Point mutations in the RUNX1/AML1 gene: another actor in RUNX leukemia

RUNX1 is a key inducer of human hematopoiesis controlling non-hematopoietic mesodermal development

The RUNX1/AML1 transcription factor is one of the key regulators of definitive hematopoietic development in mice. However, its role in early human hematopoiesis remains poorly investigated. In this study, we integrated a tdTomato reporter cassette into the RUNX1 locus of human pluripotent stem cells (hPSCs) to monitor and block the expression of the gene during hPSC differentiation. This approach demonstrated that expression of RUNX1 starts early in mesodermal specification focusing later on hemogenic endothelium (HE) and nascent hematopoietic cells. Lack of RUNX1 halted the development of CD43+ and CD235-CD45+ hematopoietic cells, preventing the production of clonogenic hematopoietic progenitors including the multilineage ones. The abrogation of RUNX1 resulted in the failure of definitive lineages, specifically T and NK cells. Remarkably, we instead observed the accumulation of RUNX1-null HE cells at the stage of blood cell generation. Moreover, the loss of the gene biased the development toward the lineage of CD43-CD146+CD90+CD73+ mesenchymal cells. RNA-seq analysis of RUNX1-null cells revealed the downregulation of top-level hematopoietic transcription factor genes and the reciprocal upregulation of genes associated with non-hematopoietic cells of mesodermal origin. Forced expression of RUNX1c in differentiating RUNX1-null hPSCs effectively rescued the development of CD45+ myeloid cells and megakaryocytes. Our data demonstrate that RUNX1 is a top hematopoietic inducer that simultaneously controls the expansion of non-hematopoietic lineages.

Integrin-α9 overexpression underlies the niche-independent maintenance of leukemia stem cells in acute myeloid leukemia

Leukemia stem cells (LSCs) are widely believed to reside in well-characterized bone marrow (BM) niches; however, the capacity of the BM niches to accommodate LSCs is insufficient, and a significant proportion of LSCs are instead maintained in regions outside the BM. The molecular basis for this niche-independent behavior of LSCs remains elusive. Here, we show that integrin-α9 overexpression (ITGA9 OE) plays a pivotal role in the extramedullary maintenance of LSCs by molecularly mimicking the niche-interacting status, through the binding with its soluble ligand, osteopontin (OPN). Retroviral insertional mutagenesis conducted on leukemia-prone Runx-deficient mice identified Itga9 OE as a novel leukemogenic event. Itga9 OE activates Akt and p38MAPK signaling pathways. The elevated Myc expression subsequently enhances ribosomal biogenesis to overcome the cell integrity defect caused by the preexisting Runx alteration. The Itga9-Myc axis, originally discovered in mice, was further confirmed in multiple human acute myeloid leukemia (AML) subtypes, other than RUNX leukemias. In addition, ITGA9 was shown to be a functional LSC marker of the best prognostic value among 14 known LSC markers tested. Notably, the binding of ITGA9 with soluble OPN, a known negative regulator against HSC activation, induced LSC dormancy, while the disruption of ITGA9-soluble OPN interaction caused rapid cell propagation. These findings suggest that the ITGA9 OE increases both actively proliferating leukemia cells and dormant LSCs in a well-balanced manner, thereby maintaining LSCs. The ITGA9 OE would serve as a novel therapeutic target in AML.

Immunoglobulin class-switch recombination: Mechanism, regulation, and related diseases

Maturation of the secondary antibody repertoire requires class-switch recombination (CSR), which switches IgM to other immunoglobulins (Igs), and somatic hypermutation, which promotes the production of high-affinity antibodies. Following immune response or infection within the body, activation of T cell-dependent and T cell-independent antigens triggers the activation of activation-induced cytidine deaminase, initiating the CSR process. CSR has the capacity to modify the functional properties of antibodies, thereby contributing to the adaptive immune response in the organism. Ig CSR defects, characterized by an abnormal relative frequency of Ig isotypes, represent a rare form of primary immunodeficiency. Elucidating the molecular basis of Ig diversification is essential for a better understanding of diseases related to Ig CSR defects and could provide clues for clinical diagnosis and therapeutic approaches. Here, we review the most recent insights on the diversification of five Ig isotypes and choose several classic diseases, including hyper-IgM syndrome, Waldenström macroglobulinemia, hyper-IgD syndrome, selective IgA deficiency, hyper-IgE syndrome, multiple myeloma, and Burkitt lymphoma, to illustrate the mechanism of Ig CSR deficiency. The investigation into the underlying mechanism of Ig CSR holds significant potential for the advancement of increasingly precise diagnostic and therapeutic approaches.

Investigations of the prognostic value of RUNX1 mutation in acute myeloid leukemia patients: Data from a real-world study

RUNX1 is one of the recurrent mutated genes in newly diagnosed acute myeloid leukemia (AML). Although historically recognized as a provisional distinct entity, the AML subtype with RUNX1 mutations (AML-RUNX1mut) was eliminated from the 2022 WHO classification system. To gain more insight into the characteristics of AML-RUNX1mut, we retrospectively analyzed 1065 newly diagnosed adult AML patients from the First Affiliated Hospital of Soochow University between January 2017 and December 2021. RUNX1 mutations were identified in 112 patients (10.5%). The presence of RUNX1 mutation (RUNX1mut) conferred a lower composite complete remission (CRc) rate (40.2% vs. 58.4%, P＜0.001), but no significant difference was observed in the 5-year overall survival (OS) rate (50.2% vs. 53.9%; HR=1.293; P=0.115) and event-free survival (EFS) rate (51.5% vs. 49.4%; HR=1.487, P=0.089), even within the same risk stratification. Multivariate analysis showed that RUNX1mut was not an independent prognostic factor for OS (HR=1.352, P=0.068) or EFS (HR=1.129, P=0.513). When patients were stratified according to induction regimen, RUNX1mut was an unfavorable factor for CRc both on univariate and multivariate analysis in patients receiving conventional chemotherapy, and higher risk stratification predicted worse OS. In those who received venetoclax plus hypomethylating agents, RUNX1mut was not predictive of CRc and comparable OS and EFS were seen between intermediate-risk and adverse-risk groups. The results of this study revealed that the impact of RUNX1mut is limited. Its prognostic value depended more on treatment and co-occurrent abnormalities. VEN-HMA may abrogate the prognostic impact of RUNX1, which merits a larger prospective cohort to illustrate.

RUNX1 targeting AKT3 promotes alveolar hypercoagulation and fibrinolytic inhibition in LPS induced ARDS

BACKGROUND

Alveolar hypercoagulation and fibrinolytic inhibition are mainly responsible for massive alveolar fibrin deposition, which are closely related with refractory hypoxemia in acute respiratory distress syndrome (ARDS). Our previous study testified runt-related transcription factor (RUNX1) participated in the regulation of this pathophysiology in this syndrome, but the mechanism is unknown. We speculate that screening the downstream genes associated with RUNX1 will presumably help uncover the mechanism of RUNX1.

METHODS

Genes associated with RUNX1 were screened by CHIP-seq, among which the target gene was verified by Dual Luciferase experiment. Then the efficacy of the target gene on alveolar hypercoagulation and fibrinolytic inhibition in LPS-induced ARDS was explored in vivo as well as in vitro. Finally, whether the regulatory effects of RUNX1 on alveolar hypercoagulation and fibrinolytic in ARDS would be related with the screened target gene was also sufficiently explored.

RESULTS

Among these screened genes, AKT3 was verified to be the direct target gene of RUNX1. Results showed that AKT3 was highly expressed either in lung tissues of LPS-induced rat ARDS or in LPS-treated alveolar epithelia cell type II (AECII). Tissue factor (TF) and plasminogen activator inhibitor 1 (PAI-1) were increasingly expressed both in lung tissues of ARDS and in LPS-induced AECII, which were all significantly attenuated by down-regulation of AKT3. Inhibition of AKT3 gene obviously ameliorated the LPS-induced lung injury as well as the collagen I expression in ARDS. RUNX1 overexpression not only promoted the expressions of TF, PAI-1, but also boosted AKT3 expression in vitro. More importantly, the efficacy of RUNX1 on TF, PAI-1 were all effectively reversed by down-regulation of AKT3 gene.

CONCLUSION

AKT3 is an important target gene of RUNX1, through which RUNX1 exerted its regulatory role on alveolar hypercoagulation and fibrinolytic inhibition in LPS-induced ARDS. RUNX1/ATK3 signaling axis is expected to be a new target for the exploration of ARDS genesis and treatment.

Multiple Roles of the RUNX Gene Family in Hepatocellular Carcinoma and Their Potential Clinical Implications

Hepatocellular carcinoma (HCC) is one of the most frequent cancers in humans, characterised by a high resistance to conventional chemotherapy, late diagnosis, and a high mortality rate. It is necessary to elucidate the molecular mechanisms involved in hepatocarcinogenesis to improve diagnosis and treatment outcomes. The Runt-related (RUNX) family of transcription factors (RUNX1, RUNX2, and RUNX3) participates in cardinal biological processes and plays paramount roles in the pathogenesis of numerous human malignancies. Their role is often controversial as they can act as oncogenes or tumour suppressors and depends on cellular context. Evidence shows that deregulated RUNX genes may be involved in hepatocarcinogenesis from the earliest to the latest stages. In this review, we summarise the topical evidence on the roles of RUNX gene family members in HCC. We discuss their possible application as non-invasive molecular markers for early diagnosis, prognosis, and development of novel treatment strategies in HCC patients.

Runt-related transcription factors in human carcinogenesis: a friend or foe?

PURPOSE

Cancer is one of the deadliest pathologies with more than 19 million new cases and 10 million cancer-related deaths across the globe. Despite development of advanced therapeutic interventions, cancer remains as a fatal pathology due to lack of early prognostic biomarkers, therapy resistance and requires identification of novel drug targets.

METHODS

Runt-related transcription factors (Runx) family controls several cellular and physiological functions including osteogenesis. Recent literatures from PubMed was mined and the review was written in comprehensive manner RESULTS: Recent literature suggests that aberrant expression of Runx contributes to tumorigenesis of many organs. Conversely, cell- and tissue-specific tumor suppressor roles of Runx are also reported. In this review, we have provided the structural/functional properties of Runx isoforms and its regulation in context of human cancer. Moreover, in an urgent need to discover novel therapeutic interventions against cancer, we comprehensively discussed the reported oncogenic and tumor suppressive roles of Runx isoforms in several tumor types and discussed the discrepancies that may have risen on Runx as a driver of malignant transformation.

CONCLUSION

Runx may be a novel therapeutic target against a battery of deadly human cancers.

The Therapeutic Potential of a Strategy to Prevent Acute Myeloid Leukemia Stem Cell Reprogramming in Older Patients

Acute myeloid leukemia (AML) is the most common and incurable leukemia subtype. Despite extensive research into the disease's intricate molecular mechanisms, effective treatments or expanded diagnostic or prognostic markers for AML have not yet been identified. The morphological, immunophenotypic, cytogenetic, biomolecular, and clinical characteristics of AML patients are extensive and complex. Leukemia stem cells (LSCs) consist of hematopoietic stem cells (HSCs) and cancer cells transformed by a complex, finely-tuned interaction that causes the complexity of AML. Microenvironmental regulation of LSCs dormancy and the diagnostic and therapeutic implications for identifying and targeting LSCs due to their significance in the pathogenesis of AML are discussed in this review. It is essential to perceive the relationship between the niche for LSCs and HSCs, which together cause the progression of AML. Notably, methylation is a well-known epigenetic change that is significant in AML, and our data also reveal that microRNAs are a unique factor for LSCs. Multiple-targeted approaches to reduce the risk of epigenetic factors, such as the administration of natural compounds for the elimination of local LSCs, may prevent potentially fatal relapses. Furthermore, the survival analysis of overlapping genes revealed that specific targets had significant effects on the survival and prognosis of patients. We predict that the multiple-targeted effects of herbal products on epigenetic modification are governed by different mechanisms in AML and could prevent potentially fatal relapses. Thus, these strategies can facilitate the incorporation of herbal medicine and natural compounds into the advanced drug discovery and development processes achievable with Network Pharmacology research.

RUNX1 mutation has no prognostic significance in paediatric AML: a retrospective study of the AML-BFM study group

In acute myeloid leukaemia (AML) RUNX1 mutation is characterised by certain clinicopathological features with poor prognosis and adverse risk by the European LeukemiaNet recommendation. Though initially considered as provisional category, the recent World Health Organisation (WHO) classification of 2022 removed RUNX1-mutated AML from the unique entity. However, the significance of RUNX1 mutation in paediatric AML remains unclear. We retrospectively analysed a German cohort of 488 paediatric patients with de novo AML, enroled in the AMLR12 or AMLR17 registry of the AML-BFM Study Group (Essen, Germany). A total of 23 paediatric AML patients (4.7%) harboured RUNX1 mutations, 18 of which (78%) had RUNX1 mutation at initial diagnosis. RUNX1 mutations were associated with older age, male gender, number of coexisting alterations and presence of FLT3-ITD but mutually exclusive of KRAS, KIT and NPM1 mutation. RUNX1 mutations did not prognostically impact overall or event-free survival. Response rates did not differ between patients with and without RUNX1 mutations. This comprehensive study, comprising the largest analysis of RUNX1 mutation in a paediatric cohort to date, reveals distinct but not unique clinicopathologic features, with no prognostic significance of RUNX1-mutated paediatric AML. These results broaden the perspective on the relevance of RUNX1 alterations in leukaemogenesis in AML.

Childhood hematopoietic stem cells constitute the permissive window for RUNX1-ETO leukemogenesis

Cancer is a very rare event at the cellular level, although it is a common disease at the body level as one third of humans die of cancer. A small subset of cells in the body harbor the cellular features that constitute a permissive window for a particular genetic change to induce cancer. The significance of a permissive window is ironically best shown by a large number of failures in generating the animal model for acute myeloid leukemia (AML) with t(8;21). Over the decades, the RUNX1-ETO fusion gene created by t(8;21) has been introduced into various types of hematopoietic cells, largely at adult stage, in mice; however, all the previous attempts failed to generate tractable AML models. In stark contrast, we recently succeeded in inducing AML with the clinical features seen in human patients by specifically introducing RUNX1-ETO in childhood hematopoietic stem cells (HSCs). This result in mice is consistent with adolescent and young adult (AYA) onset in human t(8;21) patients, and suggests that childhood HSCs constitute the permissive window for RUNX1-ETO leukemogenesis. If loss of a permissive window is induced pharmacologically, cancer cells might be selectively targeted. Such a permissive window modifier may serve as a novel therapeutic drug.

Prolonged generation of multi-lineage blood cells in wild-type animals from pluripotent stem cells

Regenerating prolonged multi-lineage hematopoiesis from pluripotent stem cells (PSCs), an unlimited cell source, is a crucial aim of regenerative hematology. In this study, we used a gene-edited PSC line and revealed that simultaneous expression of three transcription factors, Runx1, Hoxa9, and Hoxa10, drove the robust emergence of induced hematopoietic progenitor cells (iHPCs). The iHPCs engrafted successfully in wild-type animals and repopulated abundant and complete myeloid-, B-, and T-lineage mature cells. The generative multi-lineage hematopoiesis distributed normally in multiple organs, persisted over 6 months, and eventually declined over time with no leukemogenesis. Transcriptome characterization of generative myeloid, B, and T cells at the single-cell resolution further projected their identities to natural cell counterparts. Thus, we provide evidence that co-expression of exogenous Runx1, Hoxa9, and Hoxa10 simultaneously leads to long-term reconstitution of myeloid, B, and T lineages using PSC-derived iHPCs as the cell source.

The RUNX Family, a Novel Multifaceted Guardian of the Genome

The DNA repair machinery exists to protect cells from daily genetic insults by orchestrating multiple intrinsic and extrinsic factors. One such factor recently identified is the Runt-related transcription factor (RUNX) family, a group of proteins that act as a master transcriptional regulator for multiple biological functions such as embryonic development, stem cell behaviors, and oncogenesis. A significant number of studies in the past decades have delineated the involvement of RUNX proteins in DNA repair. Alterations in RUNX genes cause organ failure and predisposition to cancers, as seen in patients carrying mutations in the other well-established DNA repair genes. Herein, we review the currently existing findings and provide new insights into transcriptional and non-transcriptional multifaceted regulation of DNA repair by RUNX family proteins.

Muscle Regeneration in Holothurians without the Upregulation of Muscle Genes

The holothurian Eupentacta fraudatrix is capable of fully restoring its muscles after transverse dissection. Although the regeneration of these structures is well studied at the cellular level, the molecular basis of the process remains poorly understood. To identify genes that may be involved in the regulation of muscle regeneration, the transcriptome of the longitudinal muscle band of E. fraudatrix has been sequenced at different time periods post-injury. An analysis of the map of biological processes and pathways has shown that most genes associated with myogenesis decrease their expression during the regeneration. The only exception is the genes united by the GO term "heart valve development". This may indicate the antiquity of mechanisms of mesodermal structure transformation, which was co-opted into various morphogeneses in deuterostomes. Two groups of genes that play a key role in the regeneration have been analyzed: transcription factors and matrix metalloproteinases. A total of six transcription factor genes (Ef-HOX5, Ef-ZEB2, Ef-RARB, Ef-RUNX1, Ef-SOX17, and Ef-ZNF318) and seven matrix metalloproteinase genes (Ef-MMP11, Ef-MMP13, Ef-MMP13-1, Ef-MMP16-2, Ef-MMP16-3, Ef-MMP24, and Ef-MMP24-1) showing differential expression during myogenesis have been revealed. The identified genes are assumed to be involved in the muscle regeneration in holothurians.

Regulome analysis in B-acute lymphoblastic leukemia exposes Core Binding Factor addiction as a therapeutic vulnerability

The ETV6-RUNX1 onco-fusion arises in utero, initiating a clinically silent pre-leukemic state associated with the development of pediatric B-acute lymphoblastic leukemia (B-ALL). We characterize the ETV6-RUNX1 regulome by integrating chromatin immunoprecipitation- and RNA-sequencing and show that ETV6-RUNX1 functions primarily through competition for RUNX1 binding sites and transcriptional repression. In pre-leukemia, this results in ETV6-RUNX1 antagonization of cell cycle regulation by RUNX1 as evidenced by mass cytometry analysis of B-lineage cells derived from ETV6-RUNX1 knock-in human pluripotent stem cells. In frank leukemia, knockdown of RUNX1 or its co-factor CBFβ results in cell death suggesting sustained requirement for RUNX1 activity which is recapitulated by chemical perturbation using an allosteric CBFβ-inhibitor. Strikingly, we show that RUNX1 addiction extends to other genetic subtypes of pediatric B-ALL and also adult disease. Importantly, inhibition of RUNX1 activity spares normal hematopoiesis. Our results suggest that chemical intervention in the RUNX1 program may provide a therapeutic opportunity in ALL.

RUNX Family in Hypoxic Microenvironment and Angiogenesis in Cancers

The tumor microenvironment (TME) is broadly implicated in tumorigenesis, as tumor cells interact with surrounding cells to influence the development and progression of the tumor. Blood vessels are a major component of the TME and are attributed to the creation of a hypoxic microenvironment, which is a common feature of advanced cancers and inflamed premalignant tissues. Runt-related transcription factor (RUNX) proteins, a transcription factor family of developmental master regulators, are involved in vital cellular processes such as differentiation, proliferation, cell lineage specification, and apoptosis. Furthermore, the RUNX family is involved in the regulation of various oncogenic processes and signaling pathways as well as tumor suppressive functions, suggesting that the RUNX family plays a strategic role in tumorigenesis. In this review, we have discussed the relevant findings that describe the crosstalk of the RUNX family with the hypoxic TME and tumor angiogenesis or with their signaling molecules in cancer development and progression.

Leukopenia, macrocytosis, and thrombocytopenia occur in young adults with Down syndrome

Down syndrome (DS) is a common congenital disorder caused by trisomy 21. Due to the increase in maternal age with population aging and advances in medical treatment for fatal complications in their early childhood, the prevalence and life expectancy of DS individuals have greatly increased. Despite this rise in the number of DS adults, their hematological status remains poorly examined. Here, we report that three hematological abnormalities, leukopenia, macrocytosis, and thrombocytopenia, develop as adult DS-associated features. Multi- and uni-variate analyses on hematological data collected from 51 DS and 60 control adults demonstrated that young adults with DS are at significantly higher risk of (i) myeloid-dominant leukopenia, (ii) macrocytosis characterized by high mean cell volume (MCV) of erythrocytes, and (iii) lower platelet counts than the control. Notably, these features were more pronounced with age. Further analyses on DS adults would provide a deeper understanding and novel research perspectives for multiple aging-related disorders in the general population.

Hematopoietic Stem Cell Factors: Their Functional Role in Self-Renewal and Clinical Aspects

Hematopoietic stem cells (HSCs) possess two important properties such as self-renewal and differentiation. These properties of HSCs are maintained through hematopoiesis. This process gives rise to two subpopulations, long-term and short-term HSCs, which have become a popular convention for treating various hematological disorders. The clinical application of HSCs is bone marrow transplant in patients with aplastic anemia, congenital neutropenia, sickle cell anemia, thalassemia, or replacement of damaged bone marrow in case of chemotherapy. The self-renewal attribute of HSCs ensures long-term hematopoiesis post-transplantation. However, HSCs need to be infused in large numbers to reach their target site and meet the demands since they lose their self-renewal capacity after a few passages. Therefore, a more in-depth understanding of ex vivo HSCs expansion needs to be developed to delineate ways to enhance the self-renewability of isolated HSCs. The multifaceted self-renewal process is regulated by factors, including transcription factors, miRNAs, and the bone marrow niche. A developed classical hierarchical model that outlines the hematopoiesis in a lineage-specific manner through in vivo fate mapping, barcoding, and determination of self-renewal regulatory factors are still to be explored in more detail. Thus, an in-depth study of the self-renewal property of HSCs is essentially required to be utilized for ex vivo expansion. This review primarily focuses on the Hematopoietic stem cell self-renewal pathway and evaluates the regulatory molecular factors involved in considering a targeted clinical approach in numerous malignancies and outlining gaps in the current knowledge.

Silencing of IGF2BP1 restrains ox-LDL-induced lipid accumulation and inflammation by reducing RUNX1 expression and promoting autophagy in macrophages

Atherosclerosis (AS) is a chronic inflammatory disease with the formation and accumulation of macrophage-derived foam cells in the subendothelial space of blood vessels as one major characteristic. Insulin-like growth factor 2 messenger RNA (mRNA) binding protein 1 (IGF2BP1) is an RNA-binding factor and its elevation has been reported to be associated with macrophage infiltration into the atherosclerotic vascular wall. This study aims to investigate the roles of IGF2BP1 in AS-associated foam cell formation. Herein, ApoE-/- mice fed with high-fat diet developed atherosclerotic lesions in the aorta, where IGF2BP1 expression was upregulated and autophagy was impaired. IGF2BP1 expressed in F4/80+ macrophages and coexisted with p62. In vitro, IGF2BP1 expression was upregulated in RAW264.7 macrophages exposed to oxidized low-density lipoprotein (ox-LDL) (100 μg/ml). Interestingly, silencing of IGF2BP1 ameliorated ox-LDL-induced lipid accumulation and inflammation, and enhanced autophagic flux in macrophages. Furthermore, the expression of RUNX family transcription factor 1 (RUNX1), a gene that is able to inhibit autophagy in multiple cell types, was elevated in atherosclerotic aortas and in ox-LDL-treated macrophages. In addition, RNA immunoprecipitation results revealed that IGF2BP1 is bound to RUNX1 mRNA. Alterations induced by IGF2BP1 knockdown in ox-LDL-treated macrophages were abolished by RUNX1 overexpression. Furthermore, after autophagy inhibitor 3-methyladenine administration, silencing of IGF2BP1-reduced lipid accumulation and inflammation were recovered in RAW264.7 cells. In summary, our study demonstrated that silencing of IGF2BP1 restrained ox-LDL-induced lipid accumulation and inflammation by reducing RUNX1 expression and facilitating autophagy in macrophages. IGF2BP1/RUNX1 axis may be considered as a potential therapeutic target in AS.

The spectrum of genetic mutations in myelodysplastic syndrome: Should we update prognostication?

The natural history of patients with myelodysplastic syndrome (MDS) is dependent upon the presence and magnitude of diverse genetic and molecular aberrations. The International Prognostic Scoring System (IPSS) and revised IPSS (IPSS-R) are the most widely used classification and prognostic systems; however, somatic mutations are not currently incorporated into these systems, despite evidence of their independent impact on prognosis. Our manuscript reviews prognostic information for TP53, EZH2, DNMT3A, ASXL1, RUNX1, SRSF2, CBL, IDH 1/2, TET2, BCOR, ETV6, GATA2, U2AF1, ZRSR2, RAS, STAG2, and SF3B1. Mutations in TP53, EZH2, ASXL1, DNMT3A, RUNX1, SRSF2, and CBL have extensive evidence for their negative impact on survival, whereas SF3B1 is the lone mutation carrying a favorable prognosis. We use the existing literature to propose the incorporation of somatic mutations into the IPSS-R. More data are needed to define the broad spectrum of other genetic lesions, as well as the impact of variant allele frequencies, class of mutation, and impact of multiple interactive genomic lesions. We postulate that the incorporation of these data into MDS prognostication systems will not only enhance our therapeutic decision making but lead to targeted treatment in an attempt to improve outcomes in this formidable disease.

Circ_0027599 elevates RUNX1 expression via sponging miR-21-5p on gastric cancer progression

BACKGROUND

Increasing evidence has shown that circular RNAs (circRNAs) serve as vital regulators in tumour progression. In this study, we focused on the functions of circ_0027599 in gastric cancer (GC) progression.

METHODS

The levels of circ_0027599, runt-related transcription factor 1 (RUNX1) mRNA and microRNA-21-5p (miR-21-5p) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) assay. The protein levels of RUNX1, E-Cadherin, vimentin and N-Cadherin were measured by Western blot assay. Cell viability, colony formation, metastasis and cell cycle process were evaluated by Cell Counting Kit-8 (CCK-8) assay, colony formation assay, transwell assay and flow cytometry analysis, respectively. The interaction between circ_0027599 and miR-21-5p and the interaction between miR-21-5p and RUNX1 were verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The role of circ_0027599 in tumour growth in vivo was investigated by murine xenograft model assay.

RESULTS

Circ_0027599 and RUNX1 were downregulated in GC tissues and cells. Circ_0027599 level was associated with the overall survival of GC patients. Circ_0027599 or RUNX1 overexpression inhibited GC cell viability, colony formation, migration, invasion and cell cycle process in vitro. For mechanism analysis, circ_0027599 positively regulated RUNX1 expression via functioning as the sponge for miR-21-5p. RUNX1 inhibition reversed circ_0027599 overexpression mediated malignant behaviours of GC cells. Moreover, circ_0027599 overexpression repressed tumour growth in vivo.

CONCLUSION

Circ_0027599 overexpression repressed GC progression via modulation of miR-21-5p/RUNX1 axis, which might illumine a novel therapeutic target for GC.

The Multiple Interactions of RUNX with the Hippo-YAP Pathway

The Hippo-YAP signaling pathway serves roles in cell proliferation, stem cell renewal/maintenance, differentiation and apoptosis. Many of its functions are central to early development, adult tissue repair/regeneration and not surprisingly, tumorigenesis and metastasis. The Hippo pathway represses the activity of YAP and paralog TAZ by modulating cell proliferation and promoting differentiation to maintain tissue homeostasis and proper organ size. Similarly, master regulators of development RUNX transcription factors have been shown to play critical roles in proliferation, differentiation, apoptosis and cell fate determination. In this review, we discuss the multiple interactions of RUNX with the Hippo-YAP pathway, their shared collaborators in Wnt, TGFβ, MYC and RB pathways, and their overlapping functions in development and tumorigenesis.

A concise review on the molecular genetics of acute myeloid leukemia

Acute myeloid leukemia (AML) is the most common acute leukemia in adults that affects the myeloid lineage. The recent advances have upgraded our understanding of the cytogenetic abnormalities and molecular mutations associated with AML that further aids in prognostication and risk stratification of the disease. Based on the highly heterogeneous nature of the disease and cytogenetic profile, AML patients can be stratified into favourable, intermediate and adverse-risk groups. The recurrent genetic alterations provide novel insights into the pathogenesis, clinical characteristics and also into the overall survival of the patients. In this review we are discussing about the cytogenetics of AML and the recurrent gene alterations such us NPM1, FLT3, CEBPA, TET-2, c-KIT, DNMT3A, IDH, RUNX1, AXSL1, WT1, Ras gene mutations etc. These gene mutations serve as important prognostic markers as well as potential therapeutic targets. AML patients respond to induction chemotherapy initially and subsequently achieve complete remission (CR), eventually most of them get relapsed.

Distinct association of RUNX family expression with genetic alterations and clinical outcome in acute myeloid leukemia

BACKGROUND

The runt-related transcription factor family (RUNXs) including RUNX1, RUNX2, and RUNX3 are key transcriptional regulators in normal hematopoiesis. RUNXs dysregulations caused by aberrant expression or mutation are frequently seen in various human cancers especially in acute myeloid leukemia (AML).

OBJECTIVE

We systemically analyzed the expression of RUNXs and their relationship with clinic-pathological features and prognosis in AML patients.

METHODS

Expression of RUNXs was analyzed between AML patients and normal controls from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) projects. Correlations between RUNXs expression and clinical features together with survival were further analyzed.

RESULTS

All RUNXs expression in AML patients was significantly increased as compared with controls. RUNXs expression was found to be significantly associated with genetic abnormalities such as RUNX1 mutation, t(8;21) and inv(16)/t(16;16). By Kaplan-Meier analysis, only RUNX3 overexpression was associated with shorter overall survival (OS) and disease-free survival (DFS) among non-M3 AML patients. Notably, in high RUNX3 expression groups, patients received hematopoietic stem cell transplantation (HSCT) had markedly better OS and DFS than patients without HSCT among both all AML and non-M3 AML. In low RUNX3 expression groups, there were no significant differences in OS and DFS between HSCT and non-HSCT groups among both all AML and non-M3 AML. In addition, a total of 835 differentially expressed genes and 69 differentially expressed microRNAs were identified to be correlated with RUNX3 expression in AML.

CONCLUSION

RUNXs overexpression was a frequent event in AML, and was closely associated with diverse genetic alterations. Moreover, RUNX3 expression may be associated with clinical outcome, and helpful for guiding treatment choice between HSCT and chemotherapy in AML.

RUNX1 gene expression in Egyptian acute myeloid leukemia patients: may it have therapeutic implications?

Background

Acute myeloid leukemia represents the highest percentage of all adult acute leukemia variants. Runt-related transcription factor1 (RUNX1), a transcription factor with a known tumor suppressor function, was recently reported as a tumor promoter in acute myeloid leukemia (AML). We investigated the role of RUNX1 gene expression level in Egyptian AML patients and delineated its clinical significance.

Results

We measured RUNX1 gene expression level using reverse transcription-quantitative polymerase chain reaction and found that the RUNX1 gene expression level was significantly higher than the control group (p < 0.001). Patients with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutations had a higher expression level of RUNX1 (p = 0.023). The male patients expressed a significantly higher level of RUNX1 (p = 0.046).

Conclusions

The RUNX1 gene is highly expressed in Egyptian AML patients. It has a relation to FLT3-ITD, which may give a clue that patients carrying this mutation may benefit from new treatments that target RUNX1 in the future. Further studies on a larger number of patients with different ethnic groups may give a clearer vision of the therapeutic implications of a new molecular target.

The Emerging Role of Hematopathologists and Molecular Pathologists in Detection, Monitoring, and Management of Myeloid Neoplasms with Germline Predisposition

PURPOSE OF REVIEW

Awareness, widespread availability, and routine use of sequencing techniques in work-up of myelodysplastic syndromes and acute myeloid leukemia have facilitated increased recognition of these entities arising in a background of germline predisposition disorders (GPD).

RECENT FINDINGS

The latest revisions to the WHO classification of myeloid neoplasms incorporate "myeloid neoplasms with germline predisposition" as a separate entity due to the therapeutic implications of this diagnosis. It has become apparent that some of these entities have unique recognizable morphologic findings that can be challenging to interpret at time. Hence, much needs to be studied, posing a new layer of complexity to hematopathologists and oncologists. A thorough understanding of cytogenetic and molecular findings during disease evolution is essential. Consequently, hematopathologists and molecular pathologists play an increasing role in recognition of bone marrow morphologic features that help in recognition of underlying GPD, monitoring, and prompt identification of progression.

Targeting RUNX1 in acute myeloid leukemia: preclinical innovations and therapeutic implications

Introduction: RUNX1 is an essential transcription factor for normal and malignant hematopoiesis. RUNX1 forms a heterodimeric complex with CBFB. Germline mutations and somatic alterations (i.e. translocations, mutations and abnormal expression) are frequently associated with acute myeloid leukemia (AML) with RUNX1 mutations conferring unfavorable prognosis. Therefore, RUNX1 constitutes a potential innovative and interesting therapeutic target. In this review, we discuss recent therapeutic advances of RUNX1 targeting in AML.Areas covered: Firstly, we cover the clinical basis for RUNX1 targeting. We have subdivided recent therapeutic approaches either by common biochemical pathways or by similar pharmacological targets. Genome editing of RUNX1 induces anti-leukemic effects; however, off-target events prohibit clinical use. Several molecules inhibit the interaction between RUNX1/CBFB and control AML development and progression. BET protein antagonists target RUNX1 (i.e. specific BET inhibitors, BRD4 shRNRA, proteolysis targeting chimeras (PROTAC) or expression-mimickers). All these molecules improve survival in mutant RUNX1 AML preclinical models.Expert opinion: Some of these novel molecules have shown encouraging anti-leukemic potency at the preclinical stage. A better understanding of RUNX1 function in AML development and progression and its key downstream pathways, may result in more precise and more efficient RUNX1 targeting therapies.

Epigenetics in a Spectrum of Myeloid Diseases and Its Exploitation for Therapy

Simple Summary

The genome is stored in the limited space of the nucleus in a highly condensed form. The regulation of this packaging contributes to determining the accessibility of genes and is important for cell function. Genes affecting the genome’s packaging are frequently mutated in bone marrow cells that give rise to the different types of blood cells. Here, we first discuss the molecular functions of these genes and their role in blood generation under healthy conditions. Then, we describe how their mutations relate to a subset of diseases including blood cancers. Finally, we provide an overview of the current efforts of using and developing drugs targeting these and related genes.

Abstract

Mutations in genes encoding chromatin regulators are early events contributing to developing asymptomatic clonal hematopoiesis of indeterminate potential and its frequent progression to myeloid diseases with increasing severity. We focus on the subset of myeloid diseases encompassing myelodysplastic syndromes and their transformation to secondary acute myeloid leukemia. We introduce the major concepts of chromatin regulation that provide the basis of epigenetic regulation. In greater detail, we discuss those chromatin regulators that are frequently mutated in myelodysplastic syndromes. We discuss their role in the epigenetic regulation of normal hematopoiesis and the consequence of their mutation. Finally, we provide an update on the drugs interfering with chromatin regulation approved or in development for myelodysplastic syndromes and acute myeloid leukemia.

HCV-Associated Exosomes Upregulate RUNXOR and RUNX1 Expressions to Promote MDSC Expansion and Suppressive Functions through STAT3-miR124 Axis

RUNX1 overlapping RNA (RUNXOR) is a long non-coding RNA and plays a pivotal role in the differentiation of myeloid cells via targeting runt-related transcription factor 1 (RUNX1). We and others have previously reported that myeloid-derived suppressor cells (MDSCs) expand and inhibit host immune responses during chronic viral infections; however, the mechanisms responsible for MDSC differentiation and suppressive functions, in particular the role of RUNXOR–RUNX1, remain unclear. Here, we demonstrated that RUNXOR and RUNX1 expressions are significantly upregulated and associated with elevated levels of immunosuppressive molecules, such as arginase 1 (Arg1), inducible nitric oxide synthase (iNOS), signal transducer and activator of transcription 3 (STAT3), and reactive oxygen species (ROS) in MDSCs during chronic hepatitis C virus (HCV) infection. Mechanistically, we discovered that HCV-associated exosomes (HCV-Exo) can induce the expressions of RUNXOR and RUNX1, which in turn regulates miR-124 expression via STAT3 signaling, thereby promoting MDSC differentiation and suppressive functions. Importantly, overexpression of RUNXOR in healthy CD33⁺ myeloid cells promoted differentiation and suppressive functions of MDSCs. Conversely, silencing RUNXOR or RUNX1 expression in HCV-derived CD33⁺ myeloid cells significantly inhibited their differentiation and expressions of suppressive molecules and improved the function of co-cultured autologous CD4 T cells. Taken together, these results indicate that the RUNXOR–RUNX1–STAT3–miR124 axis enhances the differentiation and suppressive functions of MDSCs and could be a potential target for immunomodulation in conjunction with antiviral therapy during chronic HCV infection.

[RUNX1 gene mutations are associated with adverse prognosis of patients with acute myeloidleukemia]

OBJECTIVE

To explore the rate and distribution of Runt- related transcription factor 1 (RUNX1) gene mutations in patients with acute myeloid leukemia (AML) and the correlation of these mutations with the clinical characteristics and survival outcomes of the patients.

METHODS

The genomic DNA extracted from the bone marrow of 158 patients with newly diagnosed AML for PCR amplification of RUNX1 gene and sequence analysis to identify the mutations. The mutations of ASXL1, DNMT3A, TET2, FLT3, CEBPA, NPM1, IDH2, NRAS and c-KIT genes were also examined to analyze their association with RUNX1 gene mutations.

RESULTS

Among the 158 AML patients, 19 (12.0%) were found to have RUNX1 mutations in A166G (9 cases), A142T (6 cases) and A162L (4 cases). RUNX1 mutations were more frequent in elderly patients (P < 0.01) and in cases of AML subtypes M4 and M5, and were associated with more frequent CD36 and CD7 expression as compared with the wild type. RUNX1 mutations were more likely to occur in patients with normal karyotype or karyotypes associated with moderate prognostic risks, but the difference was not significant (P > 0.05). The patients with RUNX1 mutations had significantly lower complete remission (CR) rate and overall survival (OS) rate than those without the mutations (P < 0.05). RUNX1 mutations were not associated with gender, white blood cell count upon diagnosis, hemoglobin level, platelet count, bone marrow blast cell ratio or lactate dehydrogenase level (P > 0.05).

CONCLUSIONS

RUNX1 gene mutations are associated with an adverse prognosis of patients with AML.

Cooperating, congenital neutropenia-associated Csf3r and Runx1 mutations activate pro-inflammatory signaling and inhibit myeloid differentiation of mouse HSPCs

Patients with the pre-leukemia bone marrow failure syndrome called severe congenital neutropenia (CN) have an approximately 15% risk of developing acute myeloid leukemia (AML; called here CN/AML). Most CN/AML patients co-acquire CSF3R and RUNX1 mutations, which play cooperative roles in the development of AML. To establish an in vitro model of leukemogenesis, we utilized bone marrow lin^- cells from transgenic C57BL/6-d715 Csf3r mice expressing a CN patient-mimicking truncated CSF3R mutation. We transduced these cells with vectors encoding RUNX1 wild type (WT) or RUNX1 mutant proteins carrying the R139G or R174L mutations. Cells transduced with these RUNX1 mutants showed diminished in vitro myeloid differentiation and elevated replating capacity, compared with those expressing WT RUNX1. mRNA expression analysis showed that cells transduced with the RUNX1 mutants exhibited hyperactivation of inflammatory signaling and innate immunity pathways, including IL-6, TLR, NF-kappaB, IFN, and TREM1 signaling. These data suggest that the expression of mutated RUNX1 in a CSF3R-mutated background may activate the pro-inflammatory cell state and inhibit myeloid differentiation.

Genetic Predisposition to Myelodysplastic Syndrome in Clinical Practice

Myelodysplastic syndromes (MDSs) are a heterogeneous group of marrow failure disorders that primarily affect older persons but also occur at a lower frequency in children and young adults. There is increasing recognition of an inherited predisposition to MDS as well as other myeloid malignancies for patients of all ages. Germline predisposition to MDS can occur as part of a syndrome or sporadic disease. The timely diagnosis of an underlying genetic predisposition in the setting of MDS is important. This article delineates germline genetic causes of MDS and provides a scaffold for the diagnosis and management of patients in this context.

The RUNX1 Enhancer Element eR1: A Versatile Marker for Adult Stem Cells

The identification of adult stem cells is challenging because of the heterogeneity and plasticity of stem cells in different organs. Within the same tissue, stem cells may be highly proliferative, or maintained in a quiescent state and only to be activated after tissue damage. Although various stem cell markers have been successfully identified, there is no universal stem cell marker, which is exclusively expressed in all stem cells. Here, we discuss the roles of master developmental regulator RUNX1 in stem cells and the development of a 270 base pair fragment of the Runx1 enhancer (eR1) for use as stem cell marker. Using eR1 to identify stem cells offers a distinct advantage over gene promoters, which might not be expressed exclusively in stem cells. Moreover, RUNX1 has been strongly implicated in various cancer types, such as leukemia, breast, esophageal, prostate, oral, skin, and ovarian cancers?it has been suggested that RUNX1 dysfunction promotes stem cell dysfunction and proliferation. As tissue stem cells are potential candidates for cancer cells-of-origin and cancer stem cells, we will also discuss the use of eR1 to target oncogenic gene manipulations in stem cells and to track subsequent neoplastic changes.

Complex Interplay between the RUNX Transcription Factors and Wnt/β-Catenin Pathway in Cancer: A Tango in the Night

Cells are designed to be sensitive to a myriad of external cues so they can fulfil their individual destiny as part of the greater whole. A number of well-characterised signalling pathways dictate the cell's response to the external environment and incoming messages. In healthy, well-ordered homeostatic systems these signals are tightly controlled and kept in balance. However, given their powerful control over cell fate, these pathways, and the transcriptional machinery they orchestrate, are frequently hijacked during the development of neoplastic disease. A prime example is the Wnt signalling pathway that can be modulated by a variety of ligands and inhibitors, ultimately exerting its effects through the β-catenin transcription factor and its downstream target genes. Here we focus on the interplay between the three-member family of RUNX transcription factors with the Wnt pathway and how together they can influence cell behaviour and contribute to cancer development. In a recurring theme with other signalling systems, the RUNX genes and the Wnt pathway appear to operate within a series of feedback loops. RUNX genes are capable of directly and indirectly regulating different elements of the Wnt pathway to either strengthen or inhibit the signal. Equally, β-catenin and its transcriptional co-factors can control RUNX gene expression and together they can collaborate to regulate a large number of third party co-target genes.

The Clinical, Molecular, and Mechanistic Basis of RUNX1 Mutations Identified in Hematological Malignancies

RUNX1 plays an important role in the regulation of normal hematopoiesis. RUNX1 mutations are frequently found and have been intensively studied in hematological malignancies. Germline mutations in RUNX1 cause familial platelet disorder with predisposition to acute myeloid leukemia (FPD/AML). Somatic mutations of RUNX1 are observed in various types of hematological malignancies, such as AML, acute lymphoblastic leukemia (ALL), myelodysplastic syndromes (MDS), myeloproliferative neoplasm (MPN), chronic myelomonocytic leukemia (CMML), and congenital bone marrow failure (CBMF). Here, we systematically review the clinical and molecular characteristics of RUNX1 mutations, the mechanisms of pathogenesis caused by RUNX1 mutations, and potential therapeutic strategies to target RUNX1-mutated cases of hematological malignancies.

Role of RUNX Family Transcription Factors in DNA Damage Response

Cells are constantly exposed to endogenous and exogenous stresses that can result in DNA damage. In response, they have evolved complex pathways to maintain genomic integrity. RUNX family transcription factors (RUNX1, RUNX2, and RUNX3 in mammals) are master regulators of development and differentiation, and are frequently dysregulated in cancer. A growing body of research also implicates RUNX proteins as regulators of the DNA damage response, often acting in conjunction with the p53 and Fanconi anemia pathways. In this review, we discuss the functional role and mechanisms involved in RUNX factor mediated response to DNA damage and other cellular stresses. We highlight the impact of these new findings on our understanding of cancer predisposition associated with RUNX factor dysregulation and their implications for designing novel approaches to prevent cancer formation in affected individuals.

RUNX1 Mutations in the Leukemic Progression of Severe Congenital Neutropenia

Somatic RUNX1 mutations are found in approximately 10% of patients with de novo acute myeloid leukemia (AML), but are more common in secondary forms of myelodysplastic syndrome (MDS) or AML. Particularly, this applies to MDS/AML developing from certain types of leukemia-prone inherited bone marrow failure syndromes. How these RUNX1 mutations contribute to the pathobiology of secondary MDS/AML is still unknown. This mini-review focusses on the role of RUNX1 mutations as the most common secondary leukemogenic hit in MDS/AML evolving from severe congenital neutropenia (SCN).

Comparison of mutational profiles and clinical outcomes in patients with acute myeloid leukemia with mutated RUNX1 versus acute myeloid leukemia with myelodysplasia-related changes with mutated RUNX1

Studies comparing the prognostic role of RUNX1 mutations (RUNX1^mut) in acute myeloid leukemia (AML) and acute myeloid leukemia-with myelodysplasia-related changes (AML-MRC) are limited. Our study examines the genetic profile of 118 RUNX1^mut AML patients including 57 AML with RUNX1^mut and 61 AML-MRC with RUNX1^mut and 100 AML, NOS patients with wild type RUNX1 (RUNX1^wt). Results revealed that AML-MRC patients with RUNX1^mut had shorter median overall survival (OS) (11 ± 3.3 months) when compared to AML with RUNX1^mut (19 ± 7.1 months) and AML, NOS with RUNX1^wt (not reached) (p = .001). The most common concurrent mutations observed in AML-MRC with RUNX1^mut patients were DNMT3A, SRSF2, ASXL1, and IDH2 while in AML with RUNX1^mut patients were ASXL1, SRSF2, TET2, IDH2, and DNMT3A. ASXL1 and TET2 mutations appeared to adversely affect OS in AML-MRC, but not in AML with RUNX1^mut. Concurrent RUNX1/DNMT3A mutations, in contrast had negative impact on OS in AML with RUNX1^mut, but not in AML-MRC with RUNX1^mut.

RUNX1 mutations enhance self-renewal and block granulocytic differentiation in human in vitro models and primary AMLs

To unravel molecular mechanisms by which Runt-related transcription factor 1 (RUNX1) mutations contribute to leukemic transformation, we introduced the RUNX1-S291fs300X mutation in human CD34⁺ stem/progenitor cells and in human induced pluripotent stem cells (iPSCs). In both models, RUNX1mut overexpression strongly impaired myeloid commitment. Instead, self-renewal was enhanced, as shown, by increased long-term culture-initiating cell frequencies and enhanced colony-forming cell replating capacity. Long-term suspension cultures with RUNX1mut-transduced cord blood (CB) CD34⁺ cells continued for more than 100 days, during which the cells displayed an immature granulocyte-macrophage progenitor-like CD34⁺/CD123⁺/CD45RA⁺ phenotype. The CD34⁺/CD38^- hematopoietic stem cell (HSC) population most likely acted as cell of origin, as HSCs provided the best long-term proliferative potential on overexpression of RUNX1mut. CEBPA expression was reduced in RUNX1mut cells, and reexpression of CEBPA partly restored differentiation. RNA-seq analysis on CB/iPSC systems and on primary patient samples confirmed that RUNX1 mutations induce a myeloid differentiation block, and that a common set of RUNX1mut-upregulated target genes was strongly enriched for gene ontology terms associated with nucleosome assembly and chromatin structure. Interestingly, in comparison with AML1-ETO binding in acute myeloid leukemias (AMLs), we found significantly distinct genomic distribution and differential expression for RUNX1mut of genes such as TCF4, MEIS1, and HMGA2 that may potentially contribute to the underlying difference in clinical outcomes between RUNX1mut and AML1-ETO patients. In conclusion, RUNX1mut appears to induce a specific transcriptional program that contributes to leukemic transformation.

The functional mechanisms of mutations in myelodysplastic syndrome

Overlapping spectrum of mutated genes affected in myelodysplastic syndrome (MDS) and primary acute myeloid leukemia suggest common pathogenic mechanisms. However, the frequencies of specific mutations are significantly different between them, which implies they might determine specific disease phenotype. For instance, there are overrepresentations of mutations in RNA splicing factors or epigenetic regulators in MDS. We provide an overview of recent advances in our understanding of the biology of MDS and related disorders. Our focus is how mutations of in splicing factors or epigenetic regulators identified in MDS patients demonstrate phenotypes in knockin/knockout mouse models. For instance, mutant Srsf2 mice could alter Srsf2's normal sequence-specific RNA binding activity. It exhibited changing in the recognition of specific exonic splicing enhancer motifs to drive recurrent missplicing of Ezh2, which reduces Ezh2 expression by promoting nonsense-mediated decay. Consistent with this, SRSF2 mutations are mutually exclusive with EZH2 loss-of-function mutations in MDS patients. We also review how gene editing technology identified unique associations between pathogenic mechanisms and targeted therapy using lenalidomide, including: (i) how haploinsufficiency of the genes located in the commonly deleted region in del(5q) MDS patients promotes MDS; (ii) how lenalidomide causes selective elimination of del(5q) MDS cells; and (iii) why del(5q) MDS patients become resistant to lenalidomide. Thus, this review describes our current understanding of the mechanistic and biological effects of mutations in spliceosome and epigenetic regulators by comparing wild-type normal to mutant function as well as a brief overview of the recent progresses in MDS biology.

RUNX family: Oncogenes or tumor suppressors (Review)

Runt-related transcription factor (RUNX) proteins belong to a transcription factors family known as master regulators of important embryonic developmental programs. In the last decade, the whole family has been implicated in the regulation of different oncogenic processes and signaling pathways associated with cancer. Furthermore, a suppressor tumor function has been also reported, suggesting the RUNX family serves key role in all different types of cancer. In this review, the known biological characteristics, specific regulatory abilities and experimental evidence of RUNX proteins will be analyzed to demonstrate their oncogenic potential and tumor suppressor abilities during oncogenic processes, suggesting their importance as biomarkers of cancer. Additionally, the importance of continuing with the molecular studies of RUNX proteins' and its dual functions in cancer will be underlined in order to apply it in the future development of specific diagnostic methods and therapies against different types of cancer.

Thermodynamic investigation of DNA-binding affinity of wild-type and mutant transcription factor RUNX1

Transcription factor RUNX1 and its binding partner CBFβ play a critical role in gene regulation for hematopoiesis. Mutations of RUNX1 cause ~10% of acute myeloid leukemia (AML) with a particularly poor prognosis. The current paradigm for the leukemogenesis is that insufficient activity of wild-type (WT) RUNX1 impairs hematopoietic differentiation. The majority of mutant RUNX1 proteins lose the DNA-binding affinity and inhibit WT RUNX1 by depletion of CBFβ. Here, isothermal titration calorimetry (ITC) was used to quantitatively study the interactions of WT and three clinical mutant RUNX1, CBFβ and DNA. Our data show that the binding of RUNX1 to DNA is enthalpy-driven, and the affinity decreases in the order of WT > S114L > R139Q >> K83E, which support previous observations and conclusion. To find potentially beneficial RUNX1 mutations that could increase the overall RUNX1 activity, K83R and H179K mutations of RUNX1 were designed, using structure-based computational modeling, and found to possess significantly higher DNA-binding affinities than does WT RUNX1. K83R and H179K mutant RUNX1 could therefore be protein-based RUNX1 activators.

Signal Transducer and Activator of Transcription (STATs) Proteins in Cancer and Inflammation: Functions and Therapeutic Implication

Signal Transducer and Activator of Transcription (STAT) pathway is connected upstream with Janus kinases (JAK) family protein and capable of integrating inputs from different signaling pathways. Each family member plays unique functions in signal transduction and crucial in mediating cellular responses to different kind of cytokines. STAT family members notably STAT3 and STAT5 have been involved in cancer progression whereas STAT1 plays opposite role by suppressing tumor growth. Persistent STAT3/5 activation is known to promote chronic inflammation, which increases susceptibility of healthy cells to carcinogenesis. Here, we review the role of STATs in cancers and inflammation while discussing current therapeutic implications in different cancers and test models, especially the delivery of STAT3/5 targeting siRNA using nanoparticulate delivery system.

RUNX proteins desensitize multiple myeloma to lenalidomide via protecting IKZFs from degradation

Ikaros family zinc finger protein 1 and 3 (IKZF1 and IKZF3) are transcription factors that promote multiple myeloma (MM) proliferation. The immunomodulatory imide drug (IMiD) lenalidomide promotes myeloma cell death via Cereblon (CRBN)-dependent ubiquitylation and proteasome-dependent degradation of IKZF1 and IKZF3. Although IMiDs have been used as first-line drugs for MM, the overall survival of refractory MM patients remains poor and demands the identification of novel agents to potentiate the therapeutic effect of IMiDs. Using an unbiased screen based on mass spectrometry, we identified the Runt-related transcription factor 1 and 3 (RUNX1 and RUNX3) as interactors of IKZF1 and IKZF3. Interaction with RUNX1 and RUNX3 inhibits CRBN-dependent binding, ubiquitylation, and degradation of IKZF1 and IKZF3 upon lenalidomide treatment. Inhibition of RUNXs, via genetic ablation or a small molecule (AI-10-104), results in sensitization of myeloma cell lines and primary tumors to lenalidomide. Thus, RUNX inhibition represents a valuable therapeutic opportunity to potentiate IMiDs therapy for the treatment of multiple myeloma.

Alternative translation initiation generates the N-terminal truncated form of RUNX1 that retains hematopoietic activity

Transcription factor RUNX1 plays a crucial role in hematopoiesis and its activity is tightly regulated at both the transcriptional and posttranslational levels. However, translational control of RUNX1 expression has not been fully understood. In this study, we demonstrated that RUNX1b mRNA is translated from two alternative initiation sites, Met-1 and Met-25, giving full-length RUNX1b and a shorter protein lacking the first 24 amino acids (RUNX1ΔN24). Presence/absence of strong Kozak consensus sequences around Met-1 determines which initiation site is mainly used in RUNX1b cDNA. Selective disruption of either Met-1 or Met-25 abrogates expression of the corresponding protein while facilitating the production of another protein. The RUNX1b cDNA containing 65bp natural promoter sequences mainly produces full-length RUNX1b in human cord blood cells, but disruption of Met-1 in this cDNA also induced translation from Met-25. Consistent with these data, disruption of endogenous RUNX1b around Met-1 using CRISPR/Cas9 induced selective expression of RUNX1ΔΝ24 in several leukemia cell lines. RUNX1ΔN24 protein is more stable than full-length RUNX1b and retains hematopoietic activity. We also found that FLAG-tagged full-length RUNX1 showed altered activity, indicating the influence of N-terminal FLAG-tag on RUNX1 function. The alternative translation initiation of RUNX1b may participate in fine tuning RUNX1 activity.

Disease modeling of bone marrow failure syndromes using iPSC-derived hematopoietic stem progenitor cells

The plasticity of induced pluripotent stem cells (iPSCs) with the potential to differentiate into virtually any type of cells and the feasibility of generating hematopoietic stem progenitor cells (HSPCs) from patient-derived iPSCs (iPSC-HSPCs) has many potential applications in hematology. For example, iPSC-HSPCs are being used for leukemogenesis studies and their application in various cell replacement therapies is being evaluated. The use of iPSC-HSPCs can now provide an invaluable resource for the study of diseases associated with the destruction of HSPCs, such as bone marrow failure syndromes (BMFSs). Recent studies have shown that generating iPSC-HSPCs from patients with acquired aplastic anemia and other BMFSs is not only feasible, but is also a powerful tool for understanding the pathogenesis of these disorders. In this article, we highlight recent advances in the application of iPSCs for disease modeling of BMFSs and discuss the discoveries of these studies that provide new insights in the pathophysiology of these conditions.

Expression and Prognosis Analyses of Runt-Related Transcription Factor Family in Human Leukemia

Despite advances in early diagnosis and treatment, cancer remains the major reason for mortality worldwide. The Runt-related transcription factor (RUNX) family has been reported to participate in diverse human diseases. However, little is known about their expression and prognostic values in human leukemia. Herein, we conducted a detailed cancer versus normal analysis. The mRNA expression levels of the RUNX family in various kinds of cancers, including leukemia, were analyzed via the ONCOMINE and GEPIA (Gene Expression Profiling Interactive Analysis) databases. We observed that the mRNA expression levels of RUNX1, RUNX2, and RUNX3 were all increased in most cancers compared with normal tissues, especially in leukemia. Moreover, the expression levels of RUNX1, RUNX2, and RUNX3 are also highly expressed in almost all cancer cell lines, particularly in acute myeloid leukemia (AML) cell lines, analyzed by Cancer Cell Line Encyclopedia (CCLE) and European Bioinformatics Institute (EMBL-EBI) databases. Further, the LinkedOmics and GEPIA databases were used to evaluate the prognostic values. In survival analyses based on LinkedOmics, higher expression of RUNX1 and RUNX2 indicated a better overall survival (OS), but with no significance, whereas increased RUNX3 revealed a poor OS in leukemia. In addition, the GEPIA dataset was also used to perform survival analyses, and results manifested that the expression of RUNX1 and RUNX2 had no remarkable correction with OS in leukemia, but it showed highly expressed RUNX3 was significantly related with poor OS in leukemia. In conclusion, the RUNX family showed significant expression differences between cancer and normal tissues, especially leukemia, and RUNX3 could be a promising prognostic biomarker for leukemia.