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

Abstract

BackgroundThe 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.MethodsWe 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.ResultsThe 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).ConclusionThe 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.

The MRN protein complex genes: MRE11 and RAD50 and susceptibility to head and neck cancers

“…Similar results were reported in our current and previous study among non-selected breast cancer patients [11]. In our another study we confirmed the association of the variant allele of the RAD50 rs171660505 with decreased risk of the childhood acute lymphoblastic leukemia [18]. A. Choudhury and colleagues have genotyped SNPs in DSB signalling genes and found an marginally association of the MRE11 3′UTR SNP rs2155209 with bladder cancer [17].…”

Heterozygous p.I171V mutation of the NBN gene as a risk factor for lung cancer development

“…A higher frequency of occurrence of the heterozygous c.657del5 mutation has been observed in patients with melanoma and non-Hodgkin lymphoma (22). However, other studies have reported that c.657del5 did not occur more frequently in breast (9,22), colorectal (22) and larynx cancer (13), which suggests that this variant is not a risk factor for these malignancies. Similarly, in the present study, no association between the occurrence of the c.657del5 mutation and the risk of developing lung cancer was observed.…”

“…The occurrence of the p.I171V variant in the NBN gene has been previously linked with elevated risk of several types of cancer. A significantly higher frequency of the p.I171V variant was observed in ALL, breast, larynx and colorectal cancer, and in multiple primary tumors of the head and neck (9,13,15). However, such an association was not observed for solid malignancies in children (11).…”

“…The frequency of constitutional mutations in the fifth and sixth exons of the NBN gene was estimated in a group of 453 adults (139 females and 314 males) diagnosed with lung cancer, and in healthy controls ( The results for the control samples were obtained in previous studies (10,13,14). All the patients signed an informed consent form approved by the Ethics Committee of the University of Medical Sciences in Poznań (approval no.…”

“…DNA was extracted from blood using the columns provided in the QIAamp DNA Blood Mini Kit (Qiagen GmbH, Hilden, Germany), according to the manufacturer's instructions, and from Guthrie cards, as described previously (13,15). The mutation in the fifth exon of the NBN gene (p.I171V) was assessed by restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction (PCR) products, using MunI (MfeI) restriction enzyme (Fermentas, Thermo Fisher Scientific, Inc., Pittsburgh, PA, USA).…”