Signal transduction inhibitors in treatment of myelodysplastic syndromes

The novel peptide PEP-Z-2 potentially treats renal fibrosis in vivo and in vitro by regulating TGF-β/Smad/AKT/MAPK signaling

Renal fibrosis is a process in which excessive deposition of extracellular matrix leads to an increase in tissue hardness and gradual destruction of the renal parenchyma. Chronic kidney disease (CKD) commonly progresses to end-stage renal disease (ESRD), ultimately leading to renal failure. This disease has high incidence and mortality rates, but to date, effective treatment options are lacking. PEP-Z-2 is a collagen peptide isolated from redlip croaker scales and may have potential fibroprotective activity. In this study, PEP-Z-2 was found to alleviate unilateral ureteral obstruction (UUO)- and folic acid (FA)-induced kidney injury in a mouse model, reduce collagen deposition in tissues, normalize renal function, reduce the expression of fibrosis markers, reduce reactive oxygen species (ROS) production, and restore the balance of the oxidant/antioxidant system. In vitro experiments also demonstrated that PEP-Z-2 inhibits the TGF-β-induced differentiation of fibroblasts and renal tubular epithelial cells into myofibroblasts and reduces the production of extracellular matrix (ECM) proteins such as fibronectin, Col I, and α-SMA, demonstrating notable therapeutic effects on renal fibrosis. This effect is achieved by regulating the TGF-β/Smad/AKT/MAPK pathway. Our research suggested that PEP-Z-2 is a potential therapeutic drug for renal fibrosis, and peptides from aquatic organisms may constitute a new class of candidate drugs for the treatment of renal fibrosis and even other types of organ fibrosis.

Targeted therapies for myelodysplastic syndromes/neoplasms (MDS): current landscape and future directions

INTRODUCTION

Myelodysplastic syndromes/neoplasms (MDS) are a heterogeneous group of hematologic malignancies that are stratified into high-risk (HR-MDS) and low-risk (LR-MDS) categories. Until recently, LR-MDS has been typically managed by supportive measures and erythropoiesis-stimulating agents (ESAs); whereas management of HR-MDS typically included hypomethylating agents and allogeneic hematopoietic stem cell transplant. However, the limited rates and durations of response observed with these interventions prompted the search for targeted therapies to improve the outcomes among patients with MDS.

AREAS COVERED

Here, we review the current landscape of targeted therapies in MDS. These include pyruvate kinase and hypoxia-inducible factor (HIF) activators; TGF-beta, telomerase, BCL2 and isocitrate dehydrogenase (IDH) inhibitors; as well as novel approaches targeting inflammation, pyroptosis, immune evasion, and RNA splicing machinery.

EXPERT OPINION

This review highlights the progress and challenges in MDS treatment. Despite some promising results, many therapies remain in early development or have faced setbacks, emphasizing the need for a more comprehensive understanding of the disease's pathobiology. Continued research into targeted therapies, homogenous clinical trial designs, as well as increased incorporation of molecular prognostic tools and artificial intelligence into trial design are essential for developing effective treatments for MDS and improving patient outcomes.

C3a/C3aR synergies with TGF-β to promote epithelial-mesenchymal transition of renal tubular epithelial cells via the activation of the NLRP3 inflammasome

BACKGROUND

Complement component 3a and its receptor (C3a/C3aR) and the nucleotide-binding oligomerization domain-like receptor protein-3 (NLRP3) inflammasome contribute to epithelial-mesenchymal transition (EMT). However, the relationship between C3a/C3aR and the NLRP3 inflammasome in EMT remains unclear. This study aimed to elucidate the roles of C3a/C3aR and the NLRP3 inflammasome involved in TGF-β-induced EMT.

METHOD

Mouse renal tubular epithelial cells (TCMK-1) were exposed to C3a and TGF-β for 48 h. C3aR antagonist, MCC950, an inhibitor of the NLRP3 inflammasome and PD98059, an inhibitor of ERK signaling, were respectively applied to pretreat the cells at 30 min before C3a and TGF-β administration.The cells were collected for western blot, immunofluorescence staining and ELISA. Unilateral ureteral obstruction (UUO) models were established using male C57BL/6 wild-type (WT) mice and age-matched C3aR-deficient mice. MCC950 was intraperitoneally injected in UUO mice. Kidney samples were collected for immunohistochemistry staining.

RESULTS

In vitro, C3a synergized with TGF-β to promote EMT and the activation of the NLRP3 inflammasome. Inhibition of C3aR attenuated EMT and the activation of the NLRP3 inflammasome. Inhibition of the NLRP3 inflammasome alleviated EMT but didn't affect the expression of C3aR. Inhibition of ERK signaling inhibited the activation of the NLRP3 inflammasome. In vivo, the expression of IL-1β was significantly higher in UUO mice compared to the sham-operated mice. C3aR deficiency and inhibition of the NLRP3 Inflammasome contributed to decreased IL-1β in UUO mice.

CONCLUSION

Our data revealed that C3a/C3aR synergies with TGF-β to activate the NLRP3 inflammasome to promote epithelial-mesenchymal transition of renal tubular epithelial cells through ERK signaling, and the way in which C3aR activates the inflammasome is to promote the assembly of the NLRP3 inflammasome.

Subclones with variants of uncertain clinical significance might contribute to ineffective hemopoiesis and leukemia predisposition

BACKGROUND

Splicing modifications, genomic instability, and hypomethylation are central mechanisms promoting myelodysplasia and acute myeloid leukemia (AML). In this real-life retrospective study, to elucidate pathophysiology of clonal hemopoiesis in hematological malignancies, we investigated clinical significance of mutations in leukemia-related genes of known pathogenetic significance and of variants of uncertain clinical significance (VUS) in a cohort of patients with MDS and AML.

METHODS

A total of 59 consecutive subjects diagnosed with MDS, 48 with AML, and 17 with clonal cytopenia with unknown significance were screened for somatic mutations in AML-related genes by next-generation sequencing.

RESULTS

We showed that TET2, SETBP1, ASXL1, EZH2, RUNX1, SRSF2, DNMT3A, and IDH1/2 were commonly mutated. MDS patients also showed a high genetic complexity, especially for SETBP1. Moreover, the presence of SETBP1 wild-type or two or more simultaneous VUS variants identified a subgroup of AML and MDS patients with better outcome, while the presence of single SETBP1 VUS variant was related to a worse prognosis, regardless TET2 mutational status.

CONCLUSIONS

In conclusions, we linked both pathogenic and VUS variants in AML-related genes to clonal hematopoiesis; therefore, we proposed to consider those variants as prognostic markers in leukemia and myelodysplasia. However, further studies in larger prospective cohorts are required to validate our results.

Epithelial cell dysfunction in chronic rhinosinusitis: the epithelial-mesenchymal transition

INTRODUCTION

Epithelial-mesenchymal transition (EMT) is a type of epithelial cell dysfunction, which is widely present in the nasal mucosa of patients with chronic rhinosinusitis (CRS), especially CRS with nasal polyps, and contributes to pathogenesis of the disease. EMT is mediated via complex mechanisms associated with multiple signaling pathways.

AREAS COVERED

We have summarized the underlying mechanisms and signaling pathways promoting EMT in CRS. Strategies or drugs/agents targeting the genes and pathways related to the regulation of EMT are also discussed for their potential use in the treatment of CRS and asthma. A literature search of studies published in English from 2000 to 2023 was conducted using the PubMed database, employing CRS, EMT, signaling, mechanisms, targeting agents/drugs, as individual or combinations of search terms.

EXPERT OPINION

EMT in nasal epithelium not only leads to epithelial cell dysfunction but also plays an important role in nasal tissue remodeling in CRS. A comprehensive understanding of the mechanisms underlying EMT and the development of drugs/agents targeting these mechanisms may provide new treatment strategies for CRS.

The genetics of myelodysplastic syndromes and the opportunities for tailored treatments

Genomic instability, microenvironmental aberrations, and somatic mutations contribute to the phenotype of myelodysplastic syndrome and the risk for transformation to AML. Genes involved in RNA splicing, DNA methylation, histone modification, the cohesin complex, transcription, DNA damage response pathway, signal transduction and other pathways constitute recurrent mutational targets in MDS. RNA-splicing and DNA methylation mutations seem to occur early and are reported as driver mutations in over 50% of MDS patients. The improved understanding of the molecular landscape of MDS has led to better disease and risk classification, leading to novel therapeutic opportunities. Based on these findings, novel agents are currently under preclinical and clinical development and expected to improve the clinical outcome of patients with MDS in the upcoming years. This review provides a comprehensive update of the normal gene function as well as the impact of mutations in the pathogenesis, deregulation, diagnosis, and prognosis of MDS, focuses on the most recent advances of the genetic basis of myelodysplastic syndromes and their clinical relevance, and the latest targeted therapeutic approaches including investigational and approved agents for MDS.

CRISPR/CasRx-Mediated RNA Knockdown Reveals That ACE2 Is Involved in the Regulation of Oligodendroglial Cell Morphological Differentiation

Angiotensin-converting enzyme 2 (ACE2) plays a role in catalyzing angiotensin II conversion to angiotensin (1–7), which often counteracts the renin-angiotensin system. ACE2 is expressed not only in the cells of peripheral tissues such as the heart and kidney, but also in those of the central nervous system (CNS). Additionally, ACE2 acts as the receptor required for the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), whose binding leads to endocytotic recycling and possible degradation of the ACE2 proteins themselves. One of the target cells for SARS-CoV-2 in the CNS is oligodendrocytes (oligodendroglial cells), which wrap neuronal axons with their differentiated plasma membranes called myelin membranes. Here, for the first time, we describe the role of ACE2 in FBD-102b cells, which are used as the differentiation models of oligodendroglial cells. Unexpectedly, RNA knockdown of ACE2 with CasRx-mediated gRNA or the cognate siRNA promoted oligodendroglial cell morphological differentiation with increased expression or phosphorylation levels of differentiation and/or myelin marker proteins, suggesting the negative role of ACE2 in morphological differentiation. Notably, ACE2′s intracellular region preferentially interacted with the active GTP-bound form of Ras. Thus, knockdown of ACE2 relatively increased GTP-bound Ras in an affinity-precipitation assay. Indeed, inhibition of Ras resulted in decreasing both morphological differentiation and expression or phosphorylation levels of marker proteins, confirming the positive role of Ras in differentiation. These results indicate the role of ACE2 itself as a negative regulator of oligodendroglial cell morphological differentiation, newly adding ACE2 to the list of regulators of oligodendroglial morphogenesis as well as of Ras-binding proteins. These findings might help us to understand why SARS-CoV-2 causes pathological effects in the CNS.

Targeting TGF-β signal transduction for fibrosis and cancer therapy

Transforming growth factor β (TGF-β) has long been identified with its intensive involvement in early embryonic development and organogenesis, immune supervision, tissue repair, and adult homeostasis. The role of TGF-β in fibrosis and cancer is complex and sometimes even contradictory, exhibiting either inhibitory or promoting effects depending on the stage of the disease. Under pathological conditions, overexpressed TGF-β causes epithelial-mesenchymal transition (EMT), extracellular matrix (ECM) deposition, cancer-associated fibroblast (CAF) formation, which leads to fibrotic disease, and cancer. Given the critical role of TGF-β and its downstream molecules in the progression of fibrosis and cancers, therapeutics targeting TGF-β signaling appears to be a promising strategy. However, due to potential systemic cytotoxicity, the development of TGF-β therapeutics has lagged. In this review, we summarized the biological process of TGF-β, with its dual role in fibrosis and tumorigenesis, and the clinical application of TGF-β-targeting therapies.

Utilizing network pharmacology to explore potential mechanisms of YiSui NongJian formula in treating myelodysplastic syndrome

The study aims to explore potential mechanisms of YiSui NongJian formula (YSNJF) in treating myelodysplastic syndromes (MDS) by network pharmacology-based strategy. Active compounds and corresponding potential therapeutic targets of YSNJF were harvested by utilizing the database of TCMSP (Traditional Chinese Medicine Systems Pharmacology) and BATMAN-TCM (Bioinformatics Analysis Tool for Molecular mechanism of Traditional Chinese Medicine). MDS targets were adopted from GeneCard, KEGG (Kyoto Encyclopedia of Genes and Genomes), TTD (Therapeutic Target Database), DrugBank, and DisGeNet. Then a network of YSNJF- compounds-target-MDS network was harvested. The protein–protein interaction (PPI) network was then generated by the Sting database and subjected to Cytoscape software to harvest major and core targets network by topological analysis. Genes from the core targets network were further subjected to Gene Ontology (GO) and KEGG enrichment analysis to figure out potential targeting pathways. Finally, a compounds-targets-pathways network was generated by Cytoscape. A total of 210 active compounds and 768 corresponding potential therapeutic targets were harvested from ingredients of YSNJF. MDS was shown to have 772 potential treating targets with 98 intersected targets corresponding to 98 active compounds in YSNJF. Topological analysis revealed that 15 targets formed the core PPI network. Further, GO and KEGG enrichment analysis revealed that those core targets were mainly enriched on cell cycle- and immune-related pathways. The present study revealed that therapeutic effects of YSNJF on MDS might be achieved through regulating cell cycle- and immune-related pathways.

Inhibition of TGFβ1 and TGFβ3 promotes hematopoiesis in Fanconi anemia

Fanconi anemia (FA) is a chromosome instability syndrome with congenital abnormalities, cancer predisposition and bone marrow failure (BMF). Although hematopoietic stem and progenitor cell (HSPC) transplantation is the recommended therapy, new therapies are needed for FA patients without suitable donors. BMF in FA is caused, at least in part, by a hyperactive growth-suppressive transforming growth factor β (TGFβ) pathway, regulated by the TGFβ1, TGFβ2, and TGFβ3 ligands. Accordingly, the TGFβ pathway is an attractive therapeutic target for FA. While inhibition of TGFβ1 and TGFβ3 promotes blood cell expansion, inhibition of TGFβ2 is known to suppress hematopoiesis. Here, we report the effects of AVID200, a potent TGFβ1- and TGFβ3-specific inhibitor, on FA hematopoiesis. AVID200 promoted the survival of murine FA HSPCs in vitro. AVID200 also promoted in vitro the survival of human HSPCs from patients with FA, with the strongest effect in patients progressing to severe aplastic anemia or myelodysplastic syndrome (MDS). Previous studies have indicated that the toxic upregulation of the nonhomologous end-joining (NHEJ) pathway accounts, at least in part, for the poor growth of FA HSPCs. AVID200 downregulated the expression of NHEJ-related genes and reduced DNA damage in primary FA HSPC in vitro and in in vivo models. Collectively, AVID200 exhibits activity in FA mouse and human preclinical models. AVID200 may therefore provide a therapeutic approach to improving BMF in FA.

Transforming growth factor (TGF)-β pathway as a therapeutic target in lower risk myelodysplastic syndromes

The transforming growth factor (TGF)-β superfamily comprises more than 30 soluble growth factors that play a central role in erythropoiesis and are part of a tightly regulated myelosuppressive negative feedback loop under physiologic conditions. TGF-β receptor activation and phosphorylation trigger a regulatory circuit of activating and inhibitory SMAD proteins and increased activation of the TGF-β signaling pathway either by a loss of negative feedback or constitutive activation has been associated with the myelosuppression and ineffective erythropoiesis in myelodysplastic syndromes (MDS). Anemia is the predominant cause of morbidity and quality of life impairment in patients with lower-risk (LR)-MDS, and there are very limited therapy options for these patients after failure of erythropoiesis stimulating agents (ESAs). Targeting the aberrant TGF-ß signaling pathway has therefore been investigated as a promising therapeutic approach to resolve the ineffective erythropoiesis in LR-MDS. In this article, we provide a brief overview of the TGF-β signaling cascade in hematopoiesis under physiologic conditions and its role in MDS pathogenesis. We also review preclinical and clinical data for the activin receptor type IIA ligand traps sotatercept and luspatercept that have recently shown promising results in overcoming the myelosuppressive effects of TGF-β signaling alterations to improve hematopoiesis in transfusion-dependent, non-del(5q) LR-MDS patients. Additional potential targets within the TGF-β pathway have also been identified in preclinical experiments and may provide further therapeutic options. Finally, combining different TGF-β pathway inhibitors or using them in combination with ESAs or the immunomodulator lenalidomide might have synergistic effects as well.

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

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

Transforming growth factor β1-mediated functional inhibition of mesenchymal stromal cells in myelodysplastic syndromes and acute myeloid leukemia

Mesenchymal stromal cells are involved in the pathogenesis of myelodysplastic syndromes and acute myeloid leukemia, but the underlying mechanisms are incompletely understood. To further characterize the pathological phenotype we performed RNA sequencing of mesenchymal stromal cells from patients with myelodysplastic syndromes and acute myeloid leukemia and found a specific molecular signature of genes commonly deregulated in these disorders. Pathway analysis showed a strong enrichment of genes related to osteogenesis, senescence, inflammation and inhibitory cytokines, thereby reflecting the structural and functional deficits of mesenchymal stromal cells in myelodysplastic syndromes and acute myeloid leukemia on a molecular level. Further analysis identified transforming growth factor β1 as the most probable extrinsic trigger factor for this altered gene expression. Following exposure to transforming growth factor β1, healthy mesenchymal stromal cells developed functional deficits and adopted a phenotype reminiscent of that observed in patient-derived stromal cells. These suppressive effects of transforming growth factor β1 on stromal cell functionality were abrogated by SD-208, an established inhibitor of transforming growth factor β receptor signaling. Blockade of transforming growth factor β signaling by SD-208 also restored the osteogenic differentiation capacity of patient-derived stromal cells, thus confirming the role of transforming growth factor β1 in the bone marrow microenvironment of patients with myelodysplastic syndromes and acute myeloid leukemia. Our findings establish transforming growth factor β1 as a relevant trigger causing functional inhibition of mesenchymal stromal cells in myelodysplastic syndromes and acute myeloid leukemia and identify SD-208 as a candidate to revert these effects.

Regulation of Hematopoiesis and Hematological Disease by TGF-β Family Signaling Molecules

Throughout the lifetime of an individual, hematopoietic stem cells (HSCs) maintain the homeostasis of normal hematopoiesis through the precise generation of mature blood cells. Numerous genetic studies in mice have shown that stem-cell quiescence is critical for sustaining primitive long-term HSCs in vivo. In this review, we first examine the crucial roles of transforming growth factor β (TGF-β) and related signaling molecules in not only regulating the well-known cytostatic effects of these molecules but also governing the self-renewal capacity of HSCs in their in vivo microenvironmental niche. Second, we discuss the current evidence indicating that TGF-β signaling has a dual function in disorders of the hematopoietic system. In particular, we examine the paradox that, although intrinsic TGF-β signaling is essential for regulating the survival and resistance to therapy of chronic myelogenous leukemia (CML) stem cells, genetic changes that abrogate TGF-β signaling can lead to the development of several hematological malignancies.

8-Hydroxydeoxyguanosine as a biomarker of oxidative DNA damage in workers exposed to low-dose benzene

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Gasoline station attendants have higher urinary t,t,-MA and 8-OHdG levels.

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There is strong correlation between 8-OHdG and benzene exposure level.

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8-OHdG levels are significantly correlated also with job seniority.

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Low-level chronic exposure to benzene can determine oxidative damage on DNA.

The present study aims to investigate the relation between exposure to low-dose benzene and the occurrence of oxidative DNA damage in gasoline station workers, as well as the possible role of interfering or confounding factors.

Urine levels of 8-OHdG were evaluated by a competitive immunoassay in a group of 80 men, employed in gasoline stations located in East Sicily and compared with a control group (n = 63) of male office employees not occupationally exposed to benzene. Information regarding socio-demographic characteristics, lifestyle and job-related records were provided through a questionnaire.

Significantly higher (p < 0.05) urinary t,t,-MA and 8-OHdG levels were observed in gasoline station attendants compared to subjects not exposed to benzene.

Pearson’s test demonstrated a strong correlation (r = 0.377, p < 0.001) between 8-OHdG and benzene exposure level. 8-OHdG significantly correlated also with job seniority, (r = 0.312, p < 0.01), whereas the relation with age resulted weaker (r = 0.242, p < 0.05). Multiple linear regression analysis, performed to exclude a role for confounding factors, showed that variables like gender, smoking habit, alcohol consumption and BMI did not have a significant influence on the measured biomarkers. No subject enrolled in the study presented signs or symptoms of work-related disease or other illness linked to oxidative stress.

These results suggest that low-level chronic exposure to benzene among gasoline station attendants can determine oxidative damage on DNA, as indicated by alteration of 8-OHdG which may represent a non-invasive biomarker of early genotoxic damage in exposed subjects.

Management of lower-risk myelodysplastic syndromes without del5q: current approach and future trends

INTRODUCTION

Myelodysplastic syndromes (MDS) are characterized by progressive bone marrow failure manifesting as blood cytopenia and a variable risk of progression into acute myeloid leukemia. MDS is heterogeneous in biology and clinical behavior. MDS are generally divided into lower-risk (LR) and higher-risk (HR) MDS. Goals of care in HR-MDS focus on changing the natural history of the disease, whereas in LR-MDS symptom control and quality of life are the main goals. Areas covered: We review the epidemiology, tools of risk assessment, and the available therapeutic modalities for LR-MDS. We discuss the use of erythropoiesis stimulating agents (ESAs), immunosuppressive therapy (IST), lenalidomide and the hypomethylating agents (HMAs). We also discuss the predictors of response, combination treatment modalities, and management of iron overload. Lastly, we overview the most promising investigational agents for LR-MDS. Expert commentary: It remains unclear how to best incorporate a wealth of new genetic and epigenetic prognostic markers into risk assessment tools especially for LR-MDS patients. Only a subset of patients respond to current treatment modalities and most responders eventually lose their response. Once standard therapeutic options fail, management becomes more challenging. Combination-based approaches have been largely unsuccessful. Among the most promising investigational are the TPO agonists, TGF- β pathway inhibitors, telomerase inhibitors, and the splicing modifiers.

Lenalidomide use in myelodysplastic syndromes: Insights into the biologic mechanisms and clinical applications

Myelosysplastic syndromes (MDS) include a heterogeneous group of clonal myeloid neoplasms characterized by ineffective hematopoiesis leading to blood cytopenias and a variable risk of progression into acute myeloid leukemia (AML). Although the hypomethylating agent azacitidine prolongs survival among patients with higher risk (HR)-MDS compared with conventional care, no drug has been shown conclusively to prolong survival or delay progression to AML among patients with lower-risk MDS (LR-MDS). Lenalidomide is the drug with the most impressive clinical activity in the subset of anemic LR-MDS patients who harbor a deletion of the long arm of chromosome 5 (5q-), where it leads to high rates of transfusion independence and cytogenetic responses. Furthermore, lenalidomide delays progression to AML and prolongs survival among responders. In this article, we review the recently recognized mechanisms of action of lenalidomide and discuss the most recent clinical data regarding its use in patients with both 5q- MDS as well as non-5q- MDS. Finally, we forecast the future directions to improve the efficacy of lenalidomide in MDS with and without 5q-. Cancer 2017;123:1703-1713. © 2017 American Cancer Society.

Efficacy of the polo-like kinase inhibitor rigosertib, alone or in combination with Abelson tyrosine kinase inhibitors, against break point cluster region-c-Abelson-positive leukemia cells

The potency of Abelson (ABL) tyrosine kinase inhibitors (TKIs) against chronic myeloid leukemia (CML) has been demonstrated. However, ABL TKI resistance can develop. In this study, we investigated the efficacy of a combination therapy including rigosertib (ON 01910.Na), a polo-like kinase (PLK) and phosphoinositide 3-kinase (PI3K) inhibitor, and ABL TKIs. A 72-h rigosertib treatment was found to inhibit cell growth, induce apoptosis, reduce phosphorylation of the breakpoint cluster region-c (BCR)-ABL and its substrate Crk-L, and increase the activities of caspase 3 and poly (ADP-ribose) polymerase (PARP). This combination therapy also exerted a synergistic inhibitory effect on Philadelphia chromosome (Ph)-positive cell proliferation and reduced the phosphorylation of BCR-ABL and Crk-L while increasing that of cleaved PARP and the H2A.X histone. Rigosertib also potently inhibited the growth of ABL TKI-resistant cells, and cotreatment with ABL TKIs and rigosertib induced higher cytotoxicity. These results indicate that rigosertib treatment may be a powerful strategy against ABL TKI-resistant cells and could enhance the cytotoxic effects of ABL TKIs.

Autoimmunity and Inflammation in Myelodysplastic Syndromes

Autoimmune and inflammatory conditions (AICs) are encountered in up to 25% of patients with myelodysplastic syndromes (MDS). A wide range of AICs have been reported in association with MDS and can range from limited clinical manifestations to systemic diseases affecting multiple organs. Vasculitides, connective tissue diseases, and inflammatory arthritis are frequently reported in different studies; noninfectious fever and constitutional symptoms at presentation are common. Associations between AICs and specific MDS characteristics vary by study, but the available data suggest that AICs cluster more often in younger patients with higher-risk MDS. In general, AICs do not seem to confer worse survival, although certain AICs may be associated with adverse outcome (e.g. vasculitis) or progression of MDS (Sweet's syndrome). Nonetheless, these complications may have a significant impact on quality of life and affect the timing and type of MDS-directed therapy. The mainstay of management of these complications in the short term relies on immunosuppressive drugs. Increasing evidence suggests that hypomethylating agents may be effective in treating these complications and reduce steroid dependence. While the pathogenesis of AICs is incompletely understood, growing appreciation of cellular immune deregulation, cytokine hypersecretion, and the genetic heterogeneity underlying MDS may improve our understanding of common pathways linking MDS, inflammation, and autoimmunity.

Pexmetinib: A Novel Dual Inhibitor of Tie2 and p38 MAPK with Efficacy in Preclinical Models of Myelodysplastic Syndromes and Acute Myeloid Leukemia

Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) suppress normal hematopoietic activity in part by enabling a pathogenic inflammatory milieu in the bone marrow. In this report, we show that elevation of angiopoietin-1 in myelodysplastic CD34(+) stem-like cells is associated with higher risk disease and reduced overall survival in MDS and AML patients. Increased angiopoietin-1 expression was associated with a transcriptomic signature similar to known MDS/AML stem-like cell profiles. In seeking a small-molecule inhibitor of this pathway, we discovered and validated pexmetinib (ARRY-614), an inhibitor of the angiopoietin-1 receptor Tie-2, which was also found to inhibit the proinflammatory kinase p38 MAPK (which is overactivated in MDS). Pexmetinib inhibited leukemic proliferation, prevented activation of downstream effector kinases, and abrogated the effects of TNFα on healthy hematopoietic stem cells. Notably, treatment of primary MDS specimens with this compound stimulated hematopoiesis. Our results provide preclinical proof of concept for pexmetinib as a Tie-2/p38 MAPK dual inhibitor applicable to the treatment of MDS/AML. Cancer Res; 76(16); 4841-9. ©2016 AACR.

Synthesis and p38 Inhibitory Activity of Some Novel Substituted N,N'-Diarylurea Derivatives

We have identified a novel series of substituted N,N'-diarylurea p38α inhibitors. The inhibitory activity of the target compounds against the enzyme p38α, MAPKAPK2 in BHK cells, TNF-α release in LPS-stimulated THP-1 cells and p38α binding experiments were tested. Among these compounds, 25a inhibited the p38α enzyme with an IC50 value of 0.47 nM and a KD value of 1.54 × 10(-8) and appears to be the most promising one in the series.

Model-based adaptive phase I trial design of post-transplant decitabine maintenance in myelodysplastic syndrome

Background

This report focuses on the adaptive phase I trial design aimed to find the clinically applicable dose for decitabine maintenance treatment after allogeneic hematopoietic stem cell transplantation in patients with higher-risk myelodysplastic syndrome and secondary acute myeloid leukemia.

Methods

The first cohort (three patients) was given the same initial daily dose of decitabine (5 mg/m²/day, five consecutive days with 4-week intervals). In all cohorts, the doses for Cycles 2 to 4 were individualized using pharmacokinetic-pharmacodynamic modeling and simulations. The goal of dose individualization was to determine the maximum dose for each patient at which the occurrence of grade 4 (CTC-AE) toxicities for both platelet and neutrophil counts could be avoided. The initial doses for the following cohorts were also estimated with the data from the previous cohorts in the same manner.

Results

In all but one patient (14 out of 15), neutrophil count was the dose-limiting factor throughout the cycles. In cycles where doses were individualized, the median neutrophil nadir observed was 1100/mm³ (grade 2) and grade 4 toxicity occurred in 5.1 % of all cycles (while it occurred in 36.8 % where doses were not individualized). The initial doses estimated for cohorts 2 to 5 were 4, 5, 5.5, and 5 mg/m²/day, respectively. The median maintenance dose was 7 mg/m²/day.

Conclusions

We determined the acceptable starting dose and individualized the maintenance dose for each patient, while minimizing the toxicity using the adaptive approach. Currently, 5 mg/m²/day is considered to be the most appropriate starting dose for the regimen studied.

Trial registration

Clinicaltrials.gov NCT01277484

Biology of the bone marrow microenvironment and myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are characterized by cytopenias resulting from ineffective hematopoiesis with a predisposition to transform to acute myeloid leukemia (AML). Recent evidence suggests that the hematopoietic stem cell microenvironment contributes to the pathogenesis of MDS. Inflammation and hypoxia within the bone marrow are key regulators of hematopoietic stem and progenitor cells that can lead to several bone marrow failure syndromes, including MDS. In this brief review, we provide an overview of the clinical and molecular features of MDS, the bone marrow microenvironment, and specific pathways that lead to abnormal blood cell development in MDS. Characterization of key steps in the pathogenesis of MDS will lead to new approaches to treat patients with this disease.

Genetic and molecular targets in lymphoma: implications for prognosis and treatment

Lymphomas are the most common hematologic malignancies with approximately 79,000 new cases estimated for 2013 in the USA. Despite improved outcomes, relapse or recurrence remains a common problem with conventional cytotoxic therapy. Recently, many genetic and molecular mechanisms that drive various cellular events like apoptosis, angiogenesis and cell motility have been more clearly delineated. These new findings, coupled with the advent of high-throughput screening technology have led to the discovery of many compounds that can target specific mutations and/or influence deregulated transcription. In this review, we intend to provide a concise overview of genetic and molecular events that drive cellular processes in lymphomas and represent potential therapeutic targets. Additionally, we briefly discuss the prognostic significance of select biological markers.

TGF-β signaling in the control of hematopoietic stem cells

Blood is a tissue with high cellular turnover, and its production is a tightly orchestrated process that requires constant replenishment. All mature blood cells are generated from hematopoietic stem cells (HSCs), which are the self-renewing units that sustain lifelong hematopoiesis. HSC behavior, such as self-renewal and quiescence, is regulated by a wide array of factors, including external signaling cues present in the bone marrow. The transforming growth factor-β (TGF-β) family of cytokines constitutes a multifunctional signaling circuitry, which regulates pivotal functions related to cell fate and behavior in virtually all tissues of the body. In the hematopoietic system, TGF-β signaling controls a wide spectrum of biological processes, from homeostasis of the immune system to quiescence and self-renewal of HSCs. Here, we review key features and emerging concepts pertaining to TGF-β and downstream signaling pathways in normal HSC biology, featuring aspects of aging, hematologic disease, and how this circuitry may be exploited for clinical purposes in the future.

Rigosertib induces cell death of a myelodysplastic syndrome-derived cell line by DNA damage-induced G2/M arrest

A multi-kinase inhibitor, rigosertib (ON 01910.Na) has recently been highlighted as a novel type of anti-cancer agent for the treatment of the myelodysplastic syndromes (MDS), but its action mechanisms remain to be clarified. We investigated the in vitro effects of rigosertib on an MDS-derived cell line MDS-L and a myeloid leukemia cell line HL-60. Rigosertib suppressed the proliferation of both HL-60 and MDS-L cells and induced apoptosis by inhibition of the PI3 kinase/Akt pathway. As the effects on cell cycle, rigosertib treatment promoted the phosphorylation of histone H2AX and led to the DNA damage-induced G2/M arrest. In addition, an immunofluorescence staining study demonstrated the abnormal localization of aurora A kinase, suggesting that rigosertib causes perturbation of spindle assembly and deregulated mitotic patterns towards cell cycle arrest and apoptosis. We also found that rigosertib exerted growth inhibitory effects on two lymphoid cell lines, Jurkat and Ramos. We further examined the molecular pathways influenced by rigosertib from the gene expression profiling data of MDS-L cells and found a possible involvement of rigosertib treatment in the upregulation of the genes related to microtubule kinetics and the downregulation of the mRNA degradation system. The gene set enrichment analysis showed the suppression of "nonsense-mediated mRNA decay (NMD)" as the most significantly affected gene set. These data provide a new aspect and a potential utility of rigosertib for the treatment of refractory hematopoietic malignancies.

Changes of T-lymphocyte subpopulation and differential expression pattern of the T-bet and GATA-3 genes in diffuse large B-cell lymphoma patients after chemotherapy

BACKGROUND AND OBJECTIVE

T cell-mediated immunity plays an important role in enhancing antitumor response.This study aimed to investigate the changes in the T-lymphocyte subpopulation and to characterize the differential expression pattern of corresponding regulatory genes in peripheral blood mononuclear cells (PBMCs) from diffuse large B cell lymphoma (DLBCL) patients before and after chemotherapy.

METHODS

A total of 56 DLBCL patients were recruited for analysis of T-cell subset distribution in the peripheral blood using flow cytometry; serum interferon (IFN)-γ and interleukin (IL)-4 levels using enzyme-linked immunosorbent assays; and early growth response protein 1 (EGR-1), T-bet, GATA-binding protein 3 (GATA-3), and transforming growth factor (TGF)-β mRNA levels using quantitative reverse-transcription polymerase chain reaction. Twenty-six healthy subjects served as controls.

RESULTS

The percentage of CD3(+)CD4(+)T lymphocytes in peripheral blood from DLBCL patients was significantly decreased, whereas the percentages of CD3(+)CD8(+)T and CD4(+)CD25(+)T cells were significantly increased compared to those in controls (p < 0.05). Serum levels of IFN-γ and IL-4 were also significantly lower in DLBCL patients than those in controls (p < 0.05), and the levels of EGR-1, T-bet, and GATA-3 mRNA in PBMCs were lower (2.69 ± 1.48, 9.43 ± 2.14, and 20.83 ± 9.05 fold, respectively) in DLBCL patients than those in controls. Furthermore, there was a positive association between the levels of EGR-1 and T-bet mRNA (p = 0.001). However, the level of TGF-β mRNA was significantly increased in DLBCL patients, which was inversely associated with the T-bet mRNA level (p = 0.008), but positively associated with the percentage of T regulatory cells in PBMCs (p = 0.011). After three cycles of chemotherapy, the distribution of T-lymphocyte subsets in DLBCL patients were changed, and the levels of EGR-1, T-bet, and GATA-3 mRNA were significantly increased (p < 0.05) compared to those before chemotherapy.

CONCLUSIONS

These results demonstrate the changes in T-lymphocyte subpopulations and the altered expression 34 pattern of the corresponding regulatory genes in PBMCs from DLBCL patients after chemotherapy, which are associated with the response of patients to treatment. The preferential expression of the T-bet gene after chemotherapy was closely correlated with the increased expression of the EGR-1 gene and decreased expression of the TGF-β gene.

Recent developments in myelodysplastic syndromes

Once thought to be rare disorders, the myelodysplastic syndromes (MDS) are now recognized as among the most common hematological neoplasms, probably affecting >30 000 patients per year in the United States. US regulatory approval of azacitidine, decitabine, and lenalidomide between 2004 and 2006 seemed to herald a new era in the development of disease-modifying therapies for MDS, but there have been no further drug approvals for MDS indications in the United States in the last 8 years. The available drugs are not curative, and few of the compounds that are currently in development are likely to be approved in the near future. As a result, MDS diagnoses continue to place a heavy burden on both patients and health care systems. Incomplete understanding of disease pathology, the inherent biological complexity of MDS, and the presence of comorbid conditions and poor performance status in the typical older patient with MDS have been major impediments to development of effective novel therapies. Here we discuss new insights from genomic discoveries that are illuminating MDS pathogenesis, increasing diagnostic accuracy, and refining prognostic assessment, and which will one day contribute to more effective treatments and improved patient outcomes.

The MAPK ERK5, but not ERK1/2, inhibits the progression of monocytic phenotype to the functioning macrophage

Intracellular signaling pathways present targets for pharmacological agents with potential for treatment of neoplastic diseases, with some disease remissions already recorded. However, cellular compensatory mechanisms usually negate the initial success. For instance, attempts to interrupt aberrant signaling downstream of the frequently mutated ras by inhibiting ERK1/2 has shown only limited usefulness for cancer therapy. Here, we examined how ERK5, that overlaps the functions of ERK1/2 in cell proliferation and survival, functions in a manner distinct from ERK1/2 in human AML cells induced to differentiate by 1,25D-dihydroxyvitamin D3 (1,25D). Using inhibitors of ERK1/2 and of MEK5/ERK5 at concentrations specific for each kinase in HL60 and U937 cells, we observed that selective inhibition of the kinase activity of ERK5, but not of ERK1/2, in the presence of 1,25D resulted in macrophage-like cell morphology and enhancement of phagocytic activity. Importantly, this was associated with increased expression of the macrophage colony stimulating factor receptor (M-CSFR), but was not seen when M-CSFR expression was knocked down. Interestingly, inhibition of ERK1/2 led to activation of ERK5 in these cells. Our results support the hypothesis that ERK5 negatively regulates the expression of M-CSFR, and thus has a restraining function on macrophage differentiation. The addition of pharmacological inhibitors of ERK5 may influence trials of differentiation therapy of AML.

Chronic myelomonocytic leukemia prognostic classification and management: evidence base and current practice

Chronic myelomonocytic leukemia is a clonal malignancy of the ageing hematopoietic stem cell characterized by a biased differentiation leading to persistent monocytosis and inconstant hypersensitivity of myeloid progenitors to granulo-monocyte colony-stimulating factor (GM-CSF). Cytogenetic abnormalities identified in 30-40 % of patients and gene mutations detected in every patient can be used to stratify patients into risk groups that guide the therapeutic choices. TET2, SRSF2, ASXL1, and genes of the Ras pathway are the most frequently mutated genes, with ASXL1 mutations negatively affecting the disease outcome. Allogeneic stem cell transplantation is the first option to consider, especially in younger patients with poor prognostic factors. There is no firm clinical guideline in transplant-ineligible patients, but hypomethylating agents might be an interesting option. A consensus prognostic scoring system and specific response criteria are now required to facilitate the evaluation of new therapeutic strategies in clinical trials specifically dedicated to this disease.

TNF-α, a good or bad factor in hematological diseases?

Tumor necrosis factor-alpha (TNF-α) is a highly pleiotropic cytokine involved in a spectrum of physiological processes that control inflammation, anti-tumor responses and homeostasis through two receptors, TNF-R1 and TNF-R2. In general, TNF-R1 mediates cytotoxicity, resistance to infection and stimulation of NF-κB. By contrast, TNF-R2 has been implicated in proliferation of T-cell line, thymocytes and human mononuclear cells. Hematological malignancies are the types of cancer that affect normal hematopoiesis, have a speedy development, high lethal rate and until now still have no effective treatment. Several studies have shown that inflammatory cytokines play an important role in the onset and progress of these diseases. In this review, we summarize the recent studies and evaluate the positive or negative role of TNF-α in some hematological malignancies or diseases with a malignant tendency.

Modified activin receptor IIB ligand trap mitigates ineffective erythropoiesis and disease complications in murine β-thalassemia

In β-thalassemia, unequal production of α- and β-globin chains in erythroid precursors causes apoptosis and inhibition of late-stage erythroid differentiation, leading to anemia, ineffective erythropoiesis (IE), and dysregulated iron homeostasis. Here we used a murine model of β-thalassemia intermedia (Hbb(th1/th1) mice) to investigate effects of a modified activin receptor type IIB (ActRIIB) ligand trap (RAP-536) that inhibits Smad2/3 signaling. In Hbb(th1/th1) mice, treatment with RAP-536 reduced overactivation of Smad2/3 in splenic erythroid precursors. In addition, treatment of Hbb(th1/th1) mice with RAP-536 reduced α-globin aggregates in peripheral red cells, decreased the elevated reactive oxygen species present in erythroid precursors and peripheral red cells, and alleviated anemia by promoting differentiation of late-stage erythroid precursors and reducing hemolysis. Notably, RAP-536 treatment mitigated disease complications of IE, including iron overload, splenomegaly, and bone pathology, while reducing erythropoietin levels, improving erythrocyte morphology, and extending erythrocyte life span. These results implicate signaling by the transforming growth factor-β superfamily in late-stage erythropoiesis and reveal potential of a modified ActRIIB ligand trap as a novel therapeutic agent for thalassemia syndrome and other red cell disorders characterized by IE.

Immunological derangement in hypocellular myelodysplastic syndromes

Hypocellular or hypoplastic myelodysplastic syndromes (HMDS) are a distinct subgroup accounting for 10-15% of all MDS patients, that are characterized by the presence of bone marrow (BM) hypocellularity, various degree of dysmyelopoiesis and sometimes abnormal karyotype. Laboratory and clinical evidence suggest that HMDS share several immune-mediated pathogenic mechanisms with acquired idiopathic aplastic anemia (AA). Different immune-mediated mechanisms have been documented in the damage of marrow hematopoietic progenitors occurring in HMDS; they include oligoclonal expansion of cytotoxic T lymphocytes (CTLs), polyclonal expansion of various subtypes of T helper lymphocytes, overexpression of FAS-L and of the TNF-related apoptosis-inducing ligand (TRAIL), underexpression of Flice-like inhibitory protein long isoform (FLIPL) in marrow cells as well as higher release of Th1 cytokines, such as interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α). It has also been documented that some HMDS patients have higher frequency of polymorphisms linked both to high production of proinflammatory cytokines such as TNF-α and transforming growth factor-β and to the inhibition of T-cell mediated immune responses such as interleukin-10, further suggesting that immune-mediated mechanisms similar to those seen in AA patients may also operate in HMDS. Clinically, the strongest evidence for immune-mediated hematopoietic suppression in some HMDS is the response to immunosuppression including mainly cyclosporine, anti-thymocyte globulin and/or cyclosporine, or alemtuzumab. Here we review all these immune mechanisms as well as the influence of this deranged cellular and humoral immunologic mileau on the initiation and possible progression of MDS. All these observations are pivotal not only for a better understanding of MDS pathophysiology, but also for their immediate clinical implications, eventually leading to the identification of MDS patients who may benefit from immunosuppression.