Decitabine encapsulation in nanovector to improve acute myeloid leukemia treatment

Acute myeloid leukemia (AML) mainly affects adult patients, and for older ones unfit for intensive chemotherapy only few therapies are available. Hypomethylating agents, as decitabine, is a labeled option but its plasma half-life is short whereas a long cell exposure time improves response rate. Only intravenous administration is available, whereas an oral route is generally preferred by patients. Consequently, to enhance plasma half-life and to develop an oral decitabine formulation, in this work decitabine was encapsulated in nanoparticles. Two different strategies were tested: decitabine loaded into lipid nanocapsules (DAC-LNC), and a decitabine-prodrug synthesis [3’(OH)-5’(OH)-(lauroyl)2-modified DAC] encapsulated into LNC (DAC-(C12)2-LNC). DAC-LNC and DAC-(C12)2-LNC particles were obtained with sizes of 26.5 ± 0.5 nm and 27.45 ± 0.05 nm respectively, and drug payloads of 0.47 ± 0.06 mg/mL and 5.8 ± 0.5 mg/mL (corresponding to 2.3 ± 0.2 mg/mL of decitabine). Both formulations were able to increase in vitro human plasma half-life by protecting decitabine from degradations. Compared to free-decitabine solutions, both nanoparticle formulations were able to preserve decitabine cytotoxicity on an AML cell line (HEL). Moreover, permeability studies across an adenocarcinoma cell model (Caco-2 cells) demonstrated that DAC-LNC improve decitabine’s intestinal permeability whereas DAC-(C12)2-LNC decreased it. However, this drawback could be countered by the enhanced decitabine’s stability in gastrointestinal fluids thanks to DAC-(C12)2-LNC, leading to more available drug for absorption. Globally, both formulation have demonstrated their ability to improve DAC plasma half-life in vitro and their potential for oral administration. In vivo pharmacokinetics evaluations may now confirm interests of such strategies

Outcome of Ph negative myeloproliferative neoplasms transforming to accelerated or leukemic phase

Myeloproliferative neoplasms (MPN) are chronic disorders that can sometimes evolve into accelerated or leukemic phases. We retrospectively identified 122 patients with such blastic phases. The overall median survival was four months: 10.2 months for patients treated with intensive treatments compared to three months for best supportive care (p = .005). Azacytidine, intensive chemotherapies, or allogeneic stem cell transplantation gave the highest median survivals with 9, 10.2, and 19.4 months, respectively. Accelerated phases (AP) had a longer median survival compared to acute leukemia (4.8 months vs. 3.1 months; p = .02). In this retrospective and observational study, we observe that the longest survivals are seen in patients eligible for intensive treatments. Azacytidine shows interesting results in patients non-fit for intensive chemotherapy. Supportive care should probably be restricted to elderly patients and those with unfavorable karyotype. An early diagnosis of AP could also result in a better survival rate

Knocking-Down Cyclin A2 by siRNA Suppresses Apoptosis and Switches Differentiation Pathways in K562 Cells upon Administration with Doxorubicin

Cyclin A2 is critical for the initiation of DNA replication, transcription and cell cycle regulation. Cumulative evidences indicate that the deregulation of cyclin A2 is tightly linked to the chromosomal instability, neoplastic transformation and tumor proliferation. Here we report that treatment of chronic myelogenous leukaemia K562 cells with doxorubicin results in an accumulation of cyclin A2 and follows by induction of apoptotic cell death. To investigate the potential preclinical relevance, K562 cells were transiently transfected with the siRNA targeting cyclin A2 by functionalized single wall carbon nanotubes. Knocking down the expression of cyclin A2 in K562 cells suppressed doxorubicin-induced growth arrest and cell apoptosis. Upon administration with doxorubicin, K562 cells with reduced cyclin A2 showed a significant decrease in erythroid differentiation, and a small fraction of cells were differentiated along megakaryocytic and monocyte-macrophage pathways. The results demonstrate the pro-apoptotic role of cyclin A2 and suggest that cyclin A2 is a key regulator of cell differentiation. To the best of our knowledge, this is the first report that knocking down expression of one gene switches differentiation pathways of human myeloid leukemia K562 cells

Genetic diversity, linkage disequilibrium and power of a large grapevine (Vitis vinifera L) diversity panel newly designed for association studies

UMR-AGAP Equipe DAVV (Diversité, adaptation et amélioration de la vigne) ; équipe ID (Intégration de Données)International audienceAbstractBackgroundAs for many crops, new high-quality grapevine varieties requiring less pesticide and adapted to climate change are needed. In perennial species, breeding is a long process which can be speeded up by gaining knowledge about quantitative trait loci linked to agronomic traits variation. However, due to the long juvenile period of these species, establishing numerous highly recombinant populations for high resolution mapping is both costly and time-consuming. Genome wide association studies in germplasm panels is an alternative method of choice, since it allows identifying the main quantitative trait loci with high resolution by exploiting past recombination events between cultivars. Such studies require adequate panel design to represent most of the available genetic and phenotypic diversity. Assessing linkage disequilibrium extent and panel power is also needed to determine the marker density required for association studies.ResultsStarting from the largest grapevine collection worldwide maintained in Vassal (France), we designed a diversity panel of 279 cultivars with limited relatedness, reflecting the low structuration in three genetic pools resulting from different uses (table vs wine) and geographical origin (East vs West), and including the major founders of modern cultivars. With 20 simple sequence repeat markers and five quantitative traits, we showed that our panel adequately captured most of the genetic and phenotypic diversity existing within the entire Vassal collection. To assess linkage disequilibrium extent and panel power, we genotyped single nucleotide polymorphisms: 372 over four genomic regions and 129 distributed over the whole genome. Linkage disequilibrium, measured by correlation corrected for kinship, reached 0.2 for a physical distance between 9 and 458 Kb depending on genetic pool and genomic region, with varying size of linkage disequilibrium blocks. This panel achieved reasonable power to detect associations between traits with high broad-sense heritability (> 0.7) and causal loci with intermediate allelic frequency and strong effect (explaining > 10 % of total variance).ConclusionsOur association panel constitutes a new, highly valuable resource for genetic association studies in grapevine, and deserves dissemination to diverse field and greenhouse trials to gain more insight into the genetic control of many agronomic traits and their interaction with the environment

Cell cycle regulation of cyclin A gene expression by the cyclic AMP-responsive transcription factors CREB and CREM.

Cyclin A is a pivotal regulatory protein which, in mammalian cells, is involved in the S phase of the cell cycle. Transcription of the human cyclin A gene is cell cycle regulated. We have investigated the role of the cyclic AMP (cAMP)-dependent signalling pathway in this cell cycle-dependent control. In human diploid fibroblasts (Hs 27), induction of cyclin A gene expression at G1/S is stimulated by 8-bromo-cAMP and suppressed by the protein kinase A inhibitor H89, which was found to delay S phase entry. Transfection experiments showed that the cyclin A promoter is inducible by activation of the adenylyl cyclase signalling pathway. Stimulation is mediated predominantly via a cAMP response element (CRE) located at positions -80 to -73 with respect to the transcription initiation site and is able to bind CRE-binding proteins and CRE modulators. Moreover, activation by phosphorylation of the activators CRE-binding proteins and CRE modulator tau and levels of the inducible cAMP early repressor are cell cycle regulated, which is consistent with the pattern of cyclin A inducibility by cAMP during the cell cycle. These results suggest that the CRE is, at least partly, implicated in stimulation of cyclin A transcription at G1/S