Characterization of direct oral anticoagulants use in adult hematopoietic stem cell transplant recipients.

Direct oral anticoagulants (DOACs) for venous thromboembolism (VTE) treatment are of interest in oncology due to ease of administration and lack of need for therapeutic monitoring compared to other anticoagulants. Data supporting their use in patients with hematologic malignancies post-hematopoietic stem cell transplant (HCT) are limited. The purpose of the study is to characterize DOAC use in HCT patients. This multicenter, retrospective cohort analysis included allogeneic and autologous HCT recipients. The primary outcome was major bleeding. Secondary outcomes included clinically relevant non-major bleeding (CRNMB)/minor bleeding and VTE recurrence. Of 126 patients, 91 (72.2%) patients received an autologous HCT, and 35 (27.8%) patients received an allo-HCT. No major bleeding occurred in either transplant recipient groups. In autologous HCT recipients, CRNMB/minor bleeding occurred in four (4.4%) patients and VTE recurrence occurred in one (1.1%) patient. For allogeneic HCT recipients, CRNMB/minor bleeding occurred in five (14.3%) patients and VTE recurrence occurred in two (5.7%) patients. For patients that experienced a CRNMB, five (100%) of the allogeneic HCT and two (50%) of the autologous HCT recipients were thrombocytopenic at the time of bleeding. Only 38.5% of patients who experienced a drug-drug interaction requiring DOAC dose adjustment received the appropriate dose adjustment. DOACs were associated with low rates of recurrent VTE and no major bleeding events, similar to published data on DOAC use in the general cancer patient population. This suggests that DOACs may be safe therapeutic options with proactive management of drug interactions and careful monitoring for bleeding events, especially in the allogeneic HCT population where minor bleeding rates were slightly higher.

Macrophage-to-endothelial cell crosstalk by the cholesterol metabolite 27HC promotes atherosclerosis in male mice.

Hypercholesterolemia and vascular inflammation are key interconnected contributors to the pathogenesis of atherosclerosis. How hypercholesterolemia initiates vascular inflammation is poorly understood. Here we show in male mice that hypercholesterolemia-driven endothelial activation, monocyte recruitment and atherosclerotic lesion formation are promoted by a crosstalk between macrophages and endothelial cells mediated by the cholesterol metabolite 27-hydroxycholesterol (27HC). The pro-atherogenic actions of macrophage-derived 27HC require endothelial estrogen receptor alpha (ERα) and disassociation of the cytoplasmic scaffolding protein septin 11 from ERα, leading to extranuclear ERα- and septin 11-dependent activation of NF-κB. Furthermore, pharmacologic inhibition of cyp27a1, which generates 27HC, affords atheroprotection by reducing endothelial activation and monocyte recruitment. These findings demonstrate cell-to-cell communication by 27HC, and identify a major causal linkage between the hypercholesterolemia and vascular inflammation that partner to promote atherosclerosis. Interventions interrupting this linkage may provide the means to blunt vascular inflammation without impairing host defense to combat the risk of atherosclerotic cardiovascular disease that remains despite lipid-lowering therapies.

Epo-IGF1R cross talk expands stress-specific progenitors in regenerative erythropoiesis and myeloproliferative neoplasm.

We found that in regenerative erythropoiesis, the erythroid progenitor landscape is reshaped, and a previously undescribed progenitor population with colony-forming unit-erythroid (CFU-E) activity (stress CFU-E [sCFU-E]) is expanded markedly to restore the erythron. sCFU-E cells are targets of erythropoietin (Epo), and sCFU-E expansion requires signaling from the Epo receptor (EpoR) cytoplasmic tyrosines. Molecularly, Epo promotes sCFU-E expansion via JAK2- and STAT5-dependent expression of IRS2, thus engaging the progrowth signaling from the IGF1 receptor (IGF1R). Inhibition of IGF1R and IRS2 signaling impairs sCFU-E cell growth, whereas exogenous IRS2 expression rescues cell growth in sCFU-E expressing truncated EpoR-lacking cytoplasmic tyrosines. This sCFU-E pathway is the major pathway involved in erythrocytosis driven by the oncogenic JAK2 mutant JAK2(V617F) in myeloproliferative neoplasm. Inability to expand sCFU-E cells by truncated EpoR protects against JAK2(V617F)-driven erythrocytosis. In samples from patients with myeloproliferative neoplasm, the number of sCFU-E-like cells increases, and inhibition of IGR1R and IRS2 signaling blocks Epo-hypersensitive erythroid cell colony formation. In summary, we identified a new stress-specific erythroid progenitor cell population that links regenerative erythropoiesis to pathogenic erythrocytosis.

Erythropoietin regulation of red blood cell production: from bench to bedside and back.

More than 50 years of efforts to identify the major cytokine responsible for red blood cell (RBC) production (erythropoiesis) led to the identification of erythropoietin (EPO) in 1977 and its receptor (EPOR) in 1989, followed by three decades of rich scientific discovery. We now know that an elaborate oxygen-sensing mechanism regulates the production of EPO, which in turn promotes the maturation and survival of erythroid progenitors. Engagement of the EPOR by EPO activates three interconnected signaling pathways that drive RBC production via diverse downstream effectors and simultaneously trigger negative feedback loops to suppress signaling activity. Together, the finely tuned mechanisms that drive endogenous EPO production and facilitate its downstream activities have evolved to maintain RBC levels in a narrow physiological range and to respond rapidly to erythropoietic stresses such as hypoxia or blood loss. Examination of these pathways has elucidated the genetics of numerous inherited and acquired disorders associated with deficient or excessive RBC production and generated valuable drugs to treat anemia, including recombinant human EPO and more recently the prolyl hydroxylase inhibitors, which act partly by stimulating endogenous EPO synthesis. Ongoing structure-function studies of the EPOR and its essential partner, tyrosine kinase JAK2, suggest that it may be possible to generate new "designer" drugs that control selected subsets of cytokine receptor activities for therapeutic manipulation of hematopoiesis and treatment of blood cancers.

Installation of a cancer promoting WNT/SIX1 signaling axis by the oncofusion protein MLL-AF9.

BACKGROUND: Chromosomal translocation-induced expression of the chromatin modifying oncofusion protein MLL-AF9 promotes acute myelocytic leukemia (AML). Whereas WNT/ß-catenin signaling has previously been shown to support MLL-AF9-driven leukemogenesis, the mechanism underlying this relationship remains unclear. METHODS: We used two novel small molecules targeting WNT signaling as well as a genetically modified mouse model that allow targeted deletion of the WNT protein chaperone Wntless (WLS) to evaluate the role of WNT signaling in AML progression. ATAC-seq and transcriptome profiling were deployed to understand the cellular consequences of disrupting a WNT signaling in leukemic initiating cells (LICs). FINDINGS: We identified Six1 to be a WNT-controlled target gene in MLL-AF9-transformed leukemic initiating cells (LICs). MLL-AF9 alters the accessibility of Six1 DNA to the transcriptional effector TCF7L2, a transducer of WNT/ß-catenin gene expression changes. Disruption of WNT/SIX1 signaling using inhibitors of the Wnt signaling delays the development of AML. INTERPRETATION: By rendering TCF/LEF-binding elements controlling Six1 accessible to TCF7L2, MLL-AF9 promotes WNT/ß-catenin-dependent growth of LICs. Small molecules disrupting WNT/ß-catenin signaling block Six1 expression thereby disrupting leukemia driven by MLL fusion proteins.

Dynamic Change of Transcription Pausing through Modulating NELF Protein Stability Regulates Granulocytic Differentiation.

The NELF complex is a metazoan-specific factor essential for establishing transcription pausing. Although NELF has been implicated in cell fate regulation, the cellular regulation of NELF and its intrinsic role in specific lineage differentiation remains largely unknown. Using mammalian hematopoietic differentiation as a model system, here we identified a dynamic change of NELF-mediated transcription pausing as a novel mechanism regulating hematopoietic differentiation. We found a sharp decrease of NELF protein abundance upon granulocytic differentiation and a subsequent genome-wide reduction of transcription pausing. This loss of pausing coincides with activation of granulocyte-affiliated genes and diminished expression of progenitor markers. Functional studies revealed that sustained expression of NELF inhibits granulocytic differentiation, whereas NELF depletion in progenitor cells leads to premature differentiation towards the granulocytic lineage. Our results thus uncover a previously unrecognized regulation of transcription pausing by modulating NELF protein abundance to control cellular differentiation.

Fasting selectively blocks development of acute lymphoblastic leukemia via leptin-receptor upregulation.

New therapeutic approaches are needed to treat leukemia effectively. Dietary restriction regimens, including fasting, have been considered for the prevention and treatment of certain solid tumor types. However, whether and how dietary restriction affects hematopoietic malignancies is unknown. Here we report that fasting alone robustly inhibits the initiation and reverses the leukemic progression of both B cell and T cell acute lymphoblastic leukemia (B-ALL and T-ALL, respectively), but not acute myeloid leukemia (AML), in mouse models of these tumors. Mechanistically, we found that attenuated leptin-receptor (LEPR) expression is essential for the development and maintenance of ALL, and that fasting inhibits ALL development by upregulation of LEPR and its downstream signaling through the protein PR/SET domain 1 (PRDM1). The expression of LEPR signaling-related genes correlated with the prognosis of pediatric patients with pre-B-ALL, and fasting effectively inhibited B-ALL growth in a human xenograft model. Our results indicate that the effects of fasting on tumor growth are cancer-type dependent, and they suggest new avenues for the development of treatment strategies for leukemia.

Uncoupling JAK2 V617F activation from cytokine-induced signalling by modulation of JH2 αC helix.

The mechanisms by which JAK2 is activated by the prevalent pseudokinase (JH2) V617F mutation in blood cancers remain elusive. Via structure-guided mutagenesis and transcriptional and functional assays, we identify a community of residues from the JH2 helix αC, SH2-JH2 linker and JH1 kinase domain that mediate V617F-induced activation. This circuit is broken by altering the charge of residues along the solvent-exposed face of the JH2 αC, which is predicted to interact with the SH2-JH2 linker and JH1. Mutations that remove negative charges or add positive charges, such as E596A/R, do not alter the JH2 V617F fold, as shown by the crystal structure of JH2 V617F E596A. Instead, they prevent kinase domain activation via modulation of the C-terminal residues of the SH2-JH2 linker. These results suggest strategies for selective V617F JAK2 inhibition, with preservation of wild-type function.

In Vivo Quantitative Microcomputed Tomographic Analysis of Vasculature and Organs in a Normal and Diseased Mouse Model.

Non-bone in vivo micro-CT imaging has many potential applications for preclinical evaluation. Specifically, the in vivo quantification of changes in the vascular network and organ morphology in small animals, associated with the emergence and progression of diseases like bone fracture, inflammation and cancer, would be critical to the development and evaluation of new therapies for the same. However, there are few published papers describing the in vivo vascular imaging in small animals, due to technical challenges, such as low image quality and low vessel contrast in surrounding tissues. These studies have primarily focused on lung, cardiovascular and brain imaging. In vivo vascular imaging of mouse hind limbs has not been reported. We have developed an in vivo CT imaging technique to visualize and quantify vasculature and organ structure in disease models, with the goal of improved quality images. With 1-2 minutes scanning by a high speed in vivo micro-CT scanner (Quantum CT), and injection of a highly efficient contrast agent (Exitron nano 12000), vasculature and organ structure were semi-automatically segmented and quantified via image analysis software (Analyze). Vessels of the head and hind limbs, and organs like the heart, liver, kidneys and spleen were visualized and segmented from density maps. In a mouse model of bone metastasis, neoangiogenesis was observed, and associated changes to vessel morphology were computed, along with associated enlargement of the spleen. The in vivo CT image quality, voxel size down to 20 µm, is sufficient to visualize and quantify mouse vascular morphology. With this technique, in vivo vascular monitoring becomes feasible for the preclinical evaluation of small animal disease models.

Regulation of Hematopoiesis and Methionine Homeostasis by mTORC1 Inhibitor NPRL2.

Nitrogen permease regulator-like 2 (NPRL2) is a component of a conserved complex that inhibits mTORC1 (mammalian Target Of Rapamycin Complex 1) in response to amino acid insufficiency. Here, we show that NPRL2 is required for mouse viability and that its absence significantly compromises fetal liver hematopoiesis in developing embryos. Moreover, NPRL2 KO embryos have significantly reduced methionine levels and exhibit phenotypes reminiscent of cobalamin (vitamin B12) deficiency. Consistent with this idea, NPRL2 KO liver and mouse embryonic fibroblasts (MEFs) show defective processing of the cobalamin-transport protein transcobalamin 2, along with impaired lysosomal acidification and lysosomal gene expression. NPRL2 KO MEFs exhibit a significant defect in the cobalamin-dependent synthesis of methionine from homocysteine, which can be rescued by supplementation with cyanocobalamin. Taken together, these findings demonstrate a role for NPRL2 and mTORC1 in the regulation of lysosomal-dependent cobalamin processing, methionine synthesis, and maintenance of cellular re-methylation potential, which are important during hematopoiesis.

Genome editing of mouse fibroblasts by homologous recombination for sustained secretion of PDGF-B and augmentation of wound healing.

BACKGROUND: Exogenous cytokines, such as platelet-derived growth factor (PDGF)-B, can augment wound healing, but sustained delivery to maintain therapeutic levels remains a problem. "Genome editing" is a new technology in which precise genome modifications are made within cells using engineered site-specific nucleases. Genome editing avoids many of the complications associated with traditional gene therapy and the use of viral vectors, including random integration, imprecise gene expression, and inadvertent oncogene activation. METHODS: This study demonstrates site-specific nuclease-mediated integration of a PDGF-B transgene into a predefined locus within the genome of primary mouse fibroblasts. Engineered fibroblasts were applied to splinted mouse wounds and evaluated after 14 days and 5 months for the retention of engineered fibroblasts, wound healing morphology, angiogenesis, and systemic PDGF-B expression. RESULTS: The application of engineered PDGF-B-expressing fibroblasts enhanced wound healing compared with controls. Low-level, constitutive expression of PDGF-B was achieved without detectable levels of systemic PDGF-B. The mechanism of improved wound healing is, at least in part, the result of increased wound vascularization, as the wounds treated with PDGF-B fibroblasts had a blood vessel density 2.5 times greater than controls. After 5 months, the engineered fibroblasts persisted in the wound bed. No adverse effects were detected from the application of these fibroblasts after 5 months as assessed by hematoxylin and eosin staining of wounds and by mouse necropsy. CONCLUSIONS: These data support that site-specific genome editing allows for sustained cell-based cytokine delivery. Furthermore, sustained release of PDGF-B increases the speed and quality of wound healing after a single application.

Changing trends in the proportions of small (≤ 2 cm) proximal and non-proximal gastric carcinomas treated at a high-volume tertiary medical center in China.

OBJECTIVE: Guided by the recently established histological criteria of the gastroesophageal junction (GEJ), we aimed to investigate and compare trends in the proportions of small (≤ 2 cm) proximal gastric carcinoma (PGC) vs non-PGC (NPGC) in Chinese patients over an 8-year period. METHODS: The study was conducted with consecutive surgical resected specimens of small PGC that was located within 3 cm below the GEJ and NPGC (located at all other gastric regions) treated at a single medical center in China. Differences in proportions between the two groups were compared. RESULTS: Among all 313 cases, 111 (35.5%) were classified as PGC and the remaining 202 (64.5%) as NPGC. Patients with PGC were significantly elder than those with NPGC, and none aged younger than 40 years. The proportions of PGC significantly and progressively increased from 16% in 2004 to 45% in 2011, in contrast to a steady decreasing trend for NPGC from 84% to 55% over the same period. The difference in trends between the two groups approached, but was not at a statistically significant level (P = 0.08). Proportions of small cancers in the gastric corpus and in female patients remained low and stable, in contrast to a significantly higher proportion in male patients (P < 0.05). CONCLUSIONS: Our data showed a significantly upward-shifting trend in the proportions of small PGC, primarily in elderly male patients, in contrast to a downward shifting trend in NPGC over the most recent 8-year period in Chinese patients.

Safety of onabotulinum toxin a injection to the central upper eyelid and eyebrow regions.

PURPOSE: To evaluate the safety of onabotulinum toxin A injected into the central upper eyelid and eyebrow regions. METHODS: The authors retrospectively reviewed the charts of all patients undergoing onabotulinum toxin A injection to the central upper eyelid and eyebrow between February, 2012, and November, 2012. Age, gender, indication, injection sites, number of central units, total number of units, and occurrence of adverse events were all recorded. RESULTS: A total of 300 procedures on 88 patients were performed, in whom the central upper eyelid and/or central eyebrow was injected with onabotulinum toxin A. There were 68 female and 20 male patients. Average age was 68.7±13.3 years (range, 42-92 years). Indications for central eyelid/eyebrow treatment included blepharospasm (34 patients, 176 procedures), hemifacial spasm (21 patients, 40 procedures), facial nerve disorders (2 patients, 9 procedures), and facial rhytides/eyebrow ptosis (31 patients, 75 procedures). The amount of neurotoxin injected into the central eyelid and eyebrow ranged from 2 to 12.5 units per encounter. Complications included diplopia (4% of total encounters), lagophthalmos (1% of total encounters), blepharoptosis (1% of total encounters), and blurry vision (1% of total encounters). Minor local effects, including bruising, bleeding, pain, and mild swelling, were recorded in 3.3% of total encounters. CONCLUSIONS: Placement of onabotulinum toxin A into the central upper eyelid and eyebrow is associated with a low rate of blepharoptosis. Central eyelid and eyebrow neurotoxin injection can be safely added to the regimen when treatment calls for chemodenervation of the central orbicularis oculi.

Dimensions and anatomic variations of the orbicularis oculi muscle in nonpreserved, fresh-frozen human cadavers.

PURPOSE: To determine average dimensions of the orbicularis oculi muscle (OOM) from the orbital rim and to investigate polymorphic variations through anatomical dissection of nonpreserved, fresh-frozen human cadavers. METHODS: The OOM was exposed using sharp and blunt dissection until its distal borders were identified. A metric ruler was used to measure the superior (S line), inferior (I line), and lateral (L line) dimensions of the OOM from the orbital rim. Data collection included age, gender, and race. Data were analyzed using 2-sample t tests, paired t tests, and mixed effect models. A p-value of ≤0.05 was considered statistically significant. RESULTS: A total of 40 hemifaces of 20 cadavers were dissected. All specimens were Caucasian. Ten specimens were men. Average age was 73.9 years (56-92 years). The overall S line was 1.4 cm (95% confidence interval [CI], 1.23-1.57), the I line was 1.2 cm (95% CI, 1.00-1.36), and the L line was 2.5 cm (95% CI, 2.27-2.68). Men had significantly larger average T, L, and S line values than women (p = 0.003, 0.005, 0.008, respectively). I lines did not differ significantly between genders (p = 0.28). CONCLUSIONS: In senescent Caucasians, the OOM extends approximately 1.4 cm superior, 1.2 cm inferior, and 2.5 cm lateral to the orbital rim. The muscle extends significantly further superiorly and laterally in Caucasian men than in women. Knowledge of the extent of the OOM should improve the understanding and the treatment of conditions affecting this region.

Using functional signature ontology (FUSION) to identify mechanisms of action for natural products.

A challenge for biomedical research is the development of pharmaceuticals that appropriately target disease mechanisms. Natural products can be a rich source of bioactive chemicals for medicinal applications but can act through unknown mechanisms and can be difficult to produce or obtain. To address these challenges, we developed a new marine-derived, renewable natural products resource and a method for linking bioactive derivatives of this library to the proteins and biological processes that they target in cells. We used cell-based screening and computational analysis to match gene expression signatures produced by natural products to those produced by small interfering RNA (siRNA) and synthetic microRNA (miRNA) libraries. With this strategy, we matched proteins and miRNAs with diverse biological processes and also identified putative protein targets and mechanisms of action for several previously undescribed marine-derived natural products. We confirmed mechanistic relationships for selected siRNAs, miRNAs, and compounds with functional roles in autophagy, chemotaxis mediated by discoidin domain receptor 2, or activation of the kinase AKT. Thus, this approach may be an effective method for screening new drugs while simultaneously identifying their targets.

Cbl ubiquitination of p85 is essential for Epo-induced EpoR endocytosis.

Erythropoietin (Epo) binding to the Epo receptor (EpoR) elicits downstream signaling that is essential for red blood cell production. One important negative regulatory mechanism to terminate Epo signaling is Epo-induced EpoR endocytosis and degradation. Defects in this mechanism play a key role in the overproduction of erythrocytes in primary familial and congenital polycythemia (PFCP). Here we have identified a novel mechanism mediating Epo-dependent EpoR internalization. Epo induces Cbl-dependent ubiquitination of the p85 regulatory subunit of PI3K, which binds to phosphotyrosines on EpoR. Ubiquitination allows p85 to interact with the endocytic protein epsin-1, thereby driving EpoR endocytosis. Knockdown of Cbl, expression of its dominant negative forms, or expression of an epsin-1 mutant devoid of ubiquitin-interacting motifs all compromise Epo-induced EpoR internalization. Mutated EpoRs mimicking those from PFCP patients cannot bind p85, co-localize with epsin-1, or internalize on Epo stimulation and exhibit Epo hypersensitivity. Similarly, knockdown of Cbl also causes Epo hypersensitivity in primary erythroid progenitors. Restoring p85 binding to PFCP receptors rescues Epo-induced epsin-1 co-localization and EpoR internalization and normalizes Epo hypersensitivity. Our results uncover a novel Cbl/p85/epsin-1 pathway in EpoR endocytosis and show that defects in this pathway contribute to excessive Epo signaling and erythroid hyperproliferation in PFCP.

Chemical principles for the design of a novel fluorescent probe with high cancer-targeting selectivity and sensitivity.

Understanding of principles governing selective and sensitive cancer targeting is critical for development of chemicals for cancer diagnostics and treatment. We determined the underlying mechanisms of how a novel fluorescent small organic molecule, 3,6-bis(1-methyl-4-vinylpyridinium)carbazole diiodide (BMVC), selectively labels cancer cells but not normal cells. We show that BMVC is retained in the lysosomes of normal cells. In cancer cells, BMVC escapes lysosomal retention and localizes to the mitochondria or to the nucleus, where DNA-binding dramatically increases BMVC fluorescence intensity, allowing it to light up only cancer cells. Structure-function analyses of BMVC derivatives show that hydrogen-bonding capacity is a key determinant of lysosomal retention in normal cells, whereas lipophilicity directs these derivatives to the mitochondria or the nucleus in cancer cells. In addition, drug-resistant cancer cells preferentially retain BMVC in their lysosomes compared to drug-sensitive cancer cells, and BMVC can be released from drug-resistant lysosomes using lysosomotropic agents. Our results further our understanding of how properties of cellular organelles differ between normal and cancer cells, which can be exploited for diagnostic and/or therapeutic use. We also provide physiochemical design principles for selective targeting of small molecules to different organelles. Moreover, our results suggest that agents which can increase lysosomal membrane permeability may re-sensitize drug-resistant cancer cells to chemotherapeutic agents.

Ab initio modeling and experimental assessment of Janus Kinase 2 (JAK2) kinase-pseudokinase complex structure.

The Janus Kinase 2 (JAK2) plays essential roles in transmitting signals from multiple cytokine receptors, and constitutive activation of JAK2 results in hematopoietic disorders and oncogenesis. JAK2 kinase activity is negatively regulated by its pseudokinase domain (JH2), where the gain-of-function mutation V617F that causes myeloproliferative neoplasms resides. In the absence of a crystal structure of full-length JAK2, how JH2 inhibits the kinase domain (JH1), and how V617F hyperactivates JAK2 remain elusive. We modeled the JAK2 JH1-JH2 complex structure using a novel informatics-guided protein-protein docking strategy. A detailed JAK2 JH2-mediated auto-inhibition mechanism is proposed, where JH2 traps the activation loop of JH1 in an inactive conformation and blocks the movement of kinase αC helix through critical hydrophobic contacts and extensive electrostatic interactions. These stabilizing interactions are less favorable in JAK2-V617F. Notably, several predicted binding interfacial residues in JH2 were confirmed to hyperactivate JAK2 kinase activity in site-directed mutagenesis and BaF3/EpoR cell transformation studies. Although there may exist other JH2-mediated mechanisms to control JH1, our JH1-JH2 structural model represents a verifiable working hypothesis for further experimental studies to elucidate the role of JH2 in regulating JAK2 in both normal and pathological settings.