ABSTRACT
Monosomy 5 and deletions of the chromosome 5q (-5/del(5q)) are recurrent events in de novo adult acute myeloid leukemia (AML), reaching up to 40% of cases in secondary AML. These chromosome anomalies are associated with TP53 mutations and with very poor prognosis. Using the large Leucegene genomic and transcriptomic dataset composed of 48 -5/del(5q) patient specimens and 367 control AML, we identified DELE1 - located in the common deleted region - as the most consistently downregulated gene in these leukemias. DELE1 encodes a mitochondrial protein recently characterized as the relay of mitochondrial stress to the cytosol through a newly defined OMA1-DELE1-HRI pathway which ultimately leads to the activation of ATF4, the master transcription factor of the integrated stress response. Here, we showed that the partial loss of DELE1 expression observed in -5/del(5q) patients was sufficient to significantly reduce the sensitivity to mitochondrial stress in AML cells. Overall, our results suggest that DELE1 haploinsufficiency could represent a new driver mechanism in -5/del(5q) AML.
Subject(s)
Haploinsufficiency , Leukemia, Myeloid, Acute , Mitochondrial Proteins , Monosomy , Adult , Humans , Apoptosis/genetics , Chromosome Deletion , Chromosomes, Human, Pair 5/genetics , Leukemia, Myeloid, Acute/genetics , Mitochondrial Proteins/geneticsABSTRACT
Acute myeloid leukemias (AML) with mutations in the NPM1 gene (NPM1c+) represent a large AML subgroup with varying response to conventional treatment, highlighting the need to develop targeted therapeutic strategies for this disease. We screened a library of clinical drugs on a cohort of primary human AML specimens and identified the BCL2 inhibitor ABT-199 as a selective agent against NPM1c+ AML. Mutational analysis of ABT-199-sensitive and -resistant specimens identified mutations in NPM1, RAD21, and IDH1/IDH2 as predictors of ABT-199 sensitivity. Comparative transcriptome analysis further uncovered BCL2A1 as a potential mediator of ABT-199 resistance in AML. In line with our observation that RAD21 mutation confers sensitivity to ABT-199, we provide functional evidence that reducing RAD21 levels can sensitize AML cells to BCL2 inhibition. Moreover, we demonstrate that ABT-199 is able to produce selective anti-AML activity in vivo toward AML with mutations associated with compound sensitivity in PDX models. Overall, this study delineates the contribution of several genetic events to the response to ABT-199 and provides a rationale for the development of targeted therapies for NPM1c+ AML.
Subject(s)
Antineoplastic Agents/pharmacology , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Drug Resistance, Neoplasm/genetics , Leukemia, Myeloid, Acute/genetics , Minor Histocompatibility Antigens/genetics , Proto-Oncogene Proteins c-bcl-2/genetics , Sulfonamides/pharmacology , Humans , Leukemia, Myeloid, Acute/drug therapy , Mutation , Nuclear Proteins/genetics , Nucleophosmin , Tumor Cells, CulturedABSTRACT
Patients diagnosed with acute myeloid leukemia with complex karyotype (CK AML) have an adverse prognosis using current therapies, especially when accompanied by TP53 alterations. We hereby report the RNA-sequencing analysis of the 68 CK AML samples included in the Leucegene 415 patient cohort. We confirm the frequent occurrence of TP53 alterations in this subgroup and further characterize the allele expression profile and transcript alterations of this gene. We also document that the RAS pathway (N/KRAS, NF1, PTPN11, BRAF) is frequently altered in this disease. Targeted chemical interrogation of genetically characterized primary CK AML samples identifies polo-like kinase 1 (PLK1) inhibitors as the most selective agents for this disease subgroup. TP53 status did not alter sensitivity to PLK1 inhibitors. Interestingly, CK AML specimens display a G2/M transcriptomic signature that includes higher expression levels of PLK1 and correlates with PLK1 inhibition sensitivity. Together, our results highlight vulnerability in CK AML. In line with these in vitro data, volasertib shows a strong anti-AML activity in xenotransplantation mouse models of human adverse AML. Considering that PLK1 inhibitors are currently being investigated clinically in AML and myelodysplastic syndromes, our results provide a new rationale for PLK1-directed therapy in patients with adverse cytogenetic AML.
Subject(s)
Cell Cycle Proteins/antagonists & inhibitors , Leukemia, Myeloid, Acute/drug therapy , Leukemia, Myeloid, Acute/genetics , Protein Kinase Inhibitors/therapeutic use , Protein Serine-Threonine Kinases/antagonists & inhibitors , Proto-Oncogene Proteins/antagonists & inhibitors , Pteridines/therapeutic use , Adult , Aged , Aged, 80 and over , Animals , Cell Line, Tumor , Female , G2 Phase Cell Cycle Checkpoints/drug effects , Humans , Karyotype , M Phase Cell Cycle Checkpoints/drug effects , Male , Mice , Middle Aged , Tumor Suppressor Protein p53/genetics , Young Adult , Polo-Like Kinase 1ABSTRACT
In this study, we show the high frequency of spontaneous γδ T-cell leukemia (T-ALL) occurrence in mice with biallelic deletion of enhancer of zeste homolog 2 (Ezh2). Tumor cells show little residual H3K27 trimethylation marks compared with controls. EZH2 is a component of the PRC2 Polycomb group protein complex, which is associated with DNA methyltransferases. Using next-generation sequencing, we identify alteration in gene expression levels of EZH2 and acquired mutations in PRC2-associated genes (DNMT3A and JARID2) in human adult T-ALL. Together, these studies document that deregulation of EZH2 and associated genes leads to the development of mouse, and likely human, T-ALL.
Subject(s)
DNA-Binding Proteins/metabolism , Histone-Lysine N-Methyltransferase/metabolism , Leukemia-Lymphoma, Adult T-Cell/metabolism , Transcription Factors/metabolism , Acute Disease , Animals , DNA-Binding Proteins/genetics , Enhancer of Zeste Homolog 2 Protein , Histone-Lysine N-Methyltransferase/genetics , Humans , Leukemia-Lymphoma, Adult T-Cell/genetics , Mice , Mice, Inbred C57BL , Mice, Transgenic , Polycomb Repressive Complex 2 , Polycomb-Group Proteins , Protein Binding , Repressor Proteins/genetics , Repressor Proteins/metabolism , Transcription Factors/geneticsABSTRACT
It has become increasingly clear that the cells within the tumor microenvironment play a critical role in cancer growth and metastasis. Studies in experimental models suggest that carcinoma-associated fibroblasts (CAF) differ from normal fibroblasts and are capable of promoting cancer progression through a variety of mechanisms. At present, a definitive view is lacking on whether genomic abnormalities are present and whether they might underlie the observed phenotypic differences. This study reports the molecular analysis of the largest series of breast CAFs reported to date, with an array comparative genomic hybridization-based DNA copy number analysis of cultured CAFs derived from 25 freshly resected human breast cancers. We found DNA copy number changes consisting of the whole arm of chromosomes 6p and 9p plus interstitial 4q loss in only one sample. No abnormalities were observed in non-tumor-associated fibroblast counterparts. Karyotyping of the same CAF revealed further chromosomal abnormalities, which included clonal loss of chromosomes, chromosomal duplications, and less frequent chromosomal rearrangements. These abnormalities were not associated with alterations in the global gene expression profile of this particular CAF, relative to its non-tumor-associated fibroblast counterpart. Moreover, this particular patient's CAF also displayed the only p53 mutation in the cohort, the first time such a mutation has been reported in freshly cultured human CAFs. These findings argue that the procancerous effects of CAFs are unlikely to be due to DNA copy number-type genomic abnormalities in the CAFs themselves. As such, breast CAFs should be mainly regarded as genomically stable cellular constituents that exist within complex cancer microenvironments.
