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.

• Klíčová slova
• ATLD, DNA repair, MRE11, NBN, NBS, NBSLD, NGS, RAD50, TP53, hereditary cancer syndromes, variant interpretation,
• MeSH
• ATM protein genetika   metabolismus   MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• enzymy opravy DNA genetika   metabolismus   MeSH
• homologní protein MRE11 genetika   metabolismus   MeSH
• hydrolasy působící na anhydridy kyselin genetika   metabolismus   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• lidé MeSH
• nádorové supresorové proteiny * genetika   MeSH
• oprava DNA genetika   MeSH
• proteiny buněčného cyklu * metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• ATM protein MeSH
• DNA vazebné proteiny MeSH
• enzymy opravy DNA MeSH
• homologní protein MRE11 MeSH
• hydrolasy působící na anhydridy kyselin MeSH
• jaderné proteiny MeSH
• nádorové supresorové proteiny * MeSH
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu * MeSH
• RAD50 protein, human MeSH Prohlížeč

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.

• Klíčová slova
• MRE11, NBN, RAD50, germline variants, meta‐analysis,
• Publikační typ
• časopisecké články MeSH

The MRN (MRE11-RAD50-NBS1) complex is essential for repair of DNA double-strand breaks and stalled replication forks. Mutations of the MRN complex subunit MRE11 cause the hereditary cancer-susceptibility disease ataxia-telangiectasia-like disorder (ATLD). Here we show that MRE11 directly interacts with PIH1D1, a subunit of heat-shock protein 90 cochaperone R2TP complex, which is required for the assembly of large protein complexes, such as RNA polymerase II, small nucleolar ribonucleoproteins and mammalian target of rapamycin complex 1. The MRE11-PIH1D1 interaction is dependent on casein kinase 2 (CK2) phosphorylation of two acidic sequences within the MRE11 C terminus containing serines 558/561 and 688/689. Conversely, the PIH1D1 phospho-binding domain PIH-N is required for association with MRE11 phosphorylated by CK2. Consistent with these findings, depletion of PIH1D1 resulted in MRE11 destabilization and affected DNA-damage repair processes dependent on MRE11. Additionally, mutations of serines 688/689, which abolish PIH1D1 binding, also resulted in decreased MRE11 stability. As depletion of R2TP frequently leads to instability of its substrates and as truncation mutation of MRE11 lacking serines 688/689 leads to decreased levels of the MRN complex both in ATLD patients and an ATLD mouse model, our results suggest that the MRN complex is a novel R2TP complex substrate and that their interaction is regulated by CK2 phosphorylation.

• MeSH
• ATM protein metabolismus   MeSH
• buněčné jádro metabolismus   MeSH
• DNA vazebné proteiny metabolismus   MeSH
• enzymy opravy DNA metabolismus   MeSH
• fosforylace fyziologie   MeSH
• jaderné proteiny metabolismus   MeSH
• kaseinkinasa II metabolismus   MeSH
• lidé MeSH
• mutace fyziologie   MeSH
• myši MeSH
• oprava DNA fyziologie   MeSH
• poškození DNA fyziologie   MeSH
• proteiny regulující apoptózu metabolismus   MeSH
• proteiny tepelného šoku metabolismus   MeSH
• ribonukleoproteiny malé jadérkové metabolismus   MeSH
• RNA-polymerasa II metabolismus   MeSH
• serin metabolismus   MeSH
• teleangiektatická ataxie metabolismus   MeSH
• TOR serin-threoninkinasy metabolismus   MeSH
• vazba proteinů fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ATM protein MeSH
• DNA vazebné proteiny MeSH
• enzymy opravy DNA MeSH
• jaderné proteiny MeSH
• kaseinkinasa II MeSH
• proteiny regulující apoptózu MeSH
• proteiny tepelného šoku MeSH
• ribonukleoproteiny malé jadérkové MeSH
• RNA-polymerasa II MeSH
• serin MeSH
• TOR serin-threoninkinasy MeSH

Hepatocellular carcinoma (HCC) mainly stems from liver cirrhosis and its genetic predisposition is believed to be rare. However, two recent studies describe pathogenic/likely pathogenic germline variants (PV) in cancer-predisposition genes (CPG). As the risk of de novo tumors might be increased in PV carriers, especially in immunosuppressed patients after a liver transplantation, we analyzed the prevalence of germline CPG variants in HCC patients considered for liver transplantation. Using the panel NGS targeting 226 CPGs, we analyzed germline DNA from 334 Czech HCC patients and 1662 population-matched controls. We identified 48 PVs in 35 genes in 47/334 patients (14.1%). However, only 7/334 (2.1%) patients carried a PV in an established CPG (PMS2, 4×NBN, FH or RET). Only the PV carriers in two MRN complex genes (NBN and RAD50) were significantly more frequent among patients over controls. We found no differences in clinicopathological characteristics between carriers and non-carriers. Our study indicated that the genetic component of HCC is rare. The HCC diagnosis itself does not meet criteria for routine germline CPG genetic testing. However, a low proportion of PV carriers may benefit from a tailored follow-up or targeted therapy and germline testing could be considered in liver transplant recipients.

• Klíčová slova
• MRN complex, genetic predisposition, germline mutation, hepatocellular carcinoma, liver cirrhosis, liver transplantation, panel sequencing,
• Publikační typ
• časopisecké články MeSH

B-Myb, a highly conserved member of the Myb transcription factor family, is expressed ubiquitously in proliferating cells and controls the cell cycle dependent transcription of G2/M-phase genes. Deregulation of B-Myb has been implicated in oncogenesis and loss of genomic stability. We have identified B-Myb as a novel interaction partner of the Mre11-Rad50-Nbs1 (MRN) complex, a key player in the repair of DNA double strand breaks. We show that B-Myb directly interacts with the Nbs1 subunit of the MRN complex and is recruited transiently to DNA-damage sites. In response to DNA-damage B-Myb is phosphorylated by protein kinase GSK3β and released from the MRN complex. A B-Myb mutant that cannot be phosphorylated by GSK3β disturbs the regulation of pro-mitotic B-Myb target genes and leads to inappropriate mitotic entry in response to DNA-damage. Overall, our work suggests a novel function of B-Myb in the cellular DNA-damage signalling.

• MeSH
• ATM protein metabolismus   MeSH
• biologické modely MeSH
• buněčné linie MeSH
• DNA vazebné proteiny chemie   metabolismus   MeSH
• dvouřetězcové zlomy DNA MeSH
• enzymy opravy DNA chemie   metabolismus   MeSH
• fosforylace MeSH
• GSK3B metabolismus   MeSH
• homologní protein MRE11 chemie   metabolismus   MeSH
• hydrolasy působící na anhydridy kyselin MeSH
• interakční proteinové domény a motivy MeSH
• jaderné proteiny chemie   metabolismus   MeSH
• lidé MeSH
• mitóza genetika   MeSH
• multiproteinové komplexy metabolismus   MeSH
• mutace MeSH
• oprava DNA MeSH
• poškození DNA * MeSH
• proteiny buněčného cyklu chemie   genetika   metabolismus   MeSH
• regulace genové exprese MeSH
• sekvence aminokyselin MeSH
• signální transdukce * MeSH
• trans-aktivátory chemie   genetika   metabolismus   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ATM protein MeSH
• DNA vazebné proteiny MeSH
• enzymy opravy DNA MeSH
• GSK3B MeSH
• homologní protein MRE11 MeSH
• hydrolasy působící na anhydridy kyselin MeSH
• jaderné proteiny MeSH
• multiproteinové komplexy MeSH
• MYBL2 protein, human MeSH Prohlížeč
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH
• RAD50 protein, human MeSH Prohlížeč
• trans-aktivátory MeSH

BACKGROUND: The ATM kinase constitutes a master regulatory hub of DNA damage and activates the p53 response pathway by phosphorylating the MDM2 protein, which develops an affinity for the p53 mRNA secondary structure. Disruption of this interaction prevents the activation of the nascent p53. The link of the MDM2 protein-p53 mRNA interaction with the upstream DNA damage sensor ATM kinase and the role of the p53 mRNA in the DNA damage sensing mechanism, are still highly anticipated. METHODS: The proximity ligation assay (PLA) has been extensively used to reveal the sub-cellular localisation of the protein-mRNA and protein-protein interactions. ELISA and co-immunoprecipitation confirmed the interactions in vitro and in cells. RESULTS: This study provides a novel mechanism whereby the p53 mRNA interacts with the ATM kinase enzyme and shows that the L22L synonymous mutant, known to alter the secondary structure of the p53 mRNA, prevents the interaction. The relevant mechanistic roles in the DNA Damage Sensing pathway, which is linked to downstream DNA damage response, are explored. Following DNA damage (double-stranded DNA breaks activating ATM), activated MDMX protein competes the ATM-p53 mRNA interaction and prevents the association of the p53 mRNA with NBS1 (MRN complex). These data also reveal the binding domains and the phosphorylation events on ATM that regulate the interaction and the trafficking of the complex to the cytoplasm. CONCLUSION: The presented model shows a novel interaction of ATM with the p53 mRNA and describes the link between DNA Damage Sensing with the downstream p53 activation pathways; supporting the rising functional implications of synonymous mutations altering secondary mRNA structures.

• Klíčová slova
• DNA Damage Sensing, Genotoxic stress, MDM2, MRN complex, Precision medicine, RNA secondary structure, Synonymous mutations,
• MeSH
• ATM protein MeSH
• lidé MeSH
• nádorový supresorový protein p53 MeSH
• oprava DNA MeSH
• polynukleotid-5'-hydroxylkinasa * MeSH
• poškození DNA MeSH
• protoonkogenní proteiny c-mdm2 * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• dopisy MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ATM protein, human MeSH Prohlížeč
• ATM protein MeSH
• nádorový supresorový protein p53 MeSH
• polynukleotid-5'-hydroxylkinasa * MeSH
• protoonkogenní proteiny c-mdm2 * MeSH

In the present study, we investigated the anticancer action of the trithiolato arene ruthenium complex, [(η-p-MeC6H4Pr)2Ru2(μ-S-p-C6H4OH)3]Cl, named diruthenium-2, both in vitro and in vivo. The mechanism of antiproliferative, cytotoxic, and DNA-damaging activity, and the effect on expressions of cell cycle regulatory proteins were investigated using a WST-1-based proliferation assay, lactate dehydrogenase leakage assay, comet assay, flow cytometry, and western blot analysis. In-vivo anticancer activity was evaluated using Ehrlich tumor-bearing NMRI mice. Diruthenium-2 inhibited the growth of all cancer cell lines used, the most sensitive being gastric (AGS), breast cancer (BT-549, MCF-7, MDA-MB-231), and leukemic (HL-60, MOLT-4) cells. In MCF-7 cells, it caused a G1/S cell cycle arrest, along with an increase in the expression of protein p21 and cyclin B1. We also observed increased levels of MRN complex proteins, which, together with the results from the comet assay, indicate the formation of DNA double-strand breaks. In tumor-bearing mice, diruthenium-2 at doses of 3 and 5 mg/kg inhibits the growth of solid Ehrlich tumor, although weaker than cisplatin. However, it did not prolong the post-therapeutic survival. Our results suggest the in-vitro potential of diruthenium-2 should be further evaluated in studies using other in-vivo models.

• MeSH
• antitumorózní látky chemie   farmakologie   MeSH
• HL-60 buňky MeSH
• komplexní sloučeniny chemie   farmakologie   MeSH
• léky antitumorózní - screeningové testy MeSH
• leukemie farmakoterapie   MeSH
• lidé MeSH
• MFC-7 buňky MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádory prsu farmakoterapie   MeSH
• nádory žaludku farmakoterapie   MeSH
• ruthenium chemie   farmakologie   MeSH
• xenogenní modely - testy antitumorózní aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antitumorózní látky MeSH
• komplexní sloučeniny MeSH
• ruthenium MeSH

Poly(ADP-ribosyl)ation is a reversible post-translational modification synthetized by ADP-ribose transferases and removed by poly(ADP-ribose) glycohydrolase (PARG), which plays important roles in DNA damage repair. While well-studied in somatic tissues, much less is known about poly(ADP-ribosyl)ation in the germline, where DNA double-strand breaks are introduced by a regulated program and repaired by crossover recombination to establish a tether between homologous chromosomes. The interaction between the parental chromosomes is facilitated by meiotic specific adaptation of the chromosome axes and cohesins, and reinforced by the synaptonemal complex. Here, we uncover an unexpected role for PARG in coordinating the induction of meiotic DNA breaks and their homologous recombination-mediated repair in Caenorhabditis elegans. PARG-1/PARG interacts with both axial and central elements of the synaptonemal complex, REC-8/Rec8 and the MRN/X complex. PARG-1 shapes the recombination landscape and reinforces the tightly regulated control of crossover numbers without requiring its catalytic activity. We unravel roles in regulating meiosis, beyond its enzymatic activity in poly(ADP-ribose) catabolism.

• MeSH
• buněčné jádro metabolismus   MeSH
• Caenorhabditis elegans genetika   metabolismus   MeSH
• DNA metabolismus   MeSH
• dvouřetězcové zlomy DNA * MeSH
• glykosidhydrolasy genetika   metabolismus   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• oprava DNA fyziologie   MeSH
• poly-ADP-ribosylace MeSH
• polyadenosindifosfátribosa metabolismus   MeSH
• posttranslační úpravy proteinů MeSH
• proteiny Caenorhabditis elegans genetika   metabolismus   MeSH
• zárodečné buňky MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• DNA MeSH
• glykosidhydrolasy MeSH
• jaderné proteiny MeSH
• poly ADP-ribose glycohydrolase MeSH Prohlížeč
• polyadenosindifosfátribosa MeSH
• proteiny Caenorhabditis elegans MeSH
• SYP-1 protein, C elegans MeSH Prohlížeč

A growing body of evidence supports the notion that cancer resistance is driven by a small subset of cancer stem cells (CSC), responsible for tumor initiation, growth, and metastasis. Both CSC and chemoresistant cancer cells may share common qualities to activate a series of self-defense mechanisms against chemotherapeutic drugs. Here, we aimed to identify proteins in chemoresistant triple-negative breast cancer (TNBC) cells and corresponding CSC-like spheroid cells that may contribute to their resistance. We have identified several candidate proteins representing the subfamilies of DNA damage response (DDR) system, the ATP-binding cassette, and the 26S proteasome degradation machinery. We have also demonstrated that both cell types exhibit enhanced DDR when compared to corresponding parental counterparts, and identified RAD50 as one of the major contributors in the resistance phenotype. Finally, we have provided evidence that depleting or blocking RAD50 within the Mre11-Rad50-NBS1 (MRN) complex resensitizes CSC and chemoresistant TNBC cells to chemotherapeutic drugs.

• Klíčová slova
• DNA damage repair, RAD50, cancer stem cells, chemoresistance, triple-negative breast cancer,
• MeSH
• chemorezistence účinky léků   genetika   MeSH
• cisplatina aplikace a dávkování   MeSH
• cyklofosfamid aplikace a dávkování   MeSH
• DNA vazebné proteiny genetika   MeSH
• doxorubicin aplikace a dávkování   MeSH
• enzymy opravy DNA genetika   MeSH
• homologní protein MRE11 genetika   MeSH
• hydrolasy působící na anhydridy kyselin genetika   MeSH
• jaderné proteiny genetika   MeSH
• lidé MeSH
• nádorové kmenové buňky účinky léků   metabolismus   MeSH
• poškození DNA účinky léků   MeSH
• přežití po terapii bez příznaků nemoci MeSH
• proteiny buněčného cyklu genetika   MeSH
• triple-negativní karcinom prsu farmakoterapie   genetika   MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cisplatina MeSH
• cyklofosfamid MeSH
• DNA vazebné proteiny MeSH
• doxorubicin MeSH
• enzymy opravy DNA MeSH
• homologní protein MRE11 MeSH
• hydrolasy působící na anhydridy kyselin MeSH
• jaderné proteiny MeSH
• MRE11 protein, human MeSH Prohlížeč
• NBN protein, human MeSH Prohlížeč
• proteiny buněčného cyklu MeSH
• RAD50 protein, human MeSH Prohlížeč

Cancer therapy failure is a fundamental challenge in cancer treatment. One of the most common reasons for therapy failure is the development of acquired resistance of cancer cells. DNA-damaging agents are frequently used in first-line chemotherapy regimens and DNA damage response, and DNA repair pathways are significantly involved in the mechanisms of chemoresistance. MRE11, a part of the MRN complex involved in double-strand break (DSB) repair, is connected to colorectal cancer (CRC) patients' prognosis. Our previous results showed that single-nucleotide polymorphisms (SNPs) in the 3' untranslated region (3'UTR) microRNA (miRNA) binding sites of MRE11 gene are associated with decreased cancer risk but with shorter survival of CRC patients, which implies the role of miRNA regulation in CRC. The therapy of colorectal cancer utilizes oxaliplatin (oxalato(trans-l-1,2-diaminocyclohexane)platinum), which is often compromised by chemoresistance development. There is, therefore, a crucial clinical need to understand the cellular processes associated with drug resistance and improve treatment responses by applying efficient combination therapies. The main aim of this study was to investigate the effect of miRNAs on the oxaliplatin therapy response of CRC patients. By the in silico analysis, miR-140 was predicted to target MRE11 and modulate CRC prognosis. The lower expression of miR-140 was associated with the metastatic phenotype (p < 0.05) and poor progression-free survival (odds ratio (OR) = 0.4, p < 0.05). In the in vitro analysis, we used miRNA mimics to increase the level of miR-140 in the CRC cell line. This resulted in decreased proliferation of CRC cells (p < 0.05). Increased levels of miR-140 also led to increased sensitivity of cancer cells to oxaliplatin (p < 0.05) and to the accumulation of DNA damage. Our results, both in vitro and in vivo, suggest that miR-140 may act as a tumor suppressor and plays an important role in DSB DNA repair and, consequently, CRC therapy response.

• Klíčová slova
• DNA damage, DNA repair, MRE11, colorecal cancer, miR-140, miRNA, oxaliplatin, therapy response,
• Publikační typ
• časopisecké články MeSH