Haploinsufficient loss of multiple 5q genes may fine-tune Wnt signaling in del(5q) therapy-related myeloid neoplasms.
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ABSTRACT:
SUBMITTER: Stoddart A
PROVIDER: S-EPMC4692148 | biostudies-literature | 2015 Dec
REPOSITORIES: biostudies-literature
Publications
Haploinsufficient loss of multiple 5q genes may fine-tune Wnt signaling in del(5q) therapy-related myeloid neoplasms.
Stoddart Angela A Nakitandwe Joy J Chen Shann-Ching SC Downing James R JR Le Beau Michelle M MM
Blood 20151113 26
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Project description:Deletion of the chromosome 5q [del(5q)] is one of the most common cytogenetic abnormalities observed in patients with de novo myelodysplastic syndromes (MDS) and therapy-related MDS or acute myeloid leukemia (t-MDS/tAML). Emerging evidence indicates that activation of the Wnt/β-catenin pathway contributes to the development of myeloid neoplasms with del(5q). Whether β-catenin is a potential therapeutic target for myeloid neoplasms with del(5q) has yet to be evaluated. Here, we report that genetic deletion of a single allele of β-catenin rescues ineffective hematopoiesis in an Apc haploinsufficient mouse model, which recapitulates several characteristic features of the preleukemic stage of myeloid neoplasms with a -5/del(5q). In addition, loss of a single allele of β-catenin reversed the defective self-renewal capacity of Apc-haploinsufficient hematopoietic stem cells and reduced the frequency of apoptosis induced by Apc haploinsufficiency. Suppression of β-catenin by indomethacin or β-catenin shRNA reduced proliferation and survival of human leukemia cell lines with del(5q) but not of control leukemia cell lines in vitro; β-catenin inactivation also inhibited leukemia progression in vivo in xenograft mice reconstituted with del(5q) leukemia cell lines. Inhibition of β-catenin also stunted growth and colony-forming abilities of primary bone marrow cells from del(5q) AML patients in vitro Overall, our data support the idea that β-catenin could serve as a therapeutic target for the treatment of myeloid neoplasms with del(5q). Cancer Res; 77(15); 4116-26. ©2017 AACR.
| S-EPMC5559383 | biostudies-literature
Project description: Not available
| S-EPMC7271604 | biostudies-literature
Project description:BackgroundDeletion of chromosome 5q (del(5q)) is the most common karyotypic abnormality in myeloid neoplasms.Materials and methodsTo define the pathogenic molecular features associated with del(5q), next-generation sequencing was applied to 133 patients with myeloid neoplasms (MDS; N = 69, MDS/MPN; N = 5, sAML; N = 29, pAML; N = 30) with del(5q) as a sole abnormally or a part of complex karyotype and results were compared to molecular features of patients diploid for chr5.FindingsA number of 5q genes with haploinsufficient expression and/or recurrent somatic mutations were identified; for these genes, CSNK1A1 and G3BP1 within the commonly deleted 5q region and DDX41 within a commonly retained region were most commonly affected by somatic mutations. These genes showed consistent haploinsufficiency in deleted cases; low expression/mutations of G3BP1 or DDX41 were associated with poor survival, likely due to decreased cellular function. The most common mutations on other chromosomes in patients with del(5q) included TP53, and mutations of FLT3 (ITD or TKD), NPM1 or TET2 and were mutually exclusive. Serial sequencing allowed for definition of clonal architecture and dynamics, in patients with exome sequencing allelic imbalance for informative SNPs facilitated simultaneous approximation of clonal size of del(5q) and clonal burden for somatic mutations.InterpretationOur results illuminate the spectrum of molecular defects characteristic of del(5q), their clinical impact and succession of stepwise evolution.
| S-EPMC5351647 | biostudies-literature
Project description: Not available
| S-EPMC7768807 | biostudies-literature
Project description:The most common chromosomal abnormalities in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are -5/del(5q) and -7/del(7q). When -5/del(5q) and -7/del(7q) coexist in patients, a poor prognosis is typically associated. Given that -5/del(5q) and/or -7/del(7q) often are accompanied with additional recurrent chromosomal alterations, genetic change(s) on the accompanying chromosome(s) other than chromosomes 5 and 7 may be important factor(s) affecting leukemogenesis and disease prognosis. Using an integrated analysis of karyotype, FISH and array CGH results in this study, we evaluated the smallest region of overlap (SRO) of chromosomes 5 and 7 as well as copy number alterations (CNAs) on the other chromosomes. Moreover, the relationship between the CNAs and del(5q) and -7/del(7q) was investigated by categorizing the cases into three groups based on the abnormalities of chromosomes 5 and 7 [group I: cases only with del(5q), group II: cases only with -7/del(7q) and group III: concurrent del(5q) and del(7q) cases]. The overlapping SRO of chromosome 5 from groups I and III was 5q31.1-33.1 and of chromosome 7 from groups II and III was 7q31.31-q36.1. A total of 318 CNAs were observed; ~ 78.3% of them were identified on chromosomes other than chromosomes 5 and 7, which were defined as 'other CNAs'. Group III was a distinctive group carrying the most high number (HN) CNAs, cryptic CNAs and 'other CNAs'. The loss of TP53 was highly associated with del(5q). The loss of ETV6 was specifically associated with group III. These CNAs or genes may play a secondary role in disease progression and should be further evaluated for their clinical significance and influence on therapeutic approaches in patients with MDS/AML carrying del(5q) and/or -7/del(7q) in large-scale, patient population study.
| S-EPMC4571549 | biostudies-literature
Project description:Loss of a whole chromosome 5 or a deletion of the long arm, del(5q), is a recurring abnormality in myelodysplastic syndromes (MDSs) and acute myeloid leukemia (AML). To identify a leukemia-related gene on chromosome 5, we previously delineated a 970-kb segment of 5q31 that is deleted in all patients examined, and prepared a transcript map of this region. EGR1 is a candidate tumor suppressor gene within the commonly deleted segment of 5q, and encodes a zinc finger transcription factor. To test the hypothesis that loss of function of Egr1 is an initiating event in the pathogenesis of AML/MDS, Egr1-deficient mice were treated with a potent DNA alkylating agent, N-ethyl-nitrosourea (ENU), to induce secondary cooperating mutations. Egr1(+/-) and Egr1(-/-) mice treated with ENU developed immature T-cell lymphomas (CD4(+), CD8(+)) or a myeloproliferative disorder (MPD) at increased rates and with shorter latencies than that of wild-type littermates. The MPD was characterized by an elevated white blood cell count, anemia, and thrombocytopenia with ineffective erythropoiesis. Biallelic mutations of Egr1 were not observed in MPDs in Egr1(+/-) mice. Our data suggest that haploinsufficiency for Egr1 plays a role in murine leukemogenesis, and in the development of AML/MDS characterized by abnormalities of chromosome 5.
| S-EPMC1924479 | biostudies-literature
Project description:Rho signaling is a conserved mechanism for generating forces through activation of contractile actomyosin. How this pathway can produce different cell morphologies is poorly understood. In the Drosophila embryonic epithelium, we investigate how Rho signaling controls force asymmetry to drive morphogenesis. We study a distinct morphogenetic process termed 'alignment'. This process results in striking columns of rectilinear cells connected by aligned cell-cell contacts. We found that this is driven by contractile actomyosin cables that elevate tension along aligning interfaces. Our data show that polarization of Rho effectors, Rok and Dia, directs formation of these cables. Constitutive activation of these effectors causes aligning cells to instead invaginate. This suggests that moderating Rho signaling is essential to producing the aligned geometry. Therefore, we tested for feedback that could fine-tune Rho signaling. We discovered that F-actin exerts negative feedback on multiple nodes in the pathway. Further, we present evidence that suggests that Rok in part mediates feedback from F-actin to Rho in a manner independent of Myo-II. Collectively, our work suggests that multiple feedback mechanisms regulate Rho signaling, which may account for diverse morphological outcomes.
| S-EPMC6503953 | biostudies-literature
Project description:TRAF-interacting protein with forkhead-associated domain B (TIFAB) is a haploinsufficient gene in del(5q) myelodysplastic syndrome (MDS). Deletion of Tifab results in progressive bone marrow (BM) and blood defects, including skewed hematopoietic stem/progenitor cell (HSPC) proportions and altered myeloid differentiation. A subset of mice transplanted with Tifab knockout (KO) HSPCs develop a BM failure with neutrophil dysplasia and cytopenia. In competitive transplants, Tifab KO HSPCs are out-competed by wild-type (WT) cells, suggesting a cell-intrinsic defect. Gene expression analysis of Tifab KO HSPCs identified dysregulation of immune-related signatures, and hypersensitivity to TLR4 stimulation. TIFAB forms a complex with TRAF6, a mediator of immune signaling, and reduces TRAF6 protein stability by a lysosome-dependent mechanism. In contrast, TIFAB loss increases TRAF6 protein and the dynamic range of TLR4 signaling, contributing to ineffective hematopoiesis. Moreover, combined deletion of TIFAB and miR-146a, two genes associated with del(5q) MDS/AML, results in a cooperative increase in TRAF6 expression and hematopoietic dysfunction. Re-expression of TIFAB in del(5q) MDS/AML cells results in attenuated TLR4 signaling and reduced viability. These findings underscore the importance of efficient regulation of innate immune/TRAF6 signaling within HSPCs by TIFAB, and its cooperation with miR-146a as it relates to the pathogenesis of hematopoietic malignancies, such as del(5q) MDS/AML.
| S-EPMC4612089 | biostudies-literature
Project description:To understand the effect of loss of Hnrnpa0, an RNA-binding protein shown to regulate transcript stability via binding to the AU-rich elements (AREs) of mRNAs, on myelopoiesis, we used RNAi interference to model Hnrnpa0 loss in an experimental murine cell system, and then used global expression profiling techniques to determine the impact of that knockdown on gene expression, especially ARE-containing genes. The PUER system is a murine myeloid progenitor cell line expressing the tamoxifen (4-OHT) responsive, PU.1-ER fusion gene, allowing controlled myeloid differentiation in cells in which Hnrnpa0 expression has been altered via RNAi technology. By examining perturbations in gene expression both before and during myeloid differentiation, we have shown the Hnrnpa0 loss preferentially alters ARE-containing genes, leading to a shift in myeloid specification away from the monocytic lineage.
2012-08-08 | GSE39934 | GEO
Project description:The control of mRNA stability plays a central role in orchestrating gene-regulatory networks in hematopoietic cell growth, differentiation and tumorigenesis. HNRNPA0, which encodes an RNA-binding protein shown to regulate transcript stability via binding to the AU-rich elements of mRNAs, is located within the commonly deleted segment of 5q31.2 in myeloid neoplasms with a del(5q), and is expressed at haploinsufficient levels in these patients. We show that HNRNPA0 is normally highly expressed in hematopoietic stem cells and exhibits dynamic changes in expression during the course of differentiation. To model HNRNPA0 haploinsufficiency, we used RNAi interference in primary murine cells and an experimental cell system, and found that reduced Hnrnpa0 expression leads to a shift from monocytic towards granulocytic differentiation. Microarray-based global expression profiling revealed that Hnrnpa0 knockdown disproportionally impacts AU-rich containing transcripts and alters expression of myeloid specification genes. In therapy-related myeloid neoplasms with a del(5q), AU-rich containing mRNAs are enriched in transcripts that encode proteins associated with increased growth and proliferation. Our findings implicate haploinsufficiency of HNRNPA0 as one of the key initiating mutations in the pathogenesis of myeloid neoplasms with a del(5q), and suggest that therapies that target AU-rich elements warrant consideration in efforts to develop new mechanism-based treatment strategies.
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