Publications by authors named "Veronique Mansat-De Mas"

38 Publications

Activation of Vitamin D Receptor Pathway Enhances Differentiating Capacity in Acute Myeloid Leukemia with Isocitrate Dehydrogenase Mutations.

Cancers (Basel) 2021 Oct 19;13(20). Epub 2021 Oct 19.

Centre de Recherches en Cancérologie de Toulouse, Université de Toulouse, Inserm, Centre National de Recherche Scientifique, CEDEX 1, 31037 Toulouse, France.

Relapses and resistance to therapeutic agents are major barriers in the treatment of acute myeloid leukemia (AML) patients. These unfavorable outcomes emphasize the need for new strategies targeting drug-resistant cells. As IDH mutations are present in the preleukemic stem cells and systematically conserved at relapse, targeting IDH mutant cells could be essential to achieve a long-term remission in the IDH mutant AML subgroup. Here, using a panel of human AML cell lines and primary AML patient specimens harboring IDH mutations, we showed that the production of an oncometabolite (R)-2-HG by IDH mutant enzymes induces vitamin D receptor-related transcriptional changes, priming these AML cells to differentiate with pharmacological doses of ATRA and/or VD. This activation occurs in a CEBPα-dependent manner. Accordingly, our findings illuminate potent and cooperative effects of IDH mutations and the vitamin D receptor pathway on differentiation in AML, revealing a novel therapeutic approach easily transferable/immediately applicable to this subgroup of AML patients.
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http://dx.doi.org/10.3390/cancers13205243DOI Listing
October 2021

The CADM1 tumor suppressor gene is a major candidate gene in MDS with deletion of the long arm of chromosome 11.

Blood Adv 2021 Oct 12. Epub 2021 Oct 12.

Belgian Cancer Registry, Brussels, Belgium.

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal hematopoietic stem-cell disorders characterized by ineffective hematopoiesis leading to peripheral cytopenias and in a substantial proportion of cases to acute myeloid leukemia. The deletion of the long arm of chromosome 11, del(11q), is a rare but recurrent clonal event in MDS. Here, we detail the largest series of 113 cases of MDS and myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN) harboring a del(11q) analyzed at clinical, cytological, cytogenetic and molecular levels. Female predominance, a survival prognosis similar to other MDS, a low monocyte count and dysmegakaryopoiesis were the specific clinical and cytological features of del(11q) MDS. In most cases, del(11q) was isolated, primary and interstitial encompassing the 11q22-23 region containing ATM, KMT2A and CBL genes. The common deleted region at 11q23.2 is centered on an intergenic region between CADM1 (also known as TSLC1, Tumour Suppressor in Lung Cancer 1) and NXPE2. CADM1 was expressed in all myeloid cells analyzed in contrast to NXPE2. At the functional level, the deletion of Cadm1 in murine Lineage-Sca1+Kit+ cells modifies the lymphoid to myeloid ratio in bone marrow although not altering their multi-lineage hematopoietic reconstitution potential after syngenic transplantation. Together with the frequent simultaneous deletions of KMT2A, ATM and CBL and mutations of ASXL1, SF3B1 and CBL, we show that CADM1 may be important in the physiopathology of the del(11q) MDS, extending its role as tumor-suppressor gene from solid tumors to hematopoietic malignancies.
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http://dx.doi.org/10.1182/bloodadvances.2021005311DOI Listing
October 2021

Autophagy a Close Relative of AML Biology.

Biology (Basel) 2021 Jun 18;10(6). Epub 2021 Jun 18.

Centre de Recherches en Cancérologie de Toulouse (CRCT), Université de Toulouse, Inserm, CNRS, 31037 Toulouse, France.

Autophagy, which literally means "eat yourself", is more than just a lysosomal degradation pathway. It is a well-known regulator of cellular metabolism and a mechanism implicated in tumor initiation/progression and therapeutic resistance in many cancers. However, whether autophagy acts as a tumor suppressor or promoter is still a matter of debate. In acute myeloid leukemia (AML), it is now proven that autophagy supports cell proliferation in vitro and leukemic progression in vivo. Mitophagy, the specific degradation of mitochondria through autophagy, was recently shown to be required for leukemic stem cell functions and survival, highlighting the prominent role of this selective autophagy in leukemia initiation and progression. Moreover, autophagy in AML sustains fatty acid oxidation through lipophagy to support mitochondrial oxidative phosphorylation (OxPHOS), a hallmark of chemotherapy-resistant cells. Nevertheless, in the context of therapy, in AML, as well as in other cancers, autophagy could be either cytoprotective or cytotoxic, depending on the drugs used. This review summarizes the recent findings that mechanistically show how autophagy favors leukemic transformation of normal hematopoietic stem cells, as well as AML progression and also recapitulates its ambivalent role in resistance to chemotherapies and targeted therapies.
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http://dx.doi.org/10.3390/biology10060552DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8235674PMC
June 2021

Characteristic vacuolization of myeloid precursors and UBA1 mutation in a woman with monosomy X.

Int J Lab Hematol 2021 Jun 10. Epub 2021 Jun 10.

Laboratoire d'Hématologie, Centre Hospitalo-universitaire (CHU) de Toulouse, Institut Universitaire du Cancer de Toulouse-Oncopole (IUCT-O), Toulouse, France.

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http://dx.doi.org/10.1111/ijlh.13617DOI Listing
June 2021

Genomic analysis of primary and secondary myelofibrosis redefines the prognostic impact of ASXL1 mutations: a FIM study.

Blood Adv 2021 03;5(5):1442-1451

Service d'Hématologie, CH Perpignan, Perpignan, France.

We aimed to study the prognostic impact of the mutational landscape in primary and secondary myelofibrosis. The study included 479 patients with myelofibrosis recruited from 24 French Intergroup of Myeloproliferative Neoplasms (FIM) centers. The molecular landscape was studied by high-throughput sequencing of 77 genes. A Bayesian network allowed the identification of genomic groups whose prognostic impact was studied in a multistate model considering transitions from the 3 conditions: myelofibrosis, acute leukemia, and death. Results were validated using an independent, previously published cohort (n = 276). Four genomic groups were identified: patients with TP53 mutation; patients with ≥1 mutation in EZH2, CBL, U2AF1, SRSF2, IDH1, IDH2, NRAS, or KRAS (high-risk group); patients with ASXL1-only mutation (ie, no associated mutation in TP53 or high-risk genes); and other patients. A multistate model found that both TP53 and high-risk groups were associated with leukemic transformation (hazard ratios [HRs] [95% confidence interval], 8.68 [3.32-22.73] and 3.24 [1.58-6.64], respectively) and death from myelofibrosis (HRs, 3.03 [1.66-5.56] and 1.77 [1.18-2.67], respectively). ASXL1-only mutations had no prognostic value that was confirmed in the validation cohort. However, ASXL1 mutations conferred a worse prognosis when associated with a mutation in TP53 or high-risk genes. This study provides a new definition of adverse mutations in myelofibrosis with the addition of TP53, CBL, NRAS, KRAS, and U2AF1 to previously described genes. Furthermore, our results argue that ASXL1 mutations alone cannot be considered detrimental.
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http://dx.doi.org/10.1182/bloodadvances.2020003444DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948260PMC
March 2021

Characteristic vacuolisation of granulocytic and erythroid precursors associated with VEXAS syndrome.

Br J Haematol 2021 Jul 2;194(1). Epub 2021 Mar 2.

Haematology Laboratory Medicine, Cancer University Institute of Toulouse - Oncopole, Toulouse, France.

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http://dx.doi.org/10.1111/bjh.17381DOI Listing
July 2021

Autophagy regulates fatty acid availability for oxidative phosphorylation through mitochondria-endoplasmic reticulum contact sites.

Nat Commun 2020 08 13;11(1):4056. Epub 2020 Aug 13.

Cancer Research Center of Toulouse (CRCT), INSERM U1037, CNRS ERL5294, University of Toulouse, Toulouse, France.

Autophagy has been associated with oncogenesis with one of its emerging key functions being its contribution to the metabolism of tumors. Therefore, deciphering the mechanisms of how autophagy supports tumor cell metabolism is essential. Here, we demonstrate that the inhibition of autophagy induces an accumulation of lipid droplets (LD) due to a decrease in fatty acid β-oxidation, that leads to a reduction of oxidative phosphorylation (OxPHOS) in acute myeloid leukemia (AML), but not in normal cells. Thus, the autophagic process participates in lipid catabolism that supports OxPHOS in AML cells. Interestingly, the inhibition of OxPHOS leads to LD accumulation with the concomitant inhibition of autophagy. Mechanistically, we show that the disruption of mitochondria-endoplasmic reticulum (ER) contact sites (MERCs) phenocopies OxPHOS inhibition. Altogether, our data establish that mitochondria, through the regulation of MERCs, controls autophagy that, in turn finely tunes lipid degradation to fuel OxPHOS supporting proliferation and growth in leukemia.
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http://dx.doi.org/10.1038/s41467-020-17882-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7426880PMC
August 2020

Inhibition of ubiquitin-specific protease 7 sensitizes acute myeloid leukemia to chemotherapy.

Leukemia 2021 02 23;35(2):417-432. Epub 2020 May 23.

Cancer Research Center of Toulouse, INSERM U1037, CNRS ERL 5294, Université de Toulouse, Toulouse, France.

Resistance of acute myeloid leukemia (AML) to therapeutic agents is frequent. Consequently, the mechanisms leading to this resistance must be understood and addressed. In this paper, we demonstrate that inhibition of deubiquitinylase USP7 significantly reduces cell proliferation in vitro and in vivo, blocks DNA replication progression and increases cell death in AML. Transcriptomic dataset analyses reveal that a USP7 gene signature is highly enriched in cells from AML patients at relapse, as well as in residual blasts from patient-derived xenograft (PDX) models treated with clinically relevant doses of cytarabine, which indicates a relationship between USP7 expression and resistance to therapy. Accordingly, single-cell analysis of AML patient samples at relapse versus at diagnosis showed that a gene signature of the pre-existing subpopulation responsible for relapse is enriched in transcriptomes of patients with a high USP7 level. Furthermore, we found that USP7 interacts and modulates CHK1 protein levels and functions in AML. Finally, we demonstrated that USP7 inhibition acts in synergy with cytarabine to kill AML cell lines and primary cells of patients with high USP7 levels. Altogether, these data demonstrate that USP7 is both a marker of resistance to chemotherapy and a potential therapeutic target in overcoming resistance to treatment.
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http://dx.doi.org/10.1038/s41375-020-0878-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245510PMC
February 2021

STAT5-dependent regulation of CDC25A by miR-16 controls proliferation and differentiation in FLT3-ITD acute myeloid leukemia.

Sci Rep 2020 02 5;10(1):1906. Epub 2020 Feb 5.

Cancer Research Center of Toulouse (CRCT), INSERM U1037, CNRS ERL5294, University of Toulouse, Toulouse, France.

We recently identified the CDC25A phosphatase as a key actor in proliferation and differentiation in acute myeloid leukemia expressing the FLT3-ITD mutation. In this paper we demonstrate that CDC25A level is controlled by a complex STAT5/miR-16 transcription and translation pathway working downstream of this receptor. First, we established by CHIP analysis that STAT5 is directly involved in FLT3-ITD-dependent CDC25A gene transcription. In addition, we determined that miR-16 expression is repressed by FLT3-ITD activity, and that STAT5 participates in this repression. In accordance with these results, miR-16 expression was significantly reduced in a panel of AML primary samples carrying the FLT3-ITD mutation when compared with FLT3wt cells. The expression of a miR-16 mimic reduced CDC25A protein and mRNA levels, and RNA interference-mediated down modulation of miR-16 restored CDC25A expression in response to FLT3-ITD inhibition. Finally, decreasing miR-16 expression partially restored the proliferation of cells treated with the FLT3 inhibitor AC220, while the expression of miR-16 mimic stopped this proliferation and induced monocytic differentiation of AML cells. In summary, we identified a FLT3-ITD/STAT5/miR-16/CDC25A axis essential for AML cell proliferation and differentiation.
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http://dx.doi.org/10.1038/s41598-020-58651-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7002454PMC
February 2020

More than ten percent of relapses occur after five years in AML patients with mutation.

Leuk Lymphoma 2020 05 5;61(5):1226-1229. Epub 2020 Feb 5.

Service d'Hématologie, Institut Universitaire du Cancer de Toulouse-Oncopole, Centre Hospitalier Universitaire de Toulouse, Toulouse, France.

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http://dx.doi.org/10.1080/10428194.2019.1706733DOI Listing
May 2020

Mast cell activation syndrome: High frequency of skin manifestations and anaphylactic shock.

Allergol Int 2019 Jan 7;68(1):119-121. Epub 2018 Aug 7.

Mastocytosis National Reference Center (CEREMAST), Department of Dermatology, Toulouse University Hospital, Paul Sabatier University, Toulouse, France. Electronic address:

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http://dx.doi.org/10.1016/j.alit.2018.07.003DOI Listing
January 2019

CDC25A governs proliferation and differentiation of FLT3-ITD acute myeloid leukemia.

Oncotarget 2015 Nov;6(35):38061-78

Cancer Research Center of Toulouse, Inserm UMR 1037, CNRS ERL 5294, Université de Toulouse, Oncopole, Toulouse, France.

We investigated cell cycle regulation in acute myeloid leukemia cells expressing the FLT3-ITD mutated tyrosine kinase receptor, an underexplored field in this disease. Upon FLT3 inhibition, CDC25A mRNA and protein were rapidly down-regulated, while levels of other cell cycle proteins remained unchanged. This regulation was dependent on STAT5, arguing for FLT3-ITD-dependent transcriptional regulation of CDC25A. CDC25 inhibitors triggered proliferation arrest and cell death of FLT3-ITD as well as FLT3-ITD/TKD AC-220 resistant cells, but not of FLT3-wt cells. Consistently, RNA interference-mediated knock-down of CDC25A reduced the proliferation of FLT3-ITD cell lines. Finally, the clonogenic capacity of primary FLT3-ITD AML cells was reduced by the CDC25 inhibitor IRC-083864, while FLT3-wt AML and normal CD34+ myeloid cells were unaffected. In good agreement, in a cohort of 100 samples from AML patients with intermediate-risk cytogenetics, high levels of CDC25A mRNA were predictive of higher clonogenic potential in FLT3-ITD+ samples, not in FLT3-wt ones.Importantly, pharmacological inhibition as well as RNA interference-mediated knock-down of CDC25A also induced monocytic differentiation of FLT3-ITD positive cells, as judged by cell surface markers expression, morphological modifications, and C/EBPα phosphorylation. CDC25 inhibition also re-induced monocytic differentiation in primary AML blasts carrying the FLT3-ITD mutation, but not in blasts expressing wild type FLT3. Altogether, these data identify CDC25A as an early cell cycle transducer of FLT3-ITD oncogenic signaling, and as a promising target to inhibit proliferation and re-induce differentiation of FLT3-ITD AML cells.
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http://dx.doi.org/10.18632/oncotarget.5706DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4741984PMC
November 2015

Antileukemic Activity of 2-Deoxy-d-Glucose through Inhibition of N-Linked Glycosylation in Acute Myeloid Leukemia with FLT3-ITD or c-KIT Mutations.

Mol Cancer Ther 2015 Oct 23;14(10):2364-73. Epub 2015 Jul 23.

Cancer Research Center of Toulouse (CRCT), UMR1037 INSERM, ERL5294 CNRS, Toulouse, France. Université Toulouse III Paul Sabatier, Toulouse, France. Service d'Hématologie, Institut Universitaire du Cancer de Toulouse Oncopole, Toulouse, France.

We assessed the antileukemic activity of 2-deoxy-d-glucose (2-DG) through the modulation of expression of receptor tyrosine kinases (RTK) commonly mutated in acute myeloid leukemia (AML). We used human leukemic cell lines cells, both in vitro and in vivo, as well as leukemic samples from AML patients to demonstrate the role of 2-DG in tumor cell growth inhibition. 2-DG, through N-linked glycosylation inhibition, affected the cell-surface expression and cellular signaling of both FTL3-ITD and mutated c-KIT and induced apoptotic cell death. Leukemic cells harboring these mutated RTKs (MV4-11, MOLM-14, Kasumi-1, and TF-1 c-KIT D816V) were the most sensitive to 2-DG treatment in vitro as compared with nonmutated cells. 2-DG activity was also demonstrated in leukemic cells harboring FLT3-TKD mutations resistant to the tyrosine kinase inhibitor (TKI) quizartinib. Moreover, the antileukemic activity of 2-DG was particularly marked in c-KIT-mutated cell lines and cell samples from core binding factor-AML patients. In these cells, 2-DG inhibited the cell-surface expression of c-KIT, abrogated STAT3 and MAPK-ERK pathways, and strongly downregulated the expression of the receptor resulting in a strong in vivo effect in NOD/SCID mice xenografted with Kasumi-1 cells. Finally, we showed that 2-DG decreases Mcl-1 protein expression in AML cells and induces sensitization to both the BH3 mimetic inhibitor of Bcl-xL, Bcl-2 and Bcl-w, ABT-737, and cytarabine. In conclusion, 2-DG displays a significant antileukemic activity in AML with FLT3-ITD or KIT mutations, opening a new therapeutic window in a subset of AML with mutated RTKs.
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http://dx.doi.org/10.1158/1535-7163.MCT-15-0163DOI Listing
October 2015

Role of ASXL1 and TP53 mutations in the molecular classification and prognosis of acute myeloid leukemias with myelodysplasia-related changes.

Oncotarget 2015 Apr;6(10):8388-96

Département d'Oncologie Moléculaire, Centre de Recherche en Cancérologie de Marseille (CRCM), Institut Paoli-Calmettes, UMR1068 Inserm, Marseille, France.

Acute myeloid leukemias (AML) with myelodysplasia-related changes (AML-MRC) are defined by the presence of multilineage dysplasia (MLD), and/or myelodysplastic syndrome (MDS)-related cytogenetics, and/or previous MDS. The goal of this study was to identify distinct biological and prognostic subgroups based on mutations of ASXL1, RUNX1, DNMT3A, NPM1, FLT3 and TP53 in 125 AML-MRC patients according to the presence of MLD, cytogenetics and outcome. ASXL1 mutations (n=26, 21%) were associated with a higher proportion of marrow dysgranulopoiesis (mutant vs. wild-type: 75% vs. 55%, p=0.030) and were mostly found in intermediate cytogenetic AML (23/26) in which they predicted inferior 2-year overall survival (OS, mutant vs. wild-type: 14% vs. 37%, p=0.030). TP53 mutations (n=28, 22%) were mostly found in complex karyotype AML (26/28) and predicted poor outcome within unfavorable cytogenetic risk AML (mutant vs. wild-type: 9% vs. 40%, p=0.040). In multivariate analysis, the presence of either ASXL1 or TP53 mutation was the only independent factor associated with shorter OS (HR, 95%CI: 2.53, 1.40-4.60, p=0.002) while MLD, MDS-related cytogenetics and previous MDS history did not influence OS. We conclude that ASXL1 and TP53 mutations identify two molecular subgroups among AML-MRCs, with specific poor prognosis. This could be useful for future diagnostic and prognostic classifications.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4480760PMC
http://dx.doi.org/10.18632/oncotarget.3460DOI Listing
April 2015

Prognostic impact of JAK2V617F mutation in myelodysplatic syndromes: A matched case control study.

Leuk Res Rep 2013 30;2(2):64-6. Epub 2013 Aug 30.

Service d'Hématologie Clinique, Hôpital Avicenne, APHP, et Paris 13 Université, Bobigny, France.

While in RARS-T, JAK2V617F mutation is common and associated with good prognosis, the clinical and prognostic impact of this mutation in other MDS is unknown. We collected data from 132 non-RARS-T MDS with known JAK2V617F mutation status. JAK2V617F mutation was significantly correlated with lower progression to AML (p<.0011) and better overall survival (OS, p=.011). OS difference persisted after matching on age, sex, IPSS and % marrow blast (p=.031). Thus, in MDS other than RARS-T, JAK2V617F mutation may be associated with favorable outcome.
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http://dx.doi.org/10.1016/j.lrr.2013.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3850389PMC
December 2013

Hemophagocytic syndrome in patients with acute myeloid leukemia undergoing intensive chemotherapy.

Haematologica 2014 Mar 18;99(3):474-80. Epub 2013 Oct 18.

Hemophagocytic lymphohistiocytosis is a condition of immune dysregulation characterized by severe organ damage induced by a hyperinflammatory response and uncontrolled T-cell and macrophage activation. Secondary hemophagocytic lymphohistiocytosis typically occurs in association with severe infections or malignancies. Patients with acute myeloid leukemia may be prone to develop hemophagocytic lymphohistiocytosis because of an impaired immune response and a high susceptibility to severe infections. In a series of 343 patients treated by intensive chemotherapy over a 5-year period in our center, we identified 32 patients (9.3%) with fever, very high ferritin levels, and marrow hemophagocytosis (i.e. patients with hemophagocytic lymphohistiocytosis). Compared to patients without hemophagocytic lymphohistiocytosis, these 32 patients had hepatomegaly, pulmonary or neurological symptoms, liver abnormalities, lower platelet count and higher levels of C-reactive protein as well as prolonged pancytopenia. A microbial etiology for the hemophagocytosis was documented in 24 patients: 14 bacterial infections, 9 Herpesviridae infections and 11 fungal infections. The treatment of hemophagocytic lymphohistiocytosis consisted of corticosteroids and/or intravenous immunoglobulins along with adapted antimicrobial therapy. Patients with hemophagocytic lymphohistiocytosis had a median overall survival of 14.9 months, which was significantly shorter than that of patients without hemophagocytic lymphohistiocytosis (22.1 months) (P=0.0016). Hemophagocytic lymphohistiocytosis was significantly associated with a higher rate of induction failure, mainly due to deaths in aplasia. Hemophagocytic lymphohistiocytosis can be diagnosed in up to 10% of patients with acute myeloid leukemia undergoing intensive chemotherapy and is associated with early mortality. Fever, very high ferritin levels and marrow hemophagocytosis represent the cornerstone of the diagnosis. Further biological studies are needed to better characterize and recognize this syndrome in patients with acute myeloid leukemia.
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http://dx.doi.org/10.3324/haematol.2013.097394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943310PMC
March 2014

CXXC5 (retinoid-inducible nuclear factor, RINF) is a potential therapeutic target in high-risk human acute myeloid leukemia.

Oncotarget 2013 Sep;4(9):1438-48

Inserm, U1016, Institut Cochin, F-75014, Paris, France.

The retinoid-responsive gene CXXC5 localizes to the 5q31.2 chromosomal region and encodes a retinoid-inducible nuclear factor (RINF) that seems important during normal myelopoiesis. We investigated CXXC5/RINF expression in primary human acute myeloid leukemia (AML) cells derived from 594 patients, and a wide variation in CXXC5/RINF mRNA levels was observed both in the immature leukemic myeloblasts and in immature acute lymphoblastic leukemia cells. Furthermore, patients with low-risk cytogenetic abnormalities showed significantly lower levels compared to patients with high-risk abnormalities, and high RINF/CXXC5/ mRNA levels were associated with decreased overall survival for patients receiving intensive chemotherapy for newly diagnosed AML. This association with prognosis was seen both when investigating (i) an unselected patient population as well as for patients with (ii) normal cytogenetic and (iii) core-binding factor AML. CXXC5/RINF knockdown in AML cell lines caused increased susceptibility to chemotherapy-induced apoptosis, and regulation of apoptosis also seemed to differ between primary human AML cells with high and low RINF expression. The association with adverse prognosis together with the antiapoptotic effect of CXXC5/RINF suggests that targeting of CXXC5/RINF should be considered as a possible therapeutic strategy, especially in high-risk patients who show increased expression in AML cells compared with normal hematopoietic cells.
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http://dx.doi.org/10.18632/oncotarget.1195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3824541PMC
September 2013

Time from diagnosis to intensive chemotherapy initiation does not adversely impact the outcome of patients with acute myeloid leukemia.

Blood 2013 Apr 30;121(14):2618-26. Epub 2013 Jan 30.

Service d'Hématologie, Centre Hospitalier Universitaire de Toulouse, Hôpital Purpan, Toulouse, France.

In acute myeloid leukemia (AML), new strategies assess the potential benefit of genetically targeted therapy at diagnosis. This implies waiting for laboratory tests and therefore a delay in initiation of chemotherapy. We studied the impact of time from diagnosis to treatment (TDT) on overall survival, early death, and response rate in a retrospective series of 599 newly diagnosed AML patients treated by induction chemotherapy between 2000 and 2009. The effect of TDT was assessed using multivariate analysis. TDT was analyzed as a continuous variable using a specific polynomial function to model the shape and form of the relationship. The median TDT was 8 days (interquartile range, 4-16) and was significantly longer in patients with a white blood cell count (WBC) <50 Giga per liter (G/L) (P < .0001) and in older patients (P = .0004). In multivariate analysis, TDT had no impact on overall survival (P = .4095) compared with age >60 years, secondary AML, WBC >50 G/L, European LeukemiaNet risk groups, and Eastern Cooperative Oncology Group performance status. Furthermore, TDT was not associated with response rate and early death. Thus, waiting a short period of time for laboratory tests to characterize leukemias better and design adapted therapeutic strategies at diagnosis seems possible.
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http://dx.doi.org/10.1182/blood-2012-09-454553DOI Listing
April 2013

High frequency of GATA2 mutations in patients with mild chronic neutropenia evolving to MonoMac syndrome, myelodysplasia, and acute myeloid leukemia.

Blood 2013 Jan 6;121(5):822-9. Epub 2012 Dec 6.

Department of Hematology, Centre Hospitalier Universitaire Toulouse Purpan, Toulouse, France.

Unlabelled: Congenital neutropenia is a group of genetic disorders that involve chronic neutropenia and susceptibility to infections. These neutropenias may be isolated or associated with immunologic defects or extra-hematopoietic manifestations. Complications may occur as infectious diseases, but also less frequently as myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). Recently, the transcription factor GATA2 has been identified as a new predisposing gene for familial AML/MDS. In the present study, we describe the initial identification by exome sequencing of a GATA2 R396Q mutation in a family with a history of chronic mild neutropenia evolving to AML and/or MDS. The subsequent analysis of the French Severe Chronic Neutropenia Registry allowed the identification of 6 additional pedigrees and 10 patients with 6 different and not previously reportedGATA2 mutations (R204X, E224X, R330X, A372T, M388V, and a complete deletion of the GATA2 locus). The frequent evolution to MDS and AML in these patients reveals the importance of screening GATA2 in chronic neutropenia associated with monocytopenia because of the frequent hematopoietic transformation, variable clinical expression at onset, and the need for aggressive therapy in patients with poor clinical outcome.

Key Points: Mutations of key transcription factor in myeloid malignancies.
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http://dx.doi.org/10.1182/blood-2012-08-447367DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3714670PMC
January 2013

Focal adhesion kinase splice variants maintain primitive acute myeloid leukemia cells through altered Wnt signaling.

Stem Cells 2012 Aug;30(8):1597-610

Inserm U1043, CNRS U5282, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France.

Focal adhesion kinase (FAK) activity contributes to many advanced cancer phenotypes, but little is known about its role in human acute myeloid leukemia (AML). Here, we show that FAK splice variants are abnormally expressed in the primitive leukemic cells of poor prognosis AML patients. In the CD34(+) 38(-) 123(+) long-term culture-initiating cell-enriched leukemic cells of these patients, FAK upregulates expression of Frizzled-4 and phosphorylates Pyk2 to enable the required association of Pyk2 with the Wnt5a/Frizzled-4/LRP5 endocytosis complex and downstream activation of β-catenin, thereby replacing the Wnt3a-controlled canonical pathway used by normal hematopoietic stem cells. Transduction of primitive normal human hematopoietic cells with FAK splice variants induces a marked increase in their clonogenic activity and signaling via the Wnt5a-controlled canonical pathway. Targeting FAK or β-catenin efficiently eradicates primitive leukemic cells in vitro suggesting that FAK could be a useful therapeutic target for improved treatment of poor prognosis AML cases.
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http://dx.doi.org/10.1002/stem.1157DOI Listing
August 2012

Do AML patients with DNMT3A exon 23 mutations benefit from idarubicin as compared to daunorubicin? A single center experience.

Oncotarget 2011 Nov;2(11):850-61

Laboratoire d'Hématologie, CHU de Toulouse, Hôpital Purpan.

Mutations in DNMT3A encoding DNA methyltransferase 3A were recently described in patients with acute myeloid leukemia. To assess their prognostic significance, we determined the mutational status of DNMT3A exon 23 in 288 patients with AML excluding acute promyelocytic leukemia, aged from 18 to 65 years and treated in Toulouse University Hospital. A mutation was detected in 39 patients (13.5%). All DNMT3A exon 23+ patients had intermediate-risk cytogenetics. Mutations significantly correlated with a higher WBC count (p less than 0.001), NPM1 and FLT3-ITD mutations (p=0.027). DNMT3A mutations were conserved through xenotransplantation in immunodeficient mice. No difference in outcome between DNMT3A exon 23+ and DNMT3A exon 23- patients was found even if the results were stratified by NPM1 or FLT3-ITD status. However, DNMT3A exon 23+ patients had better median DFS (not reached vs 11.6 months, p=0.009) and OS (not reached vs 14.3 months, p=0.005) as compared to DNMT3A exon 23- patients when treated with idarubicin, whereas patients treated with daunorubicin had similar outcome regardless the DNMT3A status. This study shows that DNMT3A mutations have no impact on outcome but could be a predictive factor for response to idarubicin and thus, could have a direct influence in the way AML patients should be managed.
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http://dx.doi.org/10.18632/oncotarget.347DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3260002PMC
November 2011

The cell cycle regulator CDC25A is a target for JAK2V617F oncogene.

Blood 2012 Feb 7;119(5):1190-9. Epub 2011 Nov 7.

INSERM UMR 1037-Cancer Research Center of Toulouse, Université de Toulouse, Centre Hospitalier Universitaire Purpan, Toulouse, France.

The JAK2(V617F) mutation is present in the majority of patients with polycythemia vera and one-half of those with essential thrombocythemia and primary myelofibrosis. JAK2(V617F) is a gain-of-function mutation resulting in constitutive JAK2 signaling involved in the pathogenesis of these diseases. JAK2(V617F) has been shown to promote S-phase entry. Here, we demonstrate that the CDC25A phosphatase, a key regulator of the G1/S cell-cycle transition, is constitutively overexpressed in JAK2(V617F)-positive cell lines, JAK2-mutated patient CD36(+) progenitors, and in vitro-differentiated proerythroblasts. Accordingly, CDC25A is overexpressed in BM and spleen of Jak2(V617F) knock-in mice compared with wild-type littermates. By using murine FDC-P1-EPOR and human HEL and SET-2 cell lines, we found that JAK2(V617F)-induced CDC25A up-regulation was caused neither by increased CDC25A transcription or stability nor by the involvement of its upstream regulators Akt and MAPK. Instead, our results suggest that CDC25A is regulated at the translational level through STAT5 and the translational initiation factor eIF2α. CDC25A inhibition reduces the clonogenic and proliferative potential of JAK2(V617F)-expressing cell lines and erythroid progenitors while moderately affecting normal erythroid differentiation. These results suggest that CDC25A deregulation may be involved in hematopoietic cells expansion in JAK2(V617F) patients, making this protein an attracting potential therapeutic target.
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http://dx.doi.org/10.1182/blood-2011-01-327742DOI Listing
February 2012

TET2 mutations in secondary acute myeloid leukemias: a French retrospective study.

Haematologica 2011 Jul 20;96(7):1059-63. Epub 2011 Apr 20.

Service d'Hématologie Biologique, GH Broca-Cochin-Hôtel-Dieu, Paris, France.

Ten-eleven translocation 2 (TET2) mutations have been involved in myeloid malignancies. This retrospective study aims at evaluating the frequency and impact of TET2 mutations in 247 secondary acute myeloid leukemia cases referred to as myelodysplasia-related changes (n=201) or therapy-related (n=46) leukemias. Mutation of at least one copy of the TET2 gene was detected in 49 of 247 (19.8%) patients who presented with older age, higher hemoglobin level, higher neutrophil and monocyte counts, and lower platelet count. TET2 mutations were significantly less frequent in therapy-related (8.7%) than myelodysplasia-related changes (22.3%; P=0.035) leukemias and strongly associated with normal karyotype (P<0.001). TET2 mutations did not significantly associate with NPM1, FLT3-ITD or FLT3-D835, WT1, or N- or K-RAS mutations. Complete remission was achieved in 57% of evaluable patients who had received intensive chemotherapy. In this group, TET2 mutations did not influence the complete remission rate or overall survival.
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http://dx.doi.org/10.3324/haematol.2011.040840DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3128227PMC
July 2011

Human acute myelogenous leukemia stem cells are rare and heterogeneous when assayed in NOD/SCID/IL2Rγc-deficient mice.

J Clin Invest 2011 Jan 13;121(1):384-95. Epub 2010 Dec 13.

Division of Hematology and Oncology, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.

Human leukemic stem cells, like other cancer stem cells, are hypothesized to be rare, capable of incomplete differentiation, and restricted to a phenotype associated with early hematopoietic progenitors or stem cells. However, recent work in other types of tumors has challenged the cancer stem cell model. Using a robust model of xenotransplantation based on NOD/SCID/IL2Rγc-deficient mice, we confirmed that human leukemic stem cells, functionally defined by us as SCID leukemia-initiating cells (SL-ICs), are rare in acute myelogenous leukemia (AML). In contrast to previous results, SL-ICs were found among cells expressing lineage markers (i.e., among Lin+ cells), CD38, or CD45RA, all markers associated with normal committed progenitors. Remarkably, each engrafting fraction consistently recapitulated the original phenotypic diversity of the primary AML specimen and contained self-renewing leukemic stem cells, as demonstrated by secondary transplants. While SL-ICs were enriched in the Lin-CD38- fraction compared with the other fractions analyzed, SL-ICs in this fraction represented only one-third of all SL-ICs present in the unfractionated specimen. These results indicate that human AML stem cells are rare and enriched but not restricted to the phenotype associated with normal primitive hematopoietic cells. These results suggest a plasticity of the cancer stem cell phenotype that we believe has not been previously described.
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http://dx.doi.org/10.1172/JCI41495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3007135PMC
January 2011

Interlaboratory development and validation of a HRM method applied to the detection of JAK2 exon 12 mutations in polycythemia vera patients.

PLoS One 2010 Jan 26;5(1):e8893. Epub 2010 Jan 26.

CHU BREST, Laboratoire d'Hematologie, Brest, France.

Background: Myeloproliferative disorders are characterized by clonal expansion of normal mature blood cells. Acquired mutations giving rise to constitutive activation of the JAK2 tyrosine kinase has been shown to be present in the majority of patients. Since the demonstration that the V617F mutation in the exon 14 of the JAK2 gene is present in about 90% of patients with Polycythemia Vera (PV), the detection of this mutation has become a key tool for the diagnosis of these patients. More recently, additional mutations in the exon 12 of the JAK2 gene have been described in 5 to 10% of the patients with erythrocytosis. According to the updated WHO criteria the presence of these mutations should be looked for in PV patients with no JAK2 V617F mutation. Reliable and accurate methods dedicated to the detection of these highly variable mutations are therefore necessary.

Methods/findings: For these reasons we have defined the conditions of a High Resolution DNA Melting curve analysis (HRM) method able to detect JAK2 exon 12 mutations. After having validated that the method was able to detect mutated patients, we have verified that it gave reproducible results in repeated experiments, on DNA extracted from either total blood or purified granulocytes. This HRM assay was further validated using 8 samples bearing different mutant sequences in 4 different laboratories, on 3 different instruments.

Conclusion: The assay we have developed is thus a valid method, adapted to routine detection of JAK2 exon 12 mutations with highly reproducible results.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0008893PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2811183PMC
January 2010

Constitutive activation of the DNA damage signaling pathway in acute myeloid leukemia with complex karyotype: potential importance for checkpoint targeting therapy.

Cancer Res 2009 Nov 20;69(22):8652-61. Epub 2009 Oct 20.

Université de Toulouse, LBCMCP, Centre National de la Recherche Scientifique, LBCMCP-UMR5088, Toulouse, France.

Genomic instability in solid tumors participates in the oncogenetic process and is associated with the activation of the DNA damage response pathway. Here, we report the activation of the constitutive DNA damage and checkpoint pathway associated with complex karyotypes in samples from patients with acute myeloid leukemia (AML). We show that antagonizing CHK1 kinase with a small inhibitory compound or by RNA interference strongly reduces the clonogenic properties of high-DNA damage level AML samples, particularly those with complex karyotypes. Moreover, we observe a beneficial effect of CHK1 inhibition in high-DNA damage level AML samples treated with 1-beta-d-arabinofuranosylcytosine. In contrast, CHK1 inhibition has no effect on the clonogenic properties of normal hematopoietic progenitors. All together, our results indicate that CHK1 inhibition may represent an attractive therapeutic opportunity in AML with complex karyotype.
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http://dx.doi.org/10.1158/0008-5472.CAN-09-0939DOI Listing
November 2009

TET2 mutation is an independent favorable prognostic factor in myelodysplastic syndromes (MDSs).

Blood 2009 Oct 7;114(15):3285-91. Epub 2009 Aug 7.

Assistance Publique-Hôpitaux de Paris (AP-HP), Service d'Hématologie Biologique, Hôpital Cochin-Hôtel-Dieu, Paris, France.

Oncogenic pathways underlying in the development of myelodysplastic syndromes (MDS) remain poorly characterized, but mutations of the ten-eleven translocation 2 (TET2) gene are frequently observed. In the present work, we evaluated the prognostic impact of TET2 mutations in MDS. Frameshift, nonsense, missense mutations, or defects in gene structure were identified in 22 (22.9%) of 96 patients (95% confidence interval [CI], 14.5-31.3 patients). Mutated and unmutated patients did not significantly differ in initial clinical or hematologic parameters. The 5-year OS was 76.9% (95% CI, 49.2%-91.3%) in mutated versus 18.3% (95% CI, 4.2%-41.1%) in unmutated patients (P = .005). The 3-year leukemia-free survival was 89.3% (95% CI, 63.1%-97.0%) in mutated versus 63.7% (95% CI, 48.2%-75.4%) in unmutated patients (P = .035). In univariate analysis (Cox proportional hazard model), the absence of TET2 mutation was associated with a 4.1-fold (95% CI, 1.4-12.0-fold) increased risk of death (P = .009). In multivariate analysis adjusted for age, International Prognostic Scoring System, and transfusion requirement, the presence of TET2 mutation remained an independent factor of favorable prognosis (hazard ratio, 5.2; 95% CI, 1.6-16.3; P = .005). These results indicate that TET2 mutations observed in approximately 20% of patients, irrespective of the World Health Organization or French-American-British subtype, represent a molecular marker for good prognosis in MDS.
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http://dx.doi.org/10.1182/blood-2009-04-215814DOI Listing
October 2009

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

J Exp Med 2008 Oct 20;205(11):2499-506. Epub 2008 Oct 20.

Institut National de Santé et de Recherche Médicale, U563, Centre de Physiopathologie de Toulouse-Purpan, 31300 Toulouse, France.

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.
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http://dx.doi.org/10.1084/jem.20080285DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2571925PMC
October 2008

Cell-surface MMP-9 regulates the invasive capacity of leukemia blast cells with monocytic features.

Cell Cycle 2008 Apr 18;7(8):1047-53. Epub 2008 Jan 18.

Institut de Pharmacologie et de Biologie Structurale, Université Toulouse/CNRS UMR 5089, Toulouse, France.

The metalloprotease 9 (MMP-9), a known mediator of tumour invasion, is secreted as a 92 kDa pro-form but a non-secreted variant of 85 Kda has been described. The importance of this variant pro-form in tumor progression remains poorly defined. We previously showed that the DNA repair protein Ku interacts at the cell surface of leukaemia cell lines with the 85 Kda pro-form of MMP-9 and these Ku/MMP-9 complexes regulates cell invasion, highlighting their importance in haematological malignancies. We demonstrate here that all samples of acute myeloid leukaemia (AML) blasts purified from bone marrow of 16 affected patients express the 85 Kda form of MMP-9. However, only AML that display monocytic lineage markers (AML4/5) express this form at the cell surface with co-expression of the membrane associated form of Ku. Blocking antibodies directed against Ku or MMP-9 specifically inhibited cell invasion of those expressing Ku/MMP-9 on the cell surface. The membrane form of Ku might represent an important factor in the exposition to the cell surface of this specific MMP-9 pro-form in AML with monocytic features. These results might have important functional significance in the occurrence of extra-medullar infiltrates of leukaemia cells that occurs frequently during the onset of monocyte-related AML sub-types.
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http://dx.doi.org/10.4161/cc.7.8.5645DOI Listing
April 2008

Tumor necrosis factor-alpha inhibits hTERT gene expression in human myeloid normal and leukemic cells.

Blood 2005 Nov 14;106(9):3200-5. Epub 2005 Jul 14.

Institut National de la Santé et de la Recherche Médicale (INSERM) U563, Centre Hospitalier et Universitaire (CHU) Purpan, Toulouse, France.

Telomerase catalytic subunit (hTERT) has been shown to play a critical role not only in telomere homeostasis but also in cellular survival, DNA repair, and genetic stability. In a previous study, we described that tumor necrosis factor-xalpha (TNFxalpha) induced in the leukemic KG1 cells a senescence state characterized by decreased hTERT activity followed by prolonged growth arrest, increasedx beta-galactosidase activity, telomere shortening, and major chromosomal instability. Interestingly, granulocyte-macrophage colony-stimulating factor (GM-CSF) abrogated all these events. In the present study, we show for the first time that TNFxalpha acts by inhibiting the hTERT gene in both normal CD34x+ cells and fresh leukemic cells. Using KG1 cells as a representative cellular model, we show that TNFxalpha induced sphingomyelin hydrolysis, ceramide production, and c-Jun N-terminal kinase (JNK) activation, all of which are critical components of TNFxalpha signaling, resulting in hTERT gene inhibition. Moreover, we provide evidence that the protective effect of GM-CSF is related to its capacity to interfere with both ceramide generation and ceramide signaling. Negative regulation of the hTERT gene may represent one mechanism by which TNFxalpha interferes with normal hemopoiesis.
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http://dx.doi.org/10.1182/blood-2005-04-1386DOI Listing
November 2005
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