Project description:ATRA is an active metabolite of vitamin A that is frequently used for the treatment of acute promyelocytic leukemia (APL) patients. Despite the success of this treatment, some APL patients are refractory or relapse. This emphasis the need for new therapeutic strategies aiming to improve the anti-cancer effect of ATRA. We and other have previously shown that autophagy is activated during ATRA-induced granulocytic differentiation of acute promyelocytic leukemia cells. Although the transcription effect of ATRA on autophagy has been well-documented, little is known on the post-transcription/ post-translational regulation autophagy in response to ATRA. Given the importance of calcium ions in the control of autophagy, we hypothesized that calcium ions are involved in the initiation of autophagy by ATRA in APL cells. We thus examined how ATRA regulate intracellular calcium and sense perturbation of Ca2+ responses to autophagy, differentiation and cell death in APL cells.
Project description:The differentiation of leukemia stem cells (LSCs) is generally regarded as a one-way alterative process to self-renewal. However, how differentiation impacts LSC stemness has largely been unexplored. Here we show that before reaching terminal differentiation (TD), apical LSCs of mouse acute promyelocytic leukemia passed through a partial differentiation (PD) stage, wherein the leukemia cells re-initiated leukemia via de-differentiation albeit at a reduced rate. Notably, while retinoic acid (RA) preferentially drove the transition of LSC to PD, monocytic Irf8 skewed PD cells to terminal maturation over de-differentiation and/or expansion. Remarkably, the combined use of RA and Irf8 induction depleted the total leukemogenic potential, which indicates that discrete stage- or lineage-specific mechanisms elaborate a step-wise LSC differentiation. We used microarrays to detail the global programme of gene expression indicating the molecular mechanisms unerlying the the process of LSC step-wise differentiation. Retroviral GFP-labled mouse APL cells (bone marrow sample) were repopulated in vivo through transplantation into syngenic recipients. At the proper time points, the GFP positive APL bone marrow cells were collected and sorted for UNSC, UNPD and UNTD samples through FACS. RA-PD and RA-TD cells were sorted from bone marrow tissue treated with ATRA (all trans retinoic acid) for 5 days. The freshly isolated samples were then lysed for RNA extration. Each sample had two biological replicates.
Project description:Co-targeting the plasticity and heterogeneity of cancer is fundamental to achieve and maintain complete remission (CR). We exploited murine models of acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia driven by the promyelocytic leukemia/retinoic acid receptor (PML-RARα) oncofusion protein, which recruits histone deacetylase (HDAC)-containing complexes. We investigated the effect of two HDAC inhibitors: valproic acid (VPA), and SAHA/vorinostat with all-trans retinoic acid (ATRA), on the bulk cells and LICs of two APLs with different LIC frequencies. VPA and SAHA selectively target the bulk APL cells and LICs respectively. VPA+SAHA+ATRA combination induced CR in an APL model with lower LIC frequency.
Project description:Here we report a new fusion gene, STRN3-RARA, in acute promyelocytic leukemia (APL). It cooperates with UTX deficiency to drive full-blown APL in mice. Although STRN3-RARA leukemia quickly relapses after all-trans retinoic acid treatment, it can be restrained by cepharanthine.
Project description:Acute promyelocytic leukemia (APL) is a hematological disease characterized by a balanced reciprocal translocation that leads to the synthesis of the oncogenic fusion protein PML-RARα. APL is mainly managed by a differentiation therapy based on the administration of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). However, therapy resistance, differentiation syndrome, and relapses require the development of new low-toxicity therapies based on the induction of blasts differentiation. Here, we performed a high-throughput gene expression profile of the ATRA-resistant acute promyelocytic leukemia (APL) cellline (aka R4) treated with a CHK1 inhibitor or DMSO as control.
Project description:The origin of aberrant DNA methylation in cancer remains largely unknown. In this study, we elucidated the DNA methylome in primary Acute Promyelocytic Leukemia (APL) and the role of PML-RARa in establishing these patterns. APL patients showed increased genome-wide DNA methylation with higher variability than healthy CD34+ cells, promyelocytes and remission bone marrow. A core set of differentially methylated regions in APL was identified. Age at diagnosis, Sanz score and Flt3-mutation status characterized methylation subtypes. Transcription factor binding sites, e.g. c-myc binding sites were associated with low methylation. SUZ12 and REST binding sites identified in embryonic stem cells were, however, preferentially DNA hypermethylated in APL. Unexpectedly, PML-RARa binding sites were also protected from aberrant DNA methylation in APL. In line, myeloid cells from pre-leukemic PML-RARa knock-in mice did not show altered DNA methylation and expression of PML-RARa in hematopoietic progenitor cells prevented differentiation without affecting DNA methylation. ATRA treatment of APL blasts did also not result in DNA methylation changes. These results suggest that aberrant DNA methylation is associated with leukemia phenotype but not required for PML-RARa-mediated initiation of leukemogenesis. Bisulphite converted DNA from the 10 samples were hybridised to the Illumina Infinium 450k Human Methylation Beadchip
Project description:To better understand the pathogenesis of acute promyelocytic leukemia (APL, FAB M3 AML), we identified genes that are expressed differently in APL cells compared to other acute myeloid leukemia subtypes, and to normal promyelocytes. Comparative gene expression analysis of 14 M3, 62 other AML (M0, M1, M2 and M4) and 5 enriched normal promyelocyte samples revealed a signature of 1,121 genes that are specifically dysregulated in M3 samples relative to other AML, and that do not simply represent normal promyelocyte expression (â??M3-specific signatureâ??). We used a novel, high throughput digital platform (Nanostring's nCounter system) to evaluate a subset of the most significantly dysregulated genes in 30 AML samples; 33 of 37 evaluable gene expression patterns were validated. In an additional analysis, we selected only genes that are dysregulated in M3 both compared to other AML subtypes, and to purified normal CD34+ cells, promyelocytes, and/or neutrophils, thereby isolating a 478 gene "composite M3 dysregulome". Surprisingly, the expression of only a few of these genes was significantly altered in PR-9 cells after PML-RARA induction, suggesting that most of these genes are not direct targets of PML-RARA. Comparison of the M3-specific signature to our previously described murine APL dysregulome revealed 33 commonly dysregulated genes, including JUN, EGR1, and TNF. Collectively, these results suggest that PML-RARA initiates a transcriptional cascade which generates a unique downstream expression signature in both primary human and mouse APL cells. Experiment Overall Design: 14 human APL/M3 AML samples were compared to 62 AML samples of other AML FAB subtypes (bone marrow aspirates collected at diagnosis, included in GSE10358), to fractionated cells from normal human bone marrow aspirates (5 CD34+ cells, 5 promyelocytes, 5 neutrophils/PMNs), and to PR9 cells before and after Zinc-induction of PML-RARA.
Project description:We report the use of RNAseq to determine genomewide transcriptional changes induced by all-trans retinoic acid differentiation of NB4 acute promyelocytic leukemia (APL) cells.
Project description:The aim of this study was to gain insight into the potential mechanism of resistance to arsenic trioxide (ATO). The gene expression profile of naive (NB4) (Acute promyelocytic leukemia (APL) cell line and one of its in house generated ATO resistant sub clone (NB4-VM-AsR1) was done using whole genome microarray and compared to generate the differential expression profile which will give insight into the mechanisms of ATO resistance in APL. Agilent one-color experiment,Organism: Human ,Agilent Whole Genome Human 4x44k (AMADID: 014850) , Labeling kit: Agilent Quick-Amp labeling Kit (p/n5190-0442) naive versus arsenic trioxide resistant acute promyelocytic leukemia cell line NB4