Doporučené postupy klinické péče o nosiče patogenních variant v klinicky relevantních genech predisponujících ke vzniku Lynchova syndromu a karcinomu kolorekta definují kroky primární a sekundární prevence, která by měla být osobám ve vysokém riziku vzniku dědičných nádorů v ČR poskytnuta. Tvorba doporučených postupů byla organizována pracovní skupinou onkogenetiky Společnosti lékařské genetiky a genomiky při České lékařské společnosti J. E. Purkyně ve spolupráci se zástupci onkologie, onkogynekologie a gastroenterologie. Doporučené postupy vycházejí z aktuálních doporučení National Comprehensive Cancer Network (NCCN), Evropské společnosti pro klinickou onkologii (ESMO) a zohledňují kapacitní možnosti našeho zdravotnictví.
The guidelines for clinical practice for carriers of pathogenic variants in clinically relevant genes predisposing to Lynch syndrome and colorectal cancer define the steps of primary and secondary prevention that should be provided to the individuals at high risk of developing hereditary cancer in the Czech Republic. The drafting of the guidelines was organized by the Oncogenetics Working Group of the Society for Medical Genetics and Genomics of J. E. Purkyně Czech Medical Society, in cooperation with representatives of oncology, oncogynecology, and gastroenterology. The guidelines are based on the current recommendations of the National Comprehensive Cancer Network (NCCN), European Society of Medical Oncology (ESMO) and take into account the capacity of the Czech healthcare system.
- MeSH
- Epithelial Cell Adhesion Molecule genetics MeSH
- Colorectal Neoplasms, Hereditary Nonpolyposis genetics MeSH
- Genetic Predisposition to Disease * genetics MeSH
- Colorectal Neoplasms * genetics MeSH
- Mismatch Repair Endonuclease PMS2 genetics MeSH
- MutL Protein Homolog 1 genetics MeSH
- Practice Guidelines as Topic MeSH
- Germ-Line Mutation genetics MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
- Geographicals
- Czech Republic MeSH
Homologous recombination involves the formation of branched DNA molecules that may interfere with chromosome segregation. To resolve these persistent joint molecules, cells rely on the activation of structure-selective endonucleases (SSEs) during the late stages of the cell cycle. However, the premature activation of SSEs compromises genome integrity, due to untimely processing of replication and/or recombination intermediates. Here, we used a biochemical approach to show that the budding yeast SSEs Mus81 and Yen1 possess the ability to cleave the central recombination intermediate known as the displacement loop or D-loop. Moreover, we demonstrate that, consistently with previous genetic data, the simultaneous action of Mus81 and Yen1, followed by ligation, is sufficient to recreate the formation of a half-crossover precursor in vitro. Our results provide not only mechanistic explanation for the formation of a half-crossover, but also highlight the critical importance for precise regulation of these SSEs to prevent chromosomal rearrangements.
- MeSH
- Crossing Over, Genetic * MeSH
- DNA-Binding Proteins * metabolism genetics MeSH
- Endonucleases * metabolism genetics MeSH
- Homologous Recombination MeSH
- Holliday Junction Resolvases metabolism genetics MeSH
- Saccharomyces cerevisiae Proteins * metabolism genetics MeSH
- Saccharomyces cerevisiae genetics metabolism MeSH
- Publication type
- Journal Article MeSH
The MRE11, RAD50, and NBN genes encode the MRN complex sensing DNA breaks and directing their repair. While carriers of biallelic germline pathogenic variants (gPV) develop rare chromosomal instability syndromes, the cancer risk in heterozygotes remains controversial. We performed a systematic review and meta-analysis of 53 studies in patients with different cancer diagnoses to better understand the cancer risk. We found an increased risk (odds ratio, 95% confidence interval) for gPV carriers in NBN for melanoma (7.14; 3.30-15.43), pancreatic cancer (4.03; 2.14-7.58), hematological tumors (3.42; 1.14-10.22), and prostate cancer (2.44, 1.84-3.24), but a low risk for breast cancer (1.29; 1.00-1.66) and an insignificant risk for ovarian cancer (1.53; 0.76-3.09). We found no increased breast cancer risk in carriers of gPV in RAD50 (0.93; 0.74-1.16; except of c.687del carriers) and MRE11 (0.87; 0.66-1.13). The secondary burden analysis compared the frequencies of gPV in MRN genes in patients from 150 studies with those in the gnomAD database. In NBN gPV carriers, this analysis additionally showed a high risk for brain tumors (5.06; 2.39-9.52), a low risk for colorectal (1.64; 1.26-2.10) and hepatobiliary (2.16; 1.02-4.06) cancers, and no risk for endometrial, and gastric cancer. The secondary burden analysis showed also a moderate risk for ovarian cancer (3.00; 1.27-6.08) in MRE11 gPV carriers, and no risk for ovarian and hepatobiliary cancers in RAD50 gPV carriers. These findings provide a robust clinical evidence of cancer risks to guide personalized clinical management in heterozygous carriers of gPV in the MRE11, RAD50, and NBN genes.
- MeSH
- DNA-Binding Proteins genetics MeSH
- DNA Repair Enzymes genetics MeSH
- Genetic Predisposition to Disease * MeSH
- MRE11 Homologue Protein * genetics MeSH
- Acid Anhydride Hydrolases * genetics MeSH
- Nuclear Proteins * genetics MeSH
- Humans MeSH
- Neoplasms * genetics MeSH
- Cell Cycle Proteins * genetics MeSH
- Germ-Line Mutation * MeSH
- Check Tag
- Humans MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Meta-Analysis MeSH
- Systematic Review MeSH
DNA double-strand breaks (DSBs), such as those produced by radiation and radiomimetics, are amongst the most toxic forms of cellular damage, in part because they involve extensive oxidative modifications at the break termini. Prior to completion of DSB repair, the chemically modified termini must be removed. Various DNA processing enzymes have been implicated in the processing of these dirty ends, but molecular knowledge of this process is limited. Here, we demonstrate a role for the metallo-β-lactamase fold 5'-3' exonuclease SNM1A in this vital process. Cells disrupted for SNM1A manifest increased sensitivity to radiation and radiomimetic agents and show defects in DSB damage repair. SNM1A is recruited and is retained at the sites of DSB damage via the concerted action of its three highly conserved PBZ, PIP box and UBZ interaction domains, which mediate interactions with poly-ADP-ribose chains, PCNA and the ubiquitinated form of PCNA, respectively. SNM1A can resect DNA containing oxidative lesions induced by radiation damage at break termini. The combined results reveal a crucial role for SNM1A to digest chemically modified DNA during the repair of DSBs and imply that the catalytic domain of SNM1A is an attractive target for potentiation of radiotherapy.
- MeSH
- DNA metabolism genetics MeSH
- DNA Breaks, Double-Stranded * radiation effects MeSH
- DNA Repair Enzymes * metabolism genetics MeSH
- Exodeoxyribonucleases * metabolism genetics MeSH
- Humans MeSH
- DNA Repair * MeSH
- Proliferating Cell Nuclear Antigen metabolism genetics MeSH
- Cell Cycle Proteins MeSH
- Ubiquitination MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Meiotic recombination is of central importance for the proper segregation of homologous chromosomes, but also for creating genetic diversity. It is initiated by the formation of double-strand breaks (DSBs) in DNA catalysed by evolutionarily conserved Spo11, together with additional protein partners. Difficulties in purifying the Spo11 protein have limited the characterization of its biochemical properties and of its interactions with other DSB proteins. In this study, we have purified fragments of Spo11 and show for the first time that Spo11 can physically interact with Mre11 and modulates its DNA binding, bridging, and nuclease activities. The interaction of Mre11 with Spo11 requires its far C-terminal region, which is in line with the severe meiotic phenotypes of various mre11 mutations located at the C-terminus. Moreover, calibrated ChIP for Mre11 shows that Spo11 promotes Mre11 recruitment to chromatin, independent of DSB formation. A mutant deficient in Spo11 interaction severely reduces the association of Mre11 with meiotic chromatin. Consistent with the reduction of Mre11 foci in this mutant, it strongly impedes DSB formation, leading to spore death. Our data provide evidence that physical interaction between Spo11 and Mre11, together with end-bridging, promote normal recruitment of Mre11 to hotspots and DSB formation.
- MeSH
- Chromatin * metabolism MeSH
- DNA-Binding Proteins metabolism genetics MeSH
- DNA Breaks, Double-Stranded * MeSH
- Endodeoxyribonucleases * metabolism genetics MeSH
- Exodeoxyribonucleases metabolism genetics MeSH
- Meiosis * genetics MeSH
- Mutation MeSH
- Saccharomyces cerevisiae Proteins * metabolism genetics MeSH
- Saccharomyces cerevisiae cytology genetics metabolism MeSH
- Protein Binding MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Targeting poly(ADP-ribose) glycohydrolase (PARG) is currently explored as a therapeutic approach to treat various cancer types, but we have a poor understanding of the specific genetic vulnerabilities that would make cancer cells susceptible to such a tailored therapy. Moreover, the identification of such vulnerabilities is of interest for targeting BRCA2;p53-deficient tumors that have acquired resistance to poly(ADP-ribose) polymerase inhibitors (PARPi) through loss of PARG expression. Here, by performing whole-genome CRISPR/Cas9 drop-out screens, we identify various genes involved in DNA repair to be essential for the survival of PARG;BRCA2;p53-deficient cells. In particular, our findings reveal EXO1 and FEN1 as major synthetic lethal interactors of PARG loss. We provide evidence for compromised replication fork progression, DNA single-strand break repair, and Okazaki fragment processing in PARG;BRCA2;p53-deficient cells, alterations that exacerbate the effects of EXO1/FEN1 inhibition and become lethal in this context. Since this sensitivity is dependent on BRCA2 defects, we propose to target EXO1/FEN1 in PARPi-resistant tumors that have lost PARG activity. Moreover, EXO1/FEN1 targeting may be a useful strategy for enhancing the effect of PARG inhibitors in homologous recombination-deficient tumors.
- MeSH
- Flap Endonucleases genetics metabolism therapeutic use MeSH
- DNA Repair Enzymes genetics MeSH
- Exodeoxyribonucleases genetics MeSH
- Glycoside Hydrolases genetics metabolism MeSH
- Humans MeSH
- Tumor Suppressor Protein p53 * genetics metabolism MeSH
- Neoplasms * drug therapy genetics MeSH
- DNA Repair MeSH
- Poly(ADP-ribose) Polymerase Inhibitors pharmacology MeSH
- DNA Damage MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Upper tract urothelial carcinoma (UTUC) is the third most common malignancy associated with Lynch syndrome (LS). The current European urology guidelines recommend screening for LS in patients with UTUC up to the age of 60 years. In this study, we examined a cohort of patients with UTUC for potential association with LS in order to establish the sensitivity of current guidelines in detecting LS. A total of 180 patients with confirmed diagnosis of UTUC were enrolled in the study during a 12-year period (2010-2022). Loss of DNA-mismatch repair proteins (MMRp) expression was identified in 15/180 patients (8.3%). Germline analysis was eventually performed in 8 patients confirming LS in 5 patients (2.8%), including 4 germline mutations in MSH6 and 1 germline mutation in MSH2. LS-related UTUC included 3 females and 2 males, with a mean age of 66.2 years (median 71 years, range 46-75 years). Four of five LS patients (all with MSH6 mutation) were older than 65 years (mean age 71.3, median 72 years). Our findings indicate that LS-associated UTUCs can occur in patients with LS older than 60 years. In contrast to previous studies which used mainly highly pre-selected populations with already diagnosed LS, the most frequent mutation in our cohort involved MSH6 gene. All MSH6 mutation carriers were > 65 years, and UTUC was the first LS manifestation in 2/4 patients. Using current screening guidelines, a significant proportion of patients with LS-associated UTUC may be missed. We suggest universal immunohistochemical MMRp screening for all UTUCs, regardless of age and clinical history.
- MeSH
- Colorectal Neoplasms, Hereditary Nonpolyposis * diagnosis genetics pathology MeSH
- Carcinoma, Transitional Cell * genetics MeSH
- Middle Aged MeSH
- Humans MeSH
- Mismatch Repair Endonuclease PMS2 genetics MeSH
- MutL Protein Homolog 1 genetics MeSH
- Urinary Bladder Neoplasms * MeSH
- DNA Mismatch Repair MeSH
- Aged MeSH
- Urology * MeSH
- Germ-Line Mutation MeSH
- Check Tag
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Východiská: Lynchov syndróm (LS) je autozomálne dominantné dedičné ochorenie, ktoré sa prejavuje zvýšením rizika vzniku nádorových ochorení, a to predovšetkým kolorektálneho a endometriálneho karcinómu. Nedávne štúdie preukázali aj asociáciu medzi LS a nádorovým ochorením prsníka. Cieľom tejto štúdie je poukázať na možný výskyt prítomnosti mutácií v génoch asociovaných s LS u pacientov s rakovinou prsníka a na potrebu zahrnúť vyšetrenie Lynch asociovaných génov u pacientov s familiárnym a opakovaným výskytom rakoviny prsníka ako aj s výskytom ďalších Lynch asociovaných nádorových ochorení. Materiál a metódy: Analyzovali sme vzorky nádorového tkaniva od 78 pacientov s primárnym nádorom prsníka. U pacientov sme analyzovali panel génov asociovaný s rizikom vzniku rakoviny prsníka, pričom sme sa v rámci našej štúdie sústredili primárne na výskyt mutácií v mismatch-repair génoch. DNA izolovaná z nádorového tkaniva bola sekvenovaná pomocou metódy sekvenovania novej generácie (next generation sequencing – NGS) a podrobená analýze pomocou nástroja Ingenuity Variant Analysis. Na potvrdenie zárodočnej mutácie sme vyšetrili krvnú vzorku pacientky pomocou NGS. Výsledky: V rámci našej analýzy sa nám v nádorovom tkanive prsníka podarilo identifikovať variant v géne PMS2 u jednej pacientky. Prítomnosť mutácie naznačuje, že vzniknuté nádorové ochorenie môže byť následkom LS. Z hľadiska patogenity sa jednalo o pravdepodobne patogénny variant, nakoľko sme odhalili deléciu v exónovej oblasti, ktorá viedla k frameshift mutácii. Navyše sme identifikovali aj jednonukleotidové patogénne varianty v génoch TP53 a PIK3CA. Pre definitívne stanovenie diagnózy LS u pacientky sme vyšetrili krvnú vzorku, kde sme tiež identifikovali mutáciu génu PMS2. Záver: LS je u mnohých Lynch asociovaných nádorových ochorení poddiagnostikovaný. V prípade familiárneho výskytu rakoviny prsníka a ďalších Lynch asociovaných génov je však dôležité myslieť aj na možnú diagnózu LS a v prípade, že pacient spĺňa diagnostické kritéria, uskutočniť aj genetické vyšetrenie Lynch asociovaných génov.
Background: Lynch syndrome (LS) is an autosomal dominant inherited disorder which causes an increased risk of cancer, especially colorectal and endometrial carcinomas. Recent studies have shown an association between LS and breast cancer as well. The aim of our study is to highlight the possible presence of mutations in genes associated with LS in patients with breast cancer and the need to include the examination of Lynch-associated genes in patients with a family history of breast cancer as well as in patients with recurrent breast cancer, as well as with the occurrence of other Lynch-associated cancer. Materials and methods: We analyzed tumor tissue samples from 78 patients with primary breast cancer. Our samples were tested with a gene panel associated with the risk of developing breast cancer, while in our study we focused primarily on the occurrence of mutations in mismatch-repair genes. DNA isolated from tumor tissue was sequenced using next generation sequencing (NGS) and analyzed using the Ingenuity Variant Analysis tool. To confirm the germline mutation, we examined the patient‘s blood sample using NGS sequencing. Results: As a result of our analysis, we managed to identify a mutation in the PMS2 gene in one patient‘s breast tumor tissue. The presence of this mutation indicates that the resulting cancer may be a consequence of LS. As for pathogenicity, this was probably a pathogenic variant, as we detected deletions in the exon region, which led to frameshift mutation. Moreover, we also identified single-nucleotide pathogenic variants in the TP53 and PIK3CA genes. To definitively establish the diagnosis of LS in the patient, we examined a blood sample, where we also identified a mutation of the PMS2 gene. Conclusion: LS is underdiagnosed in many Lynch-associated cancers. However, in the case of a familial occurrence of breast cancer and other Lynch-associated genes, it is important to think about a possible diagnosis of LS and, if the patient meets the diagnostic criteria, to carry out a genetic examination of Lynch-associated genes.
- MeSH
- Colorectal Neoplasms, Hereditary Nonpolyposis diagnosis genetics pathology MeSH
- Genetic Predisposition to Disease MeSH
- Humans MeSH
- Mismatch Repair Endonuclease PMS2 genetics MeSH
- Mutation MeSH
- Breast Neoplasms * genetics MeSH
- Pilot Projects MeSH
- Germ-Line Mutation MeSH
- Check Tag
- Humans MeSH
- Female MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
ArdB proteins are known to inhibit the activity of the type I restriction-modification (RM-I) system, in particular EcoKI (IA family). The mechanism of ArdB's activity still remains unknown; the spectrum of targets inhibited has been poorly studied. In this work, it was shown that the presence of the ardB gene from the R64 plasmid could suppress the activity of EcoAI endonuclease (IB family) in Escherichia coli TG1 cells. Due to the absence of specificity of ArdB to a certain RM-I system (it inhibits both the IA- and IB-family), it can be assumed that the mechanism of the anti-restriction activity of this protein does not depend on the sequence DNA at the recognition site nor the structure of the restriction enzyme of the RM-I systems.
The MRE11, RAD50, and NBN genes encode for the nuclear MRN protein complex, which senses the DNA double strand breaks and initiates the DNA repair. The MRN complex also participates in the activation of ATM kinase, which coordinates DNA repair with the p53-dependent cell cycle checkpoint arrest. Carriers of homozygous germline pathogenic variants in the MRN complex genes or compound heterozygotes develop phenotypically distinct rare autosomal recessive syndromes characterized by chromosomal instability and neurological symptoms. Heterozygous germline alterations in the MRN complex genes have been associated with a poorly-specified predisposition to various cancer types. Somatic alterations in the MRN complex genes may represent valuable predictive and prognostic biomarkers in cancer patients. MRN complex genes have been targeted in several next-generation sequencing panels for cancer and neurological disorders, but interpretation of the identified alterations is challenging due to the complexity of MRN complex function in the DNA damage response. In this review, we outline the structural characteristics of the MRE11, RAD50 and NBN proteins, the assembly and functions of the MRN complex from the perspective of clinical interpretation of germline and somatic alterations in the MRE11, RAD50 and NBN genes.
- MeSH
- Ataxia Telangiectasia Mutated Proteins genetics metabolism MeSH
- DNA-Binding Proteins genetics metabolism MeSH
- DNA Repair Enzymes genetics metabolism MeSH
- MRE11 Homologue Protein genetics metabolism MeSH
- Acid Anhydride Hydrolases genetics metabolism MeSH
- Nuclear Proteins genetics metabolism MeSH
- Humans MeSH
- Tumor Suppressor Proteins * genetics MeSH
- DNA Repair genetics MeSH
- Cell Cycle Proteins * metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
