Spatially- and temporally-controlled postnatal p53 knockdown cooperates with embryonic Schwann cell precursor Nf1 gene loss to promote malignant peripheral nerve sheath tumor formation

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive sarcomas that arise sporadically or in association with the Neurofibromatosis type 1 (NF1) cancer predisposition syndrome. In individuals with NF1, MPNSTs are hypothesized to arise from Nf1-deficient Schwann cell precursor cells following the somatic acquisition of secondary cooperating genetic mutations (e.g., p53 loss). To model this sequential genetic cooperativity, we coupled somatic lentivirus-mediated p53 knockdown in the adult right sciatic nerve with embryonic Schwann cell precursor Nf1 gene inactivation in two different Nf1 conditional knockout mouse strains. Using this approach, ~60% of mice with Periostin-Cre-mediated Nf1 gene inactivation (Periostin-Cre; Nf1(flox/flox) mice) developed tumors classified as low-grade MPNSTs following p53 knockdown (mean, 6 months). Similarly, ~70% of Nf1+/- mice with GFAP-Cre-mediated Nf1 gene inactivation (GFAP-Cre; Nf1(flox/null) mice) developed low-grade MPNSTs following p53 knockdown (mean, 3 months). In addition, wild-type and Nf1+/- mice with GFAP-Cre-mediated Nf1 loss develop MPNSTs following somatic p53 knockout with different latencies, suggesting potential influences of Nf1+/- stromal cells in MPNST pathogenesis. Collectively, this new MPNST model system permits the analysis of somatically-acquired events as well as tumor microenvironment signals that potentially cooperate with Nf1 loss in the development and progression of this deadly malignancy

Effect of Dapagliflozin on Outpatient Worsening of Patients With Heart Failure and Reduced Ejection Fraction A Prespecified Analysis of DAPA-HF

BACKGROUND: In the DAPA-HF trial (Dapagliflozin and Prevention of Adverse Outcomes in Heart Failure), dapagliflozin, added to guideline-recommended therapies, reduced the risk of mortality and heart failure (HF) hospitalization. We examined the frequency and significance of episodes of outpatient HF worsening, requiring the augmentation of oral therapy, and the effects of dapagliflozin on these additional events. METHODS: Patients in New York Heart Association functional class II to IV, with a left ventricular ejection fraction RESULTS: Overall, 36% more patients experienced the expanded, in comparison with the primary, composite outcome. In the placebo group, 684 of 2371 (28.8%) patients and, in the dapagliflozin group, 527 of 2373 (22.2%) participants experienced the expanded outcome (hazard ratio, 0.73 [95% CI, 0.65-0.82]; P CONCLUSION: In DAPA-HF, outpatient episodes of HF worsening were common, were of prognostic importance, and were reduced by dapagliflozin

Expanding colonies and expanding repeats

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Phosphorylation of p53 by IκB kinase 2 promotes its degradation by β-TrCP

Functional inactivation of p53 and constitutive activation of the NF-κB pathway has been associated with several human cancers. In this study, we show that IκB kinase 2 (IKK2/IKKβ), which is critical for NF-κB activation, also phosphorylates p53. Phosphorylation of p53 at serines 362 and 366 by IKK2 leads to its recruitment to and ubiquitination by β-TrCP1. Degradation of ubiquitinated p53 is independent of Mdm2, because it occurs in both wild-type and Mdm2−/− cells. SiRNA-mediated reduction in the levels of β-TrCP1 and other members of the SCFβ−TrCP1E3 ubiquitin ligase complex or overexpression of a dominant negative form of β-TrCP1 enhances p53 stability. Substitutions at Ser-362 and 366 of p53 by alanines (p53 AA) result in reduced phosphorylation of p53 by IKK2, decreased association with β-TrCP1, and thus increased stability of p53 and expression of p53 target genes such as p21, altering the G1 phase of the cell cycle. Our results identify IKK2 and β-TrCP1 as novel regulators of the p53 pathway and suggest that blocking of IKK2 and β-TrCP1 could be a means of regulating p53 stability and thereby modulating its biological activity

Efficient transduction of liver and muscle after in utero injection of lentiviral vectors with different pseudotypes

In this study we investigate the efficacy of lentiviral vectors of different pseudotypes for gene transfer to tissues of the preimmune fetus. BALB/c fetuses at 14-15 days' gestation received lentiviral vectors carrying the transgene lacZ under the control of the human cytomegalovirus (CMV) promoter by intramuscular (i.m.) or intrahepatic (i.h.) injection. We pseudotyped the lentiviral vectors with vesicular stomatitis virus (VSV-G), with Mokola virus, or with Ebola virus envelope glycoproteins. We harvested the pups at time points between 5 days and 9 months following injection and performed a detailed histologic assessment. The efficiency and distribution of transduction after in utero administration was highly dependent upon the route of administration and the pseudotype of vector used. Biodistribution studies showed widespread distribution of vector sequences in multiple tissues, albeit at very low levels, and transduced cells were found in significant numbers only in liver, heart, and muscle. Overall, VSV-G was the most efficient in transducing hepatocytes, whereas Mokola and Ebola were more efficient in transducing myocytes. Transduction of cardiomyocytes was observed after both i.m. and i.h. injection of all three vectors. Our findings of long-term transduction of skeletal myocytes and cardiomyocytes after in utero administration suggest a novel strategy for the treatment of congenital muscular dystrophie

Establishment of human iPSC-based models for the study and targeting of glioma initiating cells

International audienceGlioma tumour-initiating cells (GTICs) can originate upon the ă transformation of neural progenitor cells (NPCs). Studies on GTICs have ă focused on primary tumours from which GTICs could be isolated and the ă use of human embryonic material. Recently, the somatic genomic landscape ă of human gliomas has been reported. RTK (receptor tyrosine kinase) and ă p53 signalling were found dysregulated in similar to 90% and 86% of ă all primary tumours analysed, respectively. Here we report on the use of ă human-induced pluripotent stem cells (hiPSCs) for modelling ă gliomagenesis. Dysregulation of RTK and p53 signalling in hiPSC-derived ă NPCs (iNPCs) recapitulates GTIC properties in vitro. In vivo ă transplantation of transformed iNPCs leads to highly aggressive tumours ă containing undifferentiated stem cells and their differentiated ă derivatives. Metabolic modulation compromises GTIC viability. Last, ă screening of 101 anti-cancer compounds identifies three molecules ă specifically targeting transformed iNPCs and primary GTICs. Together, ă our results highlight the potential of hiPSCs for studying human ă tumourigenesis

Disease-corrected haematopoietic progenitors from Fanconi anemia induced pluripotent stem cells

The generation of induced pluripotent stem (iPS) cells has enabled the derivation of patient-specific pluripotent cells and/nprovided valuable experimental platforms to model human disease. Patient-specific iPS cells are also thought to hold great/ntherapeutic potential, although direct evidence for this is still lacking. Here we show that, on correction of the genetic defect,/nsomatic cells from Fanconi anaemia patients can be reprogrammed to pluripotency to generate patient-specific iPS cells. These cell lines appear indistinguishable from human embryonic stem cells and iPS cells from healthy individuals. Most importantly, we show that corrected Fanconi-anaemia-specific iPS cells can give rise to haematopoietic progenitors of the myeloid and erythroid lineages that are phenotypically normal, that is, disease-free. These data offer proof-of-concept that iPS cell technology can be used for the generation of disease-corrected, patient-specific cells with potential value for cell therapy applications