References of "Lambert, Frédéric"
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See detailGenetic basis of congenital erythrocytosis: mutation update and online databases.
Bento, Celeste; Percy, Melanie J.; Gardie, Betty et al

in Human mutation (2014), 35(1), 15-26

Congenital erythrocytosis (CE), or congenital polycythemia, represents a rare and heterogeneous clinical entity. It is caused by deregulated red blood cell production where erythrocyte overproduction ... [more ▼]

Congenital erythrocytosis (CE), or congenital polycythemia, represents a rare and heterogeneous clinical entity. It is caused by deregulated red blood cell production where erythrocyte overproduction results in elevated hemoglobin and hematocrit levels. Primary congenital familial erythrocytosis is associated with low erythropoietin (Epo) levels and results from mutations in the Epo receptor gene (EPOR). Secondary CE arises from conditions causing tissue hypoxia and results in increased Epo production. These include hemoglobin variants with increased affinity for oxygen (HBB, HBA mutations), decreased production of 2,3-bisphosphoglycerate due to BPGM mutations, or mutations in the genes involved in the hypoxia sensing pathway (VHL, EPAS1, and EGLN1). Depending on the affected gene, CE can be inherited either in an autosomal dominant or recessive mode, with sporadic cases arising de novo. Despite recent important discoveries in the molecular pathogenesis of CE, the molecular causes remain to be identified in about 70% of the patients. With the objective of collecting all the published and unpublished cases of CE the COST action MPN&MPNr-Euronet developed a comprehensive Internet-based database focusing on the registration of clinical history, hematological, biochemical, and molecular data (http://www.erythrocytosis.org/). In addition, unreported mutations are also curated in the corresponding Leiden Open Variation Database. [less ▲]

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See detailTransient leukemia in a newborn without Down syndrome: case report and review of the literature.
Rozen, Laurence; Huybrechts, Sophie; Dedeken, Laurence et al

in European journal of pediatrics (2013)

Transient neonatal leukemia occurs almost exclusively in Down syndrome babies. We report here the unusual case of a newborn without Down syndrome who presented neonatal transient leukemia and who achieved ... [more ▼]

Transient neonatal leukemia occurs almost exclusively in Down syndrome babies. We report here the unusual case of a newborn without Down syndrome who presented neonatal transient leukemia and who achieved spontaneously complete remission. Trisomy 21 and GATA1 mutation were both present in leukemic cells. While close follow-up is advised since true leukemia may develop later, the patient is still in remission for 2.5 years. We performed a literature review of 15 other similar cases. Conclusion: Our case of transient leukemia without Down syndrome and the literature review highlight the important role of trisomy 21 and GATA1 mutation in the development of transient neonatal leukemia. [less ▲]

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See detailEVI1-mediated down regulation of MIR449A is essential for the survival of EVI1 positive leukaemic cells.
De Weer, An; Van der Meulen, Joni; Rondou, Pieter et al

in British Journal of Haematology (2011), 154(3), 337-48

Chromosomal rearrangements involving the MECOM (MDS1 and EVI1 complex) locus are recurrent genetic events in myeloid leukaemia and are associated with poor prognosis. In this study, we assessed the role ... [more ▼]

Chromosomal rearrangements involving the MECOM (MDS1 and EVI1 complex) locus are recurrent genetic events in myeloid leukaemia and are associated with poor prognosis. In this study, we assessed the role of MECOM locus protein EVI1 in the transcriptional regulation of microRNAs (miRNAs) involved in the leukaemic phenotype. For this, we profiled expression of 366 miRNAs in 38 MECOM-rearranged patient samples, normal bone marrow controls and MECOM (EVI1) knock down/re-expression models. Cross-comparison of these miRNA expression profiling data showed that MECOM rearranged leukaemias are characterized by down regulation of MIR449A. Reconstitution of MIR449A expression in MECOM-rearranged cell line models induced apoptosis resulting in a strong decrease in cell viability. These effects might be mediated in part by MIR449A regulation of NOTCH1 and BCL2, which are shown here to be bona fide MIR449A targets. Finally, we confirmed that MIR449A repression is mediated through direct promoter occupation of the EVI1 transcriptional repressor. In conclusion, this study reveals MIR449A as a crucial direct target of the MECOM locus protein EVI1 involved in the pathogenesis of MECOM-rearranged leukaemias and unravels NOTCH1 and BCL2 as important novel targets of MIR449A. This EVI1-MIR449A-NOTCH1/BCL2 regulatory axis might open new possibilities for the development of therapeutic strategies in this poor prognostic leukaemia subgroup. [less ▲]

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See detailRefinement of 1p36 alterations not involving PRDM16 in myeloid and lymphoid malignancies.
Duhoux, Francois P; Ameye, Genevieve; Lambot, Virginie et al

in PLoS ONE (2011), 6(10), 26311

Fluorescence in situ hybridization was performed to characterize 81 cases of myeloid and lymphoid malignancies with cytogenetic 1p36 alterations not affecting the PRDM16 locus. In total, three subgroups ... [more ▼]

Fluorescence in situ hybridization was performed to characterize 81 cases of myeloid and lymphoid malignancies with cytogenetic 1p36 alterations not affecting the PRDM16 locus. In total, three subgroups were identified: balanced translocations (N = 27) and telomeric rearrangements (N = 15), both mainly observed in myeloid disorders; and unbalanced non-telomeric rearrangements (N = 39), mainly observed in lymphoid proliferations and frequently associated with a highly complex karyotype. The 1p36 rearrangement was isolated in 12 cases, mainly myeloid disorders. The breakpoints on 1p36 were more widely distributed than previously reported, but with identifiable rare breakpoint cluster regions, such as the TP73 locus. We also found novel partner loci on 1p36 for the known multi-partner genes HMGA2 and RUNX1. We precised the common terminal 1p36 deletion, which has been suggested to have an adverse prognosis, in B-cell lymphomas [follicular lymphomas and diffuse large B-cell lymphomas with t(14;18)(q32;q21) as well as follicular lymphomas without t(14;18)]. Intrachromosomal telomeric repetitive sequences were detected in at least half the cases of telomeric rearrangements. It is unclear how the latter rearrangements occurred and whether they represent oncogenic events or result from chromosomal instability during oncogenesis. [less ▲]

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See detailEVI1-mediated down regulation of MIR449A is essential for the survival of EVI1 positive leukaemic cells.
De Weer, An; Van der Meulen, Joni; Rondou, Pieter et al

in British Journal of Haematology (2011), 154(3), 337-48

Chromosomal rearrangements involving the MECOM (MDS1 and EVI1 complex) locus are recurrent genetic events in myeloid leukaemia and are associated with poor prognosis. In this study, we assessed the role ... [more ▼]

Chromosomal rearrangements involving the MECOM (MDS1 and EVI1 complex) locus are recurrent genetic events in myeloid leukaemia and are associated with poor prognosis. In this study, we assessed the role of MECOM locus protein EVI1 in the transcriptional regulation of microRNAs (miRNAs) involved in the leukaemic phenotype. For this, we profiled expression of 366 miRNAs in 38 MECOM-rearranged patient samples, normal bone marrow controls and MECOM (EVI1) knock down/re-expression models. Cross-comparison of these miRNA expression profiling data showed that MECOM rearranged leukaemias are characterized by down regulation of MIR449A. Reconstitution of MIR449A expression in MECOM-rearranged cell line models induced apoptosis resulting in a strong decrease in cell viability. These effects might be mediated in part by MIR449A regulation of NOTCH1 and BCL2, which are shown here to be bona fide MIR449A targets. Finally, we confirmed that MIR449A repression is mediated through direct promoter occupation of the EVI1 transcriptional repressor. In conclusion, this study reveals MIR449A as a crucial direct target of the MECOM locus protein EVI1 involved in the pathogenesis of MECOM-rearranged leukaemias and unravels NOTCH1 and BCL2 as important novel targets of MIR449A. This EVI1-MIR449A-NOTCH1/BCL2 regulatory axis might open new possibilities for the development of therapeutic strategies in this poor prognostic leukaemia subgroup. [less ▲]

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See detailGuidelines for an integrated diagnostic approach of chronic lymphoproliferative disorders in the routine laboratory of haematology in Belgium.
Nollet, F.; Bakkus, M.; Meeus, P. et al

in Acta Clinica Belgica (2009), 64(6), 494-504

This paper summarizes the minimal workout of chronic lymphoproliferative disorders in a routine laboratory of haematology as recommended by a team of experienced laboratory supervisors in Belgium, taking ... [more ▼]

This paper summarizes the minimal workout of chronic lymphoproliferative disorders in a routine laboratory of haematology as recommended by a team of experienced laboratory supervisors in Belgium, taking into account the specific organisation of healthcare in Belgium, the innovations in the field of molecular analyses and related reimbursement. The starting point was essentially based upon clinical and/or haematological indications and it is emphasized that conclusions should be drawn in close dialogue with the clinician and experts in cytogenetics and histopathology. Reports made in the laboratory should be based upon an integration of cytomorphological, immunophenotypical and molecular data. These guidelines are not intended to be used as universal 'diagnostic pathways', but should be useful in developing local diagnostic pathways. It is well understood that this consensus, being valid anno 2009, may rapidly change with new technologies being introduced and new targets discovered. [less ▲]

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See detailCyclinD1-negative mantle cell lymphoma with cryptic t(12;14)(p13;q32) and cyclin D2 overexpression
Herens, Christian ULg; Lambert, Frédéric ULg; Quintanilla-Martinez, L. et al

in Blood (2008), 111(3), 1745-1746

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See detailCyclin D1-negative mantle cell lymphoma with cryptic t(12;14)(p13;q32) and cyclin D2 overexpression.
Herens, Christian ULg; Lambert, Frédéric ULg; Quintanilla-Martinez, Leticia et al

in Blood (2008), 111(3), 1745-6

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See detailConsultations in molecular diagnostics - A case of FIP1L1-PDGFRA-positive chronic eosinophilic leukemia with a rare FIP1L1 breakpoint
Lambert, Frédéric ULg; Heimann, Pierre; Herens, Christian ULg et al

in Journal of Molecular Diagnostics (2007), 9(3), 414-419

The idiopathic hypereosinophilic syndrome (HES) has remained for a long time a diagnosis of exclusion. Differential diagnosis between the HES and the related chronic eosinophilic leukemia (CEL) relied on ... [more ▼]

The idiopathic hypereosinophilic syndrome (HES) has remained for a long time a diagnosis of exclusion. Differential diagnosis between the HES and the related chronic eosinophilic leukemia (CEL) relied on the identification of signs of clonality that allowed, when present, the reclassification of patients as CEL. Recently, a new acquired mutation was described in approximately 50% of the HES/CEL patients: a cryptic deletion on chromosome band 4q12 generating a FIP1IL1-PDGFRA fusion gene. According to the World Health Organization classification, this clonal abnormality has been proposed as a new surrogate marker for chronic eosinophilic leukemia diagnosis. Fluorescence in situ hybridization and reverse transcriptase-polymerase chain reaction protocols were developed for an accurate del(4)(q12q12) and FIP1L1-PDGFRA fusion gene detection. Here, we report a patient with a rare FIP1L1 intron 16 breakpoint located outside of the reported FIP1L1 breakpoint region (ie, from FIP1L1 introns 9 to 13). This case illustrates the risk of false-negative results with diagnostic procedures that do not take into account the occurrence of rare FIP1L1 breakpoints. As targeted therapy with tyrosine kinase inhibitors has dramatically changed the prognosis of FIP1L1-PDGFRA (+) CEL, false-negative results could hamper accurate diagnosis and treatment. [less ▲]

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See detailDuplication of the MYB oncogene in T-cell acute lymphoblastic leukemia
Lahortiga, Idoya; De Keersmaecker, Kim; Van Vlierberghe, Pieter et al

in Haematologica (2007, June), 92(Suppl. 1), 164

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See detailDuplication of the MYB oncogene in T cell acute lymphoblastic leukemia
Lahortiga, Idoya; De Keersmaecker, Kim; Van Vlierberghe, Pieter et al

in Nature Genetics (2007), 39(5), 593-595

We identified a duplication of the MYB oncogene in 8.4% of individuals with T cell acute lymphoblastic leukemia (T-ALL) and in five T-ALL cell lines. The duplication is associated with a threefold ... [more ▼]

We identified a duplication of the MYB oncogene in 8.4% of individuals with T cell acute lymphoblastic leukemia (T-ALL) and in five T-ALL cell lines. The duplication is associated with a threefold increase in MYB expression, and knockdown of MYB expression initiates T cell differentiation. Our results identify duplication of MYB as an oncogenic event and suggest that MYB could be a therapeutic target in human T-ALL. [less ▲]

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See detailSufasalazine unveils a contact-independent HSV-TK/ganciclovir gene therapy bystander effect in malignant gliomas
Robe, Pierre ULg; Nguyen-Khac, Minh-Tuan ULg; Lambert, Frédéric ULg et al

in International Journal of Oncology (2007), 30(1), 283-290

The efficacy of HSV-TK/ganciclovir-based gene therapy on malignant gliomas largely relies on the amplitude of the bystander effect. In these experiments, the anti-inflammatory drug Sulfasalazine increased ... [more ▼]

The efficacy of HSV-TK/ganciclovir-based gene therapy on malignant gliomas largely relies on the amplitude of the bystander effect. In these experiments, the anti-inflammatory drug Sulfasalazine increased the HSV-TK/ganciclovir bystander effect in C6, 9L and LN18 cells but not in U87 glioma cells. Using bi-compartmental culture devices and conditioned medium transfer experiments, we showed that in C6, 9L and LN18 cells but not in U87 cells, Sulfasalazine also unveiled a new, contact-independent mechanism of HSV-TK/ganciclovir bystander effect. Upon treatment with ganciclovir, human LN18-TK but not U87-TK cells synthetized and released TNF-alpha in the culture medium. Sulfasalazine sensitized glioma cells to the toxic effect of TNF-alpha. and enhanced its secretion in LN18-TK cells in response to GCV treatment. The caspase-8 inhibitor Z-IETD-FMK and a blocking antibody to TNF-alpha both inhibited the contact-independent bystander effect in LN18 cells. Taken together, these results suggest that TNF-alpha mediates the contact-independent bystander effect in LN18 cells. The treatment with GCV and/or Sulfasalazine of tumor xenografts consisting of a mix of 98% C6 and 2% C6-TK cells shows that Sulfasalazine is also a potent adjunct to the in vivo treatment of gliomas. [less ▲]

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See detailArray-CGH analysis of T-ALL patients and cell lines
Lahortiga, I.; Graux, C.; Mentens, N. et al

in Blood (2006, November 16), 108(11, Part 2), 195-196

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See detailCombined locked nucleic acid and molecular beacon technologies for sensitive detection of the JAK2(V617F) somatic single-base sequence variant
Sidon, P.; Heimann, P.; Lambert, Frédéric ULg et al

in Clinical Chemistry (2006), 52(7), 1436-1438

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See detailA quantitative study of peripheral blood stem cell contamination in diffuse large-cell non-Hodgkin's lymphoma: one-half of patients significantly mobilize malignant cells.
Jacquy, C.; Soree, A.; Lambert, Frédéric ULg et al

in British Journal of Haematology (2000), 110(3), 631-7

Autologous transplantation using peripheral blood stem cells (PBSCs) collected after chemotherapy, followed by growth factor administration (ASCT), is increasingly used in the treatment of non-Hodgkin's ... [more ▼]

Autologous transplantation using peripheral blood stem cells (PBSCs) collected after chemotherapy, followed by growth factor administration (ASCT), is increasingly used in the treatment of non-Hodgkin's lymphoma (NHL). However, quantitative data regarding contaminating malignant cells in the harvests are still scarce. We prospectively investigated 37 diffuse large-cell lymphomas (DLCLs) in complete remission (CR) that were treated according to multicentric protocols at our centre. DNA was extracted from the diagnostic lymph node. The complementarity-determining region (CDR) III was sequenced and a patient-specific oligomer synthesized. Contamination was evaluated semiquantitatively by polymerase chain reaction (PCR) and was confirmed by a limiting dilution analysis. PBSCs collected at regeneration after administration of granulocyte colony-stimulating factor (G-CSF), steady-state bone marrow (BM) and peripheral blood samples at CR were compared. DNA was available in 37 patients, from which 22 rearrangements could be sequenced. Patients (n = 15) who had both the required follow-up samples and a suitable clonal marker were investigated. In two cases, the patient-specific PCR assay set up at diagnosis later gave false-negative results in samples in which clonal DNA was still detectable by other sets of primers. PBSC contamination was highly variable: 7 out of 15 patients showed a PBSC/BM ratio of NHL cells greater than 1 log, whereas 8 out of 15 patients showed no difference and could vary from one apheresis to another. Eight ASCTs were performed, five of which used highly contaminated PBSCs: four patients relapsed early, three with disseminated lymphoma. Thus, 50% of DLCLs in CR seem to mobilize significantly malignant cells at regeneration under G-CSF. Considering the higher numbers of cells reinfused, this translates into a much higher number of lymphoma cells reinfused when compared with autologous bone marrow transplantation (ABMT). However, their clonogenic potential remains unknown and, despite concerning observations in certain cases, it is still unclear whether this has an impact upon the outcome of ASCT. [less ▲]

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