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TGF-? Inhibition Rescues Hematopoietic Stem Cell Defects and Bone Marrow Failure in Fanconi Anemia.

ABSTRACT: 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.

SUBMITTER: Zhang H

PROVIDER: S-EPMC4860147 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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TGF-β Inhibition Rescues Hematopoietic Stem Cell Defects and Bone Marrow Failure in Fanconi Anemia.

Zhang Haojian H Kozono David E DE O'Connor Kevin W KW Vidal-Cardenas Sofia S Rousseau Alix A Hamilton Abigail A Moreau Lisa L Gaudiano Emily F EF Greenberger Joel J Bagby Grover G Soulier Jean J Grompe Markus M Parmar Kalindi K D'Andrea Alan D AD

Cell stem cell 20160324 5

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-β (TGF-β) pathway-mediated growth suppression as a cause of BMF in FA. Blocking the TGF-β pathway improves the survival of F ...[more]

PMID: 27053300

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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.

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.

Project description:PurposeThe inherited bone marrow failure syndromes (IBMFS) are a heterogeneous group of genetic disorders that share the inability of the bone marrow to produce an adequate number of blood cells. The 4 most frequent syndromes are Fanconi anemia (FA), dyskeratosis congenita (DC), Diamond-Blackfan anemia (DBA), and Shwachman-Diamond syndrome (SDS). All 4 syndromes have been associated with various physical abnormalities. As part of a genotype/phenotype/cancer susceptibility study, we determined the prevalence of ophthalmic manifestations in these 4 syndromes.DesignCross-sectional study of a patient cohort.ParticipantsSeventy-five patients with an IBMFS and 121 of their first-degree relatives were seen in the National Eye Institute, National Institutes of Health, from 2001 to 2007. The patient group included 22 with FA, 28 with DC, 19 with DBA, and 6 with SDS.MethodsEvery participant underwent a complete ophthalmic evaluation and digital facial photography with an adhesive paper ruler on the patient's forehead for an internal measure of scale. Interpupillary distance (IPD), inner canthal distance (ICD), outer canthal distance (OCD), palpebral fissure length (PFL), and corneal diameter (CD) were measured. Thirteen of the 22 patients with FA underwent axial length (AL) measurements by A-scan ultrasonography.Main outcome measuresType and prevalence of ophthalmic manifestations.ResultsNinety-five percent of patients with FA had at least 1 abnormal parameter, and 25% of patients had at least 4 abnormal parameters. Eighty-two percent of patients had small palpebral fissures, 69% of patients had simple microphthalmia, 64% of patients had small OCD, 55% of patients had microcornea, 28% of patients had ptosis, and 6% of patients had epicanthal folds. In patients with DC, abnormalities of the lacrimal drainage system (29%) were the most prevalent findings, followed by retinal abnormalities (pigmentary changes, retinal neovascularization, retinal detachment, exudative retinopathy) in 21%, cicatricial entropion with trichiasis and blepharitis in 7% each, and sparse eyelashes and congenital cataract in 3.5% each. No significant ophthalmic abnormalities were seen in patients with DBA or SDS.ConclusionsSyndrome-specific ocular findings are associated with FA and DC and may antedate diagnosis of the specific syndrome. Early recognition of these abnormalities is important for optimal management.

Dataset Information

TGF-? Inhibition Rescues Hematopoietic Stem Cell Defects and Bone Marrow Failure in Fanconi Anemia.

Publications

TGF-β Inhibition Rescues Hematopoietic Stem Cell Defects and Bone Marrow Failure in Fanconi Anemia.

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