The genetic basis of phenotypic heterogeneity in myelodysplastic syndromes

Caspase 8 deletion causes infection/inflammation-induced bone marrow failure and MDS-like disease in mice

Myelodysplastic syndromes (MDS) are a heterogeneous group of pre-leukemic hematopoietic disorders characterized by cytopenia in peripheral blood due to ineffective hematopoiesis and normo- or hypercellularity and morphologic dysplasia in bone marrow (BM). An inflammatory BM microenvironment and programmed cell death of hematopoietic stem/progenitor cells (HSPCs) are thought to be the major causes of ineffective hematopoiesis in MDS. Pyroptosis, apoptosis and necroptosis (collectively, PANoptosis) are observed in BM tissues of MDS patients, suggesting an important role of PANoptosis in MDS pathogenesis. Caspase 8 (Casp8) is a master regulator of PANoptosis, which is downregulated in HSPCs from most MDS patients and abnormally spliced in HSPCs from MDS patients with SRSF2 mutation. To study the role of PANoptosis in hematopoiesis, we generated inducible Casp8 knockout mice (Casp8-/-). Mx1-Cre-Casp8-/- mice died of BM failure within 10 days of polyI:C injections due to depletion of HSPCs. Rosa-ERT2Cre-Casp8-/- mice are healthy without significant changes in BM hematopoiesis within the first 1.5 months after Casp8 deletion. Such mice developed BM failure upon infection or low dose polyI:C/LPS injections due to the hypersensitivity of Casp8-/- HSPCs to infection or inflammation-induced necroptosis which can be prevented by Ripk3 deletion. However, impaired self-renewal capacity of Casp8-/- HSPCs cannot be rescued by Ripk3 deletion due to activation of Ripk1-Tbk1 signaling. Most importantly, mice transplanted with Casp8-/- BM cells developed MDS-like disease within 4 months of transplantation as demonstrated by anemia, thrombocytopenia and myelodysplasia. Our study suggests an essential role for a balance in Casp8, Ripk3-Mlkl and Ripk1-Tbk1 activities in the regulation of survival and self-renewal of HSPCs, the disruption of which induces inflammation and BM failure, resulting in MDS-like disease.

The evolution of preclinical models for myelodysplastic neoplasms

Myelodysplastic Neoplasms (MDS) are a group of clonal disorders characterized by ineffective hematopoiesis and morphologic dysplasia. Clinical manifestations of MDS vary widely and are dictated in large part by a range of genetic aberrations. The lack of robust in vitro models for MDS has limited the ability to conduct high throughput drug screens, which in turn has hampered the development of novel therapies for MDS. There are very few well-characterized MDS cell lines, and the available cell lines expand poorly in vitro. Conventional xenograft mouse models can provide an in vivo vessel to provide growth of cancer cells, but human MDS cells engraft poorly. Three-dimensional (3D) scaffold models that form human "ossicles" represent a promising new approach and can reproduce the intricate communication between hematopoietic stem and progenitor cells and their environment. Genetically engineered mice utilize specific mutations and may not represent the entire array of human MDS; however, genetically engineered mice provided in vivo proof of principle for novel agents such as luspatercept, demonstrating the clinical utility of this approach. This review offers an overview of available preclinical MDS models and potential approaches to accelerate accurate clinical translation.

Myelodysplastic Syndromes and Myelodysplastic Syndromes/Myeloproliferative Neoplasms: A Real-World Experience From a Developing Country

PURPOSE

Myelodysplastic syndromes (MDS) include a heterogeneous group of clonal bone marrow disorders characterized by ineffective hematopoiesis. They manifest as dysplasia in bone marrow hemopoietic elements associated with peripheral cytopenias with variable risk of AML transformation.

PATIENTS AND METHODS

We analyzed retrospectively registry data collected prospectively from patients with primary MDS and patients with MDS/myeloproliferative neoplasm (MPN) in the Jordan University Hospital between January 2007 and September 2021. The registry captured epidemiologic information such as date of diagnosis, age, gender, date of AML transformation, cytogenetics, MDS subtype, risk group according to Revised International Prognostic Scoring System, and survival. The registry also captured baseline ferritin, B12, and lactate dehydrogenase levels.

RESULTS

A total of 112 patients with MDS and MDS/MPN were included in the registry. Median age at diagnosis was 59 years. The male-to-female ratio was about 1.2. In a multivariate cox regression model, baseline serum ferritin significantly affected survival as patients with levels exceeding 1,000 μg/L had a risk of death three times higher compared with those with <1,000 μg/L levels (P < .05).

CONCLUSION

To our knowledge, our study is the first comprehensive study examining the epidemiology and prognostic factors in patients with MDS and patients with MDS/MPN in Jordan. Our results show that MDS and MDS/MPN epidemiology in Jordan is different compared with Western countries. Our results also show that baseline serum ferritin levels can be used as a prognostic marker for patients with MDS.

Myeloid-derived suppressor cells inhibit natural killer cells in myelodysplastic syndromes through the TIGIT/CD155 pathway

OBJECTIVE

This experiment will explore the role of TIGIT/PVR signaling pathway in the pathogenesis of MDS immune tolerance through in vitro co-culture of NK cells and MDSC cells.

METHODS

Flow cytometry was used to detect the expression percentage of MDSCs and CD155 on MDSCs in the bone marrow of MDS patients and controls. The expression of NK cell surface receptors (NKG2D, NKp30, NKp46), secreted cytokines (perforin, granzyme B, CD107a, IFN-γ) and NK cell apoptosis rate were detected by flow cytometry to evaluate the effect of MDSCs on NK cell function.

RESULTS

The number of MDSCs in bone marrow of MDS patients was notably higher than that of the control group (8.39 ± 7.01 vs 2.31 ± 1.65, P = 0.0001). Compared with the control group, the expression of CD155 on MDSCs in MDS group was increased (31.81 ± 21.33 vs. 10.49 ± 6.53, P < 0.0001). After NK cells were co-cultured with MDSCs, NKG2D, NKp30, NKp46, CD107a, IFN-γ, perforin and granzyme B were decreased, and the NK function partially recovered after the addition of inhibitors.

CONCLUSION

Compared with the normal control, MDSCs and CD155 on MDSCs were highly expressed in MDS patients. After co-culture with MDSCs, the expression of NK cells' surface receptors decreased, the secretion of cytokines decreased and the apoptosis rate increased. After blocking TIGIT/CD155 pathway, NK cell function was reversed, but NK cell apoptosis was not reduced.

MicroRNA-765 is upregulated in myelodysplastic syndromes and induces apoptosis via PLP2 inhibition in leukemia cells

Background

Epigenetic studies, particularly research on microRNA (miRNA), have flourished. The abnormal expression of miRNA contributes to the development of hematologic malignancies. miR-765 has been reported to inhibit cell proliferation by downregulating proteolipid protein 2 (PLP2), which causes apoptosis. We investigated miR-765 dysregulation in myelodysplastic syndromes (MDS).

Methods

We compared the expression profiles of miR-765 in 65 patients with MDS and 11 controls. Cell proliferation and apoptosis assays were performed to determine the in vitro effects of miR-765 on leukemia cells transfected with the miR-765 mimic. Reverse transcription quantitative PCR (RT-qPCR) and western blotting were performed to examine the targets of miR-765.

Results

We found that miR-765 levels were upregulated 10.2-fold in patients with MDS compared to controls. In refractory cytopenia with multilineage dysplasia, the percentage of patients with elevated miR-765 levels was significantly higher than in other forms of MDS. Experiments with leukemia cells revealed that transfection with a miR-765 mimic inhibited cell proliferation and induced apoptosis. RT-qPCR and western blotting demonstrated that the target of miR-765 was PLP2.

Conclusion

These findings imply that upregulation of miR-765 induces apoptosis via downregulation of PLP2 and may have a role in MDS pathogenesis.

Absence of early platelet increment in healthy mice during decitabine treatment

Treatment of myelodysplastic syndromes includes the administration of the hypomethylating agent decitabine. An early platelet response in decitabine-treated myelodysplastic syndrome patients is a predictor of overall survival. The effect of decitabine on megakaryocytes and the bone marrow, however, is understudied. We show that an early platelet increment was not detectable in healthy mice during decitabine treatment. Analyses of bone marrow sections revealed vessels with dilated lumina, decreased cellularity, but increased number of red blood cells and the presence of (pro)platelet-like particles. Taken together, decitabine treatment of healthy mice does not induce an early platelet increment, but affects the bone marrow.

The transcription factor DDIT3 is a potential driver of dyserythropoiesis in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are hematopoietic stem cell (HSC) malignancies characterized by ineffective hematopoiesis, with increased incidence in older individuals. Here we analyze the transcriptome of human HSCs purified from young and older healthy adults, as well as MDS patients, identifying transcriptional alterations following different patterns of expression. While aging-associated lesions seem to predispose HSCs to myeloid transformation, disease-specific alterations may trigger MDS development. Among MDS-specific lesions, we detect the upregulation of the transcription factor DNA Damage Inducible Transcript 3 (DDIT3). Overexpression of DDIT3 in human healthy HSCs induces an MDS-like transcriptional state, and dyserythropoiesis, an effect associated with a failure in the activation of transcriptional programs required for normal erythroid differentiation. Moreover, DDIT3 knockdown in CD34⁺ cells from MDS patients with anemia is able to restore erythropoiesis. These results identify DDIT3 as a driver of dyserythropoiesis, and a potential therapeutic target to restore the inefficient erythroid differentiation characterizing MDS patients.

Myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a family of myeloid cancers with diverse genotypes and phenotypes characterized by ineffective haematopoiesis and risk of transformation to acute myeloid leukaemia (AML). Some epidemiological data indicate that MDS incidence is increasing in resource-rich regions but this is controversial. Most MDS cases are caused by randomly acquired somatic mutations. In some patients, the phenotype and/or genotype of MDS overlaps with that of bone marrow failure disorders such as aplastic anaemia, paroxysmal nocturnal haemoglobinuria (PNH) and AML. Prognostic systems, such as the revised International Prognostic Scoring System (IPSS-R), provide reasonably accurate predictions of survival at the population level. Therapeutic goals in individuals with lower-risk MDS include improving quality of life and minimizing erythrocyte and platelet transfusions. Therapeutic goals in people with higher-risk MDS include decreasing the risk of AML transformation and prolonging survival. Haematopoietic cell transplantation (HCT) can cure MDS, yet fewer than 10% of affected individuals receive this treatment. However, how, when and in which patients with HCT for MDS should be performed remains controversial, with some studies suggesting HCT is preferred in some individuals with higher-risk MDS. Advances in the understanding of MDS biology offer the prospect of new therapeutic approaches.

Prognostication in myelodysplastic syndromes (neoplasms): Molecular risk stratification finally coming of age

Accurate risk prognostication is central to the management of myelodysplastic syndromes, given the widely heterogeneous clinical outcomes of these bone marrow failure disorders. Over the past decade, the rapidly expanding compendium of molecular lesions in myelodysplastic syndrome (MDS) has offered unprecedented insight into MDS pathobiology. Recently, molecular prognostic models such as the Molecular International Prognostic Scoring System (IPSS-M) have leveraged the wellspring of genetic data to improve upon traditional risk models such as the Revised IPSS (IPSS-R), but also added substantial complexity. In this review, we highlight early MDS prognostic models, the significant advancements in MDS genomics since then, and the recent advent of molecular based prognostic models. We conclude by discussing important opportunities and challenges in the management of MDS as we arrive at the molecular frontier.

Microenvironmental Features Driving Immune Evasion in Myelodysplastic Syndromes and Acute Myeloid Leukemia

Bone marrow, besides the known functions of hematopoiesis, is an active organ of the immune system, functioning as a sanctuary for several mature immune cells. Moreover, evidence suggests that hematopoietic stem cells (the bone marrow’s functional unit) are capable of directly sensing and responding to an array of exogenous stimuli. This chronic immune stimulation is harmful to normal hematopoietic stem cells, while essential for the propagation of myeloid diseases, which show a dysregulated immune microenvironment. The bone marrow microenvironment in myelodysplastic syndromes (MDS) is characterized by chronic inflammatory activity and immune dysfunction, that drive excessive cellular death and through immune evasion assist in cancer cell expansion. Acute myeloid leukemia (AML) is another example of immune response failure, with features that augment immune evasion and suppression. In this review, we will outline some of the functions of the bone marrow with immunological significance and describe the alterations in the immune landscape of MDS and AML that drive disease progression.

Dysfunctional bone marrow endothelial progenitor cells are involved in patients with myelodysplastic syndromes

Background

Myelodysplastic syndromes (MDS) are a group of heterogeneous myeloid clonal disorders characterized by ineffective haematopoiesis and immune deregulation. Emerging evidence has shown the effect of bone marrow (BM) endothelial progenitor cells (EPCs) in regulating haematopoiesis and immune balance. However, the number and functions of BM EPCs in patients with different stages of MDS remain largely unknown.

Methods

Patients with MDS (N = 30), de novo acute myeloid leukaemia (AML) (N = 15), and healthy donors (HDs) (N = 15) were enrolled. MDS patients were divided into lower-risk MDS (N = 15) and higher-risk MDS (N = 15) groups according to the dichotomization of the Revised International Prognostic Scoring System. Flow cytometry was performed to analyse the number of BM EPCs. Tube formation and migration assays were performed to evaluate the functions of BM EPCs. In order to assess the gene expression profiles of BM EPCs, RNA sequencing (RNA-seq) were performed. BM EPC supporting abilities of haematopoietic stem cells (HSCs), leukaemia cells and T cells were assessed by in vitro coculture experiments.

Results

Increased but dysfunctional BM EPCs were found in MDS patients compared with HDs, especially in patients with higher-risk MDS. RNA-seq indicated the progressive change and differences of haematopoiesis- and immune-related pathways and genes in MDS BM EPCs. In vitro coculture experiments verified that BM EPCs from HDs, lower-risk MDS, and higher-risk MDS to AML exhibited a progressively decreased ability to support HSCs, manifested as elevated apoptosis rates and intracellular reactive oxygen species (ROS) levels and decreased colony-forming unit plating efficiencies of HSCs. Moreover, BM EPCs from higher-risk MDS patients demonstrated an increased ability to support leukaemia cells, characterized by increased proliferation, leukaemia colony-forming unit plating efficiencies, decreased apoptosis rates and apoptosis-related genes. Furthermore, BM EPCs induced T cell differentiation towards more immune-tolerant cells in higher-risk MDS patients in vitro. In addition, the levels of intracellular ROS and the apoptosis ratios were increased in BM EPCs from MDS patients, especially in higher-risk MDS patients, which may be therapeutic candidates for MDS patients.

Conclusion

Our results suggest that dysfunctional BM EPCs are involved in MDS patients, which indicates that improving haematopoiesis supporting ability and immuneregulation ability of BM EPCs may represent a promising therapeutic approach for MDS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03354-2.

Predictive values of mutational variant allele frequency in overall survival and leukemic progression of myelodysplastic syndromes

BACKGROUND

The implication of mutational variant allelic frequency (VAF) has been increasingly considered in the prognostic interpretation of molecular data in myeloid malignancies. However, the impact of VAF on outcomes of myelodysplastic syndromes (MDS) has not been extensively explored.

METHODS

Targeted next-generation sequencing was performed in 350 newly diagnosed MDS cases. The associations of mutational VAF of each gene with overall survival (OS) and leukemia-free survival (LFS) were examined by multivariate Cox regression after univariate analysis.

RESULTS

Shorter OS was independently associated with DNMT3A VAF (HR 1.020 per 1% VAF increase; 95% CI 1.005-1.035; p = 0.011) and TP53 VAF (HR 1.014 per 1% VAF increase; 95% CI 1.006-1.022; p = 0.001). LFS analyses revealed that TET2 VAF (HR 1.013 per 1% VAF increase; 95% CI 1.005-1.022; p = 0.003) and TP53 VAF (HR 1.012 per 1% VAF increase; 95% CI 1.004-1.021; p = 0.005) were independently associated with faster leukemic transformation. Furthermore, we established nomograms to predict OS and LFS, respectively, by integrating independent mutational predictors into the revised International Prognostic Scoring System.

CONCLUSION

Our study highlights that VAF of certain genes should be incorporated into routine clinical prognostication of survival and leukemic transformation of MDS.

Programmed necroptosis is upregulated in low-grade myelodysplastic syndromes and may play a role in the pathogenesis

Myelodysplastic syndrome (MDS) is characterized by persistent cytopenias and evidence of morphologic dysplasia in the bone marrow (BM). Excessive hematopoietic programmed cell death (PCD) and inflammation have been observed in the bone marrow of patients with MDS, and are thought to play a significant role in the pathogenesis of the disease. Necroptosis is a major pathway of PCD that incites inflammation; however, the role of necroptosis in human MDS has not been extensively investigated. To assess PCD status in newly diagnosed MDS, we performed immunofluorescence staining with computational image analysis of formalin-fixed, paraffin-embedded BM core biopsies using cleaved caspase-3 (apoptosis marker) and necroptosis markers (receptor-interacting serine/threonine-protein kinase 1 [RIPK1], phospho-mixed lineage kinase domain-like protein [pMLKL]). Patients with MDS, but not controls without MDS or patients with de novo acute myeloid leukemia, had significantly increased expression of RIPK1 and pMLKL but not cleaved caspase-3, which was most evident in morphologically low-grade MDS (<5% BM blasts) and in MDS with low International Prognostic Scoring System risk score. RIPK1 expression highly correlated with the distribution of CD71⁺ erythroid precursors but not with CD34⁺ blast cells. We found that necroptosis is upregulated in early/low-grade MDS relative to control participants, warranting further study to define the role of necroptosis in the pathogenesis of MDS and as a potential biomarker for the diagnosis of low-grade MDS.

Molecular Targeted Therapy and Immunotherapy for Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) is a heterogeneous, clonal hematological disorder characterized by ineffective hematopoiesis, cytopenia, morphologic dysplasia, and predisposition to acute myeloid leukemia (AML). Stem cell genomic instability, microenvironmental aberrations, and somatic mutations contribute to leukemic transformation. The hypomethylating agents (HMAs), azacitidine and decitabine are the standard of care for patients with higher-risk MDS. Although these agents induce responses in up to 40-60% of patients, primary or secondary drug resistance is relatively common. To improve the treatment outcome, combinational therapies comprising HMA with targeted therapy or immunotherapy are being evaluated and are under continuous development. This review provides a comprehensive update of the molecular pathogenesis and immune-dysregulations involved in MDS, mechanisms of resistance to HMA, and strategies to overcome HMA resistance.

miR-378-3p Knockdown Recapitulates Many of the Features of Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are clonal neoplasms of the hematopoietic stem cell that result in aberrant differentiation of hematopoietic lineages due to a wide range of underlying genetic, epigenetic, and other causes. Despite the myriad etiologies, there is a recognizable MDS phenotype that has been associated with microRNA (miRNA) aberrant expression. A model of aberrant myeloid maturation mimicking MDS that is seen in MDS has been created using a stable knockdown of miR-378-3p. This model exhibited a transcriptional profile that indicates aberrant maturation and function, showed immunophenotypic and morphologic dysplasia, and displays the aberrant growth and function that characterizes MDS. Moreover, aberrant signal transduction in response to stimulation was demonstrated that is specific to the stage of myeloid maturation and mimics that seen in MDS patient samples using mass cytometry (CyTOF). The aberrant signaling, immunophenotypic changes, cellular growth, and colony formation ability seen in this myeloid model could be reversed with azacytidine (AZA) albeit without significant improvement of neutrophil function.

Reduced miR-16 levels are associated with VEGF upregulation in high-risk myelodysplastic syndromes

Objective: Overexpression of vascular endothelial growth factor (VEGF), a major angiogenic factor, was found in myelodysplastic syndromes (MDS) and showed different expression statuses in different risk groups of MDS. We aimed to investigate the possible role of microRNA (miR)-15a and miR-16 on the regulation of VEGF expression and their effect on angiogenesis in lower- and higher-risk MDS. Methods: We studied peripheral blood and bone marrow samples of MDS patients or several leukaemia and MDS cell lines by enzyme-linked immunosorbent assay, immunohistochemical staining, immunofluorescence and quantitative PCR for expression levels of VEGF, miR-15a and miR-16. MiRNA transfection and Luciferase reporter assays were conducted to investigate whether VEGF is a target of miR-16. Migration and tube formation assays were performed in cells exposed to medium from cells with overexpressed or knockdown miR-16. Results: It showed a significantly lower level of miR-16 in higher-risk MDS patients, while the VEGF levels were upregulated. Inverse correlation between VEGF and miR-16 were determined in cells lines including SKM-1, THP-1, and K562 cells. Overexpression of miR-16 in SKM-1 cells resulted in reduced VEGF secretion and cell protein levels. Direct binding of miR-16 to the 3' untranslated region (3'-UTR) of VEGF was confirmed by luciferase reporter assays. The migration and tube formation of human umbilical vein endothelial cells decreased in the presence of medium from SKM-1 cells with overexpressed miR-16. Conclusion: These data suggest that miR-16 may play a role in angiogenesis in higher-risk MDS by targeting VEGF and therefore modulating MDS progression. MiR-16 might be a novel therapeutic target in higher-risk MDS.

Integration Analysis of JAK2 or RUNX1 Mutation With Bone Marrow Blast Can Improve Risk Stratification in the Patients With Lower Risk Myelodysplastic Syndrome

Despite the improvements in prognostication of the revised International Prognostic Scoring System (IPSS-R) in myelodysplastic syndrome (MDS), there remain a portion of patients with lower risk (low/intermediate risk, LR) but poor prognostics. This study aimed to evaluate the relative contribution of mutational status when added to the IPSS-R, for estimating overall survival (OS) and progression-free survival (PFS) in patients with LR-MDS. We retrospectively analyzed clinical and laboratory variables of 328 patients diagnosed with MDS according to the FAB criteria. Twenty-nine-gene NGS assay was applied to bone marrow samples obtained at diagnosis. 233 (71.04%) patients were classified as LR-MDS. Univariate analysis showed association between inferior outcome (OS and PFS) and presence of JAK2 (p = 0.0177, p = 0.0002), RUNX1 (p = 0.0250, p = 0.0387), and U2AF1 (p = 0.0227, p = 0.7995) mutations. Multivariable survival analysis revealed JAK2 (p < 0.0001) and RUNX1 (p = 0.0215) mutations were independently prognostic for PFS in LR-MDS. Interestingly, bone marrow blast >1.5% could further predict disease progression of patients with LR-MDS (HR 8.06, 95%CI 2.95–22.04, p < 0.0001). Incorporation of JAK2, RUNX1 mutation and bone marrow blast in the IPSS-R can improve risk stratification in patients with LR-MDS. In summary, our result provided new risk factors for LR-MDS prognostics to identify candidates for early therapeutic intervention.

Prognostic effect of RUNX1 mutations in myelodysplastic syndromes: a meta-analysis

OBJECTIVES

RUNX1 mutations have been widely found in patients with myelodysplastic syndrome (MDS). Majority of reports revealed that RUNX1 mutations are associated with a poor prognosis. However, discrepancies still remain. The results of univariate analysis were not confirmed in multivariate analysis in some cases. Therefore, we performed a meta-analysis to assess the prognostic effect of RUNX1 mutations in MDS.

METHODS

We extracted data from qualified studies that were searched from PubMed, Embase and the Cochrane Library. Hazard ratios (HRs) and their 95% confidence intervals (CIs) for the overall survival (OS) and leukemia free survival (LFS) were pooled from the multivariate Cox proportional hazard models.

RESULTS

Sixteen studies containing 5422 patients were included in this meta-analysis. There were 617 patients with mutated RUNX1 and 4805 patients with wide type RUNX1. The total HR for OS was 1.43 (95% CI = 1.21-1.70, P < 0.0001) and the counterpart of LFS was 1.88 (95% CI = 1.42-2.51, P < 0.0001).

DISCUSSION AND CONCLUSION

These results suggest that the RUNX1 mutations are associated with unfavorable outcomes and shorter survival in patients with MDS. Furthermore, poor prognosis of patients might be alleviated by stem cell transplantation. Patients bearing these mutations should be prioritized for aggressive therapy.

Gene expression signatures associated with sensitivity to azacitidine in myelodysplastic syndromes

Allogeneic stem cell transplantation is currently the only curative treatment option for myelodysplastic syndromes (MDS). Pre-transplant debulking treatment have been employed for advanced MDS and we previously reported that marrow response (blast ≤ 5%) following the bridging therapy with hypomethylating agent was an independent favorable factor for survival; however, it is still not clear which patients will respond to hypomethylating agent and which genomic features can predict the response. In this study, we performed RNAseq for 23 MDS patients among which 14 (61%) and 9 (39%) patients showed marrow complete remission and primary resistance to azacitidine, respectively. Differential expression-based analyses of treatment-naive, baseline gene expression profiles revealed that molecular functions representing mitochondria and apoptosis were up-regulated in responders. In contrast, we identified genes involved in the Wnt pathway were relatively up-regulated in non-responders. In independent validation cohorts of MDS patients, the expression of gene sets specific to non-responders and responders distinguished the patients with favorable prognosis and those responded to azacitidine highlighting the prognostic and predictive implication. In addition, a systems biology approach identified genes involved in ubiquitination, such as UBC and PFDN2, which may be key players in the regulation of differential gene expression in treatment responders and non-responders. Taken together, identifying the gene expression signature may advance our understanding of the molecular mechanisms of azacitidine and may also serve to predict patient responses to drug treatment.

MCM8- and MCM9 Deficiencies Cause Lifelong Increased Hematopoietic DNA Damage Driving p53-Dependent Myeloid Tumors

Hematopoiesis is particularly sensitive to DNA damage. Myeloid tumor incidence increases in patients with DNA repair defects and after chemotherapy. It is not known why hematopoietic cells are highly vulnerable to DNA damage. Addressing this question is complicated by the paucity of mouse models of hematopoietic malignancies due to defective DNA repair. We show that DNA repair-deficient Mcm8- and Mcm9-knockout mice develop myeloid tumors, phenocopying prevalent myelodysplastic syndromes. We demonstrate that these tumors are preceded by a lifelong DNA damage burden in bone marrow and that they acquire proliferative capacity by suppressing signaling of the tumor suppressor and cell cycle controller RB, as often seen in patients. Finally, we found that absence of MCM9 and the tumor suppressor Tp53 switches tumorigenesis to lymphoid tumors without precedent myeloid malignancy. Our results demonstrate that MCM8/9 deficiency drives myeloid tumor development and establishes a DNA damage burdened mouse model for hematopoietic malignancies.

Contribution of Aberrant Toll Like Receptor Signaling to the Pathogenesis of Myelodysplastic Syndromes

Toll like receptors (TLRs) are a family of pattern recognition receptors that play a central role in the innate immune response. These receptors are expressed on a wide variety of immune and non-immune cells, and they help shape the immune response to infection and injury through the recognition of pathogen-associated molecular patterns (PAMPs) as well as endogenous damage-associated molecular patterns (DAMPs). Accumulating evidence suggests that, in addition to regulating mature effector immune cells, TLRs can influence the immune response from the level of the hematopoietic stem cell (HSC). HSCs express TLRs, and exposure to TLR ligands influences the cycling, differentiation, and function of HSCs, with chronic TLR stimulation leading to impairment of normal HSC repopulating activity. Moreover, enhanced TLR expression and signaling is associated with myelodysplastic syndromes (MDS), a heterogenous group of HSC disorders characterized by ineffective hematopoiesis and a high risk of transformation to acute leukemias. In this review, we will discuss the role of TLR signaling in the pathogenesis of MDS, focusing on the known direct and indirect effects of this type of signaling on HSCs, the mechanisms of TLR signaling upregulation in MDS, the changes in TLR expression with disease progression, and the therapeutic implications for modulating TLR signaling in the treatment of MDS.

Ribophorin II is upregulated in myelodysplastic syndromes and prevents apoptosis and cell cycle progression

IMPACT STATEMENT

This study explored the role of ribophorin II (RPN2) in myelodysplastic syndromes (MDSs) cell proliferation and growth and revealed that RPN2 knockdown suppressed OCI-AML3 cell growth and proliferation and triggered cell cycle arrest and elicited apoptosis in OCI-AML3 cells. In addition, it shed light on the etiology of RPN2's role in MDS cell proliferation that RPN2 can negatively impact enhancer of zeste homolog-2 (EZH2) expression, which in turn is able to modulate the cell cycle location and death in OCI-AML3 cells. Hence, RPN2 expression could be a latent predictor of prognosis in patients with MDS.

TP53 in Myelodysplastic Syndromes: Recent Biological and Clinical Findings

TP53 dysregulation plays a pivotal role in the molecular pathogenesis of myelodysplastic syndromes (MDS), identifying a subgroup of patients with peculiar features. In this review we report the recent biological and clinical findings of TP53-mutated MDS, focusing on the molecular pathways activation and on its impact on the cellular physiology. In MDS, TP53 mutational status is deeply associated with del(5q) syndrome and its dysregulation impacts on cell cycle, DNA repair and apoptosis inducing chromosomal instability and the clonal evolution of disease. TP53 defects influence adversely the MDS clinical outcome and the treatment response rate, thus new therapeutic approaches are being developed for these patients. TP53 allelic state characterization and the mutational burden evaluation can therefore predict prognosis and identify the subgroup of patients eligible for targeted therapy. For these reasons, in the era of precision medicine, the MDS diagnostic workup cannot do without the complete assessment of TP53 mutational profile.

Identification of a metabolic gene panel to predict the prognosis of myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is clonal disease featured by ineffective haematopoiesis and potential progression into acute myeloid leukaemia (AML). At present, the risk stratification and prognosis of MDS need to be further optimized. A prognostic model was constructed by the least absolute shrinkage and selection operator (LASSO) regression analysis for MDS patients based on the identified metabolic gene panel in training cohort, followed by external validation in an independent cohort. The patients with lower risk had better prognosis than patients with higher risk. The constructed model was verified as an independent prognostic factor for MDS patients with hazard ratios of 3.721 (1.814-7.630) and 2.047 (1.013-4.138) in the training cohort and validation cohort, respectively. The AUC of 3-year overall survival was 0.846 and 0.743 in the training cohort and validation cohort, respectively. The high-risk score was significantly related to other clinical prognostic characteristics, including higher bone marrow blast cells and lower absolute neutrophil count. Moreover, gene set enrichment analyses (GSEA) showed several significantly enriched pathways, with potential indication of the pathogenesis. In this study, we identified a novel stable metabolic panel, which might not only reveal the dysregulated metabolic microenvironment, but can be used to predict the prognosis of MDS.

Immune Dysregulation and Recurring Mutations in Myelodysplastic Syndromes Pathogenesis

Myelodysplastic syndromes (MDS) are clonal stem cell malignancies characterized by ineffective hematopoiesis leading to peripheral cytopenias and variable risk of progression to acute myeloid leukemia. Inflammation is associated with MDS pathogenesis. Several cytokines, reactive species of oxygen/nitrogen and growth factors are directly or indirectly involved in dysfunction of the MDS bone marrow (BM) microenvironment. Mutations in genes mainly regulating RNA splicing, DNA methylation and chromatin accessibility, transcription factors, signal transduction and the response to DNA damage contribute to ineffective hematopoiesis, genomic instability and MDS development. The inflammation-associated DNA damage in hematopoietic stem cells may also contribute to MDS development and progression with aggressive clinical characteristics. Many studies have aimed at clarifying mechanisms involved in the activity of immature myeloid cells as powerful modulators of the immune response and their correlation with aging, autoimmunity, and development of cancer. In this review, we explore recent advances and accumulating evidence uniting immune dysregulation, inflammaging and recurring mutations in the pathogenesis of MDS.

Mutation status and burden can improve prognostic prediction of patients with lower-risk myelodysplastic syndromes

Patients with lower‐risk myelodysplastic syndromes (LR‐MDS) as defined by the International Prognostic Scoring System (IPSS) have more favorable prognosis in general, but significant inter‐individual heterogeneity exists. In this study, we examined the molecular profile of 15 MDS‐relevant genes in 159 patients with LR‐MDS using next‐generation sequencing. In univariate COX regression, shorter overall survival (OS) was associated with mutation status of ASXL1 (P = .001), RUNX1 (P = .031), EZH2 (P = .049), TP53 (P = .016), SRSF2 (P = .046), JAK2 (P = .040), and IDH2 (P = .035). We also found significantly shorter OS in patients with an adjusted TET2 variant allele frequency (VAF) ≥18% versus those with either an adjusted TET2 VAF <18% or without TET2 mutations (median: 20.4 vs 47.8 months; P = .020; HR = 2.183, 95%CI: 1.129‐4.224). After adjustment for IPSS, shorter OS was associated with mutation status of ASXL1 (P < .001; HR = 4.306, 95% CI: 2.144‐8.650), TP53 (P = .004; HR = 4.863, 95% CI: 1.662‐14.230) and JAK2 (P = .002; HR = 5.466, 95%CI: 1.848‐16.169), as well as adjusted TET2 VAF ≥18% (P = .008; HR = 2.492, 95% CI: 1.273‐4.876). Also, OS was increasingly shorter as the number of mutational factors increased (P < .001). A novel prognostic scoring system incorporating the presence/absence of the four independent mutational factors into the IPSS further stratified LR‐MDS patients into three prognostically different groups (P < .001). The newly developed scoring system redefined 10.1% (16/159) of patients as a higher‐risk group, who could not be predicted by the currently prognostic models. In conclusion, integration of the IPSS with mutation status/burden of certain MDS‐relevant genes may improve the prognostication of patients with LR‐MDS and could help identify those with worse‐than‐expected prognosis for more aggressive treatment.

Downregulation of microRNA-144 inhibits proliferation and promotes the apoptosis of myelodysplastic syndrome cells through the activation of the AKAP12-dependent ERK1/2 signaling pathway

BACKGROUND

Myelodysplastic syndromes (MDS) represent a family of hematopoietic stem cell disorders characterized by ineffective hematopoiesis. While the functions of many microRNAs have been identified in MDS, microRNA-144 (miR-144) remains poorly understood. Thus, the aim of the present study was to determine the effects of miR-144 on cell proliferation and apoptosis in MDS cells and mechanism thereof.

METHODS

MDS-related microarrays were used for screening differentially expressed genes in MDS. The relationship between miR-144 and A-kinase anchoring protein 12 (AKAP12) was determined by a dual luciferase reporter gene assay. Subsequently, gain- and loss-function approaches were used to assess the effects of miR-144 and AKAP12 on cell proliferation, cell cycle and cell apoptosis by MTT assay and flow cytometry. Following the induction of a mouse model with MDS, the tumor tissues were extract for evaluation of apoptosis and the expression of miR-144, AKAP12, and the relevant genes associated with extracellular-regulated protein kinases 1/2 (ERK1/2) signaling pathway and apoptosis.

RESULTS

We observed significantly diminished expression of AKAP12 in MDS samples. miR-144 directly bound to AKAP12 3'UTR and reduced its expression in hematopoietic cells. Downregulation of miR-144 or upregulation of AKAP12 was observed to prolong cell cycle, inhibit cell proliferation, and induce apoptosis, accompanied by increased expression of AKAP12, p-ERK1/2, caspase-3, caspase-9, Bax, and p53, as well as decreased expression of Bcl-2. The transplanted tumors in mice with down-regulated miR-144 exhibited a lower mean tumor diameter and weight, and increased apoptosis index and expression of AKAP12 and ERK1/2.

CONCLUSION

Taken together, these studies demonstrate the stimulative role of miR-144 in MDS progression by regulating AKAP12-dependent ERK1/2 signaling pathway.

Nonclonal chromosomal alterations and poor survival in cytopenic patients without hematological malignancies

Background

Clonal chromosomal alterations (CCAs) reflect recurrent genetic changes derived from a single evolving clone, whereas nonclonal chromosomal alterations (NCCAs) comprise a single or nonrecurrent chromosomal abnormality. CCAs and NCCAs in hematopoietic cells have been partially investigated in cytopenic patients without hematological malignancies.

Methods

This single-center retrospective study included 253 consecutive patients who underwent bone marrow aspiration to determine the cause of cytopenia between 2012 and 2015. Patients with hematological malignancies were excluded. CCA was defined as a chromosomal aberration detected in more than two cells, and NCCA was defined as a chromosomal aberration detected in a single cell.

Results

The median age of the patients was 66 years. There were 135 patients without hematological malignancies (median age, 64 years; 69 females); of these, 27 patients (median age, 69 years; 8 females) harbored chromosomal abnormalities. CCAs were detected in 14 patients; the most common CCA was −Y in eight patients, followed by inv.(9) in three patients and mar1+, inv. (12), and t (19;21) in one patient each. NCCAs were detected in 13 patients; the most frequent NCCA was +Y in four patients, followed by del (20), + 8, inv. (2), − 8, and add (6) in one patient each. Moreover, nonclonal translocation abnormalities, including t (9;14), t (14;16), and t (13;21), were observed in three patients. One patient had a complex karyotype in a single cell. The remaining 106 patients with normal karyotypes comprised the control group (median age, 65 years; range, 1–92 years; 56 females). Further, follow-up analysis revealed that the overall survival of the NCCA group was worse than that of the CCA and the normal karyotype groups (P < 0.0001; log-rank test).

The survival of the NCCA-harboring cytopenic patients was worse than that of the CCA-harboring cytopenic patients without hematological malignancies, suggesting that follow-up should be considered for both CCA- and NCCA-harboring cytopenic patients.

Deficiency and haploinsufficiency of histone macroH2A1.1 in mice recapitulate hematopoietic defects of human myelodysplastic syndrome

Background

Epigenetic regulation is important in hematopoiesis, but the involvement of histone variants is poorly understood. Myelodysplastic syndromes (MDS) are heterogeneous clonal hematopoietic stem cell (HSC) disorders characterized by ineffective hematopoiesis. MacroH2A1.1 is a histone H2A variant that negatively correlates with the self-renewal capacity of embryonic, adult, and cancer stem cells. MacroH2A1.1 is a target of the frequent U2AF1 S34F mutation in MDS. The role of macroH2A1.1 in hematopoiesis is unclear.

Results

MacroH2A1.1 mRNA levels are significantly decreased in patients with low-risk MDS presenting with chromosomal 5q deletion and myeloid cytopenias and tend to be decreased in MDS patients carrying the U2AF1 S34F mutation. Using an innovative mouse allele lacking the macroH2A1.1 alternatively spliced exon, we investigated whether macroH2A1.1 regulates HSC homeostasis and differentiation. The lack of macroH2A1.1 decreased while macroH2A1.1 haploinsufficiency increased HSC frequency upon irradiation. Moreover, bone marrow transplantation experiments showed that both deficiency and haploinsufficiency of macroH2A1.1 resulted in enhanced HSC differentiation along the myeloid lineage. Finally, RNA-sequencing analysis implicated macroH2A1.1-mediated regulation of ribosomal gene expression in HSC homeostasis.

Conclusions

Together, our findings suggest a new epigenetic process contributing to hematopoiesis regulation. By combining clinical data with a discrete mutant mouse model and in vitro studies of human and mouse cells, we identify macroH2A1.1 as a key player in the cellular and molecular features of MDS. These data justify the exploration of macroH2A1.1 and associated proteins as therapeutic targets in hematological malignancies.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0724-z) contains supplementary material, which is available to authorized users.

Severely impaired terminal erythroid differentiation as an independent prognostic marker in myelodysplastic syndromes

Anemia is the defining feature in most patients with myelodysplastic syndromes (MDS), yet defects in erythropoiesis have not been well characterized. We examined freshly obtained bone marrow (BM) samples for stage-specific abnormalities during terminal erythroid differentiation (TED) from 221 samples (MDS, n = 205 from 113 unique patients; normal, n = 16) by measuring the surface expression of glycophorin A, band 3, and integrin α-4. Clinical and biologic associations were sought with presence or absence of TED and the specific stage of erythroid arrest. In 27% of MDS samples (56/205), there was no quantifiable TED documented by surface expression of integrin α-4 and band 3 by terminally differentiating erythroblasts. Absence of quantifiable TED was associated with a significantly worse overall survival (56 vs 103 months, P = .0001) and SRSF2 mutations (7/23, P < .05). In a multivariable Cox proportional hazards regression analysis, absence of TED remained independently significant across International Prognostic Scoring System-Revised (IPSS-R) categories, myeloid/erythroid ratio, and mutations in several genes. In 149/205 MDS samples, the proportion of cells undergoing TED did not follow the expected 1:2:4:8:16 doubling pattern in successive stages. Absence of TED emerged as a powerful independent prognostic marker of poor overall survival across all IPSS-R categories in MDS, and SRSF2 mutations were more frequently associated with absence of TED.

Genetic Variant Screening of DNA Repair Genes in Myelodysplastic Syndrome Identifies a Novel Mutation in the XRCC2 Gene

BACKGROUND

We aimed to detect single nucleotide polymorphisms (SNPs) and mutations in DNA repair genes and their possible association with myelodysplastic syndrome (MDS).

METHODS

Targeted enrichment resequencing of 84 DNA repair genes was initially performed on a screening cohort of MDS patients. Real-time polymerase chain reaction was used for genotyping selected SNPs in the validation cohort of patients.

RESULTS

A heterozygous frameshift mutation in the XRCC2 gene was identified. It leads to the formation of a truncated non-functional protein and decreased XRCC2 expression level. Decreased expression levels of all DNA repair genes functionally connected with mutated XRCC2 were also present. Moreover, a synonymous substitution in the PRKDC gene and 2 missense mutations in the SMUG1 and XRCC1 genes were also found. In the screening cohort, 6 candidate SNPs were associated with the tendency to develop MDS: rs4135113 (TDG, p = 0.03), rs12917 (MGMT, p = 0.003), rs2230641 (CCNH, p = 0.01), rs2228529 and rs2228526 (ERCC6, p = 0.04 and p = 0.03), and rs1799977 (MLH1, p = 0.04). In the validation cohort, only a polymorphism in MLH1 was significantly associated with development of MDS in patients with poor cytogenetics (p = 0.0004).

CONCLUSION

Our study demonstrates that genetic variants are present in DNA repair genes of MDS patients and may be associated with susceptibility to MDS.

MBD3/NuRD loss participates with KDM6A program to promote DOCK5/8 expression and Rac GTPase activation in human acute myeloid leukemia

Cancer genome sequencing studies have focused on identifying oncogenic mutations. However, mutational profiling alone may not always help dissect underlying epigenetic dependencies in tumorigenesis. Nucleosome remodeling and deacetylase (NuRD) is an ATP-dependent chromatin remodeling complex that regulates transcriptional architecture and is involved in cell fate commitment. We demonstrate that loss of MBD3, an important NuRD scaffold, in human primary acute myeloid leukemia (AML) cells associates with leukemic NuRD. Interestingly, CHD4, an intact ATPase subunit of leukemic NuRD, coimmunoprecipitates and participates with H3K27Me3/2-demethylase KDM6A to induce expression of atypical guanine nucleotide exchange factors, dedicator of cytokinesis (DOCK) 5 and 8 (DOCK5/8), promoting Rac GTPase signaling. Mechanistically, MBD3 deficiency caused loss of histone deacytelase 1 occupancy with a corresponding increase in KDM6A, CBP, and H3K27Ac on DOCK5/8 loci, leading to derepression of gene expression. Importantly, the Cancer Genome Atlas AML cohort reveals that DOCK5/ 8 levels are correlated with MBD3 and KDM6A, and DOCK5/ 8 expression is significantly increased in patients who are MBD3 low and KDM6A high with a poor survival. In addition, pharmacological inhibition of DOCK signaling selectively attenuates AML cell survival. Because MBD3 and KDM6A have been implicated in metastasis, our results may suggest a general phenomenon in tumorigenesis. Collectively, these findings provide evidence for MBD3-deficient NuRD in leukemia pathobiology and inform a novel epistasis between NuRD and KDM6A toward maintenance of oncogenic gene expression in AML.-Biswas, M., Chatterjee, S. S., Boila, L. D., Chakraborty, S., Banerjee, D., Sengupta, A. MBD3/NuRD loss participates with KDM6A program to promote DOCK5/8 expression and Rac GTPase activation in human acute myeloid leukemia.

ASXL1 and SETBP1 mutations promote leukaemogenesis by repressing TGFβ pathway genes through histone deacetylation

Mutations in ASXL1 and SETBP1 genes have been frequently detected and often coexist in myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). We previously showed that coexpression of mutant ASXL1 and SETBP1 in hematopoietic progenitor cells induced downregulation of TGFβ pathway genes and promoted the development of MDS/AML in a mouse model of bone marrow transplantation. However, whether the repression of TGFβ pathway in fact contributes to leukaemogenesis remains unclear. Moreover, mechanisms for the repression of TGFβ pathway genes in ASXL1/SETBP1-mutated MDS/AML cells have not been fully understood. In this study, we showed that expression of a constitutively active TGFβ type I receptor (ALK5-TD) inhibited leukaemic proliferation of MDS/AML cells expressing mutant ASXL1/SETBP1. We also found aberrantly reduced acetylation of several lysine residues on histone H3 and H4 around the promoter regions of multiple TGFβ pathway genes. The histone deacetylase (HDAC) inhibitor vorinostat reversed histone acetylation at these promoter regions, and induced transcriptional derepression of the TGFβ pathway genes. Furthermore, vorinostat showed robust growth-inhibitory effect in cells expressing mutant ASXL1, whereas it showed only a marginal effect in normal bone marrow cells. These data indicate that HDAC inhibitors will be promising therapeutic drugs for MDS and AML with ASXL1 and SETBP1 mutations.

Bcor insufficiency promotes initiation and progression of myelodysplastic syndrome

BCOR, encoding BCL-6 corepressor (BCOR), is X-linked and targeted by somatic mutations in various hematological malignancies including myelodysplastic syndrome (MDS). We previously reported that mice lacking Bcor exon 4 (Bcor ^ΔE4/y ) in the hematopoietic compartment developed NOTCH-dependent acute T-cell lymphoblastic leukemia (T-ALL). Here, we analyzed mice lacking Bcor exons 9 and 10 (Bcor ^ΔE9-10/y ), which express a carboxyl-terminal truncated BCOR that fails to interact with core effector components of polycomb repressive complex 1.1. Bcor ^ΔE9-10/y mice developed lethal T-ALL in a similar manner to Bcor ^ΔE4/y mice, whereas Bcor ^ΔE9-10/y hematopoietic cells showed a growth advantage in the myeloid compartment that was further enhanced by the concurrent deletion of Tet2 Tet2 ^Δ/Δ Bcor ^ΔE9-10/y mice developed lethal MDS with progressive anemia and leukocytopenia, inefficient hematopoiesis, and the morphological dysplasia of blood cells. Tet2 ^Δ/Δ Bcor ^ΔE9-10/y MDS cells reproduced MDS or evolved into lethal MDS/myeloproliferative neoplasms in secondary recipients. Transcriptional profiling revealed the derepression of myeloid regulator genes of the Cebp family and Hoxa cluster genes in Bcor ^ΔE9-10/y progenitor cells and the activation of p53 target genes specifically in MDS erythroblasts where massive apoptosis occurred. Our results reveal a tumor suppressor function of BCOR in myeloid malignancies and highlight the impact of Bcor insufficiency on the initiation and progression of MDS.

Evaluation of bone marrow microenvironment could change how myelodysplastic syndromes are diagnosed and treated

Myelodysplastic syndromes are a heterogeneous group of clonal hematopoietic disorders. However, the therapies used against the hematopoietic stem cells clones have limited efficacy; they slow the evolution toward acute myeloid leukemia rather than stop clonal evolution and eradicate the disease. The progress made in recent years regarding the role of the bone marrow microenvironment in disease evolution may contribute to progress in this area. This review presents the recent updates on the role of the bone marrow microenvironment in myelodysplastic syndromes pathogenesis and tries to find answers regarding how this information could improve myelodysplastic syndromes diagnosis and therapy.

Pathobiological Pseudohypoxia as a Putative Mechanism Underlying Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are heterogeneous hematopoietic disorders that are incurable with conventional therapy. Their incidence is increasing with global population aging. Although many genetic, epigenetic, splicing, and metabolic aberrations have been identified in patients with MDS, their clinical features are quite similar. Here, we show that hypoxia-independent activation of hypoxia-inducible factor 1α (HIF1A) signaling is both necessary and sufficient to induce dysplastic and cytopenic MDS phenotypes. The HIF1A transcriptional signature is generally activated in MDS patient bone marrow stem/progenitors. Major MDS-associated mutations (Dnmt3a, Tet2, Asxl1, Runx1, and Mll1) activate the HIF1A signature. Although inducible activation of HIF1A signaling in hematopoietic cells is sufficient to induce MDS phenotypes, both genetic and chemical inhibition of HIF1A signaling rescues MDS phenotypes in a mouse model of MDS. These findings reveal HIF1A as a central pathobiologic mediator of MDS and as an effective therapeutic target for a broad spectrum of patients with MDS.Significance: We showed that dysregulation of HIF1A signaling could generate the clinically relevant diversity of MDS phenotypes by functioning as a signaling funnel for MDS driver mutations. This could resolve the disconnection between genotypes and phenotypes and provide a new clue as to how a variety of driver mutations cause common MDS phenotypes. Cancer Discov; 8(11); 1438-57. ©2018 AACR. See related commentary by Chen and Steidl, p. 1355 This article is highlighted in the In This Issue feature, p. 1333.

miR-143/145 differentially regulate hematopoietic stem and progenitor activity through suppression of canonical TGFβ signaling

Expression of miR-143 and miR-145 is reduced in hematopoietic stem/progenitor cells (HSPCs) of myelodysplastic syndrome patients with a deletion in the long arm of chromosome 5. Here we show that mice lacking miR-143/145 have impaired HSPC activity with depletion of functional hematopoietic stem cells (HSCs), but activation of progenitor cells (HPCs). We identify components of the transforming growth factor β (TGFβ) pathway as key targets of miR-143/145. Enforced expression of the TGFβ adaptor protein and miR-145 target, Disabled-2 (DAB2), recapitulates the HSC defect seen in miR-143/145-/- mice. Despite reduced HSC activity, older miR-143/145-/- and DAB2-expressing mice show elevated leukocyte counts associated with increased HPC activity. A subset of mice develop a serially transplantable myeloid malignancy, associated with expansion of HPC. Thus, miR-143/145 play a cell context-dependent role in HSPC function through regulation of TGFβ/DAB2 activation, and loss of these miRNAs creates a preleukemic state.

Prognostic significance of SRSF2 mutations in myelodysplastic syndromes and chronic myelomonocytic leukemia: a meta-analysis

OBJECTIVE

Serine/arginine-rich splicing factor 2 (SRSF2) mutations were detected frequently in myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) patients. However, its prognostic value has not yet been fully clarified.

METHODS

In this meta-analysis, Hazard Ratio (HR) and 95% confidence interval (CI) for overall-survival (OS) were chosen to evaluate the prognostic impact of SRSF2 mutations and to compare SRSF2 mutations to those with wild-type.

RESULTS

A total of 2056 patients from 12 studies were obtained. The pooled HRs for OSsuggested that patients with MDS had a poorer prognosis (HR = 1.780, 95% CI (1.410-2.249)), while analysis on SRSF2 mutations revealed no significant effect on the prognosis of CMML patients (HR = 1.091, 95% CI (0.925-1.286)). The frequency of SRSF2 mutations was found to be 11.5% and 39.8% in patients with MDS and CMML, respectively.

DISCUSSION

This meta-analysis suggests that SRSF2 has a poor prognosis in patients with MDS, but no prognosis impact on patients with CMML.

CONCLUSION

In conclusion, SRSF2 mutations were significantly related to the shorter OS in patients with MDS which may consider as an adverse prognostic risk factor. Whereas, analysis did not show any prognostic effect on OS of CMML patients with SRSF2 mutations.

Different effects of granulocyte colony-stimulating factor and erythropoietin on erythropoiesis

Background

Red blood cells are the most abundant cells in the blood that deliver oxygen to the whole body. Erythropoietin (EPO), a positive regulator of erythropoiesis, is currently the major treatment for chronic anemia. Granulocyte colony-stimulating factor (G-CSF) is a multifunctional cytokine and a well-known regulator of hematopoietic stem cell proliferation, differentiation, and mobilization. The use of EPO in combination with G-CSF has been reported to synergistically improve erythroid responses in a group of patients with myelodysplastic syndromes who did not respond to EPO treatment alone; however, the mechanism remains unclear.

Methods

C57BL/6 J mice injected with G-CSF or EPO were used to compare the erythropoiesis status and the efficiency of erythroid mobilization by flow cytometry.

Results

In this study, we found that G-CSF induced more orthochromatophilic erythroblast production than did EPO in the bone marrow and spleen. In addition, in contrast to EPO treatments, G-CSF treatments enhanced the efficiency of the mobilization of newly synthesized reticulocytes into peripheral blood. Our results demonstrated that the effects of G-CSF on erythropoiesis and erythrocytic mobilization were independent of EPO secretion and, in contrast to EPO, G-CSF promoted progression of erythropoiesis through transition of early stage R2 (basophilic erythroblasts) to late stage R4 (orthochromatophilic erythroblasts).

Conclusions

We demonstrate for the first time that G-CSF treatments induce a faster erythropoiesis-enhancing response than that of EPO. These findings suggest an alternative approach to treating acute anemia, especially when patients are experiencing a clinical emergency in remote areas without proper blood bank supplies.

Impact of mutational studies on the diagnosis and the outcome of high-risk myelodysplastic syndromes and secondary acute myeloid leukemia patients treated with 5-azacytidine

Myelodysplastic syndromes (MDS) are stem cell disorders caused by various gene abnormalities. We performed targeted deep sequencing in 39 patients with high-risk MDS and secondary acute myeloid leukemia (sAML) at diagnosis and follow-up (response and/or relapse), with the aim to define their mutational status, to establish if specific mutations are biomarkers of response to 5-azacytidine (AZA) and/or may have impact on survival. Overall, 95% of patients harbored at least one mutation. TP53, DNMT3A and SRSF2 were the most frequently altered genes. Mutations in TP53 correlated with higher risk features and shorter overall survival (OS) and progression free survival (PFS) in univariate analysis. Patients with SRSF2 mutations were associated with better OS and PFS. Response rate was 55%; but we could not correlate the presence of TET2 and TP53 mutations with AZA response. Patients with sAML presented more variations than patients with high-risk MDS, and usually at relapse the number of mutations increased, supporting the idea that in advanced stages of the disease there is a greater genomic complexity. These results confirm that mutation analysis can add prognostic value to high-risk MDS and sAML patients, not only at diagnosis but also at follow-up.

Incorporation of mutations in five genes in the revised International Prognostic Scoring System can improve risk stratification in the patients with myelodysplastic syndrome

Gene mutations have not yet been included in the 2016 WHO classification and revised International Prognostic Scoring System (IPSS-R), which are now widely utilized to discriminate myelodysplastic syndrome (MDS) patients regarding risk of leukemia evolution and overall survival (OS). In this study, we aimed to investigate whether integration of gene mutations with other risk factors could further improve the stratification of MDS patients. Mutational analyses of 25 genes relevant to myeloid malignancies in 426 primary MDS patients showed that mutations of CBL, IDH2, ASXL1, DNMT3A, and TP53 were independently associated with shorter survival. Patients within each IPSS-R or 2016 WHO classification-defined risk group could be stratified into two risk subgroups based on the mutational status of these five genes; patients with these poor-risk mutations had an OS shorter than others in the same risk group, but similar to those with the next higher risk category. A scoring system incorporating age, IPSS-R and five poor-risk mutations could divide the MDS patients into four risk groups (P < 0.001 for both OS and leukemia-free survival). In conclusion, integration of gene mutations in current IPSS-R improves the prognostication of MDS patients and may help identify high-risk patients for more aggressive treatment in IPSS-R lower risk group.

Somatic mutations predict outcomes of hypomethylating therapy in patients with myelodysplastic syndrome

Although hypomethylating therapy (HMT) is the first line therapy in higher-risk myelodysplastic syndromes (MDS), predicting response to HMT remains an unresolved issue. We aimed to identify mutations associated with response to HMT and survival in MDS. A total of 107 Korean patients with MDS who underwent HMT (57 responders and 50 non-responders) were enrolled. Targeted deep sequencing (median depth of coverage 1,623X) was performed for 26 candidate MDS genes. In multivariate analysis, no mutation was significantly associated with response to HMT, but a lower hemoglobin level (<10g/dL, OR 3.56, 95% CI 1.22-10.33) and low platelet count (<50,000/μL, OR 2.49, 95% CI 1.05-5.93) were independent markers of poor response to HMT. In the subgroup analysis by type of HMT agents, U2AF1 mutation was significantly associated with non-response to azacitidine, which was consistent in multivariate analysis (OR 14.96, 95% CI 1.67-134.18). Regarding overall survival, mutations in DNMT1 (P=0.031), DNMT3A (P=0.006), RAS (P=0.043), and TP53 (P=0.008), and two clinical variables (male-gender, P=0.002; IPSS-R H/VH, P=0.026) were independent predicting factors of poor prognosis. For AML-free survival, mutations in DNMT3A (P<0.001), RAS (P=0.001), and TP53 (P=0.047), and two clinical variables (male-gender, P=0.024; IPSS-R H/VH, P=0.005) were independent predicting factors of poor prognosis. By combining these mutations and clinical predictors, we developed a quantitative scoring model for response to azacitidine, overall- and AML-free survival. Response to azacitidine and survival rates became worse significantly with increasing risk-scores. This scoring model can make prognosis prediction more reliable and clinically applicable.

CD41 immune staining of micromegakaryocytes improves the diagnosis of myelodysplastic syndrome and differentiation from pancytopenia

A morphometric analysis was performed on aspirated clots of bone marrow to identify the presence of micromegakaryocytes after immune staining with a monoclonal antibody raised against CD41. Quantitative and qualitative abnormalities of micromegakaryocytes were assessed based on both standard staining and CD41 immune staining. Micromegakaryocytes were largely detected in bone marrow from patients with myelodysplastic syndrome (MDS), while almost no micromegakaryocytes were present in aplastic anemia. CD41 immune staining clearly improved the efficiency of micromegakaryocyte detection under any conditions, showing strong potential as a tool for the auxiliary diagnosis of MDS and differentiation of MDS from pancytopenia, particularly aplastic anemia(AA).

The Wilms' tumor gene-1 is a prognostic factor in myelodysplastic syndrome: a meta analysis

Previous studies have suggested that Wilms’ tumor gene-1 (WT1) may be related to a decrease in both relapse-free survival (RFS) and overall survival (OS) for patients with myelodysplastic syndrome (MDS). Therefore, we conducted a meta-analysis on the utility of WT1 as a prognostic indicator of MDS. Published reports were searched in the following databases: Cochrane Library, PubMed, Embase, and Web of Science. The meta-analysis was conducted using the Cochrane Collaboration RevMan 5.2 software. Six publications with 450 total patients met the inclusion criteria and were subjected to further examination. The results showed a reduction in both overall survival (OS) and leukemia-free survival (LFS) with increasing WT1 expression levels: 1-year OS (odds ratio, OR = 0.16; 95% CI = 0.08–0.34, P < 0.001), 3-year OS (OR = 0.21; 95% CI = 0.09–0.47, P < 0.001), 5-year OS (OR = 0.24; 95% CI = 0.06–0.92, P = 0.04), 1-year LFS (OR = 0.06; 95% CI = 0.02–0.18; P < 0.001), 3-year LFS (OR = 0.20; 95% CI = 0.09–0.46; P < 0.001), and 5-year LFS (OR = 0.12; 95% CI = 0.04–0.38; P < 0.001). In terms of patients receiving hematopoietic stem cell transplantation, the cumulative incidence of relapse (CIR) was higher in the WT1 over-expression group than in the low-expression group: 1-year CIR (OR = 13.69; 95% CI = 2.99–62.62; P < 0.001), 3-year CIR (OR = 6.52; 95% CI = 2.31–18.40, P < 0.001). In conclusion, WT1 over-expression is a prognostic factor for MDS.

A Polycythemia Vera JAK2 Mutation Masquerading as a Duodenal Cancer Mutation

Next-generation sequencing (NGS) is increasingly being used in cancer care to identify both somatic tumor driver mutations that can be targeted for therapy, and heritable mutations in the germline associated with increased cancer risk. This report presents a case of a JAK2 V617F mutation falsely identified as a duodenal cancer mutation via NGS. The patient was found to have a history of polycythemia vera, a disorder with a high incidence of JAK2 somatic mutations. Buccal cell DNA showed heterozygosity for the mutation, suggesting that it was potentially germline. However, subsequent resequencing of tumor, adjacent normal tissue, and fingernail DNA confirmed the mutation was somatic, and its presence in tumor and buccal cells resulted from contaminating blood cells. This report highlights important nuances of NGS that can lead to misinterpretation of results with potential clinical implications.