Acquired resistance to oxaliplatin is not directly associated with increased resistance to DNA damage in SK-N-ASrOXALI4000, a newly established oxaliplatin-resistant sub-line of the neuroblastoma cell line SK-N-AS

The formation of acquired drug resistance is a major reason for the failure of anti-cancer therapies after initial response. Here, we introduce a novel model of acquired oxaliplatin resistance, a sub-line of the non-MYCN-amplified neuroblastoma cell line SK-N-AS that was adapted to growth in the presence of 4000 ng/mL oxaliplatin (SK-N-ASrOXALI4000). SK-N-ASrOXALI4000 cells displayed enhanced chromosomal aberrations compared to SK-N-AS, as indicated by 24-chromosome fluorescence in situ hybridisation. Moreover, SK-N-ASrOXALI4000 cells were resistant not only to oxaliplatin but also to the two other commonly used anti-cancer platinum agents cisplatin and carboplatin. SK-N-ASrOXALI4000 cells exhibited a stable resistance phenotype that was not affected by culturing the cells for 10 weeks in the absence of oxaliplatin. Interestingly, SK-N-ASrOXALI4000 cells showed no cross resistance to gemcitabine and increased sensitivity to doxorubicin and UVC radiation, alternative treatments that like platinum drugs target DNA integrity. Notably, UVC-induced DNA damage is thought to be predominantly repaired by nucleotide excision repair and nucleotide excision repair has been described as the main oxaliplatin-induced DNA damage repair system. SK-N-ASrOXALI4000 cells were also more sensitive to lysis by influenza A virus, a candidate for oncolytic therapy, than SK-N-AS cells. In conclusion, we introduce a novel oxaliplatin resistance model. The oxaliplatin resistance mechanisms in SK-N-ASrOXALI4000 cells appear to be complex and not to directly depend on enhanced DNA repair capacity. Models of oxaliplatin resistance are of particular relevance since research on platinum drugs has so far predominantly focused on cisplatin and carboplatin

Origine embryonnaire des manifestations hématologiques de l'Anémie de Fanconi

Fanconi anemia (FA), a genetic disorder due to mutations in one of the FANC complementation group genes involved in DNA repair, causes bone marrow failure very early during childhood. We hypothesized that the FA hematopoietic defect could begin in utero, and asked whether during embryonic development, Fanc genes defect could impair the expansion of HSC pool in response to replicative stress, from the first stages of HSCs amplification, focusing on early development times, when HSC amplification takes place both in FL and PL, i.e. E11.5 - E12.5. Our results not only reveals that a deep HSCs defect is already present very early during Fancg-/- mouse development, but also shows for the first time that this is also the case in human FA development. This HSC defect is even more important in the mouse Pl, where high naïve HSC amplification takes place. Actually, this HC/HSC defect is even more important at E12.5 than that described for Fancg-/- adult mice, and resemble more to the BM failure observed in humans. Transcriptomic analysis of HSCs sorted from Fancg-/- E12.5 FL and Pl and from the human FL showed striking highly conserved biological processes involving G protein-coupled receptors pathways, and epigenetic dysregulations, which might represent a hallmark of FA HSCs dysfunction during development. Further studies to explore these epigenetic alterations during fetal life might lead to development of new therapeutic approaches to prevent development of leukemias and cancers in FA patients.L'anémie de Fanconi (AF), maladie génétique due à des mutations dans l'un des gènes du groupe de complémentation FANC impliqués dans la réparation de l'ADN, provoque une aplasie médullaire très tôt dans l'enfance. Nous avons émis l'hypothèse que le défaut hématopoïétique de l'AF pourrait débuter dès la vie in utero et nous nous sommes demandés si un défaut des gènes Fanc pourrait compromettre l'expansion des CSH en réponse au stress réplicatif, dès les premiers stades d'amplification des CSH au cours du développement embryonnaire. Pour cela, nous avons concentré notre étude sur les temps de développement précoce, au moment où l'amplification des CSH a lieu à la fois dans le FF et le Pl, c'est-à-dire E11.5 - E12.5. Nos résultats révèlent un défaut profond des CSH très tôt au cours du développement chez la souris Fancg-/-, plus important dans le Pl de souris, où une amplification importante de CSH naïves a lieu. Ce défaut de CH / CSH à E12.5 est bien plus grave que celui décrit chez les souris adultes Fancg-/- et ressemble bien plus à la défaillance médullaire observée chez l'homme. De plus, nous avons montré pour la première fois que ce déficit en CSH est également présent dans le FF AF humain. L'analyse transcriptomique des CSH triées à partir de FF et de placenta Fancg-/- E12.5, et de FF humain ont montré des processus biologiques extrêmement conservés, impliquant les voies des récepteurs couplés aux protéines G et des dérégulations épigénétiques qui pourraient représenter une caractéristique de dysfonctionnement des CSH Fanconi au cours du développement. Des études complémentaires visant à explorer ces altérations épigénétiques pendant la vie foetale pourraient conduire au développement de nouvelles approches thérapeutiques afin de prévenir le développement de leucémies et de cancers chez les patients Fanconi

Embryonic origin of Fanconi Anemia' haematologic disorders

L'anémie de Fanconi (AF), maladie génétique due à des mutations dans l'un des gènes du groupe de complémentation FANC impliqués dans la réparation de l'ADN, provoque une aplasie médullaire très tôt dans l'enfance. Nous avons émis l'hypothèse que le défaut hématopoïétique de l'AF pourrait débuter dès la vie in utero et nous nous sommes demandés si un défaut des gènes Fanc pourrait compromettre l'expansion des CSH en réponse au stress réplicatif, dès les premiers stades d'amplification des CSH au cours du développement embryonnaire. Pour cela, nous avons concentré notre étude sur les temps de développement précoce, au moment où l'amplification des CSH a lieu à la fois dans le FF et le Pl, c'est-à-dire E11.5 - E12.5. Nos résultats révèlent un défaut profond des CSH très tôt au cours du développement chez la souris Fancg-/-, plus important dans le Pl de souris, où une amplification importante de CSH naïves a lieu. Ce défaut de CH / CSH à E12.5 est bien plus grave que celui décrit chez les souris adultes Fancg-/- et ressemble bien plus à la défaillance médullaire observée chez l'homme. De plus, nous avons montré pour la première fois que ce déficit en CSH est également présent dans le FF AF humain. L'analyse transcriptomique des CSH triées à partir de FF et de placenta Fancg-/- E12.5, et de FF humain ont montré des processus biologiques extrêmement conservés, impliquant les voies des récepteurs couplés aux protéines G et des dérégulations épigénétiques qui pourraient représenter une caractéristique de dysfonctionnement des CSH Fanconi au cours du développement. Des études complémentaires visant à explorer ces altérations épigénétiques pendant la vie foetale pourraient conduire au développement de nouvelles approches thérapeutiques afin de prévenir le développement de leucémies et de cancers chez les patients Fanconi.Fanconi anemia (FA), a genetic disorder due to mutations in one of the FANC complementation group genes involved in DNA repair, causes bone marrow failure very early during childhood. We hypothesized that the FA hematopoietic defect could begin in utero, and asked whether during embryonic development, Fanc genes defect could impair the expansion of HSC pool in response to replicative stress, from the first stages of HSCs amplification, focusing on early development times, when HSC amplification takes place both in FL and PL, i.e. E11.5 - E12.5. Our results not only reveals that a deep HSCs defect is already present very early during Fancg-/- mouse development, but also shows for the first time that this is also the case in human FA development. This HSC defect is even more important in the mouse Pl, where high naïve HSC amplification takes place. Actually, this HC/HSC defect is even more important at E12.5 than that described for Fancg-/- adult mice, and resemble more to the BM failure observed in humans. Transcriptomic analysis of HSCs sorted from Fancg-/- E12.5 FL and Pl and from the human FL showed striking highly conserved biological processes involving G protein-coupled receptors pathways, and epigenetic dysregulations, which might represent a hallmark of FA HSCs dysfunction during development. Further studies to explore these epigenetic alterations during fetal life might lead to development of new therapeutic approaches to prevent development of leukemias and cancers in FA patients

Première rechute extramédullaire isolée de leucémie aiguë lymphoblastique de type B chez l'enfant (résultats de l'étude COOPRALL-97)

LYON1-BU Santé (693882101) / SudocSudocFranceF

[Novel conventional therapies in onco-hemathology].

International audienceCytogenetic, molecular and phenotyping features of malignant hematologic diseases succeeded in improving their management by a more accurate stratification of patients according to several groups of risk and by providing a rational for targeted therapy. Three major types of treatment (excluding cellular therapy) are currently available in onco-hematology: conventional chemotherapy, small molecules for targeted therapy and monoclonal antibodies. Conventional chemotherapy with optimization of doses and multidrug-based regimens allowed to substantially improve survival of patients and keeps a place of choice in treatment of these diseases. Targeted treatments came from the cytogenetic and molecular characterization of hemopathies. Thus, the kinase Bcr-Abl, as a result of the translocation t(9;22)(q34;q11), has been successfully targeted by tyrosine kinase inhibitors (TKI) in chronic myeloid leukemia and Ph+ acute lymphoblastic leukemia. Molecular abnormalities like internal-tandem duplication/point activating mutations in FLT3 in some acute myeloblastic leukemia or epigenetic dysregulations in some blood malignancies can also be targeted by small molecules. Hematopoietic malignant cells are phenotypically characterized by expression of cluster of differentiation (CD) on their surface. These CD are detected by flow cytometry using specific antibodies. Monoclonal antibodies targeting different CD have been developed for treatment. Rituximab, an anti-CD20 antibody, was the first monoclonal antibody successfully developed for treatment of malignant hematologic diseases. Since rituximab, many other monoclonal antibodies are being developed. Trends in malignant hematologic diseases presented here will include treatments, which have at least entered phase I/II clinical trials in adult or childhood leukemia. They include some novel drugs of conventional chemotherapy like second-generation nucleoside analogues. We will give an overview of the small molecules targeting the different cellular pathways and we will highlight those appearing as the most promising like novel TKIs. The large field of monoclonal antibodies will be also approached focusing on antibodies developed in leukemias

S-phase lengthening induced by p16INK4a overexpression in malignant cells with wild-type pRb and p53

The p16INK4a protein is considered to regulate the cell cycle progression mainly by inhibiting cyclin-dependent kinases (CDKs) 4 and 6 activity and leading to an arrest in G0/G1. Here, we report that ectopic expression of p16INK4a in three p16-/ pRbWt/p53Wt human cancer cell lines MCF7, U2OS and U87 induces S-phase lengthening along with G1 accumulation. S-phase lengthening is suggested by the discrepancy between the unchanged or even increased percentage of cells in S phase found by flow cytometry DNA content analysis and the drop of BrdU labelling, and demonstrated by IdU/BrdU double labelling. p16INK4a induces a profound decrease in the CDK4/6-mediated pRb phosphorylation on Ser-807/811, a downregulation of CDK2 and CDK1 protein expression independently of G1 accumulation, and a decrease in Thr/Pro phosphorylation in part carried out by CDKs. In MCF7 cells, overexpression of the p16 G101W mutant, which is unable to inhibit CDK4/6 kinase activity and shows a modified subcellular localization, does not provoke the S-phase lengthening and the inhibition of Ser807/811-pRB and of Thr/Pro phosphorylation as wild-type p16INK4a does. Our results demonstrate that p16INK4a induces a S-phase lengthening independently of cellular origin. The CDK4/6 kinase activity inhibition together with the reduced expression of CDK2 and CDK1 acting downstream of G1 phase may prevent cells from any possible kinasic compensatory mechanisms, and thus lead to a cell cycle progression inhibition

Exhaustion in Myeloid Lineage and Very Early Defect in HSPC Pool: An Embryonic Origin of Fanconi Haematological Disorders

57th Annual Meeting of the American-Society-of-Hematology, Orlando, FL, DEC 05-08, 2015International audienceno abstrac