Evaluation of Caspase-9b and PP2Acα2 as potential biomarkers for chronic lymphocytic leukemia

International audienceBackground: Disruption of alternative splicing in apoptotic factors has been associated to chronic lymphocytic leukemia among other cancers and hematological malignancies. The proapoptotic proteins Caspase-9 and PP2Acα are functionally related in a direct interaction, which constitutes a promising target for cancer therapy. Both proteins present aberrant mRNA splicing variants that are antiapoptotic (Caspase-9b) and catalytically inactive (PP2Acα2), respectively. Results: In this work we have analyzed the relative abundance of the aberrant spliced forms Caspase-9b and PP2Acα2 in several cell lines and chronic lymphocytic leukemia patients and correlated it with several parameters of the disease. Despite 40 % of the patients presented Caspase-9b dysregulation, there was no direct association between alterations in Caspase-9b relative abundance and the parameters analyzed in medical records. More importantly, PP2Acα2 dysregulation was observed in 88 % of CLL patients and was related with advanced stages of the malignancy. Conclusions: Caspase-9b dysregulation seemed to be associated with the disease, although the differences between healthy donors and CLL patients were not statistically significant. However, PP2Acα2 dysregulation was significantly different between healthy donors and CLL patients and correlated with Binet B and C stages; therefore, we propose the use of PP2Acα2 dysregulation as a potential biomarker for advanced stages of chronic lymphocytic leukemia

Recommendations of the SFH (French Society of Haematology) for the diagnosis, treatment and follow-up of hairy cell leukaemia

International audienceHairy cell leukaemia (HCL) is a rare haematological malignancy, with approximately 175 new incident cases in France. Diagnosis is based on a careful examination of the blood smear and immunophenotyping of the tumour cells, with a panel of four markers being used specifically to screen for hairy cells (CD11c, CD25, CD103 and CD123). In 2011, the V600E mutation of the BRAF gene in exon 15 was identified in HCL; being present in HCL, it is absent in the variant form of HCL (HCL-v) and in splenic red pulp lymphoma (SRPL), two entities related to HCL. The management of patients with HCL has changed in recent years. A poorer response to purine nucleoside analogues (PNAs) is observed in patients with more marked leukocytosis, bulky splenomegaly, an unmutated immunoglobulin variable heavy chain (IgVH) gene profile, use of VH4-34 or with TP53 mutations. We present the recommendations of a group of 11 experts belonging to a number of French hospitals. This group met in November 2013 to examine the criteria for managing patients with HCL. The ideas and proposals of the group are based on a critical analysis of the recommendations already published in the literature and on an analysis of the practices of clinical haematology departments with experience in managing these patients. The first-line treatment uses purine analogues: cladribine or pentostatin. The role of BRAF inhibitors, whether or not combined with MEK inhibitors, is discussed. The panel of French experts proposed recommendations to manage patients with HCL, which can be used in a daily practice

Bacterial-based additives for the production of artificial snow: What are the risks to human health?

International audienceFor around two decades, artificial snow has been used by numerous winter sports resorts to ensure good snow cover at low altitude areas or more generally, to lengthen the skiing season. Biological additives derived from certain bacteria are regularly used to make artificial snow. However, the use of these additives has raised doubts concerning the potential impact on human health and the environment. In this context, the French health authorities have requested the French Agency for Environmental and Occupational Health Safety (Afsset) to assess the health risks resulting from the use of such additives. The health risk assessment was based on a review of the scientific literature, supplemented by professional consultations and expertise. Biological or chemical hazards from additives derived from the ice nucleation active bacterium Pseudomonas syringae were characterised. Potential health hazards to humans were considered in terms of infectious, toxic and allergenic capacities with respect to human populations liable to be exposed and the means of possible exposure. Taking into account these data, a qualitative risk assessment was carried out, according to four exposure scenarios, involving the different populations exposed, and the conditions and routes of exposure. It was concluded that certain health risks can exist for specific categories of professional workers (mainly snowmakers during additive mixing and dilution tank cleaning steps, with risks estimated to be negligible to low if workers comply with safety precautions). P. syringae does not present any pathogenic capacity to humans and that the level of its endotoxins found in artificial snow do not represent a danger beyond that of exposure to P. syringae endotoxins naturally present in snow. However, the risk of possible allergy in some particularly sensitive individuals cannot be excluded. Another important conclusion of this study concerns use of poor microbiological water quality to make artificial snow

High frequency of central nervous system involvement in transformed Waldenstrom macroglobulinemia

Histologicaltransformation (HT) to diffuse large B-cell lymphoma (DLBCL) is a rare event in Waldenström macroglobulinemia (WM) and is associated with a poor prognosis.1-4 It confers an inferior outcome compared with WM patients without HT.2,3 Most transformed WM patients present with elevated serum lactate dehydrogenase (LDH) levels and extranodal disease.1 Among extranodal sites, the central nervous system (CNS) is one of the most frequently involved sites identified at diagnosis of transformed WM (ranging from 13% to 18%).1,3 However, the prognostic value of CNS involvement is unknown, and the rate of CNS involvement at relapse has not been previously reported in this setting.This work was supported by Cancer Research UK [C355/A26819], FC AECC, and AIRC under the “Accelerator Award Program” [EDITOR] to M.A. and R.G.-S

Fungal infections in patients treated with ibrutinib: two unusual cases of invasive aspergillosis and cryptococcal meningoencephalitis

International audienceLetters to the edito

Identification of peptides interfering with the LRRK2/PP1 interaction

International audienceSerine/threonine phosphatases are responsible for modulating the activities of the protein kinases implicated in the development of several pathologies. Here we identified by a PEP-scan approach a peptide of LRRK2, a Parkinson's disease associated protein, interacting with the phosphatase PP1. In order to study its biological activity, the peptide was fused via its N-terminal to an optimized cell penetrating peptide. We synthesized from the original peptide five interfering peptides and identified two (Mut3DPT-LRRK2-Short and Mut3DPT-LRRK2-Long) able to disrupt the LRRK2/PP1 interaction by competition in anti-LRRK2 immunoprecipitates. Using FITC-labelled peptides, we confirmed their internalization into cell lines as well as into primary cells obtained from healthy or ill human donors. We confirmed by ELISA test the association of Mut3DPT-LRRK2-Long peptide to purified PP1 protein. The peptides Mut3DPT-LRRK2-5 to 8 with either N or C-terminal deletions were not able to disrupt the association LRRK2/PP1 nor to associate with purified PP1 protein. The interfering sequences blocking the PP1/LRRK2 interaction were also fused to a shuttle peptide able to cross the blood brain barrier and showed that the newly generated peptides BBB-LRRK2-Short and BBB-LRRK2-Long were highly resistant to protease degradation. Furthermore, they blocked PP1/LRRK2 interaction and they penetrated into cells. Hence, these newly generated peptides can be employed as new tools in the investigation of the role of the LRRK2/PP1 interaction in normal and pathological conditions

TP53, XPO1 and ATM Mutations Exclusive Distribution in the Adverse Prognosis Chronic Lymphocytic Leukemia (CLL) Group

International audienc

MPL Mutations in Essential Thrombocythemia Uncover A Common Path of Activation with Eltrombopag Dependent on W491.

Mutations in the gene (MPL) encoding the human thrombopoietin receptor (TpoR) drive sporadic and familial essential thrombocythemia (ET). We identified two ET patients that harbor double mutations in cis in MPL, namely L498W-H499C and H499Y-S505N. Using biochemical and signaling assays along with partial saturation mutagenesis we show that L498W is an activating mutation potentiated by H499C, and that H499C/Y enhance the activity of the canonical S505N mutation. L498W and H499C can activate a truncated TpoR mutant, which lacks the extracellular domain, indicating these mutations act on the transmembrane (TM)-cytosolic domain. Using a protein complementation assay we show that L498W and H499C strongly drive dimerization of TpoR. Activation by tryptophan substitution is exquisitely specific for position 498. Using structure-guided mutagenesis we identify upstream amino acid W491 as a key residue required for activation by L498W or canonical activating mutations such as S505N and W515K, as well as by eltrombopag. Structural data point to a common dimerization and activation path for TpoR via its TM domain that is shared between the small molecule agonist eltrombopag and canonical and novel activating TpoR mutations that all depend on W491, a potentially accessible extracellular residue that could become a target for therapeutic intervention