Myelodysplastic syndromes: the complexity of stem-cell diseases

Progress in the study of autophagy-related proteins affecting resistance to chemotherapeutic drugs in leukemia

Leukemia is a life-threatening malignant tumor of the hematopoietic system. Currently, the main treatment modalities are chemotherapy and hematopoietic stem cell transplantation. However, increased drug resistance due to decreased sensitivity of leukemia cells to chemotherapeutic drugs presents a major challenge in current treatments. Autophagy-associated proteins involved in autophagy initiation have now been shown to be involved in the development of various types of leukemia cells and are associated with drug resistance. Therefore, this review will explore the roles of autophagy-related proteins involved in four key autophagic processes: induction of autophagy and phagophore formation, phagophore extension, and autophagosome formation, on the development of various types of leukemias as well as drug resistance. Autophagy may become a promising therapeutic target for treating leukemia.

PARP inhibition leads to synthetic lethality with key splicing-factor mutations in myelodysplastic syndromes

BACKGROUND

Splicing factors are frequently mutated in patients with myelodysplastic syndromes and acute myeloid leukaemia. Recent studies have revealed convergent molecular defects caused by splicing factor mutations, among which R-loop dysregulation and resultant genome instability are suggested as contributing factors to disease progression. On the other hand, understanding how mutant cells survive upon aberrant R-loop formation and genome instability is essential for developing novel therapeutics.

METHODS

The immunoprecipitation was performed to identify R-loops in association with PARP1/poly-ADP-ribosylation. The western blot, immunofluorescence, and flow cytometry assays were used to test the cell viability, cell cycle arrest, apoptosis, and ATM activation in mutant cells following the treatment of the PARP inhibitor. The Srsf2(P95H) knock-in murine hematopoietic cells and MLL-AF9 transformed leukaemia model were generated to investigate the potential of the PARP inhibitor as a therapy for haematological malignancies.

RESULTS

The disease-causing mutations in SRSF2 activate PARP and elevate the overall poly-ADP-ribosylation levels of proteins in response to R-loop dysregulation. In accordance, mutant cells are more vulnerable to the PARP inhibitors in comparison to the wild-type counterpart. Notably, the synthetic lethality was further validated in the Srsf2(P95H) knock-in murine hematopoietic cell and MLL-AF9 leukaemia model.

CONCLUSIONS

Our findings suggest that mutant cells antagonise the genome threat caused by R-loop disruption by PARP activation, thus making PARP targeting a promising therapeutic strategy for myeloid cancers with mutations in SRSF2.

Ferritin-mediated mitochondrial iron homeostasis is essential for the survival of hematopoietic stem cells and leukemic stem cells

Iron metabolism plays a crucial role in cell viability, but its relationship with adult stem cells and cancer stem cells is not fully understood. The ferritin complex, responsible for intracellular iron storage, is important in this process. We report that conditional deletion of ferritin heavy chain 1 (Fth1) in the hematopoietic system reduced the number and repopulation capacity of hematopoietic stem cells (HSCs). These effects were associated with a decrease in cellular iron level, leading to impaired mitochondrial function and the initiation of apoptosis. Iron supplementation, antioxidant, and apoptosis inhibitors reversed the reduced cell viability of Fth1-deleted hematopoietic stem and progenitor cells (HSPCs). Importantly, leukemic stem cells (LSCs) derived from MLL-AF9-induced acute myeloid leukemia (AML) mice exhibited reduced Fth1 expression, rendering them more susceptible to apoptosis induced by the iron chelation compared to normal HSPCs. Modulating FTH1 expression using mono-methyl fumarate increased LSCs resistance to iron chelator-induced apoptosis. Additionally, iron supplementation, antioxidant, and apoptosis inhibitors protected LSCs from iron chelator-induced cell death. Fth1 deletion also extended the survival of AML mice. These findings unveil a novel mechanism by which ferritin-mediated iron homeostasis regulates the survival of both HSCs and LSCs, suggesting potential therapeutic strategies for blood cancer with iron dysregulation.

High PD-L1 expression is associated with unfavorable clinical features in myelodysplastic neoplasms

INTRODUCTION

Immune checkpoints are regulators of the immune system response that allow self-tolerance. Molecules such as Programmed Cell Death Protein 1 (PD-1) and its Ligand (PD-L1) participate in the immune checkpoint by signaling co-inhibition of lymphocyte responses. In cancers, PD-L1 expression is associated with the immune evasion mechanism, which favors tumor growth. The use of anti-PD-1/PD-L1 drugs is already well described in solid tumors, but still not fully understood in hematologic malignancies. Myelodysplastic neoplasms (MDSs) are heterogeneous bone marrow disorders with an increased risk of progression to Acute Myeloid Leukemia (AML). The MDS affects hematopoietic stem cells and its pathogenesis is linked to genetic and epigenetic defects, in addition to immune dysregulation. The influence of the PD-L1 on the MDS remains unknown.

METHODS

In this study, we evaluated the mRNA expression of the PD-L1 in 53 patients with MDS, classified according to the WHO 2016 Classification.

RESULTS

Patients with dyserythropoiesis presented significantly higher PD-L1 expression than patients without dyserythropoiesis (p= 0.050). Patients classified as having MDS with an excess of blasts 2 (MDS-EB2) presented a significant upregulation in the mRNA expression of the PD-L1 compared to the MDS with an excess of blasts 1 (MDS-EB1) (p= 0.050). Furthermore, we detected three patients with very high levels of PD-L1 expression, being statistically classified as outliers.

CONCLUSION

We suggested that the high expression of the PD-L1 is associated with a worse prognosis in the MDS and functional studies are necessary to evaluate the possible use of anti-PD-L1 therapies for high-risk MDS, such as the MDS-EBs.

Random walk with restart on multilayer networks: from node prioritisation to supervised link prediction and beyond

BACKGROUND

Biological networks have proven invaluable ability for representing biological knowledge. Multilayer networks, which gather different types of nodes and edges in multiplex, heterogeneous and bipartite networks, provide a natural way to integrate diverse and multi-scale data sources into a common framework. Recently, we developed MultiXrank, a Random Walk with Restart algorithm able to explore such multilayer networks. MultiXrank outputs scores reflecting the proximity between an initial set of seed node(s) and all the other nodes in the multilayer network. We illustrate here the versatility of bioinformatics tasks that can be performed using MultiXrank.

RESULTS

We first show that MultiXrank can be used to prioritise genes and drugs of interest by exploring multilayer networks containing interactions between genes, drugs, and diseases. In a second study, we illustrate how MultiXrank scores can also be used in a supervised strategy to train a binary classifier to predict gene-disease associations. The classifier performance are validated using outdated and novel gene-disease association for training and evaluation, respectively. Finally, we show that MultiXrank scores can be used to compute diffusion profiles and use them as disease signatures. We computed the diffusion profiles of more than 100 immune diseases using a multilayer network that includes cell-type specific genomic information. The clustering of the immune disease diffusion profiles reveals shared shared phenotypic characteristics.

CONCLUSION

Overall, we illustrate here diverse applications of MultiXrank to showcase its versatility. We expect that this can lead to further and broader bioinformatics applications.

CAR virus receptor mediates erythroid differentiation and migration and is downregulated in MDS

Myelodysplastic syndromes (MDS) are myeloid neoplasms presenting with dysplasia in the bone marrow (BM) and peripheral cytopenia. In most patients anemia develops. We screened for genes that are expressed abnormally in erythroid progenitor cells (EP) and contribute to the pathogenesis of MDS. We found that the Coxsackie-Adenovirus receptor (CAR = CXADR) is markedly downregulated in CD45low/CD105+ EP in MDS patients compared to control EP. Correspondingly, the erythroblast cell lines HEL, K562, and KU812 stained negative for CAR. Lentiviral transduction of the full-length CXADR gene into these cells resulted in an increased expression of early erythroid antigens, including CD36, CD71, and glycophorin A. In addition, CXADR-transduction resulted in an increased migration against a serum protein gradient, whereas truncated CXADR variants did not induce expression of erythroid antigens or migration. Furthermore, conditional knock-out of Cxadr in C57BL/6 mice resulted in anemia and erythroid dysplasia. Finally, decreased CAR expression on EP was found to correlate with high-risk MDS and decreased survival. Together, CAR is a functionally relevant marker that is down-regulated on EP in MDS and is of prognostic significance. Decreased CAR expression may contribute to the maturation defect and altered migration of EP and thus their pathologic accumulation in the BM in MDS.

Computational analysis of peripheral blood smears detects disease-associated cytomorphologies

Many hematological diseases are characterized by altered abundance and morphology of blood cells and their progenitors. Myelodysplastic syndromes (MDS), for example, are a group of blood cancers characterised by cytopenias, dysplasia of hematopoietic cells and blast expansion. Examination of peripheral blood slides (PBS) in MDS often reveals changes such as abnormal granulocyte lobulation or granularity and altered red blood cell (RBC) morphology; however, some of these features are shared with conditions such as haematinic deficiency anemias. Definitive diagnosis of MDS requires expert cytomorphology analysis of bone marrow smears and complementary information such as blood counts, karyotype and molecular genetics testing. Here, we present Haemorasis, a computational method that detects and characterizes white blood cells (WBC) and RBC in PBS. Applied to over 300 individuals with different conditions (SF3B1-mutant and SF3B1-wildtype MDS, megaloblastic anemia, and iron deficiency anemia), Haemorasis detected over half a million WBC and millions of RBC and characterized their morphology. These large sets of cell morphologies can be used in diagnosis and disease subtyping, while identifying novel associations between computational morphotypes and disease. We find that hypolobulated neutrophils and large RBC are characteristic of SF3B1-mutant MDS. Additionally, while prevalent in both iron deficiency and megaloblastic anemia, hyperlobulated neutrophils are larger in the latter. By integrating cytomorphological features using machine learning, Haemorasis was able to distinguish SF3B1-mutant MDS from other MDS using cytomorphology and blood counts alone, with high predictive performance. We validate our findings externally, showing that they generalize to other centers and scanners. Collectively, our work reveals the potential for the large-scale incorporation of automated cytomorphology into routine diagnostic workflows.

Ribosomal protein control of hematopoietic stem cell transformation through direct, non-canonical regulation of metabolism

We report here that expression of the ribosomal protein, RPL22, is frequently reduced in human myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML); reduced RPL22 expression is associated with worse outcomes. Mice null for Rpl22 display characteristics of an MDS-like syndrome and develop leukemia at an accelerated rate. Rpl22-deficient mice also display enhanced hematopoietic stem cell (HSC) self-renewal and obstructed differentiation potential, which arises not from reduced protein synthesis but from increased expression of the Rpl22 target, ALOX12, an upstream regulator of fatty acid oxidation (FAO). The increased FAO mediated by Rpl22-deficiency also persists in leukemia cells and promotes their survival. Altogether, these findings reveal that Rpl22 insufficiency enhances the leukemia potential of HSC via non-canonical de-repression of its target, ALOX12, which enhances FAO, a process that may serve as a therapeutic vulnerability of Rpl22 low MDS and AML leukemia cells.

Highlights

RPL22 insufficiency is observed in MDS/AML and is associated with reduced survivalRpl22-deficiency produces an MDS-like syndrome and facilitates leukemogenesisRpl22-deficiency does not impair global protein synthesis by HSCRpl22 controls leukemia cell survival by non-canonical regulation of lipid oxidation eTOC: Rpl22 controls the function and transformation potential of hematopoietic stem cells through effects on ALOX12 expression, a regulator of fatty acid oxidation.

Role of Bcl-2 inhibition in myelodysplastic syndromes

Myelodysplasic syndromes (MDS) are diseases occurring mainly in the elderly population. Although hematopoietic stem cell transplantation is the only hope for cure, a majority of the patients suffering from MDS are too old or frail for intensive treatment regimens such as intensive chemotherapy and transplantation. The gold standard for those patients is currently treatment with hypomethylating agents, although real-life data could not reproduce the overall survival rates reported for the pivotal azacitidine phase III study. MDS treatment is often inspired by treatment for acute myeloid leukemia (AML). The new gold standard for elderly and frail patients not able to undergo intensive treatment regimens in AML is the combination of hypomethylating agents with venetoclax, a BCL-2 inhibitor that also showed excellent treatment outcomes in other hematological malignancies. In this review, we explain the rationale for the use of venetoclax in hematological malignancies, study outcomes available so far and the current knowledge of its use in MDS.

The Role of NLRP3, a Star of Excellence in Myeloproliferative Neoplasms

Nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) is the most widely investigated inflammasome member whose overactivation can be a driver of several carcinomas. It is activated in response to different signals and plays an important role in metabolic disorders and inflammatory and autoimmune diseases. NLRP3 belongs to the pattern recognition receptors (PRRs) family, expressed in numerous immune cells, and it plays its primary function in myeloid cells. NLRP3 has a crucial role in myeloproliferative neoplasms (MPNs), considered to be the diseases best studied in the inflammasome context. The investigation of the NLRP3 inflammasome complex is a new horizon to explore, and inhibiting IL-1β or NLRP3 could be a helpful cancer-related therapeutic strategy to improve the existing protocols.

Therapeutic approaches for the management of higher risk myelodysplastic syndromes

The heterogeneous nature of myelodysplastic syndromes (MDS) demands a risk-adapted therapeutic approach, and higher risk MDS, characterized by an increased risk of transformation into acute myeloid leukemia and inferior survival, is typically defined based on an integrated assessment of cytopenias, bone marrow blast percentage, and cytogenetic findings using the revised International Prognostic Scoring System. Incorporating mutational data could further refine the risk assessment and identify those with higher-than-expected disease risk. The principal therapeutic goal in this disease subset is to modify the natural history and prolong survival. Allogeneic stem cell transplant, the only potentially curative treatment, should be offered to eligible patients. Hypomethylating agents are the only approved treatment with unsatisfactory response rates and duration, and patients who failed prior hypomethylating agents unfortunately have dismal outcomes with urgent need of novel therapeutic agents. In this review, we provide the therapeutic landscape in higher risk MDS based on the current evidence and discuss the investigational treatment options under development.

A Killer Disarmed: Natural Killer Cell Impairment in Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) treatment remains a big challenge due to the heterogeneous nature of the disease and its ability to progress to acute myeloid leukemia (AML). The only curative option is allogeneic hematopoietic stem cell transplantation (HSCT), but most patients are unfit for this procedure and are left with only palliative treatment options, causing a big unmet need in the context of this disease. Natural killer (NK) cells are attractive candidates for MDS immunotherapy due to their ability to target myeloid leukemic cells without prior sensitization, and in recent years we have seen an arising number of clinical trials in AML and, recently, MDS. NK cells are reported to be highly dysfunctional in MDS patients, which can be overcome by adoptive NK cell immunotherapy or activation of endogenous NK cells. Here, we review the role of NK cells in MDS, the contribution of the tumor microenvironment (TME) to NK cell impairment, and the most recent data from NK cell-based clinical trials in MDS.

Distinct Patterns of Clonal Evolution Drive Myelodysplastic Syndrome Progression to Secondary Acute Myeloid Leukemia

Clonal evolution in myelodysplastic syndrome (MDS) can result in clinical progression and secondary acute myeloid leukemia (sAML). To dissect changes in clonal architecture associated with this progression, we performed single-cell genotyping of paired MDS and sAML samples from 18 patients. Analysis of single-cell genotypes revealed patient-specific clonal evolution and enabled the assessment of single-cell mutational cooccurrence. We discovered that changes in clonal architecture proceed via distinct patterns, classified as static or dynamic, with dynamic clonal architectures having a more proliferative phenotype by blast count fold change. Proteogenomic analysis of a subset of patients confirmed that pathogenic mutations were primarily confined to primitive and mature myeloid cells, though we also identify rare but present mutations in lymphocyte subsets. Single-cell transcriptomic analysis of paired sample sets further identified gene sets and signaling pathways involved in two cases of progression. Together, these data define serial changes in the MDS clonal landscape with clinical and therapeutic implications.

SIGNIFICANCE

Precise clonal trajectories in MDS progression are made possible by single-cell genomic sequencing. Here we use this technology to uncover the patterns of clonal architecture and clonal evolution that drive the transformation to secondary AML. We further define the phenotypic and transcriptional changes of disease progression at the single-cell level. See related article by Menssen et al., p. 330 (31). See related commentary by Romine and van Galen, p. 270. This article is highlighted in the In This Issue feature, p. 265.

Whole-genome sequencing as an alternative to analyze copy number abnormalities in acute myeloid leukemia and myelodysplastic syndrome

Copy number aberrations (CNA) are the core determinants for diagnosis, risk stratification and prognosis in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). In this study, a shallow whole-genome sequencing-based assay, LeukoPrint, was utilized to depict genomic CNA profiles from the bone marrow of 137 newly diagnosed AML/MDS patients. It demonstrated 98.1% concordance of CNA profiles with cytogenetics and/or fluorescence in situ hybridization (FISH). It is advantageous in detecting CNAs of short segments (1 Mb) and from samples with low leukemic cell content, more accurate for describing complex karyotypes and less confounded by subjective bias. LeukoPrint improved the overall diagnostic yield by redefining the risk categories for 16 patients by presenting new information. In summary, LeukoPrint provided an automated, convenient, and cost-effective approach to describe genomic CNA profiles. It brought greater diagnostic yield and risk stratification information by incorporating into the routine cytogenetics based on the CNA-related criteria of standard ELN/IPSS-R guidelines.

MDS cells impair osteolineage differentiation of MSCs via extracellular vesicles to suppress normal hematopoiesis

Myelodysplastic syndrome (MDS) is a clonal disorder of hematopoietic stem cells (HSCs), characterized by ineffective hematopoiesis and frequent progression to leukemia. It has long remained unresolved how MDS cells, which are less proliferative, inhibit normal hematopoiesis and eventually dominate the bone marrow space. Despite several studies implicating mesenchymal stromal or stem cells (MSCs), a principal component of the HSC niche, in the inhibition of normal hematopoiesis, the molecular mechanisms underlying this process remain unclear. Here, we demonstrate that both human and mouse MDS cells perturb bone metabolism by suppressing the osteolineage differentiation of MSCs, which impairs the ability of MSCs to support normal HSCs. Enforced MSC differentiation rescues the suppressed normal hematopoiesis in both in vivo and in vitro MDS models. Intriguingly, the suppression effect is reversible and mediated by extracellular vesicles (EVs) derived from MDS cells. These findings shed light on the novel MDS EV-MSC axis in ineffective hematopoiesis.

Transfer of IGF2BP3 Through Ara-C-Induced Apoptotic Bodies Promotes Survival of Recipient Cells

Cytosine arabinoside (Ara-C) has been the standard therapeutic agent for myelodysplastic syndromes (MDS) and adult acute myeloid leukemia (AML) patients for decades. Considerable progress has been made in development of new treatments for MDS/AML patients, but drug resistance remains a major clinical problem. Apoptotic bodies (ABs), produced by late apoptotic cells, can enclose bioactive components that affect cell-cell interactions and disease progression. We isolated and identified drug-induced ABs from Ara-C-tolerance cells. Treatment of sensitive cells with Ara-C-induced ABs resulted in Ara-C-resistant phenotype. We further investigated components and functions of Ara-C-induced ABs. Proteomics analysis in combination with mass spectrometry revealed that Ara-C-induced ABs carried numerous RNA-binding proteins, notably including insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3). Delivery of AB-encapsulated IGF2BP3 promoted survival of recipient cells by activating PI3K-AKT and p42-44 MAPK pathways. High IGF2BP3 level in ABs from MDS/AML patient plasma was correlated with poor overall survival. Our findings demonstrate that AB-derived IGF2BP3 plays an essential role in acquired Ara-C resistance in MDS/AML patients, and is a potential therapeutic target for suppression of Ara-C resistance.

Bioinformatics analysis deciphering the transcriptomic signatures associated with signalling pathways and prognosis in the myelodysplastic syndromes

BACKGROUND

Several studies scatteredly identified the myelodysplastic syndromes' transcriptomic profiles (MDS). However, the exploration of transcriptional signatures, key signalling pathways, and their association with prognosis and diagnosis in the integrated multiple datasets remains lacking.

METHODS

We integrated the GSE4619, GSE19429, GSE30195, and GSE58831 microarray datasets of CD34 + cells for identifying the differentially expressed genes (DEGs) in the MDS. The series of bioinformatics methods are applied to identify the key hub genes, gene clusters, prognostic hub genes, and genes associated with diagnostic efficacy. Finally, we validated the expression differences of hub genes in the GSE114922 dataset.

RESULTS

We explored the DEGs related to gene ontology enrichment and KEGG pathways. We identified significant hub genes, including 168 upregulated hub genes (such as STAT1, IFIH1, EPRS, GRB2, RAC2, MAPK14, CASP1, and SPI1) and 52 downregulated hub genes (such as CREBBP, HIF1A, PIK3CA, EZH2, PIK3R1, MDM2, IRF4, CXCR4, PCNA, and CD19) in the MDS. In addition, we identified six significant molecular complex detection (MCODE)-derived upregulated gene clusters and one downregulated gene cluster, respectively. Moreover, we found that the higher expression level of MX2, GBP2, PXN, IFI44, FDXR, PLCB2, ASS1, ERCC4, PML, and RRAGD and the lower expression level of CD19, PAX5, TCF3, LEF1, NUSAP1, and TIMELESS hub genes are significantly correlated with shorter survival times of MDS patients. Furthermore, the area value under the ROC curve (AUC) of PXN, FDXR, PLCB2, PML, CD19, PAX5, and LEF1 prognostic genes are more than 0.80, indicating that these genes could be effectively used for the diagnostic efficacy of MDS patients.

CONCLUSIONS

Identifying key hub genes and their association with the prognosis and diagnostic efficacy may provide substantial clues for the treatment and diagnosis of MDS patients.

Inflammasome Activation in Myeloid Malignancies—Friend or Foe?

Myeloid malignancies including myelodysplastic syndromes, myeloproliferative neoplasms and acute myeloid leukemia are heterogeneous disorders originating from mutated hematopoietic stem and progenitor cells (HSPCs). Genetically, they are very heterogeneous and characterized by uncontrolled proliferation and/or blockage of differentiation of abnormal HSPCs. Recent studies suggest the involvement of inflammasome activation in disease initiation and clonal progression. Inflammasomes are cytosolic innate immune sensors that, upon activation, induce caspase-1 mediated processing of interleukin (IL) -1-cytokine members IL-1β and IL-18, as well as initiation of gasdermin D-dependent pyroptosis. Inflammasome activation leads to a pro-inflammatory microenvironment in the bone marrow, which drives proliferation and may induce clonal selection of mutated HSPCs. However, there are also contradictory data showing that inflammasome activation actually counteracts leukemogenesis. Overall, the beneficial or detrimental effect of inflammasome activation seems to be highly dependent on mutational, environmental, and immunological contexts and an improved understanding is fundamental to advance specific therapeutic targeting strategies. This review summarizes current knowledge about this dichotomous effect of inflammasome activation in myeloid malignancies and provides further perspectives on therapeutic targeting.

Targeting the Myeloid Lineages and the Immune Microenvironment in Myelodysplastic Syndromes: Novel and Evolving Therapeutic Strategies

OBJECTIVE

To discuss the recent and emerging data for novel targeted therapies in myelodysplastic syndromes (MDS).

DATA SOURCES

A literature search from January 2015 to June 2021 was performed using the key terms targeted therapies, myelodysplastic syndromes, DNA repair, erythroid differentiation therapy, epigenetic inhibitors, signal transduction inhibitors, and apoptosis-inducing agents.

STUDY SELECTION AND DATA EXTRACTION

Relevant clinical trials and articles in the English language were identified and reviewed.

DATA SYNTHESIS

MDS are a heterogeneous group of malignant blood disorders affecting the bone marrow (BM), ultimately leading to BM failure, acute leukemia, and death. Selection of treatment is influenced by the severity of symptoms, cytopenia, cytogenetics, prognostic category, medical fitness, and patient preferences. Although current therapies such as erythropoiesis stimulating agents (ESAs) and hypomethylating agents (HMAs) help improve anemia and reduce transfusion burden, limited treatment options exist when patients experience treatment failure to ESAs or HMA. Recent regulatory approval of luspatercept, which targets the erythroid differentiation pathway, represents a major therapeutic advance in the management of anemia in MDS patients who are refractory to ESAs. Many investigational targeted therapies that aim at the myeloid lineage signaling pathway and the immune microenvironment are in active development.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This nonexhaustive review summarizes and describes the recent data for targeted therapies for MDS.

CONCLUSION

The development of novel and investigational therapeutic agents continues to contribute to an improved understanding of tumor biology. The precise therapeutic role and timing of these agents remain to be elucidated.

Myelodysplastic Syndromes in the Postgenomic Era and Future Perspectives for Precision Medicine

Simple Summary

With demographic ageing, improved cancer survivorship and increased diagnostic sensitivity, incident cases of patients with Myelodysplastic Syndromes (MDS) are continuously rising, leading to a relevant impact on health care resources. Disease heterogeneity and various comorbidities are challenges for the management of the generally elderly patients. Therefore, experienced physicians and multidisciplinary teams should be involved in the establishment of the correct diagnosis, risk-assessment and personalized treatment plan. Next-generation sequencing allows for early detection of clonal hematopoiesis and monitoring of clonal evolution, but also poses new challenges for its appropriate use. At present, allogeneic hematopoietic stem cell transplantation remains the only curative treatment option for a minority of fit MDS patients. All others receive palliative treatment and will eventually progress, having an unmet need for novel therapies. Targeting compounds are in prospect for precision medicine, however, abrogation of clonal evolution to acute myeloid leukemia remains actually out of reach.

Abstract

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal disorders caused by sequential accumulation of somatic driver mutations in hematopoietic stem and progenitor cells (HSPCs). MDS is characterized by ineffective hematopoiesis with cytopenia, dysplasia, inflammation, and a variable risk of transformation into secondary acute myeloid leukemia. The advent of next-generation sequencing has revolutionized our understanding of the genetic basis of the disease. Nevertheless, the biology of clonal evolution remains poorly understood, and the stochastic genetic drift with sequential accumulation of genetic hits in HSPCs is individual, highly dynamic and hardly predictable. These continuously moving genetic targets pose substantial challenges for the implementation of precision medicine, which aims to maximize efficacy with minimal toxicity of treatments. In the current postgenomic era, allogeneic hematopoietic stem cell transplantation remains the only curative option for younger and fit MDS patients. For all unfit patients, regeneration of HSPCs stays out of reach and all available therapies remain palliative, which will eventually lead to refractoriness and progression. In this review, we summarize the recent advances in our understanding of MDS pathophysiology and its impact on diagnosis, risk-assessment and disease monitoring. Moreover, we present ongoing clinical trials with targeting compounds and highlight future perspectives for precision medicine.

Innate immune pathways and inflammation in hematopoietic aging, clonal hematopoiesis, and MDS

With a growing aged population, there is an imminent need to develop new therapeutic strategies to ameliorate disorders of hematopoietic aging, including clonal hematopoiesis and myelodysplastic syndrome (MDS). Cell-intrinsic dysregulation of innate immune- and inflammatory-related pathways as well as systemic inflammation have been implicated in hematopoietic defects associated with aging, clonal hematopoiesis, and MDS. Here, we review and discuss the role of dysregulated innate immune and inflammatory signaling that contribute to the competitive advantage and clonal dominance of preleukemic and MDS-derived hematopoietic cells. We also propose how emerging concepts will further reveal critical biology and novel therapeutic opportunities.

Expression of mRNA TNFα and level of protein TNFα after exposure sCD40L in bone marrow mononuclear cells of myelodysplastic syndromes

Background

Cytopenia is the primary phenomenon in myelodysplastic syndrome (MDS) amidst hypercellular bone marrow. The soluble CD40 ligand (sCD40L) is considered as a cytokine that can trigger synthesis of tumor necrosis factor α (TNFα) that promotes apoptosis. The objective of this study is to prove that recombinant human sCD40L (rh-sCD40L) exposure on bone marrow mononuclear cells (BMMC) MDS increases TNFα expression at mRNA level and at protein level.

Methods

BMMC from MDS patients whom diagnosed and classified using the WHO 2008 criteria, were exposed to rh-sCD40L and antiCD40L. The expressions of TNFα mRNAs were quantified by qRT-PCR, level of TNFα were measured using the ELISA method.

Results

Exposure of rh-sCD40L significantly increased the expression of TNFα mRNA. The similar exposure also significantly increased the level of TNFα compared to controls. TNFα mRNA expression on BMMC in MDS samples exposed to rh-sCD40L is 3.32 times compared to TNFα mRNA expression without exposure. level of TNFα in supernatant media exposed to rh-sCD40L in MDS samples was higher than that of control samples which were 44.44 and 4.85 pg/mL, P=0.018.

Conclusions

The sCD40L plays a role in increasing the synthesis of TNFα in mRNA level and protein level in BMMC MDS.

Pediatric MDS and bone marrow failure-associated germline mutations in SAMD9 and SAMD9L impair multiple pathways in primary hematopoietic cells

Pediatric myelodysplastic syndromes (MDS) are a heterogeneous disease group associated with impaired hematopoiesis, bone marrow hypocellularity, and frequently have deletions involving chromosome 7 (monosomy 7). We and others recently identified heterozygous germline mutations in SAMD9 and SAMD9L in children with monosomy 7 and MDS. We previously demonstrated an antiproliferative effect of these gene products in non-hematopoietic cells, which was exacerbated by their patient-associated mutations. Here, we used a lentiviral overexpression approach to assess the functional impact and underlying cellular processes of wild-type and mutant SAMD9 or SAMD9L in primary mouse or human hematopoietic stem and progenitor cells (HSPC). Using a combination of protein interactome analyses, transcriptional profiling, and functional validation, we show that SAMD9 and SAMD9L are multifunctional proteins that cause profound alterations in cell cycle, cell proliferation, and protein translation in HSPCs. Importantly, our molecular and functional studies also demonstrated that expression of these genes and their mutations leads to a cellular environment that promotes DNA damage repair defects and ultimately apoptosis in hematopoietic cells. This study provides novel functional insights into SAMD9 and SAMD9L and how their mutations can potentially alter hematopoietic function and lead to bone marrow hypocellularity, a hallmark of pediatric MDS.

When Should We Think of Myelodysplasia or Bone Marrow Failure in a Thrombocytopenic Patient? A Practical Approach to Diagnosis

Thrombocytopenia can arise from various conditions, including myelodysplastic syndromes (MDS) and bone marrow failure (BMF) syndromes. Meticulous assessment of the peripheral blood smear, identification of accompanying clinical conditions, and characterization of the clinical course are important for initial assessment of unexplained thrombocytopenia. Increased awareness is required to identify patients with suspected MDS or BMF, who are in need of further investigations by a step-wise approach. Bone marrow cytomorphology, histopathology, and cytogenetics are complemented by myeloid next-generation sequencing (NGS) panels. Such panels are helpful to distinguish reactive cytopenia from clonal conditions. MDS are caused by mutations in the hematopoietic stem/progenitor cells, characterized by cytopenia and dysplasia, and an inherent risk of leukemic progression. Aplastic anemia (AA), the most frequent acquired BMF, is immunologically driven and characterized by an empty bone marrow. Diagnosis remains challenging due to overlaps with other hematological disorders. Congenital BMF, certainly rare in adulthood, can present atypically with thrombocytopenia and can be misdiagnosed. Analyses for chromosome fragility, telomere length, and germline gene sequencing are needed. Interdisciplinary expert teams contribute to diagnosis, prognostication, and choice of therapy for patients with suspected MDS and BMF. With this review we aim to increase the awareness and provide practical approaches for diagnosis of these conditions in suspicious cases presenting with thrombocytopenia.

SETD2 deficiency accelerates MDS-associated leukemogenesis via S100a9 in NHD13 mice and predicts poor prognosis in MDS

SETD2, the histone H3 lysine 36 methyltransferase, previously identified by us, plays an important role in the pathogenesis of hematologic malignancies, but its role in myelodysplastic syndromes (MDSs) has been unclear. In this study, low expression of SETD2 correlated with shortened survival in patients with MDS, and the SETD2 levels in CD34+ bone marrow cells of those patients were increased by decitabine. We knocked out Setd2 in NUP98-HOXD13 (NHD13) transgenic mice, which phenocopies human MDS, and found that loss of Setd2 accelerated the transformation of MDS into acute myeloid leukemia (AML). Loss of Setd2 enhanced the ability of NHD13+ hematopoietic stem and progenitor cells (HSPCs) to self-renew, with increased symmetric self-renewal division and decreased differentiation and cell death. The growth of MDS-associated leukemia cells was inhibited though increasing the H3K36me3 level by using epigenetic modifying drugs. Furthermore, Setd2 deficiency upregulated hematopoietic stem cell signaling and downregulated myeloid differentiation pathways in the NHD13+ HSPCs. Our RNA-seq and chromatin immunoprecipitation-seq analysis indicated that S100a9, the S100 calcium-binding protein, is a target gene of Setd2 and that the addition of recombinant S100a9 weakens the effect of Setd2 deficiency in the NHD13+ HSPCs. In contrast, downregulation of S100a9 leads to decreases of its downstream targets, including Ikba and Jnk, which influence the self-renewal and differentiation of HSPCs. Therefore, our results demonstrated that SETD2 deficiency predicts poor prognosis in MDS and promotes the transformation of MDS into AML, which provides a potential therapeutic target for MDS-associated acute leukemia.

Prognostic Parameters in Myeloid Malignancies in a Historical Context - From Microscopy to Individualized Medicine

With this article, we would like to take the reader on a journey into the world of molecular medicine as it has evolved over the past decades, enabled by advances in genomics. These findings advanced both the development of prognostic parameters and the evolvement of therapy strategies. In this manuscript, we will present haematopoietic diseases as a prime example of this progress because they are relevant not only for their frequency but also for the evident diagnostic and therapeutic progress. The growing understanding of the underlying pathophysiology originates from the cellular pathology as it was described by, e.g., Rudolf Virchow (1821-1902). The identification of specific genomic changes in haematological malignancies and solid tumour diseases provided us with very sensitive tools for diagnostics and prediction of prognosis. Thus, it paved the way for individualized or personalized therapy. In particular, the rapid development of sequencing techniques for the human genome using Next Generation Sequencing (NGS) has contributed to this progress. Recently, artificial intelligence provided us with the tools to analyze the complex interactions of genomic alterations, course of the disease, and further factors of as yet unknown significance. With all these indisputable improvements, we should not neglect the holistic treatment mandate of personalized therapy, i.e., therapy appropriate to the individual. In this context, the treating physician should address relevant co-morbidities, the psychosocial embedding of the patient and his desire for treatment.

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.

Identification of latent core genes and pathways associated with myelodysplastic syndromes based on integrated bioinformatics analysis

Background: Myelodysplastic syndromes (MDS) are relatively common hematological malignancies characterized by dysplastic hematopoiesis in one or more of the lineages of the bone marrow. This study aimed to identify critical pathogenic biomarkers associated with the carcinogenesis and progression of MDS. Methods: To explore the candidate genes, the expression profiles of GSE2779, GSE4619, and GSE19429 were downloaded from the Gene Expression Omnibus (GEO) database, which contained CD34+ cells isolated from MDS patients and normal controls. The three microarray datasets were integrated to obtain differentially expressed genes (DEGs) and were deeply analyzed by bioinformatics methods. The construction of protein-protein interaction (PPI) network together with module analysis was performed based on Cytoscape software and the Search Tool for the Retrieval of Interacting Genes (STRING) database. Results: Our study identified 114 DEGs, which were highly enriched in various key pathways, including forkhead box protein O (FoxO) signaling pathway, the primary immunodeficiency, and hematopoietic cell lineage. Twelve core genes, such as FOXO1, PAX5 and CXCR4 were identified with a high degree of connectivity. It is plausible that FoxO signaling pathway plays an important role in MDS, and the dysregulation of FOXO1 was significantly associated with TGFβ, IL2/STAT5, Notch signaling and apoptosis pathways. Conclusion: The current study for the first time identified twelve latent indicators and their downstream targets, which might become significant biomarkers for worse clinical characteristics in MDS.

Bone Marrow Failure Syndromes, Overlapping Diseases with a Common Cytokine Signature

Bone marrow failure (BMF) syndromes are a heterogenous group of non-malignant hematologic diseases characterized by single- or multi-lineage cytopenia(s) with either inherited or acquired pathogenesis. Aberrant T or B cells or innate immune responses are variously involved in the pathophysiology of BMF, and hematological improvement after standard immunosuppressive or anti-complement therapies is the main indirect evidence of the central role of the immune system in BMF development. As part of this immune derangement, pro-inflammatory cytokines play an important role in shaping the immune responses and in sustaining inflammation during marrow failure. In this review, we summarize current knowledge of cytokine signatures in BMF syndromes.

Altered Spatial Composition of the Immune Cell Repertoire in Association to CD34+ Blasts in Myelodysplastic Syndromes and Secondary Acute Myeloid Leukemia

Simple Summary

Despite a relationship between immune dysregulation and the course of myelodysplastic syndromes (MDS) has been discussed, a detailed understanding of this phenomenon is still missing. Therefore, multiplex analyses of bone marrow biopsies (BMB) from patients with MDS and secondary acute myeloid leukemia (sAML) were performed in order to determine the repertoire of lymphocyte subpopulations and their distance to CD34⁺ blasts. In MDS and sAML samples, the composition, quantity, and spatial proximity of immune cell subsets to CD34⁺ blasts were heterogeneous and correlated to the blast counts, but not to the genetics of the diseases, while in non-neoplastic BMB no CD8⁺ and FOXP3⁺ T cells and only single MUM1p⁺ B/plasma cells were detected in a distance of ≤10 μm to CD34⁺ hematopoietic progenitor cells (HPSC). We conclude that CD8⁺ and FOXP3⁺ T cells are not part of the immediate surrounding of CD34⁺ HPSC.

Abstract

Background: Myelodysplastic syndromes (MDS) are caused by a stem cell failure and often include a dysfunction of the immune system. However, the relationship between spatial immune cell distribution within the bone marrow (BM), in relation to genetic features and the course of disease has not been analyzed in detail. Methods: Histotopography of immune cell subpopulations and their spatial distribution to CD34⁺ hematopoietic cells was determined by multispectral imaging (MSI) in 147 BM biopsies (BMB) from patients with MDS, secondary acute myeloid leukemia (sAML), and controls. Results: In MDS and sAML samples, a high inter-tumoral immune cell heterogeneity in spatial proximity to CD34⁺ blasts was found that was independent of genetic alterations, but correlated to blast counts. In controls, no CD8⁺ and FOXP3⁺ T cells and only single MUM1p⁺ B/plasma cells were detected in an area of ≤10 μm to CD34⁺ HSPC. Conclusions: CD8⁺ and FOXP3⁺ T cells are regularly seen in the 10 μm area around CD34⁺ blasts in MDS/sAML regardless of the course of the disease but lack in the surrounding of CD34⁺ HSPC in control samples. In addition, the frequencies of immune cell subsets in MDS and sAML BMB differ when compared to control BMB providing novel insights in immune deregulation.

Cytogenetic characteristics of 665 patients with myelodysplastic syndrome in China: A single-center report

The karyotype is highly important for diagnosis and prognosis in myelodysplastic syndrome (MDS). The objective of the present study was to investigate the cytogenetic characteristics of patients with MDS in China. The karyotypes of 665 Chinese patients with MDS were analyzed, and it was identified that 298 cases (298/665, 44.8%) had abnormal karyotypes. Among the 298 patients with abnormal karyotypes, the 75 patients with trisomy 8 (+8) constituted the most common subset (75/298, 25.2%). The incidence of abnormal karyotypes was significantly higher in patients who were ≥51 years old compared with those <51 years old, (54.8 vs. 34.7%, respectively; P<0.05). Based on World Health Organization (WHO) classification-based Prognostic Scoring System (WPSS) criteria, the incidence of poor-prognosis karyotypes was significantly higher (17.4 vs. 5.4%; P<0.05) in the older patient group, and based on the Revised International Prognostic Scoring System (IPSS-R) criteria, the incidence of poor-/very poor-prognosis karyotypes was also significantly higher (17.4 vs. 6.6%; P<0.05) in patients ≥51 years old compared with younger ones. Based on the WHO classification of MDS subtypes, the incidence of abnormal karyotypes in patients with high percentages of bone marrow (BM) blasts [excess blasts (EB)-I + EB-II, ≥5% blasts] was significantly higher than that in patients with low percentages of BM blasts (those with single lineage dysplasia + multilineage dysplasia, <5% blasts) (62.5 vs. 36.0%; P<0.05). The incidence of poor-prognosis karyotypes based on WPSS criteria was significantly higher in patients with high percentages of BM blasts than those with low percentages (22.0 vs. 6.9%, respectively; P<0.05), and the incidence of poor-/very poor-prognosis karyotypes based on IPSS-R criteria was also significantly higher (23.0 vs. 7.4%, respectively; P<0.05). These results demonstrate that +8 is the most common abnormal karyotype in Chinese patients with MDS. Age and the percentage of BM blasts are associated with the incidence of both abnormal karyotypes and karyotypes with poor prognosis. The results of cytogenetic abnormalities in this study will supplement the data on patients of MDS in China.

MDS-associated SF3B1 mutations enhance proinflammatory gene expression in patient blast cells

Two factors known to contribute to the development of myelodysplastic syndrome (MDS) and other blood cancers are (i) somatically acquired mutations in components of the spliceosome and (ii) increased inflammation. Spliceosome genes, including SF3B1, are mutated at high frequency in MDS and other blood cancers; these mutations are thought to be neomorphic or gain-of-function mutations that drive disease pathogenesis. Likewise, increased inflammation is thought to contribute to MDS pathogenesis; inflammatory cytokines are strongly elevated in these patients, with higher levels correlating with worsened patient outcome. In the current study, we used RNAseq to analyze pre-mRNA splicing and gene expression changes present in blast cells isolated from MDS patients with or without SF3B1 mutations. We determined that SF3B1 mutations lead to enhanced proinflammatory gene expression in these cells. Thus, these studies suggest that SF3B1 mutations could contribute to MDS pathogenesis by enhancing the proinflammatory milieu in these patients.

Efficacy of the novel tubulin polymerization inhibitor PTC-028 for myelodysplastic syndrome

Monomer tubulin polymerize into microtubules, which are highly dynamic and play a critical role in mitosis. Therefore, microtubule dynamics are an important target for anticancer drugs. The inhibition of tubulin polymerization or depolymerization was previously targeted and exhibited efficacy against solid tumors. The novel small molecule PTC596 directly binds tubulin, inhibits microtubule polymerization, downregulates MCL‐1, and induces p53‐independent apoptosis in acute myeloid leukemia cells. We herein investigated the efficacy of PTC‐028, a structural analog of PTC596, for myelodysplastic syndrome (MDS). PTC‐028 suppressed growth and induced apoptosis in MDS cell lines. The efficacy of PTC028 in primary MDS samples was confirmed using cell proliferation assays. PTC‐028 synergized with hypomethylating agents, such as decitabine and azacitidine, to inhibit growth and induce apoptosis in MDS cells. Mechanistically, a treatment with PTC‐028 induced G2/M arrest followed by apoptotic cell death. We also assessed the efficacy of PTC‐028 in a xenograft mouse model of MDS using the MDS cell line, MDS‐L, and the AkaBLI bioluminescence imaging system, which is composed of AkaLumine‐HCl and Akaluc. PTC‐028 prolonged the survival of mice in xenograft models. The present results suggest a chemotherapeutic strategy for MDS through the disruption of microtubule dynamics in combination with DNA hypomethylating agents.

Iron Overload Impairs Bone Marrow Mesenchymal Stromal Cells from Higher-Risk MDS Patients by Regulating the ROS-Related Wnt/β-Catenin Pathway

The bone marrow microenvironment plays important roles in the progression of the myelodysplastic syndrome (MDS). The higher incidence of ASXL1 and TET2 gene mutations in our iron overload (IO) MDS patients suggests that IO may be involved in the pathogenesis of MDS. The effects of IO damaging bone marrow mesenchymal stromal cells (MSCs) from higher-risk MDS patients were investigated. In our study, IO decreased the quantity and weakened the abilities of proliferation and differentiation of MSCs, and it inhibited the gene expressions of VEGFA, CXCL12, and TGF-β1 in MSCs regulating hematopoiesis. The increased level of reactive oxygen species (ROS) in MSCs caused by IO might be inducing apoptosis by activating caspase3 signals and involving in MDS progression by activating β-catenin signals. The damages of MSCs caused by IO could be partially reversed by an antioxidant or an iron chelator. Furthermore, the MSCs in IO MDS/AML patients had increased levels of ROS and apoptosis, and the expressions of caspase3 and β-catenin were increased even further. In conclusion, IO affects gene stability in higher-risk MDS patients and impairs MSCs by inducing ROS-related apoptosis and activating the Wnt/β-catenin signaling pathway, which could be partially reversed by an antioxidant or an iron chelator.

Myelodysplastic syndrome: the other cause of anemia in end-stage renal disease patients undergoing dialysis

In end-stage renal disease (ESRD) patients receiving dialysis, anemia is common and related to a higher mortality rate. Erythropoietin (EPO) resistance and iron refractory anemia require red blood cell transfusions. Myelodysplastic syndrome (MDS) is a disease with hematopoietic dysplasia. There are limited reports regarding ESRD patients with MDS. We aim to assess whether, for ESRD patients, undergoing dialysis is a predictive factor of MDS by analyzing data from the Taiwan National Health Insurance Research Database. We enrolled 74,712 patients with chronic renal failure (ESRD) who underwent dialysis and matched 74,712 control patients. In our study, we noticed that compared with the non-ESRD controls, in ESRD patients, undergoing dialysis (subdistribution hazard ratio [sHR] = 1.60, 1.16–2.19) and age (sHR = 1.03, 1.02–1.04) had positive predictive value for MDS occurrence. Moreover, more units of red blood cell transfusion (higher than 4 units per month) was also associated with a higher incidence of MDS. The MDS cumulative incidence increased with the duration of dialysis in ESRD patients. These effects may be related to exposure to certain cytokines, including interleukin-1, tumor necrosis factor-α, and tumor growth factor-β. In conclusion, we report the novel finding that ESRD patients undergoing dialysis have an increased risk of MDS.

Controlled Cycling and Quiescence Enables Efficient HDR in Engraftment-Enriched Adult Hematopoietic Stem and Progenitor Cells

Genome editing often takes the form of either error-prone sequence disruption by non-homologous end joining (NHEJ) or sequence replacement by homology-directed repair (HDR). Although NHEJ is generally effective, HDR is often difficult in primary cells. Here, we use a combination of immunophenotyping, next-generation sequencing, and single-cell RNA sequencing to investigate and reprogram genome editing outcomes in subpopulations of adult hematopoietic stem and progenitor cells. We find that although quiescent stem-enriched cells mostly use NHEJ, non-quiescent cells with the same immunophenotype use both NHEJ and HDR. Inducing quiescence before editing results in a loss of HDR in all cell subtypes. We develop a strategy of controlled cycling and quiescence that yields a 6-fold increase in the HDR/NHEJ ratio in quiescent stem cells ex vivo and in vivo. Our results highlight the tension between editing and cellular physiology and suggest strategies to manipulate quiescent cells for research and therapeutic genome editing.

SPAG6 silencing induces autophagic cell death in SKM-1 cells via the AMPK/mTOR/ULK1 signaling pathway

As a member of the cancer-testis antigen family, sperm-associated antigen 6 (SPAG6) has been reported to be associated with the pathogenesis of myelodysplastic syndromes (MDS). Previous studies have demonstrated that SPAG6 is upregulated in bone marrow from patients with MDS and MDS-transformed acute myeloid leukemia and that knockdown of SPAG6 expression levels suppressed proliferation and promote apoptosis and differentiation in SKM-1 cells. However, the association between SPAG6 and autophagy in SKM-1 cells remains unclear. Hence, the aim of the present study was to investigate this association and its underlying mechanism. The present study used a short hairpin RNA (shRNA) lentivirus to silence SPAG6 expression levels in SKM-1 cells and demonstrated that SPAG6 knockdown increased autophagy and apoptosis. Furthermore, pharmacologically inhibiting autophagy with chloroquine and 3-methyladenine decreased SPAG6 knockdown-mediated apoptosis, indicating that SPAG6 knockdown-mediated autophagy promoted apoptosis in SKM-1 cells. Additionally, compared with the expression levels in negative control-shRNA lentivirus-transfected SKM-1 cells, the protein expression levels of phosphorylated AMP-activated protein kinase (p-AMPK) and phosphorylated unc-51-like autophagy activating kinase 1 (p-ULK1) were upregulated, while phosphorylated mammalian target of rapamycin (p-mTOR) protein expression was downregulated in SPAG6-shRNA lentivirus-transfected cells. Moreover, inhibiting AMPK expression levels with Compound C, a specific inhibitor of AMPK, attenuated SPAG6 knockdown-induced autophagy and apoptosis, suggesting that AMPK-mediated autophagy enhanced the pro-apoptotic effect of SPAG6 knockdown in SKM-1 cells. Taken together, the results of the present study demonstrated that SPAG6 silencing triggered autophagy via regulation of the AMPK/mTOR/ULK1 signaling pathway, which further contributed to the apoptosis of SKM-1 cells induced by SPAG6 knockdown. Thus, the current results indicate that SPAG6 may be a potential therapeutic target against MDS, and that autophagy may represent a potential mechanism for the treatment of MDS.

The Effects of Human BDH2 on the Cell Cycle, Differentiation, and Apoptosis and Associations with Leukemia Transformation in Myelodysplastic Syndrome

Iron overload is related to leukemia transformation in myelodysplastic syndrome (MDS) patients. Siderophores help to transport iron. Type 2-hydroxybutyrate dehydrogenase (BDH2) is a rate-limiting factor in the biogenesis of siderophores. Using qRT-PCR, we analyze BDH2mRNA expression in the bone marrow (BM) of 187 MDS patients, 119 de novo acute myeloid leukemia (AML) patients, and 43 lymphoma patients with normal BM. Elevated BDH2mRNA expression in BM is observed in MDS patients (n = 187 vs. 43, normal BM; P = 0.009), and this is related to ferritin levels. Patients with higher BDH2 expression show a greater risk of leukemia progression (15.25% vs. 3.77%, lower expression; P = 0.017) and shorter leukemia-free-survival (medium LFS, 9 years vs. 7 years; P = 0.024), as do patients with a ferritin level ≥350 ng/mL. Additionally, we investigate the mechanisms related to the prognostic ability of BDH2 by using BDH2-KD THP1. The cell cycle analysis, surface markers, and special stain studies indicate that BDH2-KD induces differentiation and decreases the growth rate of THP1 cells, which is associated with the retardation of the cell cycle. Moreover, many genes, including genes related to mitochondrial catabolism, oncogenes, tumor suppressor genes, and genes related to cell differentiation and proliferation influence BDH2-KD THP1 cells. Herein, we demonstrate that BDH2 is involved in cell cycle arrest and the inhibition of differentiation in malignant cells. Furthermore, the high BDH2 expression in MDS patients could be suggestive of a poor prognostic factor. This study provides a foundation for further research on the roles of BDH2 and iron metabolism in the pathogenesis of MDS.

Myelodysplastic Syndrome with Transfusion Dependence Treated with Venetoclax

Myelodysplastic syndromes are characterized by ineffective hematopoiesis in one or more lineages of the bone marrow. They are a group of heterogeneous clonal stem cell malignancies with a high risk to progress to acute myeloid leukemia. Currently, there are no curative FDA-approved medications for myelodysplastic syndromes. Hematopoietic cell transplantation is potentially the only curative option; however, treatment is often unavailable due to age and comorbidities. Hypomethylating agents, azacitidine and decitabine, and the immunomodulatory agent, lenalidomide, are the only FDA approved medications for the treatment of MDS, all of which are noncurative. Venetoclax, an inhibitor of the antiapoptotic protein BCL-2 used to treat chronic lymphocytic leukemia, is currently being evaluated in clinical trials as a monotherapy in high-risk myelodysplastic syndromes/acute myeloid leukemia. We present a patient with transfusion-dependent myelodysplastic syndromes refractory to the current standard of care treatment not a candidate for hematopoietic cell transplantation who responded well to monotherapy treatment with venetoclax and has since remained transfusion-independent.

mTOR and STAT3 Pathway Hyper-Activation is Associated with Elevated Interleukin-6 Levels in Patients with Shwachman-Diamond Syndrome: Further Evidence of Lymphoid Lineage Impairment

Shwachman–Diamond syndrome (SDS) is a rare inherited bone marrow failure syndrome, resulting in neutropenia and a risk of myeloid neoplasia. A mutation in a ribosome maturation factor accounts for almost all of the cases. Lymphoid involvement in SDS has not been well characterized. We recently reported that lymphocyte subpopulations are reduced in SDS patients. We have also shown that the mTOR-STAT3 pathway is hyper-activated in SDS myeloid cell populations. Here we show that mTOR-STAT3 signaling is markedly upregulated in the lymphoid compartment of SDS patients. Furthermore, our data reveal elevated IL-6 levels in cellular supernatants obtained from lymphoblasts, bone marrow mononuclear and mesenchymal stromal cells, and plasma samples obtained from a cohort of 10 patients. Of note, everolimus-mediated inhibition of mTOR signaling is associated with basal state of phosphorylated STAT3. Finally, inhibition of mTOR-STAT3 pathway activation leads to normalization of IL-6 expression in SDS cells. Altogether, our data strengthen the hypothesis that SDS affects both lymphoid and myeloid blood compartment and suggest everolimus as a potential therapeutic agent to reduce excessive mTOR-STAT3 activation in SDS.

Myelodysplastic syndrome: validation of flow cytometry multilineage score system

OBJECTIVE

To validate multilineage score system correlating results of flow cytometry, cytogenetics, cytomorphology and histology from samples of patients with suspected myelodysplastic syndrome or cytopenia of unknown origin.

METHODS

A retrospective study analyzing laboratory data of 49 patients with suspected myelodysplastic syndrome or cytopenia of unknown origin, carried out between May and September 2017. The inclusion criteria were availability of flow cytometry results, and at least one more method, such as morphology, histology or cytogenetics. Thirty-eight patients were classified as diagnosis of myelodysplastic syndromes, whereas 11 were classified as normal. Patients were evaluated based on score systems, Ogata score and flow cytometry multilineage score.

RESULTS

Comparing the scores obtained in the Ogata score and the multilineage score, it was observed that in four cases the Ogata score was zero or 1 point, while the multilineage score was higher than 3 points. In addition, in 12 cases with Ogata score of 2, the multilineage score was greater than 3.

CONCLUSION

The flow cytometry multilineage score system demonstrated to be more effective in dysplasia analysis, by assessing the erythroid, monocytic, granulocytic and precursor cell lineages, apart from the parameters evaluated by the Ogata score.

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.

Genetic basis of myelodysplastic syndromes

During the past decade, substantial progress has been made in the field of the genetics of myelodysplastic syndromes (MDS). These comprise a group of chronic myeloid neoplasms with abnormal cell morphology and progression to acute myeloid leukemia (AML), where revolutionary sequencing technologies have played a major role. Through extensive sequencing of a large number of MDS genomes, a comprehensive registry of driver mutations involved in the pathogenesis of MDS has been revealed, along with their impacts on clinical phenotype and prognosis. The most frequently affected molecules are involved in DNA methylations, chromatin modification, RNA splicing, transcription, signal transduction, cohesin regulation, and DNA repair. These mutations show strong positive and negative correlations with each other, suggesting the presence of functional interactions between mutations, which dictate disease progression. Because these mutations are associated with disease phenotype, drug response, and clinical outcomes, it is essential to be familiar with MDS genetics not only for better understanding of MDS pathogenesis but also for management of 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.

Energy metabolism and drug response in myeloid leukaemic stem cells

Despite significant advances in the treatment of myeloid malignancies, many patients become resistant to therapy and ultimately succumb to their disease. Accumulating evidence over the past several years has suggested that the inadequacy of many leukaemia therapies results from their failure to target the leukaemic stem cell (LSC). For this reason, the LSC population currently represents the most critical target in the treatment of myeloid malignancies. However, while LSCs are ideal targets in the treatment of these diseases, they are also the most difficult population to target. This is due to both their heterogeneity within the LSC population, and also their phenotypic similarities with normal haematopoietic stem cells. This review will highlight the current landscape surrounding LSC biology in myeloid malignancies, with a focus on altered energy metabolism, and how that knowledge is being translated into clinical advances for the treatment of chronic and acute myeloid leukaemia and myelodysplastic syndromes.

Physical Activity, Sitting Time, and Risk of Myelodysplastic Syndromes, Acute Myeloid Leukemia, and Other Myeloid Malignancies

INTRODUCTION

There is limited research on associations of moderate-to-vigorous physical activity (MVPA) and sitting with risk of myeloid neoplasms (MN) or MN subtypes. We examined these associations in the Cancer Prevention Study-II Nutrition Cohort.

METHODS

Among 109,030 cancer-free participants (mean age 69.2, SD 6.1 years) in 1999, 409 were identified as having been diagnosed with a MN [n = 155 acute myeloid leukemia (AML), n = 154 myelodysplastic syndromes (MDS), n = 100 other ML] through June 2013. Cox proportional hazards regression was used to calculate multivariable adjusted hazard ratios (HR) and 95% confidence intervals (CI) for associations of MVPA (MET-h/wk) and sitting (h/d) with risk of all MN, myeloid leukemia only, MDS, and AML.

RESULTS

Compared with insufficient MVPA [>0-<7.5 metabolic equivalent hours/week (MET)-h/wk], the HR (95% CI) for meeting physical activity guidelines (7.5-<15 MET-h/wk MVPA) and risk of MN was 0.74 (95% CI, 0.56-0.98) and for doubling guidelines (15-<22.5 MET-h/wk) was 0.75 (0.53-1.07); however, there was no statistically significant association for higher MVPA (22.5+ MET-h/wk, HR, 0.93; 95% CI, 0.73-1.20). Similarly, meeting/doubling guidelines was associated with lower risk of MDS (HR, 0.57; 95% CI, 0.35-0.92/HR, 0.51; 95% CI, 0.27-0.98), but there was no association for 22.5+ MET-h/wk (HR, 0.93; 95% CI, 0.63-1.37). MVPA was not associated with risk of myeloid leukemia or AML. Sitting time was not associated with risk of any outcome.

CONCLUSIONS

These results suggest that there may be a nonlinear association between MVPA and risk of MDS and possibly other MN.

IMPACT

Further studies are needed to better understand the dose-response relationships between MVPA and risk of MDS, a highly fatal and understudied cancer.

High expression of PIM2 induces HSC proliferation in myelodysplastic syndromes via the IDH1/HIF1-α signaling pathway

PIM2 proto-oncogene, serine/threonine kinase (PIM2) is a serine/threonine protein kinase that is upregulated in different types of cancer and serves essential roles in the regulation of signal transduction cascades, which promote cell survival and cell proliferation. The present study demonstrated that PIM2 was highly expressed in CD34⁺ cells derived from the bone marrow of patients with myelodysplastic syndromes (MDS)/acute myeloid leukemia. The mRNA expression level of PIM2 was quantified in MDS cell lines and mRNA expression was significantly decreased compared with that in KG-1 cells. In vitro, downregulation of PIM2 by short interfering RNA (siRNA) inhibited cell proliferation and delayed G₀/G₁ cell cycle progression in the MDS cell line SKM-1. Western blotting revealed that cyclin dependent kinase 2 was markedly downregulated and cyclin dependent kinase inhibitor 1A was markedly upregulated following transfection with PIM2 siRNA. Cell Counting Kit-8 analysis demonstrated that cell proliferation of si-PIM2-transfected cells was significantly decreased compared with control cells. Reverse-transcription quantitative polymerase chain reaction and western blotting revealed that PIM2 expression was negatively correlated with isocitrate dehydrogenase [NADP(+)]1 cytosolic (IDH1) and positively correlated with hypoxia inducible factor 1 subunit α (HIF1A) in CD34⁺ MDS cells. Collectively, these results suggested that the expression of PIM2 induced increased expression of HIF1A by decreasing the expression of IDH1, resulting in increased CD34⁺ cell proliferation. Therefore, PIM2 may be a potential biomarker for the diagnosis of MDS and AML or a target for novel therapeutic agents.

Prominence of nestin-expressing Schwann cells in bone marrow of patients with myelodysplastic syndromes with severe fibrosis

Nestin-expressing stromal cells (NESCs) and Schwann cells in the bone marrow (BM) play crucial roles as a niche for normal hematopoietic stem cells in mice. It has been reported that both types of cells are decreased in myeloproliferative neoplasms in patients and also in a mouse model, whereas an increase in NESCs was reported in acute myeloid leukemia. It is thus of interest whether and how these BM stromal cells are structured in myelodysplastic syndromes (MDS). Here, we focused on NESCs and glial fibrillary acidic protein (GFAP)-expressing cells in the BM of MDS patients. We found a marked increase of NESCs in MDS with fibrosis (MDS-F) at a high frequency (9/19; 47.4%), but not in MDS without fibrosis (0/26; 0%). Intriguingly, in eight of the nine (88.9%) MDS-F cases with elevated NESCs, a majority of NESCs also expressed GFAP, with an additional increase in GFAP single-positive cells. Furthermore, in seven of them, we found a prominent structure characterized by neurofilament heavy chain staining surrounded by NESCs with GFAP expression. This structure may represent peripheral nerve axons surrounded by Schwann cells, and could be relevant to the pathophysiology of MDS-F.

The orphan nuclear receptor EAR-2 (NR2F6) inhibits hematopoietic cell differentiation and induces myeloid dysplasia in vivo

Background

In patients with myelodysplastic syndrome (MDS), bone marrow cells have an increased predisposition to apoptosis, yet MDS cells outcompete normal bone marrow (BM)-- suggesting that factors regulating growth potential may be important in MDS. We previously identified v-Erb A related-2 (EAR-2, NR2F6) as a gene involved in control of growth ability.

Methods

Bone marrow obtained from C57BL/6 mice was transfected with a retrovirus containing EAR-2-IRES-GFP. Ex vivo transduced cells were flow sorted. In some experiments cells were cultured in vitro, in other experiments cells were injected into lethally irradiated recipients, along with non-transduced bone marrow cells. Short-hairpin RNA silencing EAR-2 was also introduced into bone marrow cells cultured ex vivo.

Results

Here, we show that EAR-2 inhibits maturation of normal BM in vitro and in vivo and that EAR-2 transplant chimeras demonstrate key features of MDS. Competitive repopulation of lethally irradiated murine hosts with EAR-2-transduced BM cells resulted in increased engraftment and increased colony formation in serial replating experiments. Recipients of EAR-2-transduced grafts had hypercellular BM, erythroid dysplasia, abnormal localization of immature precursors and increased blasts; secondary transplantation resulted in acute leukemia. Animals were cytopenic, having reduced numbers of erythrocytes, monocytes and granulocytes. Suspension culture confirmed that EAR-2 inhibits granulocytic and monocytic differentiation, while knockdown induced granulocytic differentiation. We observed a reduction in the number of BFU-E and CFU-GM colonies and the size of erythroid and myeloid colonies. Serial replating of transduced hematopoietic colonies revealed extended replating potential in EAR-2-overexpressing BM, while knockdown reduced re-plating ability. EAR-2 functions by recruitment of histone deacetylases, and inhibition of differentiation in 32D cells is dependent on the DNA binding domain.

Conclusions

This data suggest that NR2F6 inhibits maturation of normal BM in vitro and in vivo and that the NR2F6 transplant chimera system demonstrates key features of MDS, and could provide a mouse model for MDS.