Project description:Resistance or relapse upon chemotherapy are major determinants of treatment failure in acute myeloid leukemia (AML). Therapy-induced senescence (TIS) is a potential outcome of chemotherapy, but its immunological consequences in AML remain unclear. We show that ex-vivo chemotherapy induces senescence in a subset of therapy-naïve AML samples. TIS is marked by elevated interferon signaling, upregulation of HLA class I/II molecules, and increased presentation of leukemia and senescence-associated peptides, conferring AML blasts antigen-presenting cell-like features. Patient-derived leukemic blasts purified from AML samples were either treated with cytarabine (AraC) or left untreated. Further, samples that exhibited a significant increase in fluorescent SA-β-Gal upon treatment were classified as Senescence High (Sen High), whereas others that showed minimal change were classified as Senescence Low (Sen Low). We employed our in-house microfluidic platform, PeptiCHIP for immunoaffinity purification followed by Ligandomics LC/MS analysis, to identify HLA class I-bound peptides in Patient-derived leukemic blasts, seeking to compare the immunopeptidome repertoire of Sen Low and Sen High samples before and after cytarabine treatment. Sen High exhibited a greater number of eluted peptides compared to Sen Low samples already at baseline. This number was further increased following chemotherapy in all Sen High samples analyzed. Conversely, the number of peptides retrieved in Sen Low samples remained low regardless of chemotherapy treatment.
Project description:Acute myeloid leukemia (AML) is a highly heterogeneous disease and reliable detection of leukemic stem cells (LSCs) across genetic subclasses has proven difficult. We aimed to transcriptionally characterize LSCs specifically in monocyte-like AML (Mono-AML) and and primitive-like AML (Prim-AML) samples using cell surface markers. We used CD64+CD11b+ to define Mature blasts and labelled the rest as Immature. To further enrich for LSC-like cells in the Immature blasts in both Mono- and Prim-AML samples, we included GPR56, a marker for LSCs. We performed RNA sequencing on the FACS-sorted LSC-like and Mature cells from 23 AML patients.
Project description:Leukemic blasts are immune cells gone awry. We hypothesized that dysregulation of inflammatory pathways contributes to the maintenance of their leukemic state and can be exploited as a cell-intrinsic, self-directed immunotherapy. To this end, we applied genome-wide screens to discover genetic vulnerabilities in acute myeloid leukemia (AML) cells that are also implicated in inflammatory pathways. We identified the immune modulator interferon regulatory factor 2 binding protein 2 (IRF2BP2) as a selective dependency in AML. We validated AML cell dependency on IRF2BP2 with genetic and protein degradation approaches in vitro and genetically in vivo. Chromatin and global gene expression studies demonstrated that IRF2BP2 represses IL1B/TNFA signaling via NF-KB, and IRF2BP2 perturbation results in an acute inflammatory state leading to AML cell death. These findings elucidate a hitherto unexplored AML dependency, reveal cell-intrinsic inflammatory signaling as a mechanism priming leukemic blasts for regulated cell death, and establish IRF2BP2-mediated transcriptional repression as a mechanism for blast survival.
Project description:Primary human AML cells (newly diagnosed, prior to treatment initation) were obtained from donor after consent and AML blasts were isolated by standard Ficoll centrifugation. AML blasts were treated with FLT3 inhibitor gilteritinib (or DMSO vehicle control) at 10 nM concentration for 6 h, followed by harvest for LC/MS.
Project description:Acute myeloid leukemia with complex karyotype (CK-AML) is characterized by three or more chromosomal aberrations, and comprises 10–12% of AML patients. It is associated with complex chromosomal rearrangements, intra-tumor heterogeneity, therapy resistance and poor overall survival. We aimed to transcriptionally characterize CK-AML by performing RNA sequencing on blasts from 4 CK-AML patient samples.
Project description:Expression of proteins regulating apoptosis (BCL-2, MCL-1, BCL-X and BAX) in acute myeloid leukemia (AML) blasts at diagnosis have been shown to be associated with disease-free survival. We previously found that the initially high apoptosis-resistance of AML cells decreased after therapy, while regaining high levels at relapse. This suggested a dynamic regulation of apoptosis. Herein, we further explored this aspect of apoptosis in AML. Firstly, the intra-individual ex vivo apoptosis-related profiles of normal lymphocytes and AML blasts showed a strong correlation, with expression values far beyond control lymphocytes. Secondly, we demonstrated that apoptosis-resistant primary AML blasts, as opposed to apoptosis-sensitive cells, were able to up-regulate BCL-2 expression in sensitive AML blasts in contact cultures (p=0.0067 and p=1.0 respectively). Using proteomics we further set out to identify novel proteins possibly engaged in apoptosis regulation. Proteomics analysis revealed that major functional protein clusters upregulated in secretomes of apoptosis-resistant AML, were presumably engaged in global gene regulation including mRNA splicing, protein translation and chromatin remodeling.
Project description:Acute Myeloid Leukemia (AML) is a heterogenous disease characterized by immature blasts at different maturation stage. We used single cell sequencing technique to analyze newly diagnosed AML patients.
Project description:NK cell effector functions are suppressed by AML-blast derived PGE2. Transcriptional regulation of human NK cells in culture with PGE2 or AML blasts was assessed via mRNA sequencing.
Project description:Expression of proteins regulating apoptosis (BCL-2, MCL-1, BCL-X and BAX) in acute myeloid leukemia (AML) blasts at diagnosis have been shown to be associated with disease-free survival. We previously found that the initially high apoptosis-resistance of AML cells decreased after therapy, while regaining high levels at relapse. This suggested a dynamic regulation of apoptosis. We hypothesized that expression of apoptosis-related proteins in AML blasts, and possibly also in bystander cells in the bone marrow, is regulated by extracellular factors present in the AML microenvironment. Tumor cell communication with its microenvironment is emerging as an important determinant playing multiple roles in cancer. Both soluble factors and extracellular vesicles (EVs), most notably exosomes, have been shown to influence cellular processes of malignant and normal cells in the tumor microenvironment. We performed a proteomics analysis of the whole secretome as well as of EVs secreted by AML blasts to pinpoint released protein factors that might mediate apoptosis-resistance.
Project description:Relapse after allo-HCT is a major cause of death of AML patients and results from immune evasion of AML blasts. Dysfunction of the p53 signaling pathway is frequent in AML and often caused by upregulation of the central p53 negative regulator Murine Double Minute 2 (MDM2). Besides its oncogenic effects p53 also regulates immune function and immune surveillance of solid cancer. We hypothesize that p53 also controls immune-related genes in AML cells and that p53 reactivation via MDM2-inhibition may enhance the immunogenicity of AML cells to allogeneic T cells.