Protein-Tyrosine Kinase Activity Profiling in Knock Down Zebrafish Embryos

BACKGROUND: Protein-tyrosine kinases (PTKs) regulate virtually all biological processes. PTKs phosphorylate substrates in a sequence-specific manner and relatively short peptide sequences determine selectivity. Here, we developed new technology to determine PTK activity profiles using peptide arrays. The zebrafish is an excellent model system to investigate signaling in the whole organism, given its wealth of genetic tools, including morpholino-mediated knock down technology. We used zebrafish embryo lysates to determine PTK activity profiles, thus providing the unique opportunity to directly compare the effect of protein knock downs on PTK activity profiles on the one hand and phenotypic changes on the other. METHODOLOGY: We used multiplex arrays of 144 distinct peptides, spotted on a porous substrate, allowing the sample to be pumped up and down, optimizing reaction kinetics. Kinase reactions were performed using complex zebrafish embryo lysates or purified kinases. Peptide phosphorylation was detected by fluorescent anti-phosphotyrosine antibody binding and the porous chips allowed semi-continuous recording of the signal. We used morpholinos to knock down protein expression in the zebrafish embryos and subsequently, we determined the effects on the PTK activity profiles. RESULTS AND CONCLUSION: Reproducible PTK activity profiles were derived from one-day-old zebrafiish embryos. Morpholino-mediated knock downs of the Src family kinases, Fyn and Yes, induced characteristic phenotypes and distinct changes in the PTK activity profiles. Interestingly, the peptide substrates that were less phosphorylated upon Fyn and Yes knock down were preferential substrates of purified Fyn and Yes. Previously, we demonstrated that Wnt11 knock down phenocopied Fyn/Yes knock down. Interestingly, Wnt11 knock down induced similar changes in the PTK activity profile as Fyn/Yes knock down. The control Nacre/Mitfa knock down did not affect the PTK activity profile significantly. Our results indicate that the novel peptide chip technology can be used to unravel kinase signaling pathways in vivo

Risk Stratification in Older Intensively Treated Patients With AML

\ua9 2024 by American Society of Clinical Oncology.PURPOSE AML is a genetically heterogeneous disease, particularly in older patients. In patients older than 60 years, survival rates are variable after the most important curative approach, intensive chemotherapy followed by allogeneic hematopoietic cell transplantation (allo-HCT). Thus, there is an urgent need in clinical practice for a prognostic model to identify older patients with AML who benefit from curative treatment. METHODS We studied 1,910 intensively treated patients older than 60 years with AML and high-risk myelodysplastic syndrome (HR-MDS) from two cohorts (NCRIAML18 and HOVON-SAKK). The median patient age was 67 years. Using a random survival forest, clinical, molecular, and cytogenetic variables were evaluated in an AML development cohort (n = 1,204) for association with overall survival (OS). Relative weights of selected variables determined the prognostic model, which was validated in AML (n = 491) and HR-MDS cohorts (n = 215). RESULTS The complete cohort had a high frequency of poor-risk features, including 2022 European LeukemiaNet adverse-risk (57.3%), mutated TP53 (14.4%), and myelodysplasia-related genetic features (65.1%). Nine variables were used to construct four groups with highly distinct 4-year OS in the (1) AML development, (2) AML validation, and (3) HR-MDS test cohorts ([1] favorable: 54% \ub1 4%, intermediate: 38% \ub1 2%, poor: 21% \ub1 2%, very poor: 4% \ub1 1%; [2] 54% \ub1 9%, 43% \ub1 4%, 27% \ub1 4%, 4% \ub1 3%; and [3] 54% \ub1 10%, 33% \ub1 6%, 14% \ub1 5%, 0% \ub1 3%, respectively). This new AML60+ classification improves current prognostic classifications. Importantly, patients within the AML60+ intermediate- and very poor-risk group significantly benefited from allo-HCT, whereas the poor-risk patients showed an indication, albeit nonsignificant, for improved outcome after allo-HCT. CONCLUSION The new AML60+ classification provides prognostic information for intensively treated patients 60 years and older with AML and HR-MDS and identifies patients who benefit from intensive chemotherapy and allo-HCT

Systemic versus localized coagulation activation contributing to organ failure in critically ill patients

In the pathogenesis of sepsis, inflammation and coagulation play a pivotal role. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation not only leads to activation of coagulation but coagulation also considerably affects inflammatory activity. The intricate relationship between inflammation and coagulation may not only be relevant for vascular atherothrombotic disease in general but has in certain clinical settings considerable consequences, for example in the pathogenesis of microvascular failure and subsequent multiple organ failure, as a result of severe infection and the associated systemic inflammatory response. Molecular pathways that contribute to inflammation-induced activation of coagulation have been precisely identified. Pro-inflammatory cytokines and other mediators are capable of activating the coagulation system and downregulating important physiological anticoagulant pathways. Activation of the coagulation system and ensuing thrombin generation is dependent on an interleukin-6-induced expression of tissue factor on activated mononuclear cells and endothelial cells and is insufficiently counteracted by physiological anticoagulant mechanisms and endogenous fibrinolysis. Interestingly, apart from the overall systemic responses, a differential local response in various vascular beds related to specific organs may occur

A randomized study of granulocyte colony-stimulating factor applied during and after chemotherapy in patients with poor risk myelodysplastic syndromes:a report from the HOVON Cooperative Group

The purpose of this study was to determine the safety and efficacy of filgrastim as an adjunct to induction and consolidation chemotherapy in poor risk patients with myelodysplastic syndrome (MDS). Filgrastim was given both during and after chemotherapy with the objective to accelerate hematopoietic repopulation and enhance the efficacy of chemotherapy. In a prospective randomized multicentre phase II trial, a total of 64 patients with poor risk primary MDS were randomized to receive either granulocyte colony-stimulating factor (G-CSF, filgrastim, AMGEN, Breda, The Netherlands) 5 mu g/kg/day subcutaneously or no G-CSF in addition to daunomycin (30 mg/m(2)/days 1, 2 and 3 intravenous bolus) and cytarabine (200 mg/m(2) days 1-7, continuous infusion). The overall complete response rate was 63%: 73% for patients receiving filgrastim as compared to 52% in the standard arm (P = 0.08). Overall survival at 2 years was estimated at 29% for patients assigned to the filgrastim arm and 16% for control patients (P = 0.22). The median time for recovery of granulocytes towards 1.0x10(9)/I post-chemotherapy was 23 days in the filgrastim-treated patients vs 35 days in the standard arm (P = 0.015). There were no differences in time of platelet recovery, length of hospital stay, duration of antibiotic use or infectious complications between the two treatment groups. However the earlier recovery of neutrophils in the filgrastim group was associated with a reduced interval of 9 days between the induction and consolidation cycle. In patients with poor risk MDS the use of filgrastim during and after induction therapy results in a significantly reduced neutrophil recovery time. Further study may be warranted to see if the apparent trend of the improved response to chemotherapy in combination with filgrastim can be confirmed in greater number of patients and to assess the effect of the addition of filgrastim on survival