The most frequent Polish ATM mutations are not susceptibility factors for tobacco-related cancers

INTRODUCTION

The inactivation of both alleles of the ATM gene leads to ataxia-telangiectasia syndrome, whereas carriers of monoallelic mutations in the ATM gene are associated with increased risk of different types of cancer. Three substitutions in the ATM gene (c.6095G>A, c.7630-2A>C, c.5932G>T) are the most common mutations causing ataxia-telangiectasia among Polish patients. The aim of this study was to determine whether these ATM mutations are associated with increased risk of tobacco-related cancers.

MATERIAL AND METHODS

783 Polish patients with tobacco-related cancers were included in the study (468 with lung cancer, 153 with a single laryngeal cancer, 86 with multiple primary tumors localized in the larynx and 76 multiple primary tumors localized in the head or neck). The control group consisted of 464 healthy subjects from the Polish population. Three ATM mutations - c.5932G>T, c.6095G>A, c.7630-2A>C - were tested among selected patients. Molecular analyses were performed using high resolution melting analysis and restriction fragment length polymorphism.

RESULTS

In the present study, we detected only one mutation, c.7630-2A>C, and no carriers of c.5932G>T, c.6095G>A mutations in the ATM gene among Polish patients with tobacco-related cancers. A patient with c.7630-2A>C mutation was diagnosed with lung adenocarcinoma, the most common type of lung cancer. One carrier of c.6095G>A mutation was found in the control group.

CONCLUSIONS

The results indicate that the studied ATM variants do not seem to be associated with tobacco-related cancers in Poland.

Inherited NBN Mutations and Prostate Cancer Risk and Survival

Purpose

The purpose of this study was to establish the contribution of four founder alleles of NBN to prostate cancer risk and cancer survival.

Materials and Methods

Five thousand one hundred eighty-nine men with prostate cancer and 6,152 controls were genotyped for four recurrent variants of NBN (657del5, R215W, I171V, and E185Q).

Results

The NBN 657del5 mutation was detected in 74 of 5,189 unselected cases and in 35 of 6,152 controls (odds ratio [OR], 2.5; p < 0.001). In carriers of 657del5 deletion, the cancer risk was restricted to men with the GG genotype of the E185Q variant of the same gene. Among men with the GG genotype, the OR associated with 657del5 was 4.4 (95% confidence interval [CI], 2.4 to 8.0). Among men with other E185Q genotypes, the OR associated with 657del5 was 1.4 (95% CI, 0.8 to 2.4) and the interaction was significant (homogeneity p=0.006). After a median follow-up of 109 months, mortality was worse for 657del5 mutation carriers than for non-carriers (hazard ratio [HR], 1.6; p=0.001). The adverse effect of 657del5 on survival was only seen on the background of the GG genotype of E185Q (HR, 1.9; p=0.0004).

Conclusion

The NBN 657del5 mutation predisposes to poor prognosis prostate cancer. The pathogenicity of this mutation, with regards to both prostate cancer risk and survival, is modified by a missense variant of the same gene (E185Q).

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.

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

BACKGROUND

The members of MRE11/RAD50/NBN (MRN) protein complex participates in DNA double-strand break repair and DNA-damage checkpoint activation. We have previously shown that the p.I171V NBN gene mutation may contribute to the development of laryngeal cancer. This study tested the hypothesis that variants of the MRE11 and RAD50 genes, previously described as cancer risk factors, predispose to increased susceptibility to head and neck cancer.

FINDINGS

In this study we analyzed the RAD50 and MRE11 genes in 358 patients: 175 with a single laryngeal cancer (LC), 115 with multiple primary tumors but one malignancy (primary or second) localized in the larynx (MPT-LC), 68 patients with multiple primary tumors localized in the head or neck (MPT) and 506 controls. No carriers of previously reported mutation in the MRE11 or RAD50 gene (particularly the pathogenic c.687delT) were detected in the present study. We identified the p.V127I variant (2/175 LC, 2/506 controls; OR=2.91; 95% CI 0.41-20.85) and p.V315L variant (2/115 MPT-LC, 1/506 controls; OR=8.96; 95% CI 0.81-99.68) of the RAD50 gene.

CONCLUSIONS

Our data indicated that previously described common genetic variations in the MRE11 and RAD50 genes do not contribute to an increased risk of laryngeal cancer and second primary tumors localized in the head and neck. Prospective studies with larger groups of patients may reveal the possible impact of these genes in tumor occurrence.

DNA repair system and prostate cancer progression: the role of NBS1 polymorphism (rs1805794)

NBS1 plays an important role in the maintenance of genomic integrity, by being involved in cellular response to DNA damage. The NBS1 rs1805794 G>C polymorphism has been investigated in several studies, but its function still remains unclear due to some controversial results. The present work aimed to evaluate the role of this polymorphism in prostate cancer progression, by performing a case-control study comparing 239 patients who were diagnosed with early disease to 186 who presented advanced disease. We also assessed NBS1 mRNA expression among the different groups by quantitative real time (qRT)-polymerase chain reaction. We found that the GG carriers presented an almost two fold increased risk for advanced prostate disease (odds ratio [OR] = 1.87; confidence interval [CI] = 1.26-2.79; p = 0.002). Further, high tumor grade (OR = 3.02; CI = 2.32-3.92; p<0.001) and high serum prostate specific antigen (PSA) (OR = 6.48; CI = 4.48-9.38; p<0.001) were consistently associated to advanced disease. Regarding NBS1 mRNA expression, we did not find any association with the different outcomes nor genotypes (p = 0.926; p = 0.894, respectively). Our results suggest for the first time that rs1805794 GG genotype appears to be associated with a higher risk for advanced prostate cancer, thus, suggesting a possible new role for NBS1 in prostate cancer progression.