymorphism in NBS1 is associated with progression from chronic hepatitis B virus infection to hepatocellular carcinoma in a Chinese population

PURPOSE

Nijmegen breakage syndrome 1 (NBS1) has a vital role in DNA double-strand break (DSB) repair, functioning as a sensor to identify and repair DNA damage and maintaining genomic stability by participating in the intra-S-phase checkpoint. Polymorphisms of NBS1 have been investigated in multiple cancers with variable results. To our best knowledge, no previous study has focused on the association between NBS1 single-nucleotide polymorphisms (SNPs) and hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Five NBS1 SNPs were selected based on their potential functional impact. A hospital-based cohort, comprising 481 patients with HBV-related HCC, 508 patients with chronic hepatitis B virus infection (CHB), and 581 healthy controls, was recruited for genotyping analysis.

RESULTS

After quality control, four SNPs were successfully genotyped (rs10464867, rs1063053, rs1805794, and rs709816), none of which were significantly associated with HCC or CHB compared with those of healthy controls. Similarly, the combined HBV-infected group (including the HCC and CHB groups) exhibited no significant associations with these SNPs compared with healthy controls. In contrast, comparison of the frequency of rs1805794 between patients with CHB and those with HCC identified a significant association (P=2.99E-03, odds ratio =1.31, 95% confidence interval =1.10-1.56).

CONCLUSION

These findings suggest that, as a non-synonymous SNP, the rs1805794 C/G polymorphism may play a role in the progression from CHB to HCC.

Clinicopathological values of NBS1 and DNA damage response genes in epithelial ovarian cancers

Epithelial ovarian cancers (EOCs) are highly lethal gynecological malignancies with a high recurrence rate. Therefore, developing prognostic markers for recurrence after chemotherapy is crucial for the treatment of ovarian cancers. As ovarian cancers frequently respond to DNA-damaging agents, we assessed the clinicopathological significance of key double-strand DNA break (DSB) repair genes, including BRCA1, BRCA2, BARD1, ATM, RAD51 and NBS1 in EOC cell lines and paraffin-embedded tissue sections from 140 EOC patients treated with cytoreductive surgery, followed by platinum-based chemotherapy. These samples were analyzed for the clinicopathological impact of DSB genes by western blot analysis, immunohistochemistry and quantitative real-time PCR. Of the DSB repair genes, BRCA1, ATM and NBS1, which are involved in the homologous recombination-mediated repair pathway, were related to aggressive parameters in EOC. When survival analysis was performed, NBS1 expression exhibited an association with EOC recurrence. Specifically, increased NBS1 expression was found in 107 out of 140 cases (76.0%) and correlated with advanced stage (P=0.001), high grade (P=0.001) and serous histology (P=0.008). The median recurrence-free survival in patients with positive and negative expression of NBS1 was 30 and 78 months, respectively (P=0.0068). In multivariate analysis, NBS1 was an independent prognostic factor for the recurrence of EOC. Together, these results suggest that NBS1 is a marker of poor prognosis for the recurrence of EOC and is associated with aggressive clinicopathological parameters.

The functional polymorphism of NBS1 p.Glu185Gln is associated with an increased risk of lung cancer in Chinese populations: case-control and a meta-analysis

NBS1 plays pivotal roles in maintaining genomic stability and cancer development. The exon variant rs1805794G>C (p.Glu185Gln) of NBS1 has been frequently studied in several association studies. However, the results were conflicting. Also, the function of this variant has never been well studied. In the current study, we performed a two centers case-control study and function assays to investigate the effect of the variant rs1805794G>C on lung cancer risk in Chinese, and a meta-analysis to summarize the data on the association between rs1805794G>C and cancer risk. We found that compared with the rs1805794GG genotype, the C genotypes (CG/CC) conferred a significantly increased risk of lung cancer in Chinese (OR=1.40, 95% CI=1.21-1.62) and interacted with medical ionizing radiation exposure on increasing cancer risk (Pinteraction=0.015). The lymphocyte cells from the C genotype individuals developed more chromatid breaks than those from the GG genotype carriers after the X-ray radiation (P=0.036). Moreover, the rs1805794C allele encoding p.185Gln attenuated NBS1's ability to repair DNA damage as the cell lines transfected with NBS1 cDNA expression vector carrying rs1805794C allele had significantly higher DNA breaks than those transfected with NBS1 cDNA expression vector carrying rs1805794G allele (P<0.05). The meta-analysis further confirmed the association between the variant rs1805794G>C and lung cancer risk, that compared with the GG genotype, the carriers of C genotypes had a 1.30-fold risk of cancer (95% CI=1.14-1.49, P=8.49×10(-5)). These findings suggest that the rs1805794G>C of NBS1 may be a functional genetic biomarker for lung cancer.

NBN and XRCC3 genetic variants in childhood acute lymphoblastic leukaemia

Nibrin and DNA repair protein XRCC3 are involved in DNA double-strand break repair. We genotyped seven tagging SNPs in these genes (rs1805794, rs709816; rs1063054; rs7141928, rs1799794, rs861530, rs861539) with the aim to analyse their association with acute lymphoblastic leukaemia (ALL), a disease, that is characterised by elevated genetic instability. Study consisted of 460 paediatric ALL cases and 552 healthy controls. For selection of DNA sequence variants we employed SNP-tagging approach, incorporating the HAPMAP CEU reference panel data. We did not find association of analysed and tagged SNPs and derived haplotypes with the ALL risk thus did not confirm the hypothesis that analysed DNA recombination repair variants account for increased susceptibility to ALL.

Copy number variation at 6q13 is associated with lung cancer risk in a Han Chinese population

Copy number variations (CNVs), a major source of human genetic polymorphism, have been suggested to have an important role in genetic susceptibility to common diseases such as cancer, immune diseases, and neurological disorders. Lung cancer is a multifactorial tumor closely associated with genetic background. Previous genome-wide association studies have identified single nucleotide polymorphisms (SNPs) that are associated with lung cancer susceptibility. This study examined the CNVR2966.1 at 6q13 and its association with lung cancer susceptibility. The CNVR2966.1 was found to be a 10,379 bp nucleotides deletion/insertion within the uniform boundaries chromosome 6: 74,648,791-74,659,169. The risk of lung cancer observed in 503 cases and 623 controls was significantly associated with copy number of CNVR2966.1, with the odds ratio (OR) being 1.38 [95% confidence interval (CI) = 1.05-1.79; P = .007] for one copy genotype compared with two copies genotype. These results suggest that CNVR2966.1 is associated with lung cancer risk.

NBN Gene Polymorphisms and Cancer Susceptibility: A Systemic Review

The relationship between DNA repair failure and cancer is well established as in the case of rare, high penetrant genes in high cancer risk families. Beside this, in the last two decades, several studies have investigated a possible association between low penetrant polymorphic variants in genes devoted to DNA repair pathways and risk for developing cancer. This relationship would be also supported by the observation that DNA repair processes may be modulated by sequence variants in DNA repair genes, leading to susceptibility to environmental carcinogens. In this framework, the aim of this review is to provide the reader with the state of the art on the association between common genetic variants and cancer risk, limiting the attention to single nucleotide polymorphisms (SNPs) of the NBN gene and providing the various odd ratios (ORs). In this respect, the NBN protein, together with MRE11 and RAD50, is part of the MRN complex which is a central player in the very early steps of sensing and processing of DNA double-strand breaks (DSBs), in telomere maintenance, in cell cycle control, and in genomic integrity in general. So far, many papers were devoted to ascertain possible association between common synonymous and non-synonymous NBN gene polymorphisms and increased cancer risk. However, the results still remain inconsistent and inconclusive also in meta-analysis studies for the most investigated E185Q NBN miscoding variant.

Tobacco smoking, NBS1 polymorphisms, and survival in lung and upper aerodigestive tract cancers with semi-Bayes adjustment for hazard ratio variation

PURPOSE

Although single nucleotide polymorphisms (SNPs) of NBS1 have been associated with susceptibility to lung and upper aerodigestive tract (UADT) cancers, their relations to cancer survival and measures of effect are largely unknown.

METHODS

Using follow-up data from 611 lung cancer cases and 601 UADT cancer cases from a population-based case-control study in Los Angeles, we prospectively evaluated associations of tobacco smoking and 5 NBS1 SNPs with all-cause mortality. Mortality data were obtained from the Social Security Death Index. We used Cox regression to estimate adjusted hazard ratios (HR) for main effects and ratios of hazard ratios (RHR) derived from product terms to assess hazard ratio variations by each SNP. Bayesian methods were used to account for multiple comparisons.

RESULTS

We observed 406 (66 %) deaths in lung cancer cases and 247 (41 %) deaths in UADT cancer cases with median survival of 1.43 and 1.72 years, respectively. Ever tobacco smoking was positively associated with mortality for both cancers. We observed an upward dose-response association between smoking pack-years and mortality in UADT squamous cell carcinoma. The adjusted HR relating smoking to mortality in non-small cell lung cancer (NSCLC) was greater for cases with the GG genotype of NBS1 rs1061302 than for cases with AA/AG genotypes (semi-Bayes adjusted RHR = 1.97; 95 % limits = 1.14, 3.41).

CONCLUSIONS

A history of tobacco smoking at cancer diagnosis was associated with mortality among patients with lung cancer or UADT squamous cell carcinoma. The HR relating smoking to mortality appeared to vary with the NBS1 rs1061302 genotype among NSCLC cases.

Functional variants in NBS1 and cancer risk: evidence from a meta-analysis of 60 publications with 111 individual studies

Several potentially functional variants of Nijmegen breakage syndrome 1 (NBS1) have been implicated in cancer risk, but individually studies showed inconclusive results. In this study, a meta-analysis based on 60 publications with a total of 39 731 cancer cases and 64 957 controls was performed. The multivariate method and the model-free method were adopted to determine the best genetic model. It was found that rs2735383 variant genotypes were associated with significantly increased overall risk of cancer under the recessive genetic model [odds ratio (OR) =1.12, 95% confidence interval (CI): 1.02-1.22, P = 0.013]. Similar results were found for rs1063054 under the dominant model effect (OR = 1.12, 95% CI: 1.01-1.23, P = 0.024). The I171V mutation, 657del5 mutation and R215W mutation also contribute to the development of cancer (for I171V, OR = 3.93, 95% CI: 1.68-9.20, P = 0.002; for 657del5, OR = 2.79, 95% CI: 2.17-3.68, P < 0.001; for R215W, OR = 1.77, 95% CI: 1.07-2.91, P = 0.025). From stratification analyses, an effect modification of cancer risks was found in the subgroups of tumour site and ethnicity for rs2735383, whereas the I171V, 657del5 and R215W showed a deleterious effect of cancer susceptibility in the subgroups of tumour site. However, rs1805794, D95N and P266L did not appear to have an effect on cancer risk. These results suggest that rs2735383, rs1063054, I171V, 657del5 and R215W are low-penetrance risk factors for cancer development.

Germline variants in MRE11/RAD50/NBN complex genes in childhood leukemia

BACKGROUND

The MRE11, RAD50, and NBN genes encode proteins of the MRE11-RAD50-NBN (MRN) complex involved in cellular response to DNA damage and the maintenance of genome stability. In our previous study we showed that the germline p.I171V mutation in NBN may be considered as a risk factor in the development of childhood acute lymphoblastic leukemia (ALL) and some specific haplotypes of that gene may be associated with childhood leukemia. These findings raise important questions about the role of mutations in others genes of the MRN complex in childhood leukemia. The aim of this study was to answer the question whether MRE11 and RAD50 alterations may be associated with childhood ALL or AML.

METHODS

We estimated the frequency of constitutional mutations and polymorphisms in selected regions of MRE11, RAD50, and NBN in the group of 220 children diagnosed with childhood leukemias and controls (n=504/2200). The analysis was performed by specific amplification of region of interest by PCR and followed by multi-temperature single-strand conformation polymorphism (PCR-MSSCP) technique. We performed two molecular tests to examine any potential function of the detected the c.551+19G>A SNP in RAD50 gene. To our knowledge, this is the first analysis of the MRE11, RAD50 and NBN genes in childhood leukemia.

RESULTS

The frequency of either the AA genotype or A allele of RAD50_rs17166050 were significantly different in controls compared to leukemia group (ALL+AML) (p<0.0019 and p<0.0019, respectively). The cDNA analysis of AA or GA genotypes carriers has not revealed evidence of splicing abnormality of RAD50 pre-mRNA. We measured the allelic-specific expression of G and A alleles at c.551+19G>A and the statistically significant overexpression of the G allele has been observed. Additionally we confirmed the higher incidence of the p.I171V mutation in the leukemia group (7/220) than among controls (12/2400) (p<0.0001).

CONCLUSION

The formerly reported sequence variants in the RAD50 and MRE11 gene may not constitute a risk factor of childhood ALL in Polish population. The RAD50_rs17166050 variant allele is linked to decreased ALL risk (p<0.0009, OR=0.6358 (95%CI: 0.4854-0.8327)). Despite the fact that there is no splicing abnormality in carriers of the variant allele but an excess of the G over the A allele was consistently observed. This data demonstrate that some specific alternations of the RAD50 gene may be associated with childhood ALL.

Functional polymorphisms in the CD44 gene and acute myeloid leukemia cancer risk in a Chinese population

CD44 is such one adhesion molecule that mediates interactions between acute myeloid leukemia (AML) cells and stromal. It has been demonstrated that CD4 plays a critical role in AML development. However, studies of functional single nucleotide polymorphisms (SNPs) in CD44 gene have not touched upon AML. This case-control study probed the contribution of functional SNPs in CD44 gene to AML susceptibility in eastern Chinese population. Five representative SNPs of CD44 (rs10836347C>T, rs13347C>T, rs1425802A>G, rs11821102G>A, rs713330T>C) were opted and genotyped in 421 AML patients and 461 healthy subjects and the association with risk of AML was estimated by logistic regression. Moreover, the potential role of rs13347C > T in AML was further explored. Compared with the rs13347CC genotype, CT carriers had a significant increase in AML susceptibility (adjusted odds ratio [OR] = 1.76; 95% confidence interval [CI] = 1.32-2.34), TT carriers had a further increased risk of AML (OR = 2.67; 95% CI = 1.69-4.21). Furthermore, our transient transfection assay and Western blot results demonstrated that the presence of rs13347T allele led to more CD44 expression. Yet, there exists no significant difference in genotype frequencies of the other four sites between cases and controls. Above findings suggest that rs13347C>T in 3'UTR of CD44 may be a genetic modifier for developing AML.

Occupational solvent exposure, genetic variation of DNA repair genes, and the risk of non-Hodgkin's lymphoma

The main objective of this study was to test the hypothesis that genetic variations in DNA repair genes may modify the association between occupational exposure to solvents and the risk of non-Hodgkin's lymphoma (NHL). A population-based case-control study was conducted on Connecticut women including 518 histologically confirmed incident NHL cases and 597 controls. Unconditional logistic regression models were used to estimate the odds ratios and effect modification from the 30 single nucleotide polymorphisms in 16 DNA repair genes of the association between solvent exposure and the risk of NHL overall and subtypes. Single nucleotide polymorphisms in MGMT (rs12917) and NBS1 (rs1805794) significantly modified the association between exposure to chlorinated solvents and the risk of NHL (Pfor interaction=0.0003 and 0.0048, respectively). After stratification by major NHL histological subtypes, MGMT (rs12917) modified the association between chlorinated solvents and the risk of diffuse large B-cell lymphoma (Pfor interaction=0.0027) and follicular lymphoma (Pfor interaction=0.0024). A significant interaction was also observed between occupational exposure to benzene and BRCA2 (rs144848) for NHL overall (Pfor interaction=0.0042). Our study results suggest that genetic variations in DNA repair genes modify the association between occupational exposure to solvents and the risk of NHL.

Association between the NBS1 Glu185Gln polymorphism and breast cancer risk: a meta-analysis

Nijmegen breakage syndrome 1 (NBS1), a vital DNA repair protein in the homologous recombination repair pathway and a signal modifier in the intra-S phase checkpoint, plays a critical role in cellular response to DNA damages and the maintenance of genomic stability. The NBS1 Glu185Gln (NBS1 E185Q, NBS1 8360G>C, rs1805794) polymorphism has been indicated to be involved in the development of cancer, but results of previous individual studies on the association between NBS1 Glu185Gln polymorphism and breast cancer risk remain controversial and inconclusive. Our meta-analysis investigated this association for the first time by pooling the odds ratios with corresponding 95 % confidence intervals (95 % CIs) of all individual publications available to date. Overall, 14 separate studies with 6,642 cases and 7,138 controls were finally included into the present meta-analysis after a comprehensive literature search of the PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases up to October 21, 2012. Overall analysis and subgroup analyses by ethnicity and source of controls were performed. Meta-analysis of total studies showed that the NBS1 Glu185Gln variant carriers were not susceptible to breast cancer (ORGln vs. Glu = 1.05, 95 % CI 0.80-1.39, P OR = 0.719; OR Gln/Gln vs. Glu/Glu = 0.82, 95 % CI 0.62-1.08, P OR = 0.154; OR Glu/Gln vs. Glu/Glu = 1.00, 95 % CI 0.90-1.13, P OR = 0.939; ORGln/Gln + Glu/Gln vs. Glu/Glu = 0.96, 95 % CI 0.83-1.11, P OR = 0.551; ORGln/Gln vs. Glu/Glu + Glu/Gln = 0.84, 95 % CI 0.67-1.05, P OR = 0.134). Similar results were observed in heterogeneity-adjusted meta-analysis of all studies. Furthermore, subgroup analyses by ethnicity and source of controls did not identify any appreciable relationship of the NBS1 Glu185Gln polymorphism with breast cancer susceptibility in any populations. Sensitivity analysis by sequentially omitting individual studies confirmed the stability and reliability of our results. Our meta-analysis of currently available data shows no association between the NBS1 Glu185Gln polymorphism and breast cancer risk.

NBS1 rs1805794G>C polymorphism is associated with decreased risk of acute myeloid leukemia in a Chinese population

As a key encoding protein gene of MRN (MRE11-RAD50-NBS1) complex, NBS1 plays a crucial role in maintaining genomic stability and preventing cell apoptosis, inflammation and tumorgenesis. Single nucleotide polymorphisms (rs2735383 and rs1805794) in NBS1 have been frequently studied in some cancers with discordant results in previous case-control studies. However, the relationship between these two functional polymorphisms and the susceptibility to acute myeloid leukemia (AML) in Chinese population has not been investigated. We performed a case-control study with 428 patients and 600 controls to detect the association between the two polymorphisms of NBS1 and the risk of AML in a Chinese population. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was carried out to determine the genotypes of potential functional SNPs in NBS1 gene. The results showed that compared with the homozygous carriers rs1805794CC, rs1805794GC genotype was significantly associated with decreased risk of AML in total subjects (adjusted odds ratio (OR) = 0.50; 95% CI = 0.37-0.67), the risk decreased even further in those carrying rs1805794GG genotype (OR = 0.23; 95% CI = 0.16-0.34). No significant association was found between rs2735383C>G polymorphism and the risk of AML (OR = 0.93; 95% CI = 0.71-1.22 for GC; OR = 0.78; 95% CI = 0.53-1.13 for CC, P = 0.152). These findings indicated that rs1805794G/C polymorphism in NBS1 may play a protective role in mediating the risk of AML.

Functional polymorphism in the EpCAM gene is associated with occurrence and advanced disease status of cervical cancer in Chinese population

The epithelial cell adhesion molecule (EpCAM) was originally identified as a tumor associated antigen, attributable to its high expression on rapidly proliferating tumors of epithelial origin. EpCAM plays vital roles in carcinogenesis, tumor progression and metastasis in most tumors. A non-synonymous polymorphism (rs1126497 C/T) was found in exon 3 of EpCAM, which cause a transition from 115 Met to 115 Thr. Another polymorphism (rs1421 A/G) in the 3'UTR causes loss of has-miR-1183 binding. We performed a multiple independent case-control analysis to assess the association between EpCAM genotypes and cervical cancer risk. Genotyping a total of 518 patients with cervical cancer and 723 control subjects in a Chinese population, we observed that the variant EpCAM genotypes (rs1126497 CT, and TT) were associated with substantially increased risk of cervical cancer. Compared with the rs1126497 CC genotype, CT genotype had a significantly increased risk of cervical cancer (Crude OR = 1.70; 95% CI = 1.33-2.20; adjusted OR = 1.72; 95% CI = 1.33-2.22), the TT carriers had a further increased risk of cervical cancer (Crude OR = 1.94; 95% CI = 1.01-3.72; adjusted OR = 1.96; 95%CI = 1.01-3.81), and there was a trend for an allele dose effect on risk of cervical cancer (P < 0.001). Moreover, the allele T increases the risk for invasive disease or metastatic disease, compared with C allele. However, there exists no significant difference in genotype frequencies of rs1421 A/G site between cases and controls (P = 0.798). These findings suggest that rs1126497 C/T polymorphism in EpCAM may be a genetic modifier for developing cervical cancer.

A functional polymorphism at microRNA-629-binding site in the 3'-untranslated region of NBS1 gene confers an increased risk of lung cancer in Southern and Eastern Chinese population

The genetic variations in NBS1 gene have been reported to be associated with cancer risk. The polymorphisms in 3'-untranslated region (3'-UTR) of NBS1 might affect gene's function and thus contribute to cancer susceptibility. We hypothesized that these polymorphisms of NBS1 are associated with the lung cancer risk. In two independent case-control studies conducted in Southern and Eastern Chinese, we genotyped three tagSNPs (rs14448, rs13312986 and rs2735383) in Southern Chinese and then validated the discovered association in Eastern Chinese. No significant association was observed for rs13312986 and rs14448; we only found that the rs2735383CC genotype had a significantly increased risk of lung cancer under a recessive genetic model in the total 1559 cases versus 1679 controls (odds ratio = 1.40, 95% confidence interval = 1.18-1.66, P = 0.0001) when compared with GG or GC genotypes; the rs2735383CC genotype carriers had lower messenger RNA and protein expression levels in tumor tissues than those of other genotypes as quantitative polymerase chain reaction and western blot shown. Luciferase assay revealed that the rs2735383C allele had a lower transcription activity than G allele, and the hsa-miR-629 but not hsa-miR-499-5P had effect on modulation of NBS1 gene in vitro. We further observed that the X-ray radiation induced more chromatid breaks in lymphocyte cells from the carriers of rs2735383CC homozygote than those from the subjects with other genotypes (P = 0.0008). Our data suggested that the rs2735383G>C variation contributes to an increased risk of lung cancer by diminishing gene's expression through binding of microRNA-629 to the polymorphic site in the 3'-UTR of NBS1 gene.

Functional NBS1 polymorphism is associated with occurrence and advanced disease status of nasopharyngeal carcinoma

As a component of the MRN (MRE11/RAD50/NBS1) complex, NBS1 plays an important role in cellular response to DNA damage and the maintenance of chromosomal integrity. The NBS1 E185Q polymorphism (8360G>C, rs1805794) has been frequently studied in some cancers with discordant results, but its association with nasopharyngeal carcinoma (NPC) in Chinese population has not been investigated. Moreover, there is no report about the association between NBS1 3'UTR variant rs2735383 and the risk of NPC. A multiple center case-control analysis was performed to assess the association between NBS1 polymorphisms and NPC risk in Eastern and Southern Chinese population. The genotypes and haplotypes were determined in 1052 cases and 1168 controls and the associations with risk of NPC were estimated by logistic regression. Cell migration assays were performed in 24-well transwell chambers to detect the effects of NBS1 E185Q SNP on cell migration. We observed significant difference in genotype frequencies at the rs1805794 C/G site between cases and controls (P(trend) < 0.0001). The C allele increases the risk for invasive disease or metastatic disease, compared with G allele. More over, CNE-2 cells (NPC cell line) transfected with pcDNA-NBS1-185Q (8360CC) had significantly higher migration levels than those transfected with pcDNA-NBS1-185E (8360GG) (P = 0.024). These findings suggest that E185Q polymorphism in NBS1 may be a genetic modifier for the occurrence and aggression of NPC.

Functional polymorphisms in CD166/ALCAM gene associated with increased risk for breast cancer in a Chinese population

Activated Leukocyte Cell Adhesion Molecules (ALCAM, also called CD166, MEMD) are cell surface immunoglobulins that are considered to be prognostic markers for breast cancer. CD166/ALCAM has gained increasing attention because of its significant association with tumor progression and the metastatic spread of breast cancer. Two polymorphisms have been identified in the CD166/ALCAM gene: 5'UTR C/T (rs6437585) and 3'UTR A/G (rs11559013). We analyzed the genotypes of 1033 individuals with breast cancer, and 1116 controls; odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression. The effects and functions of polymorphisms were examined using luciferase gene expression assays and real-time PCR analyses. Our data demonstrated that individuals with the rs6437585 CT + TT genotype had an OR of 1.38 (95% CI, 1.11-1.72) for developing breast cancer, compared to those with the CC genotype. The T allele increased the risk of breast cancer in a dose-dependent manner (P (trend) < 0.001). However, there were no significant differences found between cases and controls at the rs11559013 A/G site. Additional experiments that we performed, which focused on reporter gene expression driven by CD166/ALCAM promoters, demonstrated that the presence of an rs6437585 T allele led to greater transcriptional activity than the rs6437585 C allele. This was consistent with the increased cancer risk that we observed in our case-control analysis.