MYC Promotes Bone Marrow Stem Cell Dysfunction in Fanconi Anemia.
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ABSTRACT:
SUBMITTER: Rodriguez A
PROVIDER: S-EPMC7796920 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:We profiled primary HSPCs from Fanconi anemia (FA) patients for single cell transcriptome (scRNA-seq) to identify additional determinants of HSPC impairment leading to the bone marrow failure,. Trajectory analysis revealed that early hematopoietic differentiation potential is preserved in FA HSPCs. As expected, p53 and TGFβ pathway genes were overexpressed in HSPCs from FA patients. The oncogene MYC was also identified as one of the top over-expressed genes in FA HSPCs. Interestingly, we observed co-existence of “High-TP53” expressing HSPCs and HighMYC expressing HSPCs in FA bone marrow. Inhibition of MYC expression by the BET bromodomain inhibitor (+)-JQ1 reduced the clonogenic potential of primary HSPCs from FA patients but rescued the physiological/genotoxic stress in HSPCs from FA mice. The “High-MYC” expressing HSPCs exhibited a significant downregulation of cell adhesion genes, such as CXCR4. Consistently, HSPCs in FA patients showed a defect in adhesion to their bone marrow niche resulting in egression from the bone marrow into peripheral blood. We speculate that MYC overexpression impairs HSPC function and contributes to exhaustion of HSPCs in FA bone marrow.
2020-09-08 | GSE157591 | GEO
Project description:MYC Promotes Bone Marrow Stem Cell Dysfunction in Fanconi Anemia
| PRJNA662081 | ENA
Project description:Fanconi anemia is a complex heterogeneous genetic disorder with a high incidence of bone marrow failure, clonal evolution to acute myeloid leukemia and mesenchymal-derived congenital anomalies. Increasing evidence in Fanconi anemia and other genetic disorders points towards an interdependence of skeletal and hematopoietic development, yet the impact of the marrow microenvironment in the pathogenesis of the bone marrow failure in Fanconi anemia remains unclear. Here we demonstrated that mice with double knockout of both Fancc and Fancg genes had decreased bone formation at least partially due to impaired osteoblast differentiation from mesenchymal stem/progenitor cells. Mesenchymal stem/progenitor cells from the double knockout mice showed impaired hematopoietic supportive activity. Mesenchymal stem/progenitor cells of patients with Fanconi anemia exhibited similar cellular deficits, including increased senescence, reduced proliferation, impaired osteoblast differentiation and defective hematopoietic stem/progenitor cell supportive activity. Collectively, these studies provide unique insights into the physiological significance of mesenchymal stem/progenitor cells in supporting the marrow microenvironment, which is potentially of broad relevance in hematopoietic stem cell transplantation.
| S-EPMC5451333 | biostudies-literature
Project description:Fanconi anemia (FA) is an inherited DNA repair disorder characterized by progressive bone marrow failure (BMF) from hematopoietic stem and progenitor cell (HSPC) attrition. A greater understanding of the pathogenesis of BMF could improve the therapeutic options for FA patients. Using a genome-wide shRNA screen in human FA fibroblasts, we identify transforming growth factor-? (TGF-?) pathway-mediated growth suppression as a cause of BMF in FA. Blocking the TGF-? pathway improves the survival of FA cells and rescues the proliferative and functional defects of HSPCs derived from FA mice and FA patients. Inhibition of TGF-? signaling in FA HSPCs results in elevated homologous recombination (HR) repair with a concomitant decrease in non-homologous end-joining (NHEJ), accounting for the improvement in cellular growth. Together, our results suggest that elevated TGF-? signaling contributes to BMF in FA by impairing HSPC function and may be a potential therapeutic target for the treatment of FA.
| S-EPMC4860147 | biostudies-literature
Project description:BackgroundPatients with bone marrow failure and undiagnosed underlying Fanconi anemia may experience major toxicity if given standard-dose conditioning regimens for hematopoietic stem cell transplant. Due to clinical variability and/or potential emergence of genetic reversion with hematopoietic somatic mosaicism, a straightforward Fanconi anemia diagnosis can be difficult to make, and diagnostic strategies combining different assays in addition to classical breakage tests in blood may be needed.Design and methodsWe evaluated Fanconi anemia diagnosis on blood lymphocytes and skin fibroblasts from a cohort of 87 bone marrow failure patients (55 children and 32 adults) with no obvious full clinical picture of Fanconi anemia, by performing a combination of chromosomal breakage tests, FANCD2-monoubiquitination assays, a new flow cytometry-based mitomycin C sensitivity test in fibroblasts, and, when Fanconi anemia was diagnosed, complementation group and mutation analyses. The mitomycin C sensitivity test in fibroblasts was validated on control Fanconi anemia and non-Fanconi anemia samples, including other chromosomal instability disorders.ResultsWhen this diagnosis strategy was applied to the cohort of bone marrow failure patients, 7 Fanconi anemia patients were found (3 children and 4 adults). Classical chromosomal breakage tests in blood detected 4, but analyses on fibroblasts were necessary to diagnose 3 more patients with hematopoietic somatic mosaicism. Importantly, Fanconi anemia was excluded in all the other patients who were fully evaluated.ConclusionsIn this large cohort of patients with bone marrow failure our results confirmed that when any clinical/biological suspicion of Fanconi anemia remains after chromosome breakage tests in blood, based on physical examination, history or inconclusive results, then further evaluation including fibroblast analysis should be made. For that purpose, the flow-based mitomycin C sensitivity test here described proved to be a reliable alternative method to evaluate Fanconi anemia phenotype in fibroblasts. This global strategy allowed early and accurate confirmation or rejection of Fanconi anemia diagnosis with immediate clinical impact for those who underwent hematopoietic stem cell transplant.
| S-EPMC2663612 | biostudies-literature
Project description:Hematopoietic stem cell (HSC) attrition is considered the key event underlying progressive BM failure (BMF) in Fanconi anemia (FA), the most frequent inherited BMF disorder in humans. However, despite major advances, how the cellular, biochemical, and molecular alterations reported in FA lead to HSC exhaustion remains poorly understood. Here, we demonstrated in human and mouse cells that loss-of-function of FANCA or FANCC, products of 2 genes affecting more than 80% of FA patients worldwide, is associated with constitutive expression of the transcription factor microphthalmia (MiTF) through the cooperative, unscheduled activation of several stress-signaling pathways, including the SMAD2/3, p38 MAPK, NF-κB, and AKT cascades. We validated the unrestrained Mitf expression downstream of p38 in Fanca-/- mice, which display hallmarks of hematopoietic stress, including loss of HSC quiescence, DNA damage accumulation in HSCs, and reduced HSC repopulation capacity. Importantly, we demonstrated that shRNA-mediated downregulation of Mitf expression or inhibition of p38 signaling rescued HSC quiescence and prevented DNA damage accumulation. Our data support the hypothesis that HSC attrition in FA is the consequence of defects in the DNA-damage response combined with chronic activation of otherwise transiently activated signaling pathways, which jointly prevent the recovery of HSC quiescence.
| S-EPMC7269568 | biostudies-literature
Project description:Inherited bone marrow failure syndromes (IBMFSs) are a heterogeneous group of disorders characterized by defective hematopoiesis, impaired stem cell function, and cancer susceptibility. Diagnosis of IBMFS presents a major challenge due to the large variety of associated phenotypes, and novel, clinically relevant biomarkers are urgently needed. Our study identified nuclear interaction partner of ALK (NIPA) as an IBMFS gene, as it is significantly downregulated in a distinct subset of myelodysplastic syndrome-type (MDS-type) refractory cytopenia in children. Mechanistically, we showed that NIPA is major player in the Fanconi anemia (FA) pathway, which binds FANCD2 and regulates its nuclear abundance, making it essential for a functional DNA repair/FA/BRCA pathway. In a knockout mouse model, Nipa deficiency led to major cell-intrinsic defects, including a premature aging phenotype, with accumulation of DNA damage in hematopoietic stem cells (HSCs). Induction of replication stress triggered a reduction in and functional decline of murine HSCs, resulting in complete bone marrow failure and death of the knockout mice with 100% penetrance. Taken together, the results of our study add NIPA to the short list of FA-associated proteins, thereby highlighting its potential as a diagnostic marker and/or possible target in diseases characterized by hematopoietic failure.
| S-EPMC7260023 | biostudies-literature
Project description:FancD2 plays a central role in the human Fanconi anemia DNA damage response (DDR) pathway. Fancd2(-/-) mice exhibit many features of human Fanconi anemia including cellular DNA repair defects. Whether the DNA repair defect in Fancd2(-/-) mice results in radiologic changes in all cell lineages is unknown. We measured stress of hematopoiesis in long-term marrow cultures and radiosensitivity in clonogenic survival curves, as well as comet tail intensity, total antioxidant stores and radiation-induced gene expression in hematopoietic progenitor compared to bone marrow stromal cell lines. We further evaluated radioprotection by a mitochondrial-targeted antioxidant GS-nitroxide, JP4-039. Hematopoiesis longevity in Fancd2(-/-) mouse long-term marrow cultures was diminished and bone marrow stromal cell lines were radiosensitive compared to Fancd2(+/+) stromal cells (Fancd2(-/-) D0 = 1.4 ± 0.1 Gy, ñ = 5.0 ± 0.6 vs. Fancd2(+/+) D0 = 1.6 ± 0.1 Gy, ñ = 6.7 ± 1.6), P = 0.0124 for D0 and P = 0.0023 for ñ, respectively). In contrast, Fancd2(-/-) IL-3-dependent hematopoietic progenitor cells were radioresistant (D0 = 1.71 ± 0.04 Gy and ñ = 5.07 ± 0.52) compared to Fancd2(+/+) (D0 = 1.39 ± 0.09 Gy and ñ = 2.31 ± 0.85, P = 0.001 for D0). CFU-GM from freshly explanted Fancd2(-/-) marrow was also radioresistant. Consistent with radiosensitivity, irradiated Fancd2(-/-) stromal cells had higher DNA damage by comet tail intensity assay compared to Fancd2(+/+) cells (P < 0.0001), slower DNA damage recovery, lower baseline total antioxidant capacity, enhanced radiation-induced depletion of antioxidants, and increased CDKN1A-p21 gene transcripts and protein. Consistent with radioresistance, Fancd2(-/-) IL-3-dependent hematopoietic cells had higher baseline and post irradiation total antioxidant capacity. While, there was no detectable alteration of radiation-induced cell cycle arrest with Fancd2(-/-) stromal cells, hematopoietic progenitor cells showed reduced G2/M cell cycle arrest. The absence of the mouse Fancd2 gene product confers radiosensitivity to bone marrow stromal but not hematopoietic progenitor cells.
| S-EPMC3970166 | biostudies-literature
Project description:BackgroundBone-related complications are commonly reported in cancer patients receiving radiotherapy and are collectively referred to as the abscopal effect of irradiation, the mechanism of which remains poorly understood. When patients receive targeted radiotherapy to a tumor, the local skeleton is exposed to radiation, particularly within the bone marrow. We therefore investigated the hypothesis that single bone irradiation can induce deterioration of the skeleton outside the radiation field and is mediated by the bone marrow.MethodsUsing 4-month-old male Sprague-Dawley rats, the effects of irradiation (20 Gy, right distal femur and proximal tibia) on bone quality, microarchitecture and bone marrow, were evaluated prospectively by microcomputed tomography, histomorphometry, real-time polymerase chain reaction, and Western blot analysis.ResultsAt 12 weeks post-irradiation, bone loss of the non-irradiated bone was induced and marrow adiposity was increased. Expression of runt-related transcription factor-2 by bone mesenchymal stem cells (BMSCs) decreased after irradiation by 88.0 % (P < 0.01) at the contralateral and 82.3 % (P < 0.01) at the irradiation site 2 weeks post-irradiation and decreased by 94.5 % (P < 0.001) at the contralateral and 44.1 % (P < 0.05) at the irradiation site 12 weeks post-irradiation. Interestingly, peroxisome proliferator-activated receptor gamma expression decreased by 61.8 % (P < 0.05) at the contralateral and by 48.3 % (P < 0.05) at the irradiation site 2 weeks post-irradiation but increased by 9-fold at the contralateral (P < 0.001) and by 13-fold (P < 0.001) at the irradiation site 12 weeks post-irradiation.ConclusionsThese data highlight that radiation-induced bone complications are partly BMSC-mediated, with important implications for bone health maintenance in patients receiving radiotherapy.
| S-EPMC4704383 | biostudies-literature
Project description:The most common cause of untreatable vision loss is dysfunction of the retina. Conditions, such as age-related macular degeneration, diabetic retinopathy and glaucoma remain leading causes of untreatable blindness worldwide. Various stem cell approaches are being explored for treatment of retinal regeneration. The rationale for using bone marrow stem cells to treat retinal dysfunction is based on preclinical evidence showing that bone marrow stem cells can rescue degenerating and ischemic retina. These stem cells have primarily paracrine trophic effects although some cells can directly incorporate into damaged tissue. Since the paracrine trophic effects can have regenerative effects on multiple cells in the retina, the use of this cell therapy is not limited to a particular retinal condition. Autologous bone marrow-derived stem cells are being explored in early clinical trials as therapy for various retinal conditions. These bone marrow stem cells include mesenchymal stem cells, mononuclear cells and CD34+ cells. Autologous therapy requires no systemic immunosuppression or donor matching. Intravitreal delivery of CD34+ cells and mononuclear cells appears to be tolerated and is being explored since some of these cells can home into the damaged retina after intravitreal administration. The safety of intravitreal delivery of mesenchymal stem cells has not been well established. This review provides an update of the current evidence in support of the use of bone marrow stem cells as treatment for retinal dysfunction. The potential limitations and complications of using certain forms of bone marrow stem cells as therapy are discussed. Future directions of research include methods to optimize the therapeutic potential of these stem cells, non-cellular alternatives using extracellular vesicles, and in vivo high-resolution retinal imaging to detect cellular changes in the retina following cell therapy.
| S-EPMC5237620 | biostudies-literature