Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 5 de 5
Filter
Add more filters










Database
Language
Publication year range
2.
Blood Adv ; 4(11): 2477-2488, 2020 06 09.
Article in English | MEDLINE | ID: mdl-32502268

ABSTRACT

The engraftment potential of myeloproliferative neoplasms in immunodeficient mice is low. We hypothesized that the physiological expression of human cytokines (macrophage colony-stimulating factor, interleukin-3, granulocyte-macrophage colony-stimulating factor, and thrombopoietin) combined with human signal regulatory protein α expression in Rag2-/-Il2rγ-/- (MISTRG) mice might provide a supportive microenvironment for the development and maintenance of hematopoietic stem and progenitor cells (HSPC) from patients with primary, post-polycythemia or post-essential thrombocythemia myelofibrosis (MF). We show that MISTRG mice, in contrast to standard immunodeficient NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ and Rag2-/-Il2rγ-/- mice, supported engraftment of all patient samples investigated independent of MF disease stage or risk category. Moreover, MISTRG mice exhibited significantly higher human MF engraftment levels in the bone marrow, peripheral blood, and spleen and supported secondary repopulation. Bone marrow fibrosis development was limited to 3 of 14 patient samples investigated in MISTRG mice. Disease-driving mutations were identified in all xenografts, and targeted sequencing revealed maintenance of the primary patient sample clonal composition in 7 of 8 cases. Treatment of engrafted mice with the current standard-of-care Janus kinase inhibitor ruxolitinib led to a reduction in human chimerism. In conclusion, the established MF patient-derived xenograft model supports robust engraftment of MF HSPCs and maintains the genetic complexity observed in patients. The model is suited for further testing of novel therapeutic agents to expedite their transition into clinical trials.


Subject(s)
Hematopoietic Stem Cells , Heterografts , Primary Myelofibrosis , Animals , Humans , Mice , Mice, Inbred BALB C , Mice, Inbred NOD , Primary Myelofibrosis/genetics
3.
Nucleic Acids Res ; 48(9): 4928-4939, 2020 05 21.
Article in English | MEDLINE | ID: mdl-32297953

ABSTRACT

Replication factor C (RFC), a heteropentamer of RFC1-5, loads PCNA onto DNA during replication and repair. Once DNA synthesis has ceased, PCNA must be unloaded. Recent findings assign the uloader role primarily to an RFC-like (RLC) complex, in which the largest RFC subunit, RFC1, has been replaced with ATAD5 (ELG1 in Saccharomyces cerevisiae). ATAD5-RLC appears to be indispensable, given that Atad5 knock-out leads to embryonic lethality. In order to learn how the retention of PCNA on DNA might interfere with normal DNA metabolism, we studied the response of ATAD5-depleted cells to several genotoxic agents. We show that ATAD5 deficiency leads to hypersensitivity to methyl methanesulphonate (MMS), camptothecin (CPT) and mitomycin C (MMC), agents that hinder the progression of replication forks. We further show that ATAD5-depleted cells are sensitive to poly(ADP)ribose polymerase (PARP) inhibitors and that the processing of spontaneous oxidative DNA damage contributes towards this sensitivity. We posit that PCNA molecules trapped on DNA interfere with the correct metabolism of arrested replication forks, phenotype reminiscent of defective homologous recombination (HR). As Atad5 heterozygous mice are cancer-prone and as ATAD5 mutations have been identified in breast and endometrial cancers, our finding may open a path towards the therapy of these tumours.


Subject(s)
ATPases Associated with Diverse Cellular Activities/genetics , Antineoplastic Agents/pharmacology , DNA Damage , DNA-Binding Proteins/genetics , Poly(ADP-ribose) Polymerase Inhibitors/pharmacology , ATPases Associated with Diverse Cellular Activities/metabolism , Animals , Cell Line , Cell Line, Tumor , Chickens , Chromatin/enzymology , DNA/metabolism , DNA-Binding Proteins/metabolism , Genomic Instability , Mutagens/toxicity , Phthalazines/pharmacology , Piperazines/pharmacology , Poly (ADP-Ribose) Polymerase-1/metabolism
4.
Nucleic Acids Res ; 47(17): 9132-9143, 2019 09 26.
Article in English | MEDLINE | ID: mdl-31329989

ABSTRACT

Poly(ADP-ribose) polymerases (PARPs) facilitate the repair of DNA single-strand breaks (SSBs). When PARPs are inhibited, unrepaired SSBs colliding with replication forks give rise to cytotoxic double-strand breaks. These are normally rescued by homologous recombination (HR), but, in cells with suboptimal HR, PARP inhibition leads to genomic instability and cell death, a phenomenon currently exploited in the therapy of ovarian cancers in BRCA1/2 mutation carriers. In spite of their promise, resistance to PARP inhibitors (PARPis) has already emerged. In order to identify the possible underlying causes of the resistance, we set out to identify the endogenous source of DNA damage that activates PARPs. We argued that if the toxicity of PARPis is indeed caused by unrepaired SSBs, these breaks must arise spontaneously, because PARPis are used as single agents. We now show that a significant contributor to PARPi toxicity is oxygen metabolism. While BRCA1-depleted or -mutated cells were hypersensitive to the clinically approved PARPi olaparib, its toxicity was significantly attenuated by depletion of OGG1 or MYH DNA glycosylases, as well as by treatment with reactive oxygen species scavengers, growth under hypoxic conditions or chemical OGG1 inhibition. Thus, clinical resistance to PARPi therapy may emerge simply through reduced efficiency of oxidative damage repair.


Subject(s)
BRCA1 Protein/genetics , DNA Glycosylases/genetics , Ovarian Neoplasms/drug therapy , Poly(ADP-ribose) Polymerases/genetics , Cell Line, Tumor , DNA Breaks, Single-Stranded/drug effects , DNA Damage/drug effects , DNA Glycosylases/antagonists & inhibitors , Drug Resistance, Neoplasm/genetics , Female , Homologous Recombination/drug effects , Homologous Recombination/genetics , Humans , Ovarian Neoplasms/genetics , Ovarian Neoplasms/pathology , Oxidation-Reduction/drug effects , Phthalazines/adverse effects , Phthalazines/pharmacology , Piperazines/adverse effects , Piperazines/pharmacology , Poly(ADP-ribose) Polymerase Inhibitors/pharmacology , Reactive Oxygen Species/metabolism , Synthetic Lethal Mutations/genetics
5.
Nature ; 494(7438): 492-496, 2013 Feb 28.
Article in English | MEDLINE | ID: mdl-23446422

ABSTRACT

Cancer chromosomal instability (CIN) results in an increased rate of change of chromosome number and structure and generates intratumour heterogeneity. CIN is observed in most solid tumours and is associated with both poor prognosis and drug resistance. Understanding a mechanistic basis for CIN is therefore paramount. Here we find evidence for impaired replication fork progression and increased DNA replication stress in CIN(+) colorectal cancer (CRC) cells relative to CIN(-) CRC cells, with structural chromosome abnormalities precipitating chromosome missegregation in mitosis. We identify three new CIN-suppressor genes (PIGN (also known as MCD4), MEX3C (RKHD2) and ZNF516 (KIAA0222)) encoded on chromosome 18q that are subject to frequent copy number loss in CIN(+) CRC. Chromosome 18q loss was temporally associated with aneuploidy onset at the adenoma-carcinoma transition. CIN-suppressor gene silencing leads to DNA replication stress, structural chromosome abnormalities and chromosome missegregation. Supplementing cells with nucleosides, to alleviate replication-associated damage, reduces the frequency of chromosome segregation errors after CIN-suppressor gene silencing, and attenuates segregation errors and DNA damage in CIN(+) cells. These data implicate a central role for replication stress in the generation of structural and numerical CIN, which may inform new therapeutic approaches to limit intratumour heterogeneity.


Subject(s)
Chromosomal Instability/genetics , Colorectal Neoplasms/genetics , DNA Replication/genetics , Aneuploidy , Cell Line, Tumor , Chromosomal Instability/drug effects , Chromosome Segregation/drug effects , Chromosome Segregation/genetics , Chromosomes, Human, Pair 18/drug effects , Chromosomes, Human, Pair 18/genetics , Colorectal Neoplasms/pathology , DNA Copy Number Variations/genetics , DNA Damage/drug effects , DNA Damage/genetics , DNA Replication/drug effects , Gene Deletion , Gene Silencing , Genes, Tumor Suppressor , Humans , Mitosis/drug effects , Nucleosides/pharmacology , Phosphotransferases/genetics , RNA-Binding Proteins/genetics
SELECTION OF CITATIONS
SEARCH DETAIL
...