Chromatin accessibility and cell cycle progression are controlled by the HDAC-associated Sin3B protein in murine hematopoietic stem cells.

BACKGROUND: Blood homeostasis requires the daily production of millions of terminally differentiated effector cells that all originate from hematopoietic stem cells (HSCs). HSCs are rare and exhibit unique self-renewal and multipotent properties, which depend on their ability to maintain quiescence through ill-defined processes. Defective control of cell cycle progression can eventually lead to bone marrow failure or malignancy. In particular, the molecular mechanisms tying cell cycle re-entry to cell fate commitment in HSCs remain elusive. Previous studies have identified chromatin coordination as a key regulator of differentiation in embryonic stem cells. RESULTS: Here, we utilized genetic inactivation of the chromatin-associated Sin3B protein to manipulate cell cycle control and found dysregulated chromatin accessibility and cell cycle progression in HSCs. Single cell transcriptional profiling of hematopoietic stem and progenitor cells (HSPCs) inactivated for Sin3B reveals aberrant progression through the G1 phase of the cell cycle, which correlates with the engagement of specific signaling pathways, including aberrant expression of cell adhesion molecules and the interferon signaling program in LT-HSCs. In addition, we uncover the Sin3B-dependent accessibility of genomic elements controlling HSC differentiation, which points to cell cycle progression possibly dictating the priming of HSCs for differentiation. CONCLUSIONS: Our findings provide new insights into controlled cell cycle progression as a potential regulator of HSC lineage commitment through the modulation of chromatin features.

Non-genetic mechanisms of drug resistance in acute leukemias.

Acute leukemia is characterized by clonal heterogeneity that contributes to poor drug responses in patients. Despite treatment advances, the occurrence of relapse remains a major barrier to achieving cures as current therapeutic approaches are inadequate to effectively prevent or overcome resistance. Given that only a few genetic mutations are associated with relapse in acute leukemia patients, there is a growing focus on 'non-genetic' mechanisms that affect the hallmarks of cancer to allow leukemic cells to survive post therapy. In this review, we provide an overview of the therapeutic landscape in acute leukemias. Importantly, we discuss non-genetic mechanisms exploited by leukemic cells to promote their survival after treatment. Last, we present current strategies to prevent or overcome drug resistance in this disease.

Chromatin-Associated SIN3B Protects Cancer Cells from Genotoxic Stress-Induced Apoptosis and Dictates DNA Damage Repair Pathway Choice.

Transcription and DNA damage repair act in a coordinated manner. The scaffolding protein SIN3B serves as a transcriptional co-repressor of hundreds of cell cycle-related genes. However, the contribution of SIN3B during the DNA damage response remains unknown. Here, we show that SIN3B inactivation delays the resolution of DNA double-strand breaks and sensitizes cancer cells to DNA-damaging agents, including the chemotherapeutic drugs cisplatin and doxorubicin. Mechanistically, SIN3B is rapidly recruited to DNA damage sites where it directs the accumulation of Mediator of DNA Damage Checkpoint 1 (MDC1). In addition, we show that SIN3B inactivation favors the engagement of the alternative nonhomologous end joining (NHEJ) repair pathway over the canonical NHEJ. Altogether, our findings impute an unexpected function for the transcriptional co-repressor SIN3B as a gatekeeper of genomic integrity and a determining factor in the DNA repair choice pathway, and point to the inhibition of the SIN3B chromatin-modifying complex as a novel therapeutic vulnerability in cancer cells. IMPLICATIONS: Identifying SIN3B as a modulator of DNA damage repair choice provides novel potential therapeutic avenues to sensitize cancer cells to cytotoxic therapies.

The Sin3B chromatin modifier restricts cell cycle progression to dictate hematopoietic stem cell differentiation.

To maintain blood homeostasis, millions of terminally differentiated effector cells are produced every day. At the apex of this massive and constant blood production lie hematopoietic stem cells (HSCs), a rare cell type harboring unique self-renewal and multipotent properties. A key feature of HSCs is their ability to temporarily exit the cell cycle in a state termed quiescence. Defective control of cell cycle progression can eventually lead to bone marrow failure or malignant transformation. Recent work in embryonic stem cells has suggested that cells can more robustly respond to differentiation cues in the early phases of the cell cycle, owing to a discrete chromatin state permissive to cell fate commitment. However, the molecular mechanisms tying cell cycle re-entry to cell fate commitment in adult stem cells such as HSCs remain elusive. Here, we report that the chromatin-associated Sin3B protein is necessary for HSCs' commitment to differentiation, but dispensable for their self-renewal or survival. Transcriptional profiling of hematopoietic stem and progenitor cells (HSPCs) genetically inactivated for Sin3B at the single cell level reveals aberrant cell cycle gene expression, correlating with the defective engagement of discrete signaling programs. In particular, the loss of Sin3B in the hematopoietic compartment results in aberrant expression of cell adhesion molecules and essential components of the interferon signaling cascade in LT-HSCs. Finally, chromatin accessibility profiling in LT-HSCs suggests a link between Sin3B-dependent cell cycle progression and priming of hematopoietic stem cells for differentiation. Together, these results point to controlled progression through the G1 phase of the cell cycle as a likely regulator of HSC lineage commitment through the modulation of chromatin features.

Multi-criteria Decision Analysis Software in Healthcare Priority Setting: A Systematic Review.

OBJECTIVE: The objectives of this systematic review were to identify studies using Multi-Criteria Decision Analysis (MCDA) software tools to support health prioritisation processes and describe the technical capabilities of the MCDA software tools identified. METHODS: First, a systematic literature review was conducted in the MEDLINE, EMBASE, Web of Science, EconLit and Cochrane databases in July 2019 to identify studies that have used MCDA software for priority setting in health-related problems. Second, the MCDA software tools found in the review were downloaded (full versions, where freely available, and trial versions otherwise) and tested to extract their key technical characteristics. RESULTS: Nine studies were included, from which seven different software tools, 1000minds®, M-MACBETH, Socio Technical Allocation of Resources (STAR), Strategic Multi-Attribute Ranking Tool (SMART), Visual PROMETHEE, EVIDEM and the Prioritisation Framework, were identified. These software tools differed in terms of the operating systems (including web interface), MCDA technique(s) available for use, visualisation features, and the capability to perform Value for Money (VfM) and sensitivity analyses. CONCLUSIONS: The use of MCDA software in prioritisation processes has a number of advantages such as inclusion of several types of stakeholders and the ability to analyse a greater number of alternatives and criteria and perform real-time sensitivity analyses. Proprietary software (i.e. software with licensing fees) seemed to have more features than freely available software. However, this field is still developing, with only a few studies where MCDA software was used to support health priority setting and opportunity costs not explicitly captured in many software tools.

The HDAC-Associated Sin3B Protein Represses DREAM Complex Targets and Cooperates with APC/C to Promote Quiescence.

The mammalian DREAM complex is responsible for the transcriptional repression of hundreds of cell-cycle-related genes in quiescence. How the DREAM complex recruits chromatin-modifying entities to aid in its repression remains unknown. Using unbiased proteomics analysis, we have uncovered a robust association between the chromatin-associated Sin3B protein and the DREAM complex. We have determined that genetic inactivation of Sin3B results in the de-repression of DREAM target genes during quiescence but is insufficient to allow quiescent cells to resume proliferation. However, inactivation of APC/CCDH1 was sufficient for Sin3B-/- cells, but not parental cells, to re-enter the cell cycle. These studies identify Sin3B as a transcriptional corepressor associated with the DREAM complex in quiescence and reveals a functional cooperation between E2F target repression and APC/CCDH1 in the negative regulation of cell-cycle progression.

Notch signaling regulates arterial vasoreactivity through opposing functions of Jagged1 and Dll4 in the vessel wall.

Functional interactions between endothelial cells (ECs) and smooth muscle cells (SMCs) in the arterial wall are necessary for controlling vasoreactivity that underlies vascular resistance and tone. Key signaling pathways converge on the phosphorylation of myosin light chain (p-MLC), the molecular signature of force production in SMCs, through coordinating the relative activities of myosin light chain kinase (MLCK) and myosin phosphatase (MP). Notch signaling in the vessel wall serves critical roles in arterial formation and maturation and has been implicated in arterial vasoregulation. In this report, we hypothesized that Notch signaling through ligands Jagged1 (in SMCs) and delta-like protein-4 (Dll4; in ECs) regulates vasoreactivity via homotypic (SMC-SMC) and heterotypic (EC-SMC) cell interactions. Using ligand induction assays, we demonstrated that Jagged1 selectively induced smooth muscle MLCK gene expression and p-MLC content while inhibiting MP function (i.e., increased Ca2+ sensitization) in a Rho kinase II-dependent manner. Likewise, selective deficiency of smooth muscle Jagged1 in mice resulted in MLCK and p-MLC loss, reduced Ca2+ sensitization, and impaired arterial force generation measured by myography. In contrast, smooth muscle Notch signaling triggered by Dll4 increased expression of MP-targeting subunit 1 (MYPT1; the MP regulatory subunit), whereas arteries from endothelial Dll4-deficient mice featured reduced MYPT1 levels, enhanced force production, and impaired relaxation independent of endothelium-derived nitric oxide signaling. Taken together, this study identifies novel opposing vasoregulatory functions for ligand-specific Notch signaling in the vessel wall, underscoring instructional signaling between ECs and SMCs and suggesting that Notch signals might behave as a "rheostat" in arterial tone control. NEW & NOTEWORTHY The present study unveils novel roles for ligand-specific Notch signaling in arterial function. Smooth muscle Jagged1 and endothelial cell delta-like protein-4 ligands exhibit selective regulation of myosin light chain kinase and myosin phosphatase-targeting subunit 1/myosin phosphatase, respectively, providing a mechanistic link through which Notch signals modulate contractile activities in vascular smooth muscle. These findings may inform vascular derangements observed in human syndromes of Notch signaling deficiency while offering fundamental molecular insights into arterial physiological function.

Costo-efectividad del diagnóstico etiológico de la cervicitis por c. trachomatis basado en pruebas rápidas comparado con el abordaje sindrómico, en mujeres no gestantes con síntomas de infección del tracto genital inferior / Cost-effectiveness of etiologic diagnosis for C. trachomatis infection based on rapid tests versus syndromic approach in non-pregnant women with symptoms of lower genital tract infection

Objetivo: estimar la razón costo-efectividad del diagnóstico etiológico con pruebas rápidas para la cervicitis por C. trachomatis frente al diagnóstico sindrómico, en mujeres no gestantes con síntomas de infección del tracto genital inferior en Colombia. Materiales y métodos: se construyó un árbol de decisión para determinar la razón de costo-efectividad de la aproximación etiológica con las pruebas rápidas Acon®Plate, Acon®Duo y QuickVue® para la detección de C. trachomatis comparada con el diagnóstico sindrómico. La perspectiva fue la del sistema de salud colombiano incluyendo todos los costos médicos directos. El horizonte de tiempo fue de 15 días, ya que la unidad de resultado fue el número de casos correctamente identificados (número de verdaderos positivos y verdaderos negativos). Las características operativas de las pruebas se obtuvieron en un estudio de corte transversal diseñado y conducido para este propósito. Resultados: la alternativa más costosa y más efectiva fue QuickVue® seguida de Acon®Plate y del abordaje sindrómico. Acon®Duo fue una estrategia dominada. La razón de costo-efectividad incremental de QuickVue®, comparada con Acon®Plate, fue de $ 430.671; la de Acon®Plate, comparada con el abordaje sindrómico, fue de $ 79.747. Conclusión: si la disponibilidad a pagar (DAP) por un caso correctamente identificado adicional es mayor que $ 430.671, QuickVue® sería la mejor alternativa en términos de costo-efectividad; de otro lado, si la DAP está entre $ 79.747 y $ 430.671, Acon®Plate sería la alternativa costo-efectiva. Finalmente, si la DAP es menor que $ 79.747, el abordaje sindrómico sería la mejor alternativa en términos de costo-efectividad.

Objective: To estimate the cost-effectiveness of etiological approach with rapid tests for C. trachomatis cervicitis versus syndromic diagnosis, in non-pregnant women with symptoms of lower genital tract infection in Colombia. Materials and methods: A decision tree was developed for determining the cost-effectiveness ratio of the aetiological approach using the Acon®Plate, Acon®Duo and QuickVue® quick tests for the detection of C. trachomatis, compared with the syndromic diagnosis. The perspective was that of the Colombian healthcare system, including medical direct costs. The time period was 15 days, considering that the outcome unit was the number of cases identified correctly (number of true positives and true negatives). The operational characteristics of the tests were derived from a cross-sectional study designed and conducted for that specific purpose. Results: The more costly and effective option was QuickVue®, followed by Acon®Plate and the syndromic approach. Acon®Duo was a dominated strategy. The incremental cost-effectiveness ratio for QuickVue® compared with Acon®Plate was $430.671, and that of Acon®Plate compared with the syndromic approach was $79.747. Conclusion: If the willingness to pay (WTP) for an additional case that is correctly identified is greater than $430.671, QuickVue® would be the best option in cost-effectiveness terms. On the other hand, if the WTP is between $79.747 and $430.671, Acon®Plate would be the cost-effective strategy. Finally, if the WTP is less than $79.747, the syndromic approach would be the best option in cost-effectiveness terms.

[18FDG-PET/CT cost-effectiveness compared to CT at the end of treatment in pediatric Hodgkin's lymphoma patients]. / Costo-efectividad de 18FDG-PET/CT vs CT al final del tratamiento en pacientes pediátricos con Linfoma Hodgkin.

OBJECTIVE: Estimating the cost-effectiveness of 18FDG-PET/CT (positron emission tomography) compared to computer tomography (CT) followed by 18FDG-PET/CT as a confirmatory test for a positive case at the end of treatment in Hodgkin's lymphoma (HL) patients under 18 years-old. METHODS: A decision tree was built for comparing 18FDG-PET/CT to CT followed by 18FDG-PET/CT as a confirmatory test for a positive case in detecting residual lesions; outcome was measured in life years gained (LYG). The cost-effectiveness ratio was calculated; the threshold was 3 times the per capita GDP per LYG. Values were expressed in Colombian pesos for 2010 (1 US dollar=$ 1,897.89) and submitted to deterministic and probabilistic sensitivity analysis. RESULTS: Assuming a difference of 13 months in true positives' life expectancy compared to that for false negatives, the cost of an additional LYG with 18FDG-PET/CT compared to CT followed by 18FDG-PET/CT as a confirmatory test for a positive case when evaluating the end of pediatric HL patients' treatment was $ 34,508,590 (COP). CONCLUSION: If differential life-expectancy between true positives and false negatives is at least 1.03 years, then using 18FDG-PET/CT for evaluating the end of HL pediatric patients' therapy is a cost-effective strategy for Colombia.

Costo-efectividad de 18FDG-PET/CT vs CT al final del tratamiento en pacientes pediátricos con Linfoma Hodgkin / 18FDG-PET/CT cost-effectiveness compared to CT at the end of treatment in pediatric Hodgkin's lymphoma patients

Objetivo Estimar la costo-efectividad de 18FDG-PET/CT comparado con CT seguido de 18FDG-PET/CT como prueba confirmatoria de un caso positivo en la evaluación al final del tratamiento en pacientes menores de 18 años con Linfoma Hodgkin (LH). Métodos Se construyó un árbol de decisión donde se comparó el uso de 18FDG-PET/CT con CT seguido de 18FDG-PET/CT como prueba confirmatoria de un caso positivo en la detección de lesión residual. El resultado se midió en Años de Vida Ganados (AVG). Se calculó la razón de costo-efectividad incremental. Se utilizó como umbral 3 veces el PIB per cápita por año AVG. Valores expresados en pesos colombianos de 2010 (1 US dólar = $ 1 897,89) Se realizaron análisis de sensibilidad univariados, bivariados y probabilísticos. Resultados Suponiendo un diferencial en AVG entre verdaderos positivos y falsos negativos de 13 meses, el costo de un AVG adicional con 18FDG-PET/CT comparado con CT seguido de 18FDG-PET/CT como prueba confirmatoria de un caso positivo en la evaluación al final del tratamiento en pacientes pediátricos con LH fue $ 34 508 590. Conclusión Si el diferencial de esperanza de vida entre verdaderos positivos y falsos negativos es de al menos un 1,03 años, el uso de 18FDG-PET/CT en la evaluación al final del tratamiento de pacientes pediátricos con LH, es una estrategia costo-efectiva para Colombia.

Objective Estimating the cost-effectiveness of 18FDG-PET/CT (positron emission tomography) compared to computer tomography (CT) followed by 18FDG-PET/CT as a confirmatory test for a positive case at the end of treatment in Hodgkin's lymphoma (HL) patients under 18 years-old. Methods A decision tree was built for comparing 18FDG-PET/CT to CT followed by 18FDG-PET/CT as a confirmatory test for a positive case in detecting residual lesions; outcome was measured in life years gained (LYG). The cost-effectiveness ratio was calculated; the threshold was 3 times the per capita GDP per LYG. Values were expressed in Colombian pesos for 2010 (1 US dollar=$ 1,897.89) and submitted to deterministic and probabilistic sensitivity analysis. Results Assuming a difference of 13 months in true positives' life expectancy compared to that for false negatives, the cost of an additional LYG with 18FDG-PET/CT compared to CT followed by 18FDG-PET/CT as a confirmatory test for a positive case when evaluating the end of pediatric HL patients' treatment was $ 34,508,590 (COP). Conclusion If differential life-expectancy between true positives and false negatives is at least 1.03 years, then using 18FDG-PET/CT for evaluating the end of HL pediatric patients' therapy is a cost-effective strategy for Colombia.