Myeloid cell differentiation arrest by miR-125b-1 in myelodysplasic syndrome and acute myeloid leukemia with the t(2;11)(p21;q23) translocation

Most chromosomal translocations in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) involve oncogenes that are either up-regulated or form part of new chimeric genes. The t(2;11)(p21;q23) translocation has been cloned in 19 cases of MDS and AML. In addition to this, we have shown that this translocation is associated with a strong up-regulation of miR-125b (from 6- to 90-fold). In vitro experiments revealed that miR-125b was able to interfere with primary human CD34+ cell differentiation, and also inhibited terminal (monocytic and granulocytic) differentiation in HL60 and NB4 leukemic cell lines. Therefore, miR-125b up-regulation may represent a new mechanism of myeloid cell transformation, and myeloid neoplasms carrying the t(2;11) translocation define a new clinicopathological entity

Genomic characterization of AML with aberrations of chromosome 7: a multinational cohort of 519 patients

Background: Deletions and partial losses of chromosome 7 (chr7) are frequent in acute myeloid leukemia (AML) and are linked to dismal outcome. However, the genomic landscape and prognostic impact of concomitant genetic aberrations remain incompletely understood. Methods: To discover genetic lesions in adult AML patients with aberrations of chromosome 7 [abn(7)], 60 paired diagnostic/remission samples were investigated by whole-exome sequencing in the exploration cohort. Subsequently, a gene panel including 66 genes and a SNP backbone for copy-number variation detection was designed and applied to the remaining samples of the validation cohort. In total, 519 patients were investigated, of which 415 received intensive induction treatment, typically containing a combination of cytarabine and anthracyclines. Results: In the exploration cohort, the most frequently mutated gene was TP53 (33%), followed by epigenetic regulators (DNMT3A, KMT2C, IDH2) and signaling genes (NRAS, PTPN11). Thirty percent of 519 patients harbored ≥ 1 mutation in genes located in commonly deleted regions of chr7—most frequently affecting KMT2C (16%) and EZH2 (10%). KMT2C mutations were often subclonal and enriched in patients with del(7q), de novo or core-binding factor AML (45%). Cancer cell fraction analysis and reconstruction of mutation acquisition identified TP53 mutations as mainly disease-initiating events, while del(7q) or −7 appeared as subclonal events in one-third of cases. Multivariable analysis identified five genetic lesions with significant prognostic impact in intensively treated AML patients with abn(7). Mutations in TP53 and PTPN11 (11%) showed the strongest association with worse overall survival (OS, TP53: hazard ratio [HR], 2.53 [95% CI 1.66–3.86]; P < 0.001; PTPN11: HR, 2.24 [95% CI 1.56–3.22]; P < 0.001) and relapse-free survival (RFS, TP53: HR, 2.3 [95% CI 1.25–4.26]; P = 0.008; PTPN11: HR, 2.32 [95% CI 1.33–4.04]; P = 0.003). By contrast, IDH2-mutated patients (9%) displayed prolonged OS (HR, 0.51 [95% CI 0.30–0.88]; P = 0.0015) and durable responses (RFS: HR, 0.5 [95% CI 0.26–0.96]; P = 0.036). Conclusion: This work unraveled formerly underestimated genetic lesions and provides a comprehensive overview of the spectrum of recurrent gene mutations and their clinical relevance in AML with abn(7). KMT2C mutations are among the most frequent gene mutations in this heterogeneous AML subgroup and warrant further functional investigation

Genomic characterization of AML with aberrations of chromosome 7:a multinational cohort of 519 patients

Background: Deletions and partial losses of chromosome 7 (chr7) are frequent in acute myeloid leukemia (AML) and are linked to dismal outcome. However, the genomic landscape and prognostic impact of concomitant genetic aberrations remain incompletely understood. Methods: To discover genetic lesions in adult AML patients with aberrations of chromosome 7 [abn(7)], 60 paired diagnostic/remission samples were investigated by whole-exome sequencing in the exploration cohort. Subsequently, a gene panel including 66 genes and a SNP backbone for copy-number variation detection was designed and applied to the remaining samples of the validation cohort. In total, 519 patients were investigated, of which 415 received intensive induction treatment, typically containing a combination of cytarabine and anthracyclines. Results: In the exploration cohort, the most frequently mutated gene was TP53 (33%), followed by epigenetic regulators (DNMT3A, KMT2C, IDH2) and signaling genes (NRAS, PTPN11). Thirty percent of 519 patients harbored ≥ 1 mutation in genes located in commonly deleted regions of chr7—most frequently affecting KMT2C (16%) and EZH2 (10%). KMT2C mutations were often subclonal and enriched in patients with del(7q), de novo or core-binding factor AML (45%). Cancer cell fraction analysis and reconstruction of mutation acquisition identified TP53 mutations as mainly disease-initiating events, while del(7q) or −7 appeared as subclonal events in one-third of cases. Multivariable analysis identified five genetic lesions with significant prognostic impact in intensively treated AML patients with abn(7). Mutations in TP53 and PTPN11 (11%) showed the strongest association with worse overall survival (OS, TP53: hazard ratio [HR], 2.53 [95% CI 1.66–3.86]; P &lt; 0.001; PTPN11: HR, 2.24 [95% CI 1.56–3.22]; P &lt; 0.001) and relapse-free survival (RFS, TP53: HR, 2.3 [95% CI 1.25–4.26]; P = 0.008; PTPN11: HR, 2.32 [95% CI 1.33–4.04]; P = 0.003). By contrast, IDH2-mutated patients (9%) displayed prolonged OS (HR, 0.51 [95% CI 0.30–0.88]; P = 0.0015) and durable responses (RFS: HR, 0.5 [95% CI 0.26–0.96]; P = 0.036). Conclusion: This work unraveled formerly underestimated genetic lesions and provides a comprehensive overview of the spectrum of recurrent gene mutations and their clinical relevance in AML with abn(7). KMT2C mutations are among the most frequent gene mutations in this heterogeneous AML subgroup and warrant further functional investigation.</p

Human Hepatitis B Virus Production in Avian Cells Is Characterized by Enhanced RNA Splicing and the Presence of Capsids Containing Shortened Genomes

Experimental studies on hepatitis B virus (HBV) replication are commonly done with human hepatoma cells to reflect the natural species and tissue tropism of the virus. However, HBV can also replicate, upon transfection of virus coding plasmids, in cells of other species. In such cross-species transfection experiments with chicken LMH hepatoma cells, we previously observed the formation of HBV genomes with aberrant electrophoretic mobility, in addition to the those DNA species commonly seen in human HepG2 hepatoma cells. Here, we report that these aberrant DNA forms are mainly due to excessive splicing of HBV pregenomic RNA and the abundant synthesis of spliced DNA products, equivalent to those also made in human cells, yet at much lower level. Mutation of the common splice acceptor site abolished splicing and in turn enhanced production of DNA from full-length pgRNA in transfected LMH cells. The absence of splicing made other DNA molecules visible, that were shortened due to the lack of sequences in the core protein coding region. Furthermore, there was nearly full-length DNA in the cytoplasm of LMH cells that was not protected in viral capsids. Remarkably, we have previously observed similar shortened genomes and non-protected viral DNA in human HepG2 cells, yet exclusively in the nucleus where uncoating and final release of viral genomes occurs. Hence, two effects reflecting capsid disassembly in the nucleus in human HepG2 cells are seen in the cytoplasm of chicken LMH cells

Vision mobile et teleoperation

Available from INIST (FR), Document Supply Service, under shelf-number : AR 15727 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEMinistere de l'Enseignement Superieur et de la Recherche, 75 - Paris (France)FRFranc

Descriptions of Mikrocytos veneroïdes n. sp. and Mikrocytos donaxi n. sp. (Ascetosporea: Mikrocytida: Mikrocytiidae), detected during important mortality events of the wedge clam Donax trunculus Linnaeus (Veneroida: Donacidae), in France between 2008 and 2011

Background: Microcell parasites are small intracellular protozoans mostly detected in molluscs and can be associated with mortalities. In 2010 and 2011, strong increases in mortality events were reported in different wild beds of the wedge clam Donax trunculus Linnaeus, along the Atlantic coast of France and the presence of potential pathogens, including microcells, was investigated. Methods: Clams collected in different beds showing mortality were examined by histology. Based on histological observations, confirmatory analyses were carried out, including transmission electron microscopy (TEM) and molecular characterization. Results: Histological analyses revealed the presence of small protozoans similar to microcell parasites in different tissues of Donax trunculus , particularly in muscular and connective tissues. TEM examination confirmed the intracellular localization of the protozoans. Moreover, the lack of haplosporosomes and mitochondria suggested that the observed parasites belong to the genus Mikrocytos Farley, Wolf & Elston,  1988. Mikrocytos genus-specific PCR and in situ hybridization results supported the microscopic observations. Sequence fragments of the 18S rRNA gene shared 75–83% identity with the different Mikrocytos spp.  described previously, including Mikrocytos mackini Farley, Wolf & Elston, 1988 and M. boweri Abbott, Meyer, Lowe, Kim & Johnson, 2014. Phylogenetic analyses confirmed that the microcell parasites observed in Donax trunculus in France belong to the genus Mikrocytos and suggest the existence of two distinct species. Conclusions: Based on morphological, ultrastructural, molecular data and host information, the two microcell parasites detected in Donax trunculus belong to the genus Mikrocytos and are distinct from previously described membersofthisgenus.This  is the first report of Mikrocytos spp. found in France and infecting the clam Donax trunculus. Mikrocytos veneroïdes n. sp. was detected in different wild beds and Mikrocytos donaxi n. sp. was detected only in Audierne Bay

Postremission treatment of elderly patients with acute myeloid leukemia in first complete remission after intensive induction chemotherapy: results of the multicenter randomized Acute Leukemia French Association (ALFA) 9803 trial.

International audienceIn elderly patients with acute myeloid leukemia (AML) treated intensively, no best postremission strategy has emerged yet. This clinical trial enrolled 416 patients with AML aged 65 years or older who were considered eligible for standard intensive chemotherapy, with a first randomization comparing idarubicin with daunorubicin for all treatment sequences. After induction, an ambulatory postremission strategy based on 6 consolidation cycles administered monthly in outpatients was randomly compared with an intensive strategy with a single intensive consolidation course similar to induction. Complete remission (CR) rate was 57% with 10% induction deaths, and estimated overall survival was 27% at 2 years and 12% at 4 years, without notable differences between anthracycline arms. Among the 236 patients who reached CR, 164 (69%) were randomized for the postremission comparison. In these patients, the multivariate odds ratio in favor of the ambulatory arm was 1.51 for disease-free survival (P.05) and 1.59 for overall survival from CR (P.04). Despite repeated courses of chemotherapy associated with a longer time under treatment, the ambulatory arm was associated with significantly shorter rehospitalization duration and lower red blood cell unit and platelet transfusion requirements than observed in the intensive arm. In conclusion, more prolonged ambulatory treatment should be preferred to intensive chemotherapy as postremission therapy in elderly patients with AML reaching CR after standard intensive remission induction

Wide diversity of PAX5 alterations in B-ALL: a Groupe Francophone de Cytogénétique Hématologique study

PAX5 is the main target of somatic mutations in acute B lymphoblastic leukemia (B-ALL). We analyzed 153 adult and child B-ALL harboring karyotypic abnormalities at chromosome 9p, to determine the frequency and the nature of PAX5 alterations. We found PAX5 internal rearrangements in 21% of the cases. To isolate fusion partners, we used classic and innovative techniques (rolling circle amplification-rapid amplification of cDNA ends) and single nucleotide polymorphism-comparative genomic hybridization arrays. Recurrent and novel fusion partners were identified, including NCoR1, DACH2, GOLGA6, and TAOK1 genes showing the high variability of the partners. We noted that half the fusion genes can give rise to truncated PAX5 proteins. Furthermore, malignant cells carrying PAX5 fusion genes displayed a simple karyotype. These data strongly suggest that PAX5 fusion genes are early players in leukemogenesis. In addition, PAX5 deletion was observed in 60% of B-ALL with 9p alterations. Contrary to cases with PAX5 fusions, deletions were associated with complex karyotypes and common recurrent translocations. This supports the hypothesis of the secondary nature of the deletion. Our data shed more light on the high variability of PAX5 alterations in B-ALL. Therefore, it is probable that gene fusions occur early, whereas deletions should be regarded as a late/secondary event

Clofarabine Improves Relapse-Free Survival of Acute Myeloid Leukemia in Younger Adults with Micro-Complex Karyotype

International audienceAcute myeloid leukemia (AML) encompasses heterogeneous entities with dismal outcomes. Intermediate and unfavorable-risk AML represent the most difficult-to-treat entities. We recently reported the benefit of the clofarabine-based consolidation (CLARA) regimen compared to the standard high-dose cytarabine (HDAC) regimen in younger AML patients. Here, we aimed at assessing the clinical significance of single-nucleotide polymorphism (SNP)-array alterations and their interactions with chemotherapy regimens. A SNP-array was successfully performed in 187 out of the 221 intent-to-treat patients (CLARA arm: n = 92 patients, HDAC arm: n = 95 patients). The CLARA regimen did not significantly improve relapse-free survival (RFS) among patients who displayed a complex karyotype when compared to the HDAC regimen (4-year RFS (4y-RFS): 36.4% vs. 18.8%, respectively; p = 0.134). Defining micro-complex karyotypes from at least four SNP-array lesions enabled us to refine and enlarge the subset of adverse patients. In such patients, the CLARA regimen significantly improved RFS compared to the HDAC regimen (4y-RFS: 44.4% vs. 13.8%, respectively; p = 0.004). From our study cohort, 8% of patients displayed TP53 mutations, which were associated with an impaired RFS (4y-RFS: 20.0% vs 43.7%; p = 0.029). In a multivariate analysis, micro-complex karyotypes remained the sole poor prognostic factor in the HDAC arm (hazard ratio (HR) = 2.324 (95% confidence interval (CI) = 1.337-4.041), p = 0.003). The SNP array represents a powerful and reproductive approach to refine adverse AML patients that may benefit from alternative consolidation regimens