Phase separation forms membraneless compartments, including heterochromatin "domains" and repair foci. Pericentromeric heterochromatin mostly comprises repeated sequences prone to aberrant recombination. In Drosophila cells, "safe" homologous recombination (HR) repair of these sequences requires their relocalization to the nuclear periphery before Rad51 recruitment and strand invasion. How this mobilization initiates is unknown, and the contribution of phase separation is unclear. Here, we show that Nup98 nucleoporin is recruited to repair sites before relocalization by Sec13 or Nup88, and downstream of the Smc5/6 complex and heterochromatin protein 1 (HP1). Remarkably, Nup98 condensates are immiscible with HP1 condensates, and they are required and sufficient to mobilize repair sites and exclude Rad51, thus preventing aberrant recombination while promoting HR repair. Disrupting this pathway results in heterochromatin repair defects and widespread chromosome rearrangements, revealing an "off-pore" role for nucleoporins and phase separation in nuclear dynamics and genome integrity in a multicellular eukaryote.
- MeSH
- Chromosomal Proteins, Non-Histone metabolism genetics MeSH
- Drosophila melanogaster * genetics metabolism MeSH
- DNA Breaks, Double-Stranded MeSH
- Heterochromatin * genetics metabolism MeSH
- Chromobox Protein Homolog 5 MeSH
- Nuclear Pore Complex Proteins * metabolism genetics MeSH
- Cell Cycle Proteins metabolism genetics MeSH
- Drosophila Proteins * metabolism genetics MeSH
- Recombinational DNA Repair * MeSH
- Rad51 Recombinase * metabolism genetics MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
Many photosensitive substances suitable for photodynamic therapy (PDT) have limited applications due to their insufficient solubility in polar solvents. Our research overcomes this challenge by means of nanotechnology in order to transform hydrophobic compounds into stable aqueous solutions, enabling them to use their full potential and unique properties in cancer therapy. In this study, the novel nano-composite cGQDs-PEG-curcumin was developed to overcome the insolubility of curcumin in water and its extraordinary efficacy in PDT was evaluated. Complex characterization was performed using high-resolution transmission electron microscopy (HR-TEM), FTIR, and UV-Vis spectroscopy. Further analysis involved fluorescence lifetime imaging (FLIM), and its cellular localization was mapped with confocal microscopy. In order to evaluate PDT effectiveness, cells treated with cGQDs-PEG-curcumin were irradiated with 5 J/cm2 of 414 nm light. After irradiation, cell viability assay, scanning electron microscopy (SEM), reactive oxygen species (ROS) detection, comet assay, and γH2AX-based DNA double-strand breaks (DSBs) detection were assessed and revealed a remarkable ability of the nano-composite to induce DNA damage after irradiation without ROS production. Our findings highlight the potential of cGQDs-PEG-curcumin as a cutting-edge PDT agent, capable of disrupting cell membrane and nucleolar integrity and impairing ribosomal synthesis, which is crucial for proliferating tumour cells.
- MeSH
- Cell Nucleolus * drug effects metabolism MeSH
- DNA Breaks, Double-Stranded drug effects MeSH
- Photochemotherapy * methods MeSH
- Photosensitizing Agents * pharmacology MeSH
- Graphite * chemistry pharmacology MeSH
- Curcumin * pharmacology chemistry MeSH
- Quantum Dots * chemistry MeSH
- Humans MeSH
- Cell Line, Tumor MeSH
- Neoplasms * drug therapy MeSH
- Polyethylene Glycols * chemistry pharmacology MeSH
- DNA Damage * drug effects MeSH
- Reactive Oxygen Species metabolism MeSH
- Cell Survival drug effects MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
PI3K signaling pathway is crucial for a plethora of cellular processes and is extensively linked with tumorigenesis and chemo-/radioresistance. Although a number of small molecule inhibitors have been synthesized to control PI3K-mediated signaling, only a limited clinical success has been reached. Thus, the search for novel promising candidates is still ongoing. Herein, we present a novel series of N-(5-(2-morpholino-4-oxo-3,4-dihydroquinazolin-8-yl)pyridin-2-yl)acylamides designed to simultaneously inhibit PI3K and DNA-PK activity. Compared to a commercial DNA-PK/PI3K inhibitor AZD7648, synthesized compounds generally exhibited markedly lower baseline cytotoxicity in all tested cell lines (MC38, B16F10, 4T1, CT26 and HEK-239). Through an array of biological experiments, we selected two most promising compounds, 2 and 6. While in cell-free conditions, 6 acted as a very efficient pan-PI3K and DNA-PK inhibitor, in physiological conditions, 2 performed better and acted as a potent chemosensitizer able to increase the amount of DNA double strand breaks induced by doxorubicin. This was plausibly due to its improved ability to accumulate in nuclei as evidenced by confocal analyses. Importantly, using P-gp overexpressing CT26 cells, we found that 2 is an efficient inhibitor of multidrug resistance (MDR) able to down-regulate expression of mRNA encoding MDR-driving proteins ABCB1A, ABCB1B and ABCC1. We also demonstrate that 2 can be simply loaded into lipid nanoparticles that retain its chemosensitizing properties. Taken together, the presented study provides a solid basis for a subsequent rational structure optimization towards new generation of multitarget inhibitors able to control crucial signaling pathways involved in tumorigenesis and drug resistance.
- MeSH
- Drug Resistance, Neoplasm * drug effects MeSH
- Phosphatidylinositol 3-Kinases metabolism MeSH
- Phosphoinositide-3 Kinase Inhibitors * pharmacology MeSH
- Protein Kinase Inhibitors * pharmacology chemistry chemical synthesis MeSH
- Humans MeSH
- Drug Resistance, Multiple * drug effects MeSH
- Molecular Structure MeSH
- Mice MeSH
- Cell Line, Tumor MeSH
- ATP Binding Cassette Transporter, Subfamily B, Member 1 * antagonists & inhibitors metabolism MeSH
- Cell Proliferation drug effects MeSH
- DNA-Activated Protein Kinase * antagonists & inhibitors metabolism MeSH
- Antineoplastic Agents * pharmacology chemistry chemical synthesis MeSH
- Drug Screening Assays, Antitumor MeSH
- Dose-Response Relationship, Drug MeSH
- Structure-Activity Relationship MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
BACKGROUND: The open-label, single-arm, multicentre ORZORA trial (NCT02476968) evaluated maintenance olaparib in patients with platinum-sensitive relapsed ovarian cancer (PSR OC) with a germline (g) or somatic (s) BRCA1 and/or BRCA2 mutation (BRCAm) or a non-BRCA homologous recombination repair mutation (non-BRCA HRRm). METHODS: Patients were in response to platinum-based chemotherapy after ≥2 prior lines of treatment and underwent prospective central screening for tumour BRCA status, then central gBRCAm testing to determine sBRCAm or gBRCAm status. An exploratory cohort evaluated non-BRCA HRRm in 13 predefined genes. Patients received olaparib 400 mg (capsules) twice daily until investigator-assessed disease progression. Secondary endpoints included overall survival (OS) and safety. RESULTS: 177 patients received olaparib. At the final data cutoff (25 June 2021), median OS from study enrolment was 46.8 (95% confidence interval [CI] 37.9-54.4), 43.2 (31.7-NC [not calculated]), 47.4 (37.9-NC) and 44.9 (28.9-NC) months in the BRCAm, sBRCAm, gBRCAm and non-BRCA HRRm cohorts, respectively. No new safety signals were identified. CONCLUSION: Maintenance olaparib showed consistent clinical activity in the BRCAm and sBRCAm cohorts; exploratory analysis suggested similar activity in the non-BRCA HRRm cohort. These findings highlight that patients with PSR OC, beyond those with gBRCAm, may benefit from maintenance olaparib.
- MeSH
- Adult MeSH
- Phthalazines * administration & dosage therapeutic use adverse effects MeSH
- Middle Aged MeSH
- Humans MeSH
- Neoplasm Recurrence, Local * drug therapy genetics MeSH
- Ovarian Neoplasms * drug therapy genetics mortality pathology MeSH
- Poly(ADP-ribose) Polymerase Inhibitors * administration & dosage therapeutic use MeSH
- Piperazines * administration & dosage therapeutic use adverse effects MeSH
- BRCA1 Protein * genetics MeSH
- BRCA2 Protein * genetics MeSH
- Recombinational DNA Repair genetics MeSH
- Aged MeSH
- Germ-Line Mutation MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Clinical Trial, Phase IV MeSH
- Multicenter Study MeSH
Nonspecific structural chromosomal aberrations (CAs) are found in around 1% of circulating lymphocytes from healthy individuals but the frequency may be higher after exposure to carcinogenic chemicals or radiation. CAs have been used in the monitoring of persons exposed to genotoxic agents and radiation. Previous studies on occupationally exposed individuals have shown associations between the frequency of CAs in peripheral blood lymphocytes and subsequent cancer risk. The cause for CA formation is believed to be unrepaired or insufficiently repaired DNA double-strand breaks or other DNA damage, and additionally telomere shortening. CAs include chromosome (CSAs) and chromatid type aberrations (CTAs). In the present review, we first describe the types of CAs, the conventional techniques used for their detection and some aspects of interpreting the results. We then focus on germline genetic variation in the frequency and type of CAs measured in a genome-wide association study in healthy individuals in relation to occupational and smoking-related exposure compared to nonexposed referents. The associations (at P < 10-5) on 1473 healthy individuals were broadly classified in candidate genes from functional pathways related to DNA damage response/repair, including PSMA1, UBR5, RRM2B, PMS2P4, STAG3L4, BOD1, COPRS, and FTO; another group included genes related to apoptosis, cell proliferation, angiogenesis, and tumorigenesis, COPB1, NR2C1, COPRS, RHOT1, ITGB3, SYK, and SEMA6A; a third small group mapped to genes KLF7, SEMA5A and ITGB3 which were related to autistic traits, known to manifest frequent CAs. Dedicated studies on 153 DNA repair genes showed associations for some 30 genes, the expression of which could be modified by the implicated variants. We finally point out that monitoring of CAs is so far the only method of assessing cancer risk in healthy human populations, and the use of the technology should be made more attractive by developing automated performance steps and incorporating artificial intelligence methods into the scoring.
- MeSH
- Genome-Wide Association Study * MeSH
- Chromosome Aberrations * MeSH
- Gene-Environment Interaction MeSH
- Humans MeSH
- Lymphocytes metabolism MeSH
- Neoplasms genetics MeSH
- DNA Repair genetics MeSH
- DNA Damage MeSH
- Occupational Exposure adverse effects MeSH
- Environmental Exposure adverse effects MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
Chemoresistance poses one of the most significant challenges of cancer therapy. Carboplatin (CbPt) is one of the most used chemotherapeutics in ovarian cancer (OVC) treatment. MRE11 constitutes a part of homologous recombination (HR), which is responsible for the repair of CbPt-induced DNA damage, particularly DNA crosslinks. The study's main aim was to address the role of HR in CbPt chemoresistance in OVC and to evaluate the possibility of overcoming CbPt chemoresistance by Mirin-mediated MRE11 inhibition in an OVC cell line. Lower expression of MRE11 was associated with better overall survival in a cohort of OVC patients treated with platinum drugs (TCGA dataset, P < 0.05). Using in vitro analyses, we showed that the high expression of HR genes drives the CbPt chemoresistance in our CbPt-resistant cell line model. Moreover, the HR inhibition by Mirin not only increased sensitivity to carboplatin (P < 0.05) but also rescued the sensitivity in the CbPt-resistant model (P < 0.05). Our results suggest that MRE11 inhibition with Mirin may represent a promising way to overcome OVC resistance. More therapy options will ultimately lead to better personalized cancer therapy and improvement of patients' survival.
- MeSH
- Drug Resistance, Neoplasm * genetics drug effects MeSH
- MRE11 Homologue Protein * genetics MeSH
- Carboplatin * pharmacology therapeutic use MeSH
- Humans MeSH
- Cell Line, Tumor MeSH
- Ovarian Neoplasms * drug therapy genetics MeSH
- DNA Damage drug effects MeSH
- Antineoplastic Agents pharmacology therapeutic use MeSH
- Gene Expression Regulation, Neoplastic drug effects MeSH
- Recombinational DNA Repair * drug effects MeSH
- Check Tag
- Humans MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
We present new developments for an ab-initio model of the neutron relative biological effectiveness (RBE) in inducing specific classes of DNA damage. RBE is evaluated as a function of the incident neutron energy and of the depth inside a human-sized reference spherical phantom. The adopted mechanistic approach traces neutron RBE back to its origin, i.e. neutron physical interactions with biological tissues. To this aim, we combined the simulation of radiation transport through biological matter, performed with the Monte Carlo code PHITS, and the prediction of DNA damage using analytical formulas, which ground on a large database of biophysical radiation track structure simulations performed with the code PARTRAC. In particular, two classes of DNA damage were considered: sites and clusters of double-strand breaks (DSBs), which are known to be correlated with cell fate following radiation exposure. Within a coherent modelling framework, this approach tackles the variation of neutron RBE in a wide energy range, from thermal neutrons to neutrons of hundreds of GeV, and reproduces effects related to depth in the human-sized receptor, as well as to the receptor size itself. Besides providing a better mechanistic understanding of neutron biological effectiveness, the new model can support better-informed decisions for radiation protection: indeed, current neutron weighting (ICRP)/quality (U.S. NRC) factors might be insufficient for use in some radiation protection applications, because they do not account for depth. RBE predictions obtained with the reported model were successfully compared to the currently adopted radiation protection standards when the depth information is not relevant (at the shallowest depth in the phantom or for very high energy neutrons). However, our results demonstrate that great care is needed when applying weighting factors as a function of incident neutron energy only, not explicitly considering RBE variation in the target. Finally, to facilitate the use of our results, we propose look-up RBE tables, explicitly considering the depth variable, and an analytical representation of the maximal RBE vs. neutron energy.
MRE11 nuclease is a central player in signaling and processing DNA damage, and in resolving stalled replication forks. Here, we describe the identification and characterization of new MRE11 inhibitors MU147 and MU1409. Both compounds inhibit MRE11 nuclease more specifically and effectively than the relatively weak state-of-the-art inhibitor mirin. They also abrogate double-strand break repair mechanisms that rely on MRE11 nuclease activity, without impairing ATM activation. Inhibition of MRE11 also impairs nascent strand degradation of stalled replication forks and selectively affects BRCA2-deficient cells. Herein, we illustrate that our newly discovered compounds MU147 and MU1409 can be used as chemical probes to further explore the biological role of MRE11 and support the potential clinical relevance of pharmacological inhibition of this nuclease.
- MeSH
- MRE11 Homologue Protein * metabolism antagonists & inhibitors MeSH
- Enzyme Inhibitors * pharmacology chemistry chemical synthesis MeSH
- Humans MeSH
- Molecular Structure MeSH
- Drug Discovery MeSH
- DNA Repair drug effects MeSH
- Dose-Response Relationship, Drug MeSH
- Structure-Activity Relationship MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
AIMS: Spindle-cell/sclerosing rhabdomyosarcomas (SS-RMS) are clinically and genetically heterogeneous. They include three well-defined molecular subtypes, of which those with EWSR1/FUS::TFCP2 rearrangements were described only recently. This study aimed to evaluate five new cases of SS-RMS and to perform a clinicopathological and statistical analysis of all TFCP2-rearranged SS-RMS described in the English literature to more comprehensively characterize this rare tumour type. METHODS AND RESULTS: Cases were retrospectively selected and studied by immunohistochemistry, fluorescence in situ hybridization with EWSR1/FUS and TFCP2 break-apart probes, next-generation sequencing (Archer FusionPlex Sarcoma kit and TruSight RNA Pan-Cancer Panel). The PubMed database was searched for relevant peer-reviewed English reports. Five cases of SS-RMS were found. Three cases were TFCP2 rearranged SS-RMS, having FUSex6::TFCP2ex2 gene fusion in two cases and triple gene fusion EWSR1ex5::TFCP2ex2, VAX2ex2::ALKex2 and VAX2intron2::ALKex2 in one case. Two cases showed rhabdomyoblastic differentiation and spindle-round cell/sclerosing morphology, but were characterized by novel genetic fusions including EWSR1ex8::ZBTB41ex7 and PLOD2ex8::RBM6ex7, respectively. In the statistical analysis of all published cases, CDKN2A or ALK alterations, the use of standard chemotherapy and age at presentation in the range of 18-24 years were negatively correlated to overall survival. CONCLUSION: EWSR1/FUS::TFCP2-rearranged SS-RMS is a rare rhabdomyosarcoma subtype, affecting predominantly young adults with average age at presentation 34 years (median 29.5 years; age range 7-86 years), with a predilection for craniofacial bones, rapid clinical course with frequent bone and lung metastases, and poor prognosis (3-year overall survival rate 28%).
- MeSH
- Child MeSH
- DNA-Binding Proteins genetics MeSH
- Adult MeSH
- Gene Fusion MeSH
- In Situ Hybridization, Fluorescence MeSH
- Middle Aged MeSH
- Humans MeSH
- Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase genetics MeSH
- Adolescent MeSH
- Young Adult MeSH
- Biomarkers, Tumor genetics MeSH
- RNA-Binding Protein EWS genetics MeSH
- RNA-Binding Proteins genetics MeSH
- Retrospective Studies MeSH
- Rhabdomyosarcoma * genetics pathology MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Transcription Factors * genetics MeSH
- Check Tag
- Child MeSH
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Aged, 80 and over MeSH
- Aged MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
DNA double-strand breaks (DSBs) represent a lethal form of DNA damage that can trigger cell death or initiate oncogenesis. The activity of RNA polymerase II (RNAPII) at the break site is required for efficient DSB repair. However, the regulatory mechanisms governing the transcription cycle at DSBs are not well understood. Here, we show that Integrator complex subunit 6 (INTS6) associates with the heterotrimeric sensor of ssDNA (SOSS1) complex (comprising INTS3, INIP and hSSB1) to form the tetrameric SOSS1 complex. INTS6 binds to DNA:RNA hybrids and promotes Protein Phosphatase 2A (PP2A) recruitment to DSBs, facilitating the dephosphorylation of RNAPII. Furthermore, INTS6 prevents the accumulation of damage-associated RNA transcripts (DARTs) and the stabilization of DNA:RNA hybrids at DSB sites. INTS6 interacts with and promotes the recruitment of senataxin (SETX) to DSBs, facilitating the resolution of DNA:RNA hybrids/R-loops. Our results underscore the significance of the tetrameric SOSS1 complex in the autoregulation of DNA:RNA hybrids and efficient DNA repair.
- MeSH
- DNA-Binding Proteins metabolism MeSH
- DNA Helicases metabolism genetics MeSH
- DNA * metabolism chemistry MeSH
- DNA Breaks, Double-Stranded * MeSH
- Phosphorylation MeSH
- Homeostasis genetics MeSH
- Humans MeSH
- DNA Repair * MeSH
- Protein Phosphatase 2 metabolism genetics MeSH
- R-Loop Structures MeSH
- RNA Helicases metabolism genetics MeSH
- RNA Polymerase II * metabolism MeSH
- RNA * metabolism genetics chemistry MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
