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

NBN, RAD51 and XRCC3 Polymorphisms as Potential Predictive Biomarkers of Adjuvant Radiotherapy Toxicity in Early HER2-Positive Breast Cancer

Simple Summary

Adjuvant radiotherapy for breast cancer patients significantly improves survival and causes side effects. It is known that the response to radiotherapy is individual, but we are not yet able to predict patients with high risk for acute or late radiotherapy adverse events. This study aimed to investigate the association between homologous recombination repair (HRR) polymorphisms and radiotherapy toxicity and thus contribute to the knowledge on potential predictive biomarkers of radiotherapy toxicity in early HER2-positive breast cancer. This study was among the first to evaluate the role of HRR genetic variability with cardiac toxicity. RAD51 polymorphisms were associated with cardiac adverse events, while XRCC3 polymorphisms were associated with skin adverse events. Our results suggest that polymorphisms in key HRR genes might be used as potential biomarkers of late treatment-related adverse events in early HER2-positive breast cancer treated with radiotherapy.

Abstract

Radiotherapy (RT) for breast cancer significantly impacts patient survival and causes adverse events. Double-strand breaks are the most harmful type of DNA damage associated with RT, which is repaired through homologous recombination (HRR). As genetic variability of DNA repair genes could affect response to RT, we aimed to evaluate the association of polymorphisms in HRR genes with tumor characteristics and the occurrence of RT adverse events in early HER2-positive breast cancer. Our study included 101 breast cancer patients treated with adjuvant RT and trastuzumab. All patients were genotyped for eight single nucleotide polymorphisms in NBN, RAD51 and XRCC3 using competitive allele-specific PCR. Carriers of XRCC3 rs1799794 GG genotype were less likely to have higher tumor differentiation grade (OR = 0.05, 95% CI = 0.01–0.44, p = 0.007). Carriers of RAD51 rs1801321 TT genotype were more likely to have higher NYHA class in univariable (OR = 10.0; 95% CI = 1.63–61.33; p = 0.013) and multivariable (OR = 9.27; 95% CI = 1.28–67.02; p = 0.027) analysis. Carriers of RAD51 rs12593359 GG genotype were less likely to have higher NYHA class in univariable (OR = 0.09; 95% CI = 0.01–0.79; p = 0.030) and multivariable (OR = 0.07; 95% CI = 0.01–0.81; p = 0.034) analysis. Carriers of XRCC3 rs1799794 GG genotypes experienced more skin adverse events based on LENT-SOMA scale in univariable (OR = 5.83; 95% CI = 1.22–28.00; p = 0.028) and multivariable (OR = 10.90; 95% CI = 1.61–73.72; p = 0.014) analysis. In conclusion, XRCC3 and RAD51 polymorphisms might contribute to RT adverse events in early HER2-positive breast cancer patients.

Micronuclei Formation upon Radioiodine Therapy for Well-Differentiated Thyroid Cancer: The Influence of DNA Repair Genes Variants

Radioiodine therapy with ¹³¹I remains the mainstay of standard treatment for well-differentiated thyroid cancer (DTC). Prognosis is good but concern exists that ¹³¹I-emitted ionizing radiation may induce double-strand breaks in extra-thyroidal tissues, increasing the risk of secondary malignancies. We, therefore, sought to evaluate the induction and 2-year persistence of micronuclei (MN) in lymphocytes from 26 ¹³¹I-treated DTC patients and the potential impact of nine homologous recombination (HR), non-homologous end-joining (NHEJ), and mismatch repair (MMR) polymorphisms on MN levels. MN frequency was determined by the cytokinesis-blocked micronucleus assay while genotyping was performed through pre-designed TaqMan^® Assays or conventional PCR-restriction fragment length polymorphism (RFLP). MN levels increased significantly one month after therapy and remained persistently higher than baseline for 2 years. A marked reduction in lymphocyte proliferation capacity was also apparent 2 years after therapy. MLH1 rs1799977 was associated with MN frequency (absolute or net variation) one month after therapy, in two independent groups. Significant associations were also observed for MSH3 rs26279, MSH4 rs5745325, NBN rs1805794, and tumor histotype. Overall, our results suggest that ¹³¹I therapy may pose a long-term challenge to cells other than thyrocytes and that the individual genetic profile may influence ¹³¹I sensitivity, hence its risk-benefit ratio. Further studies are warranted to confirm the potential utility of these single nucleotide polymorphisms (SNPs) as radiogenomic biomarkers in the personalization of radioiodine therapy.

rs2735383, located at a microRNA binding site in the 3'UTR of NBS1, is not associated with breast cancer risk

NBS1, also known as NBN, plays an important role in maintaining genomic stability. Interestingly, rs2735383 G > C, located in a microRNA binding site in the 3'-untranslated region (UTR) of NBS1, was shown to be associated with increased susceptibility to lung and colorectal cancer. However, the relation between rs2735383 and susceptibility to breast cancer is not yet clear. Therefore, we genotyped rs2735383 in 1,170 familial non-BRCA1/2 breast cancer cases and 1,077 controls using PCR-based restriction fragment length polymorphism (RFLP-PCR) analysis, but found no association between rs2735383CC and breast cancer risk (OR = 1.214, 95% CI = 0.936-1.574, P = 0.144). Because we could not exclude a small effect size due to a limited sample size, we further analyzed imputed rs2735383 genotypes (r2 > 0.999) of 47,640 breast cancer cases and 46,656 controls from the Breast Cancer Association Consortium (BCAC). However, rs2735383CC was not associated with overall breast cancer risk in European (OR = 1.014, 95% CI = 0.969-1.060, P = 0.556) nor in Asian women (OR = 0.998, 95% CI = 0.905-1.100, P = 0.961). Subgroup analyses by age, age at menarche, age at menopause, menopausal status, number of pregnancies, breast feeding, family history and receptor status also did not reveal a significant association. This study therefore does not support the involvement of the genotype at NBS1 rs2735383 in breast cancer susceptibility.

Genetic variations in the homologous recombination repair pathway genes modify risk of glioma

Accumulative epidemiological evidence suggests that single nucleotide polymorphisms (SNPs) in genes involved in homologous recombination (HR) DNA repair pathway play an important role in glioma susceptibility. However, the effects of such SNPs on glioma risk remain unclear. We used a used a candidate pathway-based approach to elucidate the relationship between glioma risk and 12 putative functional SNPs in genes involved in the HR pathway. Genotyping was conducted on 771 histologically-confirmed glioma patients and 752 cancer-free controls from the Chinese Han population. Odds ratios (OR) were calculated both for each SNP individually and for grouped analyses, examining the effects of the numbers of adverse alleles on glioma risk, and evaluated their potential gene-gene interactions using the multifactor dimensionality reduction (MDR). In the single-locus analysis, two variants, the NBS1 rs1805794 (OR 1.42, 95% CI 1.15-1.76, P = 0.001), and RAD54L rs1048771 (OR 1.61, 95% CI 1.17-2.22, P = 0.002) were significantly associated with glioma risk. When we examined the joint effects of the risk-conferring alleles of these three SNPs, we found a significant trend indicating that the risk increases as the number of adverse alleles increase (P = 0.005). Moreover, the MDR analysis suggested a significant three-locus interaction model involving NBS1 rs1805794, MRE11 rs10831234, and ATM rs227062. These results suggested that these variants of the genes involved in the HR pathway may contribute to glioma susceptibility.

Associations between NBS1 Polymorphisms and Colorectal Cancer in Chinese Population

As the central protein of the double strand breaks (DSB)-induced DNA repair pathway, NBS1 participates in detecting the DSBs and plays an essential role in maintaining genomic stability. Single nucleotide polymorphisms (SNPs) in NBS1 gene were commonly tested that associated with the susceptibility to multiple cancers, but the results remained controversial. Thus, we conducted two independent hospital-based case-control studies comprising 1,072 colorectal cancer patients and 1,263 controls to evaluate the association between four NBS1 SNPs and colorectal cancer risk. The result showed that rs2735383C/G polymorphism in the 3'-untranslated region (UTR) of NBS1 was significantly associated with risk of colorectal cancer using logistic regression (P<10(-4)). Furthermore, we observed that rs2735383CC genotype was associated with substantially increased risk of colorectal cancer (odds ratio=1.55, 95% confidence interval=1.27-1.94), compared with the rs2735383GC+GG genotypes. Further functional experiments demonstrated that the rs2735383C allele in the NBS1 disrupted the binding affinity of has-miR-509-5p to the NBS1 3'-UTR in colorectal cancer cells, affecting the NBS1 transcriptional activity and expression level. In conclusion, current evidence suggests that the rs2735383C/G polymorphism might contribute to the risk for colorectal cancer.

Homologous Recombination Repair Polymorphisms and the Risk for Osteosarcoma

Background

DNA repair mechanisms are essential for maintaining genome stability, and genetic variability in DNA repair genes may contribute to cancer susceptibility. Our aim was to evaluate the influence of polymorphisms in the homologous recombination repair genes XRCC3, RAD51, and NBN on the risk for osteosarcoma.

Methods

In total, 79 osteosarcoma cases and 373 controls were genotyped for eight single nucleotide polymorphisms (SNPs) in XRCC3, RAD51, and NBN. Logistic regression was used to determine the association of these SNPs with risk for osteosarcoma.

Results

None of the investigated SNPs was associated with risk for osteosarcoma in the whole cohort of patients, however, in patients diagnosed before the age of thirty years XRCC3 rs861539 C>T and NBN rs1805794 G>C were associated with significantly decreased risk for osteosarcoma (P=0.047, OR=0.54, 95% CI=0.30–0.99 and P=0.036, OR=0.42, 95% CI=0.19–0.94, respectively). Moreover, in the carriers of a combination of polymorphic alleles in both SNPs risk for osteosarcoma was decreased even more significantly (P_trend=0.007). The risk for developing osteosarcoma was the lowest in patients with no wild-type alleles for both SNPs (P=0.039, OR=0.31, 95% CI=0.10–0.94).

Conclusions

Our results suggest that polymorphisms in homologous recombination repair genes might contribute to risk for osteosarcoma in patients diagnosed below the age of thirty years.

The impact of functional LIG4 polymorphism on platinum-based chemotherapy response and survival in non-small cell lung cancer

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.

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.

Association between vitamin D receptor poly(A) polymorphism and breast cancer risk: a meta-analysis

Vitamin D receptor (VDR) poly(A) is a common genetic polymorphism in the VDR gene, and it has been implicated to be associated with breast cancer risk. However, previous studies on the association reported inconclusive results. We performed this meta-analysis to comprehensively assess the association. Eligible studies were searched in PubMed and EMBASE databases. Odds ratio (OR) and its 95% confidence interval (95% CI) were used for statistical analysis. A total 6,631 cases and 6,718 controls from 11 case-control studies were finally included into the meta-analysis. Meta-analysis of total eligible studies showed that VDR poly(A) polymorphism was not associated with the risk of breast cancer (S versus L: OR = 0.99, 95% CI of 0.90-1.09, P = 0.84; SS versus LL: OR = 0.96, 95% CI of 0.79-1.18, P = 0.70; SS/LS versus LL: OR = 0.96, 95% CI of 0.83-1.12, P = 0.63; SS versus LL/LS: OR = 1.00, 95% CI of 0.91-1.10, P = 0.98). Meta-analysis of studies with high quality also showed that there was no association between VDR poly(A) polymorphism and breast cancer risk. In addition, in the subgroup analysis by ethnicity, no significant association was found among Caucasians. Therefore, the meta-analysis suggests that VDR poly(A) polymorphism is not associated with the risk of breast cancer. Large well-designed studies are necessary to clarify the possible association in Asians.

Association between vitamin D receptor gene Cdx2 polymorphism and breast cancer susceptibility

Vitamin D receptor (VDR) gene polymorphisms have been reported to influence susceptibility to breast cancer. However, published findings on the association between VDR Cdx2 polymorphism and breast cancer susceptibility are conflicting. To get a precise estimation of the association between VDR Cdx2 polymorphism and breast cancer susceptibility, we conducted a meta-analysis of four case-control studies with a total of 8,880 subjects (3,841 cases and 5,039 controls). The results showed that VDR Cdx2 polymorphism was not associated with risk of breast cancer (A versus G: OR = 0.96, 95% CI 0.84-1.09; AA versus GG: OR = 0.97, 95% CI 0.64-1.45; AA/GA versus GG: OR = 0.94, 95% CI 0.80-1.10; AA versus GG/GA: OR = 0.99, 95% CI 0.65-1.51). Subgroup analysis in Caucasians also showed that VDR Cdx2 polymorphism was not associated with risk of breast cancer in Caucasians. However, there was a significant association in Africans (A versus G: OR = 0.75, 95% CI 0.60-0.94; AA versus GG: OR = 0.53, 95% CI 0.29-0.99; AA/GA versus GG: OR = 0.75, 95% CI 0.57-0.97). Therefore, the association between VDR Cdx2 polymorphism and breast cancer susceptibility is only found in Africans. More studies are needed to further assess the association in Asians or Africans.