Primary Bone Marrow Cells Research Articles

A loss-of-function genetic screening reveals synergistic targeting of AKT/mTOR and WTN/\u03b2-catenin pathways for treatment of AML with high PRL-3 phosphatase

BackgroundProtein tyrosine phosphatase of regenerating liver 3 (PRL-3) is overexpressed in a subset of AML patients with inferior prognosis, representing an attractive therapeutic target. However, due to relatively shallow pocket of the catalytic site of PRL-3, it is difficult to develop selective small molecule inhibitor.MethodsIn this study, we performed whole-genome lentiviral shRNA library screening to discover synthetic lethal target to PRL-3 in AML. We used specific small molecule inhibitors to validate the synthetic lethality in human PRL-3 high vs PRL-3 low human AML cell lines and primary bone marrow cells from AML patients. AML mouse xenograft model was used to examine the in vivo synergism.ResultsThe list of genes depleted in TF1-hPRL3 cells was particularly enriched for members involved in WNT/β-catenin pathway and AKT/mTOR signaling. These findings prompted us to explore the impact of AKT/mTOR signaling inhibition in PRL-3 high AML cells in combination with WNT/β-catenin inhibitor. VS-5584, a novel, highly selective dual PI3K/mTOR inhibitor, and ICG-001, a WNT inhibitor, were used as a combination therapy. A synthetic lethal interaction between mTOR/AKT pathway inhibition and WNT/β-catenin was validated by a variety of cellular assays. Notably, we found that treatment with these two drugs significantly reduced leukemic burden and prolonged survival of mice transplanted with human PRL-3 high AML cells, but not with PRL-3 low AML cells.ConclusionsIn summary, our results support the existence of cooperative signaling networks between AKT/mTOR and WNT/β-catenin pathways in PRL-3 high AML cells. Simultaneous inhibition of these two pathways could achieve robust clinical efficacy for this subtype of AML patient with high PRL-3 expression and warrant further clinical investigation.

Down-regulation of JARID1B expression inhibits cell proliferation, induces apoptosis and blocks cell cycle in human acute lymphoblastic leukemia cells.

Acute lymphocytic leukemia (ALL) is a multi-factorial blood disease with unknown pathogenesis. Histone H3K4 methylation was significantly reduced in ALL patients, whereas jumonji AT-rich interactive domain 1B (JARID1B) was the specific demethylase of H3K4me. This study explores the expression level of JARID1B in ALL patients and down-regulated JARID1B expression in ALL cells to explore the function of JARID1B in ALL. JARID1B mRNA expression level in ALL patients was detected by Real-time PCR. The peripheral blood mononuclear cells from healthy volunteers were selected as control. JARID1B shRNA was transfected with MOLT-4 cells and BALL-1 cells. JARID1B protein expression and H3K4me2 and H3K4me3 levels were detected by Western blot assay. Cell proliferation was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Cell apoptosis and cell cycle were determined by flow cytometry. Bcl-2, Bax, Procaspase 3, and cyclin P21 expressions were evaluated by Western blot assay. JARID1B mRNA expression in primary bone marrow cells from ALL patients was significantly higher than that of healthy volunteers (p<0.05). The levels of histone H3K4me3 and H3K4me2 were up-regulated after JARID1B shRNA transfection. JARID1B shRNA significantly inhibited the proliferation of MOLT-4 and BALL-1 cells, induced apoptosis, and blocked cell cycle in G0/G1 phase compared with the control group (p<0.05). JARID1B is highly expressed in ALL. Down-regulating its expression inhibited leukemia cell proliferation, promoted apoptosis, and blocked cell cycle in G0/G1 phase through histone H3K4 methylation. JARID1B is an oncogene in ALL.

Severe hypoxia selects hematopoietic progenitors with stem cell potential from primary Myelodysplastic syndrome bone marrow cell cultures.

Myelodysplastic Syndromes (MDS) are clonal neoplasms where stem/progenitor cells endowed with self-renewal and capable of perpetuating the disease have been demonstrated. It is known that oxygen tension plays a key role in driving normal hematopoiesis and that hematopoietic stem cells are maintained in hypoxic areas of the bone marrow (BM). Hypoxia could also regulate leukemic/dysplastic hematopoiesis. We evaluated the stem cell potential of MDS cells derived from the BM of 39 MDS patients and selected under severe hypoxia. MDS cells rescued from hypoxia-incubated cultures were subjected to stem and progenitor cell assays in vitro, as well as to hematopoietic reconstitution assay in NOD-SCID mice. Incubation in severe hypoxia of cells explanted from MDS patients selected a cell subset endowed with stem cell potential, as determined in vitro. This occurred only from the BM of patients classified as IPSS low/INT-1 risk. Transplantation into NOD-SCID mice confirmed using an in vivo model that severe hypoxia selects a cell subset endowed with stem cell potential from bone marrow mononuclear cells (BMMC). derived from patients belonging to the IPSS low/int-1 risk group. Data here reported show that cells endowed with stem cell potential and capable of adapting to hypoxia and escaping hypoxia-induced apoptosis exist within MDS cell populations.

Dimethyl fumarate is highly cytotoxic in KRAS mutated cancer cells but spares non-tumorigenic cells.

KRAS mutation, one of the most common molecular alterations observed in adult carcinomas, was reported to activate the anti-oxidant program driven by the transcription factor NRF2 (Nuclear factor-erythroid 2-related factor 2). We previously observed that the antitumoral effect of Dimethyl fumarate (DMF) is dependent of NRF2 pathway inhibition. We used in vitro methods to examine the effect of DMF on cell death and the activation of the NRF2/DJ-1 antioxidant pathway. We report here that DMF is preferentially cytotoxic against KRAS mutated cancer cells. This effect was observed in patient-derived cancer cell lines harbouring a G12V KRAS mutation, compared with cell lines without such a mutation. In addition, KRAS*G12V over-expression in the human Caco-2 colon cancer cell line significantly promoted DMF-induced cell death, as well as DMF-induced- reactive oxygen species (ROS) formation and -glutathione (GSH) depletion. Moreover, in contrast to malignant cells, our data confirms that the same concentration of DMF has no significant cytotoxic effects on non-tumorigenic human ARPE-19 retinal epithelial, murine 3T3 fibroblasts and primary mice bone marrow cells; but is rather associated with NRF2 activation, decreased ROS and increased GSH levels. Furthermore, DJ-1 down-regulation experiments showed that this protein does not play a protective role against NRF2 in non-tumorigenic cells, as it does in malignant ones. This, interestingly, could be at the root of the differential effect of DMF observed between malignant and non-tumorigenic cells. Our results suggest for the first time that the dependence on NRF2 observed in mutated KRAS malignant cells makes them more sensitive to the cytotoxic effect of DMF, which thus opens up new prospects for the therapeutic applications of DMF.

Immortalization of Murine Bone Marrow-Derived Macrophages.

Macrophages are specialized phagocytes that display a variety of important functions for the host immune system. They are particularly important for the recognition of exogenous and endogenous danger signals, forming the defensive front line as part of innate immune response. As such, murine macrophages are commonly used for in vitro cell-based assays examining the mechanisms of innate immune activation, which can require the ongoing breeding and housing of a large number of genetically modified mouse strains. Here, we describe a robust protocol for the generation of immortalized bone marrow-derived macrophages (iBMDMs) from primary murine bone marrow cells. We further provide general protocols for harvesting, freezing, and thawing of bone marrow cells, maintaining iBMDMs in culture and generation of monoclonal iBMDM populations by single-cell cloning.

In vitro Osteoclastogenesis Assays Using Primary Mouse Bone Marrow Cells.

Osteoclasts are a group of bone-absorbing cells to degenerate bone matrix and play pivotal roles in bone growth and homeostasis. The unbalanced induction of osteoclast differentiation (osteoclastogenesis) in pathological conditions, such as osteoporosis, arthritis and skeleton metastasis of cancer, causes great pain, bone fracture, hypercalcemia or even death to patients. In vitro osteoclastogenesis analysis is useful to better understand osteoclast formation in physiological and pathological conditions. Here we summarized an easy-to-follow osteoclastogenesis protocol, which is suitable to evaluate the effect of different factors (cytokines, small molecular chemicals and conditioned medium from cell culture) on osteoclast differentiation using primary murine bone marrow cells.

The Activated TGFβ Pathway in Shwachman Diamond Syndrome Impairs Hematopoiesis and Is Down-Regulated By Deletion of 7q

Monosomy 7 or deletion of 7q (del(7q)) are common cytogenetic abnormalities in pediatric MDS. Monosomy 7/del(7q) frequently arises in the context of inherited bone marrow failure (BMF) syndromes such as Shwachman Diamond Syndrome (SDS), an autosomal recessive disorder caused by biallelic mutations in the SBDS gene. Monosomy 7/del(7q) is associated with high grade MDS and a high risk of malignant transformation to acute myelogenous leukemia, a major cause of morbidity and mortality for patients with inherited BMF. The basis for this propensity to develop monosomy 7/del(7q) remains unclear. Whether monosomy 7/del(7q) functions as a driver of MDS, or is merely an associated marker of clonal progression in BMF, remains a critical question. The aim of this study is to investigate the molecular consequences of del(7q) in the context of BMF with the goal of developing more effective treatments.The lack of synteny between murine and human chromosome 7 has posed a major barrier to modeling monosomy 7/del(7q). Therefore, we utilized SDS patient-derived induced pluripotent stem cells (SDS-iPSC), which recapitulate the hematopoietic defects of this BMF syndrome. Independent SDS-iPSC lines were derived from two patients with SDS. Proliferationof SDS-iPSCs was reduced relative to wild type controls without a concomitant increase in cell death. Compared to normal iPSC controls, SDS iPSC-derived CD34+ cells exhibited reduced hematopoietic differentiation to CD45+ cells, decreased erythroid and myeloid hematopoietic progenitor colony formation in methylcellulose, and impaired terminal myeloid differentiation.To study the molecular and biologic effects of del(7q), a deletion of the MDS-associated region of the long arm of chromosome 7 was genomically engineered using a previously published modified Cre-Lox approach. The deletion of 7q in SDS iPSCs spanned band q11.23 to q36.3. The SDS-del(7q) iPSCs expressed stem cell markers and formed teratomas as efficiently as their isogenic SDS iPSC controls.Deletion of 7q failed to confer a relative growth advantage even within the context of BMF. Indeed, proliferation of the SDS-del(7q) iPSCs was reduced below that of both the isogenic SDS iPSCs and normal controls without an increase in cell death. To investigate the effect of del(7q) on hematopoiesis, iPSC-derived CD34+ cells were assayed for their ability to undergo hematopoietic differentiation. SDS-del(7q) CD34+ cells demonstrated reduced differentiation to CD45+ cells, reduced methylcellulose hematopoietic progenitor colony formation and impaired terminal myeloid differentiation compared with isogenic SDS CD34+ cells. These data demonstrate that deletion of 7q fails to confer a relative growth advantage relative to isogenic SDS iPSCs and results in a further impairment of hematopoiesis.To gain insight into the mechanisms of del7q-associated clonal evolution in SDS, we performed RNA sequencing (RNAseq) of SDS and SDS-del(7q) iPSC. Expression of TGFβ pathways and their downstream targets were reduced in SDS del(7q) iPSCs compared to isogenic SDS iPSC controls. This observation was intriguing because single cell RNAseq analysis of primary SDS bone marrow cells revealed that TGFβ pathway is hyperactivated in SDS. Additionally, a quantitative DNA aptamer-based proteomic analysis demonstrated elevated levels of TGFβ ligands in plasma from six SDS patients compared to 6 age-matched controls. Western blot analysis showed increased P-SMAD2 levels in SDS iPSCs compared to SDS-del(7q) and normal controls, while total levels of SMAD2 were unchanged. Pharmacological targeting of TFGβ with small molecule inhibitors resulted in selective improvement of SDS hematopoietic colony formation without stimulating outgrowth of the isogenic SDS-del(7q) cells. Although del(7q) does not seem to confer an advantage in growth or hematopoiesis in vitro, we are testing whether the deletion of 7q might confer relative resistance to elevated TGFβ levels in vivo, resulting in an overall survival advantage of the del7q clone.These results demonstrate that the TGFβ pathway is activated in SDS, and that deletion of 7q reverses the TGFβ pathway hyperactivation in SDS. Inhibition of TGFβ selectively rescues hematopoiesis in SDS but not in isogenic del7q cells, suggesting a potential strategy to treat bone marrow failure without stimulating del7q clonal outgrowth. DisclosuresStegmaier:Novartis: Consultancy, Research Funding. Shimamura:TransCellular Therapeutics: Other: Spouse is majority shareholder.

RNA Methylation and Its Role in the Hematopoietic System

RNA methylation represents a novel expansion of traditional epigenetic concepts. RNAs can be methylated at adenine and at cytosine residues, and both modifications have distinct regulatory potential. Our work focuses on the DNMT2 enzyme, which is a member of the animal (cytosine-5) DNA methyltransferase family and has long been considered to function as a DNA methyltransferase. However, a DNA methyltransferase activity could not be confirmed conclusively and more recent work clearly demonstrates that DNMT2 is a tRNA methyltransferase. This unexpected substrate is interpreted to reflect an evolutionary ancient substrate switch from DNA to tRNA that expanded the epigenetic regulatory capacity of the DNMT family to also include RNA. To analyze the function of DNMT2, we performed a detailed analysis of knockout mice. These mice are viable and fertile, but also show a reduction of hematopoietic stem and progenitor cell populations and a cell-autonomous defect in their differentiation.1 RNA bisulfite sequencing revealed that Dnmt2 methylates C38 of tRNA Asp(GTC), Gly(GCC), and Val(AAC). Proteomic analyses from primary bone marrow cells uncovered systematic differences in protein expression that are due to specific codon mistranslation by tRNAs lacking DNMT2-dependent methylation. Together, these results illustrate the regulatory capacity of DNMT2-mediated tRNA methylation in genome recoding.2 Our current work addresses additional mechanistic aspects that link tRNA methylation to translational fidelity and investigates the relevance of DNMT2-mediated tRNA methylation for leukemogenesis.1. Tuorto F, Herbst F, Alerasool N, et al. The tRNA methyltransferase Dnmt2 is required for accurate polypeptide synthesis during haematopoiesis. EMBO J. 2015;34(18):2350-2362.2. Tuorto F, Lyko F. Genome recoding by tRNA modifications. Open Biol. 2016;6(12):160287. DisclosuresNo relevant conflicts of interest to declare.

Enhancement Of Normal Hematopoietic Stem Cells By Redox-Active Antioxidants

Injury to hematopoietic tissues is a major problem limiting the success of cancer therapy, including ionizing radiation, chemotherapy, and immunotherapy. Acute injury to hematopoietic cells challenges hematopoietic stem cells (HSCs) to regenerate for self-renewal and differentiate into different lineages of peripheral blood cells. It is well-documented that HSCs reside in a hypoxia niche and have a lower level of reactive oxygen species (ROS) than their mature progeny. Life-long measurements of local oxygen tension (pO2) in the bone marrow of living mice show that the absolute pO2 of bone marrow is Here, we demonstrate that, in transgenic mice expressing the human manganese superoxide dismutase (MnSOD) gene, a scavenger of ROS in mitochondria, the number and function of hematopoietic stem/progenitor cells (HSPCs) under physiological conditions is enhanced. Importantly, giving MnTnBuOE-2-PyP5+ (MnP), a redox- active MnSOD mimetic, to mouse primary bone marrow cells or to C57B/L6 mice significantly enhances the number of HSPCs. Mechanistically, MnP reduces superoxide to hydrogen peroxide, which activates intracellular Nrf2 signaling leading to the induction of antioxidant enzymes, including MnSOD and catalase, and mitochondrial uncoupling proteins. The results reveal a novel aspect of ROS signaling in regulating stem cell function, and suggest possible beneficial effects of MnP in treating pathological bone marrow cell loss and increasing stem cell population for bone marrow transplantation, and the development of redox-based therapies.

Osteoclast Differentiation is Downregulated by Select Polyphenolic Fractions from Dried Plum via Suppression of MAPKs and Nfatc1 in Mouse C57BL/6 Primary Bone Marrow Cells

BackgroundClinical and preclinical studies have shown that dietary supplementation with dried plum improves bone health. These osteoprotective effects are a result, in part, of the antiresorptive properties of the fruit, which appear to be mediated by its polyphenolic compounds. ObjectiveThis study was designed to determine if certain fractions of the polyphenolic compounds in dried plums are responsible for the antiresorptive effects and whether they alter mitogen-activated protein kinase (MAPK) and calcium signaling, which are essential to osteoclast differentiation and activity, under normal and inflammatory conditions. MethodsSix polyphenolic fractions were derived from the total polyphenolic extract of dried plum based on solubility. Initial screening, with the use of the Raw 264.7 monocyte and macrophage cell line, showed that 3 fractions had the most marked capacity to downregulate osteoclast differentiation. This response was confirmed in 2 of the fractions by using primary bone marrow–derived cultures and in all subsequent experiments to determine how osteoclast differentiation and function were altered with a focus on these 2 fractions in primary cultures. Data were analyzed by using ANOVA followed by post hoc analyses. ResultsBoth of the polyphenol fractions decreased osteoclast differentiation and activity coincident with downregulating nuclear factor of activated T cells, cytoplasmic, calcineurin-dependent 1 (Nfatc1), which is required for osteoclast differentiation. Calcium signaling, essential for the auto-amplification of Nfatc1, was suppressed by the polyphenolic fractions under normal conditions as indicated by suppressed mRNA expression of costimulatory receptors osteoclast-associated receptor (Oscar), signaling regulatory protein β1 (Sirpb1), and triggering receptor expressed on myeloid cells 2 (Trem2). In contrast, in the presence of tumor necrosis factor α (TNF-α), only Sirpb1 was downregulated. In addition to calcium signaling, phosphorylation of extracellular signal–regulated kinase (Erk) and p38 MAPK, involved in the expression and activation of Nfatc1, was also suppressed by the polyphenolic fractions. ConclusionThese results show that certain types of polyphenolic compounds from dried plum downregulate calcium and MAPK signaling, resulting in suppression of Nfatc1 expression, which ultimately decreases osteoclast formation and activity.

Elastase inhibitors as potential therapies for ELANE-associated neutropenia.

Mutations in ELANE, the gene for neutrophil elastase (NE), a protease expressed early in neutrophil development, are the most frequent cause of cyclic (CyN) and severe congenital neutropenia (SCN). We hypothesized that inhibitors of NE, acting either by directly inhibiting enzymatic activity or as chaperones for the mutant protein, might be effective as therapy for CyN and SCN. We investigated β-lactam-based inhibitors of human NE (Merck Research Laboratories, Kenilworth, NJ, USA), focusing on 1 inhibitor called MK0339, a potent, orally absorbed agent that had been tested in clinical trials and shown to have a favorable safety profile. Because fresh, primary bone marrow cells are rarely available in sufficient quantities for research studies, we used 3 cellular models: patient-derived, induced pluripotent stem cells (iPSCs); HL60 cells transiently expressing mutant NE; and HL60 cells with regulated expression of the mutant enzyme. In all 3 models, the cells expressing the mutant enzyme had reduced survival as measured with annexin V and FACS. Coincubation with the inhibitors, particularly MK0339, promoted cell survival and increased formation of mature neutrophils. These studies suggest that cell-permeable inhibitors of neutrophil elastase show promise as novel therapies for ELANE-associated neutropenia.

ZNF300 Promotes Megakaryocytic Differentiation

To study the function of ZNF300 in the megakaryocytes differentiation and proliferation. Public data analysis of ZNF300 expression and megakaryocyte culture were used to reveal the correlation of ZNF300 expression with leukemia and megakaryocyte differetniation; ZNF300 overexpression was mediated by lentiviral or retroviral infection, and the differentiation and proliferation of K562 cells and primary mouse bone marrow cells to magekaryocytes were measured by flow cytometry, MTT assay and colony-forming test; the ZNF300 subcellular localization was tested by separating cytosolic and nuclear extracts combined with Western blotting. The dual-luciferase assay and ChIP-qPCR were used to study ZNF300 target gene. ZNF300 expression upregulation correlated with megakaryoyte differentiation; over-expression of ZNF300 promoted CD41 and CD61 expression, inhibited cell cycle progress, and could reduce colony-forming unit. The ZNF300 locolized in nuclear and regulated C-MYC expression. ZNF300 promotes megakaryocyte differentiation.

Selective Targeting of Bromodomains of the Bromodomain-PHD Fingers Family Impairs Osteoclast Differentiation.

Histone acetyltransferases of the MYST family are recruited to chromatin by BRPF scaffolding proteins. We explored functional consequences and the therapeutic potential of inhibitors targeting acetyl-lysine dependent protein interaction domains (bromodomains) present in BRPF1–3 in bone maintenance. We report three potent and selective inhibitors: one (PFI-4) with high selectivity for the BRPF1B isoform and two pan-BRPF bromodomain inhibitors (OF-1, NI-57). The developed inhibitors displaced BRPF bromodomains from chromatin and did not inhibit cell growth and proliferation. Intriguingly, the inhibitors impaired RANKL-induced differentiation of primary murine bone marrow cells and human primary monocytes into bone resorbing osteoclasts by specifically repressing transcriptional programs required for osteoclastogenesis. The data suggest a key role of BRPF in regulating gene expression during osteoclastogenesis, and the excellent druggability of these bromodomains may lead to new treatment strategies for patients suffering from bone loss or osteolytic malignant bone lesions.

Oxidative stress-induced JNK/AP-1 signaling is a major pathway involved in selective apoptosis of myelodysplastic syndrome cells by Withaferin-A.

Myelodysplastic syndromes (MDS) are a diverse group of malignant clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, dysplastic cell morphology in one or more hematopoietic lineages, and a risk of progression to acute myeloid leukemia (AML). Approximately 50% of MDS patients respond to current FDA-approved drug therapies but a majority of responders relapse within 2-3 years. There is therefore a compelling need to identify potential new therapies for MDS treatment. We utilized the MDS-L cell line to investigate the anticancer potential and mechanisms of action of a plant-derived compound, Withaferin A (WFA), in MDS. WFA was potently cytotoxic to MDS-L cells but had no significant effect on the viability of normal human primary bone marrow cells. WFA also significantly reduced engraftment of MDS-L cells in a xenotransplantation model. Through transcriptome analysis, we identified reactive oxygen species (ROS)-activated JNK/AP-1 signaling as a major pathway mediating apoptosis of MDS-L cells by WFA. We conclude that the molecular mechanism mediating selective cytotoxicity of WFA on MDS-L cells is strongly associated with induction of ROS. Therefore, pharmacologic manipulation of redox biology could be exploited as a selective therapeutic target in MDS.

Effect of AML1-ETO Fusion Protein on Transcriptional Regulation of p14ARF

To investigate the effect of transcriptional regulation of aberrant transcription factor AML1-ETO on p14ARF. P14ARF expression both in AML1-ETO-expressing cells or U937 nonexpressing cells and in leukemia cells of AML patients with or without t(8;21) was assessed by quantitative PCR. Methylation-specific polymerase chain reaction (MSP) was used to analyze the methylation status of p14ARF promoter. The chromatin immunoprecipitation (ChIP)-based PCR was used to investigate the direct interaction between the AML1-ETO and p14ARF promoter in AML1-ETO positive leukemia cell line. And the p14ARF mRNA expression level was detected by qRT-PCR after treatment with 5-Aza. AML1-ETO-expressing cell subclone displayed low level of p14ARF mRNA in comparison with the non-transfected U937. In primary bone marrow cells of acute myeloid leukemia containing AML1-ETO, level of p14ARF mRNA was markedly lower when compared with other acute myeloid leukemias lacking this translocation. P14ARF gene promoter was non-methylated in control group and primary leukemia cells of AML patients without t(8;21) and was hyper-methylated in U937-A/E1-4 and primary leukemia cells of AML patients with t(8;21). The enriched regions in transfected cells were located within p14ARF promoter. 5-Aza could increase the expression of p14ARF. P14ARF is a possible target gene of AML1-ETO. The p14ARF silencing induced by hyper-methlylation may be an important factor for occurrence and development of the M2b subtype of acute myeloid leukemia.

β-Catenin Is a Candidate Therapeutic Target for Myeloid Neoplasms with del(5q).

Deletion of the chromosome 5q [del(5q)] is one of the most common cytogenetic abnormalities observed in patients with de novo myelodysplastic syndromes (MDS) and therapy-related MDS or acute myeloid leukemia (t-MDS/tAML). Emerging evidence indicates that activation of the Wnt/β-catenin pathway contributes to the development of myeloid neoplasms with del(5q). Whether β-catenin is a potential therapeutic target for myeloid neoplasms with del(5q) has yet to be evaluated. Here, we report that genetic deletion of a single allele of β-catenin rescues ineffective hematopoiesis in an Apc haploinsufficient mouse model, which recapitulates several characteristic features of the preleukemic stage of myeloid neoplasms with a -5/del(5q). In addition, loss of a single allele of β-catenin reversed the defective self-renewal capacity of Apc-haploinsufficient hematopoietic stem cells and reduced the frequency of apoptosis induced by Apc haploinsufficiency. Suppression of β-catenin by indomethacin or β-catenin shRNA reduced proliferation and survival of human leukemia cell lines with del(5q) but not of control leukemia cell lines in vitro; β-catenin inactivation also inhibited leukemia progression in vivo in xenograft mice reconstituted with del(5q) leukemia cell lines. Inhibition of β-catenin also stunted growth and colony-forming abilities of primary bone marrow cells from del(5q) AML patients in vitro Overall, our data support the idea that β-catenin could serve as a therapeutic target for the treatment of myeloid neoplasms with del(5q). Cancer Res; 77(15); 4116-26. ©2017 AACR.

SOCS1 function in BCR-ABL mediated myeloproliferative disease is dependent on the cytokine environment.

Treatment with tyrosine kinase inhibitors is the standard of care for Philadelphia chromosome positive leukemias. However the eradication of leukemia initiating cells remains a challenge. Circumstantial evidence suggests that the cytokine microenvironment may play a role in BCR-ABL mediated leukemogenesis and in imatinib resistance. Gene expression analyses of BCR-ABL positive ALL long-term cultured cells revealed strong reduction of SOCS mRNA expression after imatinib treatment, thereby demonstrating a strong inhibition of cytokine signaling. In this study we employed SOCS1—a strong inhibitor of cytokine signaling—as a tool to terminate external cytokine signals in BCR-ABL transformed cells in vitro and in vivo. In colony formation assays with primary bone marrow cells, expression of SOCS1 decreased colony numbers under pro-proliferative cytokines, while it conferred growth resistance to anti-proliferative cytokines. Importantly, co-expression of SOCS1 with BCR-ABL led to the development of a MPD phenotype with a prolonged disease latency compared to BCR-ABL alone in a murine bone marrow transplantation model. Interestingly, SOCS1 co-expression protected 20% of mice from MPD development. In summary, we conclude that under pro-proliferative cytokine stimulation at the onset of myeloproliferative diseases SOCS1 acts as a tumor suppressor, while under anti-proliferative conditions it exerts oncogenic function. Therefore SOCS1 can promote opposing functions depending on the cytokine environment.

Design and Fabrication of a Three-Dimensional In Vitro System for Modeling Vascular Stenosis.

Vascular stenosis, the abnormal narrowing of blood vessels, arises from defective developmental processes or atherosclerosis-related adult pathologies. Stenosis triggers a series of adaptive cellular responses that induces adverse remodeling, which can progress to partial or complete vessel occlusion with numerous fatal outcomes. Despite its severity, the cellular interactions and biophysical cues that regulate this pathological progression are poorly understood. Here, we report the design and fabrication of a three-dimensional (3D) in vitro system to model vascular stenosis so that specific cellular interactions and responses to hemodynamic stimuli can be investigated. Tubular cellularized constructs (cytotubes) were produced, using a collagen casting system, to generate a stenotic arterial model. Fabrication methods were developed to create cytotubes containing co-cultured vascular cells, where cell viability, distribution, morphology, and contraction were examined. Fibroblasts, bone marrow primary cells, smooth muscle cells (SMCs), and endothelial cells (ECs) remained viable during culture and developed location- and time-dependent morphologies. We found cytotube contraction to depend on cellular composition, where SMC-EC co-cultures adopted intermediate contractile phenotypes between SMC- and EC-only cytotubes. Our fabrication approach and the resulting artery model can serve as an in vitro 3D culture system to investigate vascular pathogenesis and promote the tissue engineering field.

MicroRNA-433-3p promotes osteoblast differentiation through targeting DKK1 expression.

Dickkopf-1 (DKK1) is a powerful antagonist of canonical WNT signaling pathway, and is regarded as a biomarker for osteoporosis. Its expression is highly correlated with bone mass and osteoblasts maturation. In this study, mouse primary bone marrow cells and osteoblast cell lines were used. Luciferase reporter assay and western blotting methods were employed to validate if miRNA-433-3p epigenetically regulated DKK1 translation. Rat bone marrow derived osteoblasts were infected with lentivirus vector in which miR-433-3p was constructed. The authors constructed lentivirus mediated miRNA-433-3p stable expression and examined the alkaline phosphatase (ALP) activity and mineral deposition level in vitro. In situ hybridization method was used to observe miR-433-3p in primary osteoblasts. We built up an OVX rat model to mimic postmenopausal osteoporosis, and found aberrant circulating miR-433-3p and miR-106b, which were not reported previously. Results showed that miR-433-3p potentially regulated DKK1 mRNA, Furthermore, the correlation of serum DKK1 with circulating miR-433-3p level was significant (r = 0.7520, p = 0.046). In the luciferase reporter assay, we found that miR-433-3p siRNA decreased luminescence signal, indicating direct regulation of miR-433-3p on DKK1 mRNA. When the miR-433-3p binding site in DKK1 3’UTR was mutant, such reduction was prohibited. Western blotting result validated that miR-433-3p inhibited over 90% of DKK1 protein expression. Similarly, the change of protein expression was not observed in mutant group. The stable expression of lentivirus mediated miR-433-3p increased ALP activity and mineralization both in human and rat derived immortalized cells. We found that primary osteoblasts had higher miR-433-3p level compared with immortal cells through real-time PCR, as well as in situ hybridization experiment. Conclusively, our findings further emphasized the vital role of miR-433-3p in DKK1/WNT/β-catenin pathway through decreasing DKK1 expression and inducing osteoblasts differentiation.

Ratio of Primary Bone Marrow Cells after Induction Chemothrapy for Two Weeks in the Patients with Ph- ALL and Its Influence on Complete Remission and Overall Progrosis

To investigate the influence of bone marrow blasts ratio after induction chemotherapy for 2 weeks in patients with Ph- ALL, and it's influence on complete remission (CR) and overall prognosis. A total of 172 patients with Ph- ALL in our hospital from March 2012 to February 2016 were selected. The bone marrow blast ratio was analyzed by the receiver-operating characteristic curve (ROC) in patients after induction chemotherapy for 2 weeks, at same time its influence on CR and overall prognosis of Ph- ALL patients was evaluated. The cutoff value of CR was 0.075, its area under ROC was 0.763; the comparison of area under ROC with Az=0.5 showed statistically significant difference, therefore 172 patients with Ph- ALL were grouped according to bone marrow blast ratio after induction chemotherapy for 2 weeks: 104 cases (60.5%) with bone marrow blast ratio <0.075, 68 cases (39.5%) with bone marrow blast ratio ≥0.075. The Ph- ALL patinets with bone marrow blast ratio <0.075 who achieved CR and finally achieved CR after induction chemotherapy for 4 weeks acconnted for 89 (85.6%) and 99(95.2%) respectively, which were significantly higher than those in Ph- ALL patients with bone marrow blast ratio≥0.075, [29(42.6%) and 52 (76.5%)](P<0.05). In addition, the influencing factor clinically reducing the OS and DFS rate of patients and enhancing the ralapse rate of patients were mainly chemotherapy, the failure of induction chemotherapy (patients did not achieve CR after induction therapy for 4 weeks), the bone marrow blast ratio≥0.075 after induction treatment for 2 weeks, and CNSL at diagnosis and so on, while the enhaced WBC count at diagnosis was poor factor affecting the DFS rate of patients. After induction chemotherapy for 2 weeks, the elevated bone marrow blast ratio in Ph- ALL patients will be infavourable to CR, and the overall prognosis is poor.