Recherche du mécanisme d'activation de la PI3kinase delta dans les leucémie aiguës myéloïdes

REIMS-BU Santé (514542104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Place de la mutation JAK2 V617F et du test clonogénique dans le diagnostic de la polyglobulie de Vasquez et de la thrombocytémie essentielle : étude rétrospective d'une cohorte de patients explorés au CHU de Reims en 2006

REIMS-BU Santé (514542104) / SudocSudocFranceF

Differential regulation of TNFα, IL-1β, IL-6, IL-8, TNFβ, and IL-10 by pentoxifylline

International audiencePentoxifylline (PTX) is a methylxanthine drug known to inhibit the production of tumor necrosis factor-alpha (TNFα), which plays a key role in inflammation. Recent studies also revealed that other cytokines may be inhibited by PTX. We investigated PTX effects on production and mRNA expression of TNFα, IL-1β, IL-6, IL-8, TNFβ and IL-10. Cytokine release was studied in 1/10 diluted whole blood culture (WB) and in peripheral blood mononuclear cell (PBMC) culture. Cytokine production was triggered in both culture systems by endotoxin (LPS) or by phorbol ester (PMA) plus phytohemagglutinin (PHA). Our results showed that expression and production of TNFα and TNFβ were inhibited by PTX in a dose-dependent manner. Moreover, we observed that depending on the way of activating cells, PTX induced an up- or a down-regulation (in PMA+PHA or LPS stimulated cells, respectively) for IL-1 and IL-6 release. We also noted that the effects of PTX on IL-6, IL-8 and IL-10 production were different in WB and in PBMC culture. In conclusion PTX acts on cytokine in a complex manner depending on cellular environment and on the method of activation

Inhibition of human TNFα and LT in cell-free extracts and in cell culture by antisense oligonucleotides

International audienceAntisense oligonucleotides (ODN), complementary to mRNA of human tumor necrosis factor α (TNFα) and lymphotoxin (LT) were tested for their ability to inhibit TNFs. TNFs production was studied in cell-free systems including wheat germ extract (WGE) and rabbit reticulocyte lysate (RRL). All ODN were effective in WGE at low concentration (0.2 μM) except those targeted to the 3′ region of TNFα mRNA. A short ODN complementary to a common region between TNFα and LT inhibited both TNFs. In contrast, high ODN concentration (50 μM) was needed to inhibit LT mRNA translation in RRL, whereas no clear inhibition of TNFα was observed unless RNase H was added to the translation mixture. ODN effects on TNFs production by stimulated cell line in culture were also investigated. Three ODN — one located in the 5′-untranslated region, one spanning the AUG initiation codon and one downstream of this AUG — were the most effective sequences to decrease TNFα production. Two ODN targeted to the AUG initiation codon of LT were also able to inhibit its production. In conclusion we confirm the role of RNase H in cell free systems, and we found that there is no correlation between ODN efficiency in a cell-free system nor in cell culture. Efficient ODN could be used for in vitro investigation of the role of TNFα and LT in mechanism in which they are involved

Design and Feasibility of a Novel, Rapid, and Simple Fluorescence 26-Plex RT-PCR Assay for Simultaneous Detection of 24 Fusion Transcripts in Adult Acute Myeloid Leukemia.

International audienceIdentification of chromosomal abnormalities is mandatory for classification of acute myeloid leukemia (AML), and the abnormalities have to be determined quickly, to allow patient enrollment in multicenter protocols and/or for selecting therapeutic strategies. Rapid AML molecular diagnosis is often difficult to achieve, however, because it is based on numerous different RT-PCR protocols. We developed a new RT-PCR method, one that does not require a nested step, to simultaneously detect all AML fusion transcripts from six major recurrent translocations found in adults: t(15;17)(q22;q12), inv(16)(p13.1q22) [t(16;16)(p13.1;q22)], t(8;21)(q22;q22), t(6;9)(p23;q34), t(9;22)(q34;q11), and t(10;11)(p13;q14). Specific primers for RT-PCR detection of the 24 fusion transcripts, along with two transcripts for controls, were designed for this 26-plex RT-PCR. Each PCR product had a different size and was separated by capillary electrophoresis. We also designed a multiplex positive control with 24 chimeric RNAs, corresponding to all chimeric RNAs tested. Compared with classical molecular biology protocols and cytogenetic analyses used as reference standards, results of the 26-plex RT-PCR method were concordant in all 204 (100%) cases of adult AML tested. Results were obtained in less than 24 hours. Because of the multiplex positive control, interpretation of the peaks was very easy, without any ambiguity. The tumor cell detection threshold was 1.5%

Cytogenetic Evolution of Human Ovarian Cell Lines Associated with Chemoresistance and Loss of Tumorigenicity

In order to identify genomic changes associated with a resistant phenotype acquisition, we used comparative genomic hybridization (CGH) to compare a human ovarian cell line, Igrov1, and four derived subcell lines, resistant to vincristine and presenting a reversion of malignant properties. Multicolor FISH (Multiplex‐FISH and Spectral Karyotype) and conventional FISH are also used to elucidate the karyotype of parental cell line. The drug‐resistant subcell lines displayed many chromosomal abnormalities suggesting the implication of different pathways leading to a multidrug resistance phenotype. However, these cell lines shared two common rearrangements: an unbalanced translocation der(8)t(8;13)(p22;q?) and a deletion of the 11p. These chromosomal imbalances could reflected the acquisition of the chemoresistance (der(8)) or the loss of tumorigenicity properties (del(11p)). Colour figure can be viewed on http://www.esacp.org/acp/2003/25‐3/struski.htm

T-cell lymphoid aggregates in bone marrow after rituximab therapy for B-cell follicular lymphoma: a marker of therapeutic efficacy?

International audienceRituximab, an anti-CD20 monoclonal antibody, is widely used in the treatment of B-cell lymphoma. Some reports have outlined histologic modifications in bone marrow specimens from patients treated with this antibody, notably the presence of CD3(+) lymphoid aggregates morphologically mimicking residual lymphoma. To gain insight into the significance of such infiltrates, serial BM trephines obtained in 39 patients with B-cell follicular lymphoma treated by rituximab and enrolled in the GOELAMS-GELA intergroup FL2000 protocol were reexamined. The 39 patients were 22 women and 17 men with a median age of 50 years (range, 29-75 years). All pretreatment bone marrow biopsies showed CD20(+) lymphomatous cells. A second biopsy was obtained between 30 and 100 days after the last rituximab injection: 19 (48%) were morphologically diagnosed as negative (no lymphoid infiltrates or only minor lymphoid aggregates) and 20 (51%) as positive because of persistent lymphoid nodules. After immunohistochemical analysis, 13 (33%) cases were reinterpreted as false-positive because of the complete absence of CD20(+) cells, with the lymphoid nodules consisting of CD3(+) and CD5(+) T cells. Most of them also expressed CD4(+), whereas only a few CD8(+) cells were present. Among these 13 false-positive cases, 12 were BCL2-IGH polymerase chain reaction-negative in the bone marrow aspirate at the time of biopsy. The 13th case turned out to be negative in the 18th-month bone marrow aspirate. In all of these cases, lymphoid aggregates had disappeared on bone marrow biopsies performed 18 months after treatment. After a mean follow-up of 4.5 years, 9 of 13 patients were in remission as compared with only 2 among the 7 patients with postrituximab persistent CD20(+) lymphomatous cells. There was no statistically significant difference between this false-positive group of patients and that with negative postrituximab bone marrow regarding sex, age, medullar involvement pattern before treatment, delay between rituximab treatment, and molecular status. Interestingly, we noted a more favorable outcome (70% versus 52% remission) for the false-positive cases, suggesting that these T-cell reactions could be the hallmark of specific antitumoral immunity after rituximab treatment and should be properly investigated

Improvement of Standardization of Molecular Analyses in Hematology: The 10-year GBMHM French Experience

International audienceMolecular tests have become an indispensable tool for the diagnosis and prognosis of hematological malignancies and are subject to accreditation according to the International Standard ISO 15189. National standardization of these techniques is essential to ensure that patients throughout France benefit from the same care. We report here on the experience of the GBMHM (Groupe des Biologistes Moléculaires des Hémopathies Malignes). By organizing External Evaluation of Quality (EEQ) programs and training meetings, the GBMHM has contributed to improvement and standardization of molecular tests in 64 French laboratories. A retrospective analysis of the quality-control results of 11 national campaigns spanning 10 years was performed for the 3 most frequently prescribed tests: BCR-ABL1, JAK2 V617F, and lymphoid clonality. For each test, particular attention was placed on comparing methodologies and their evolution throughout the period. The establishment of the BCR-ABL1, JAK2 V617F, and lymphoid clonality EEQ programs and the associated training meetings have initiated a process of collective standardization concerning the methods of implementation (JAK2 V617F) and the interpretation and formulation of results (lymphoid clonality). In addition, it resulted in objective improvement in technical performance (BCR-ABL1). Our evaluation of the impact of these EEQ programs demonstrates that it is possible to obtain reproducible values across different laboratories in France by applying national recommendations. To our knowledge, this is the first publication that evaluates the impact of a national quality assurance program on improving molecular results in hematology

Determination of genes and microRNAs involved in the resistance to fludarabine in vivo in chronic lymphocytic leukemia

Background: Chronic lymphocytic leukemia (CLL) cells are often affected by genomic aberrations targeting key regulatory genes. Although fludarabine is the standard first line therapy to treat CLL, only few data are available about the resistance of B cells to this purine nucleoside analog in vivo. Here we sought to increase our understanding of fludarabine action and describe the mechanisms leading to resistance in vivo. We performed an analysis of genomic aberrations, gene expression profiles, and microRNAs expression in CLL blood B lymphocytes isolated during the course of patients' treatment with fludarabine. Results: In sensitive patients, the differentially expressed genes we identified were mainly involved in p53 signaling, DNA damage response, cell cycle and cell death. In resistant patients, uncommon genomic abnormalities were observed and the resistance toward fludarabine could be characterized based on the expression profiles of genes implicated in lymphocyte proliferation, DNA repair, and cell growth and survival. Of particular interest in some patients was the amplification of MYC (8q) observed both at the gene and transcript levels, together with alterations of myc-transcriptional targets, including genes and miRNAs involved in the regulation of cell cycle and proliferation. Differential expression of the sulfatase SULF2 and of miR-29a, -181a, and -221 was also observed between resistant and sensitive patients before treatment. These observations were further confirmed on a validation cohort of CLL patients treated with fludarabine in vitro. Conclusion: In the present study we identified genes and miRNAs that may predict clinical resistance of CLL to fludarabine, and describe an interesting oncogenic mechanism in CLL patients resistant to fludarabine by which the complete MYC-specific regulatory network was altered (DNA and RNA levels, and transcriptional targets). These results should prove useful for understanding and overcoming refractoriness to fludarabine and also for predicting the clinical outcome of CLL patients before or early during their treatment