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" endonukleasy genetika metabolismus terapeutické užití MeSH
- enzymy opravy DNA genetika MeSH
- exodeoxyribonukleasy genetika MeSH
- glykosidhydrolasy genetika metabolismus MeSH
- lidé MeSH
- nádorový supresorový protein p53 * genetika metabolismus MeSH
- nádory * farmakoterapie genetika MeSH
- oprava DNA MeSH
- PARP inhibitory farmakologie MeSH
- poškození DNA MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články 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
- dědičné nepolypózní kolorektální nádory * diagnóza genetika patologie MeSH
- karcinom z přechodných buněk * genetika MeSH
- lidé středního věku MeSH
- lidé MeSH
- mismatch repair endonukleáza PMS2 genetika MeSH
- MutL homolog 1 genetika MeSH
- nádory močového měchýře * MeSH
- oprava chybného párování bází DNA MeSH
- senioři MeSH
- urologie * MeSH
- zárodečné mutace MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články 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
- dědičné nepolypózní kolorektální nádory diagnóza genetika patologie MeSH
- genetická predispozice k nemoci MeSH
- lidé MeSH
- mismatch repair endonukleáza PMS2 genetika MeSH
- mutace MeSH
- nádory prsu * genetika MeSH
- pilotní projekty MeSH
- zárodečné mutace MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- práce podpořená grantem 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
- 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
Five 2'-deoxyribonucleoside triphosphates (dNTPs) derived from epigenetic pyrimidines (5-methylcytosine, 5-hydroxymethylcytosine, 5-formylcytosine, 5-hydroxymethyluracil, and 5-formyluracil) were prepared and systematically studied as substrates for nine DNA polymerases in competition with natural dNTPs by primer extension experiments. The incorporation of these substrates was evaluated by a restriction endonucleases cleavage-based assay and by a kinetic study of single nucleotide extension. All of the modified pyrimidine dNTPs were good substrates for the studied DNA polymerases that incorporated a significant percentage of the modified nucleotides into DNA even in the presence of natural nucleotides. 5-Methylcytosine dNTP was an even better substrate for most polymerases than natural dCTP. On the other hand, 5-hydroxymethyl-2'-deoxyuridine triphosphate was not the best substrate for SPO1 DNA polymerase, which naturally synthesizes 5hmU-rich genomes of the SPO1 bacteriophage. The results shed light onto the possibility of gene silencing through recycling and random incorporation of epigenetic nucleotides and into the replication of modified bacteriophage genomes.
- MeSH
- 5-methylcytosin * MeSH
- deoxyribonukleosidy MeSH
- DNA-dependentní DNA-polymerasy metabolismus MeSH
- DNA metabolismus MeSH
- epigeneze genetická MeSH
- nukleotidy metabolismus MeSH
- pyrimidinové nukleotidy * MeSH
- pyrimidiny MeSH
- restrikční enzymy metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Covalent DNA interstrand crosslinks are toxic DNA damage lesions that block the replication machinery that can cause a genomic instability. Ubiquitous abasic DNA sites are particularly susceptible to spontaneous cross-linking with a base from the opposite DNA strand. Detection of a crosslink induces the DNA helicase ubiquitination that recruits NEIL3, a DNA glycosylase responsible for the lesion removal. NEIL3 utilizes several zinc finger domains indispensable for its catalytic NEI domain repairing activity. They recruit NEIL3 to the repair site and bind the single-stranded DNA. However, the molecular mechanism underlying their roles in the repair process is unknown. Here, we report the structure of the tandem zinc-finger GRF domain of NEIL3 and reveal the molecular details of its interaction with DNA. Our biochemical data indicate the preferential binding of the GRF domain to the replication fork. In addition, we obtained a structure for the catalytic NEI domain in complex with the DNA reaction intermediate that allowed us to construct and validate a model for the interplay between the NEI and GRF domains in the recognition of an interstrand cross-link. Our results suggest a mechanism for recognition of the DNA replication X-structure by NEIL3, a key step in the interstrand cross-link repair.
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.
- 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
Extracellular DNA (ecDNA) activates immune cells and is involved in the pathogenesis of diseases associated with inflammation such as sepsis, rheumatoid arthritis or metabolic syndrome. DNA can be cleaved by deoxyribonucleases (DNases), some of which are secreted out of cells. The aim of this experiment was to describe plasma DNase activity in relation to extracellular DNA in adult rats, to analyse potential sex differences and to prove whether they are related to endogenous testosterone. Adult Lewis rats (n=28) of both sexes were included in the experiment. Male rats were gonadectomized or sham-operated and compared to intact female rats. Plasma ecDNA and DNase activity were measured using fluorometry and single radial enzyme diffusion assay, respectively. Concentrations of nuclear ecDNA and mitochondrial ecDNA were determined using real-time PCR. Females had 60% higher plasma DNase activity than males ( p=0.03). Gonadectomy did not affect plasma DNase in males. Neither the concentration of total ecDNA, nor nuclear or mitochondrial DNA in plasma differed between the groups. No significant correlations between DNase and ecDNA were found. From previous studies on mice, it was expected, that male rats will have higher DNase activity. In contrast, our study in rats showed the opposite sex difference. This sex difference seems not to be caused by endogenous testosterone. Interestingly, no sex differences were observed in plasma ecDNA suggesting a complex or missing association between plasma ecDNA and DNase. The observed sex difference in plasma DNase should be taken into account in animal models of ecDNA-associated diseases.
- MeSH
- deoxyribonukleasy krev MeSH
- DNA krev MeSH
- orchiektomie MeSH
- pohlavní dimorfismus * MeSH
- potkani inbrední LEW MeSH
- testosteron krev MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
