ABSTRACT
Some patients with therapy-related myeloid neoplasms (t-MN) may have unsuspected inherited cancer predisposition syndrome (CPS). We propose a set of clinical criteria to identify t-MN patients with high risk of CPS (HR-CPS). Among 225 t-MN patients with an antecedent non-myeloid malignancy, our clinical criteria identified 52 (23%) HR-CPS patients. Germline whole-exome sequencing identified pathogenic or likely pathogenic variants in 10 of 27 HR-CPS patients compared to 0 of 9 low-risk CPS patients (37% vs. 0%, p = 0.04). These simple clinical criteria identify t-MN patients most likely to benefit from genetic testing for inherited CPS.
Subject(s)
Neoplasms, Second Primary , Neoplasms , Humans , Germ-Line Mutation , Neoplasms/genetics , Mutation , Genetic Predisposition to Disease , Genetic Testing , Neoplasms, Second Primary/geneticsABSTRACT
Therapy-related myeloid neoplasms (t-MNs) are high-risk late effects with poorly understood pathogenesis in cancer survivors. It has been postulated that, in some cases, hematopoietic stem and progenitor cells (HSPCs) harboring mutations are selected for by cytotoxic exposures and transform. Here, we evaluate this model in the context of deficiency of CUX1, a transcription factor encoded on chromosome 7q and deleted in half of t-MN cases. We report that CUX1 has a critical early role in the DNA repair process in HSPCs. Mechanistically, CUX1 recruits the histone methyltransferase EHMT2 to DNA breaks to promote downstream H3K9 and H3K27 methylation, phosphorylated ATM retention, subsequent γH2AX focus formation and propagation, and, ultimately, 53BP1 recruitment. Despite significant unrepaired DNA damage sustained in CUX1-deficient murine HSPCs after cytotoxic exposures, they continue to proliferate and expand, mimicking clonal hematopoiesis in patients postchemotherapy. As a consequence, preexisting CUX1 deficiency predisposes mice to highly penetrant and rapidly fatal therapy-related erythroleukemias. These findings establish the importance of epigenetic regulation of HSPC DNA repair and position CUX1 as a gatekeeper in myeloid transformation.
Subject(s)
Chromosomes, Mammalian , DNA Repair , Epigenesis, Genetic , Gene Expression Regulation, Leukemic , Homeodomain Proteins , Leukemia, Erythroblastic, Acute , Neoplasm Proteins , Neoplasms, Second Primary , Nuclear Proteins , Repressor Proteins , Animals , Chromosomes, Mammalian/genetics , Chromosomes, Mammalian/metabolism , Clonal Hematopoiesis , Homeodomain Proteins/genetics , Homeodomain Proteins/metabolism , Leukemia, Erythroblastic, Acute/genetics , Leukemia, Erythroblastic, Acute/metabolism , Mice , Mice, Transgenic , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Neoplasms, Second Primary/genetics , Neoplasms, Second Primary/metabolism , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Repressor Proteins/genetics , Repressor Proteins/metabolismABSTRACT
PURPOSE OF REVIEW: Loss of chromosome 7 has long been associated with adverse-risk myeloid malignancy. In the last decade, CUX1 has been identified as a critical tumor suppressor gene (TSG) located within a commonly deleted segment of chromosome arm 7q. Additional genes encoded on 7q have also been identified as bona fide myeloid tumor suppressors, further implicating chromosome 7 deletions in disease pathogenesis. This review will discuss the clinical implications of del(7q) and CUX1 mutations, both in disease and clonal hematopoiesis, and synthesize recent literature on CUX1 and other chromosome 7 TSGs. RECENT FINDINGS: Two major studies, including a new mouse model, have been published that support a role for CUX1 inactivation in the development of myeloid neoplasms. Additional recent studies describe the cellular and hematopoietic effects from loss of the 7q genes LUC7L2 and KMT2C/MLL3, and the implications of chromosome 7 deletions in clonal hematopoiesis. SUMMARY: Mounting evidence supports CUX1 as being a key chromosome 7 TSG. As 7q encodes additional myeloid regulators and tumor suppressors, improved models of chromosome loss are needed to interrogate combinatorial loss of these critical 7q genes.
Subject(s)
Myeloproliferative Disorders , Neoplasms , Animals , Chromosome Deletion , Chromosomes, Human, Pair 7/genetics , Clonal Hematopoiesis , Homeodomain Proteins/genetics , Humans , Mice , Myeloproliferative Disorders/genetics , Neoplasms/genetics , Repressor Proteins/genetics , Transcription Factors/geneticsABSTRACT
Monosomy 7 (-7) and del(7q) are high-risk cytogenetic abnormalities common in myeloid malignancies. We previously reported that CUX1, a homeodomain-containing transcription factor encoded on 7q22, is frequently inactivated in myeloid neoplasms, and CUX1 myeloid tumor suppressor activity is conserved from humans to Drosophila. CUX1-inactivating mutations are recurrent in clonal hematopoiesis of indeterminate potential as well as myeloid malignancies, in which they independently carry a poor prognosis. To determine the role for CUX1 in hematopoiesis, we generated 2 short hairpin RNA-based mouse models with â¼54% (Cux1mid) or â¼12% (Cux1low) residual CUX1 protein. Cux1mid mice develop myelodysplastic syndrome (MDS) with anemia and trilineage dysplasia, whereas CUX1low mice developed MDS/myeloproliferative neoplasms and anemia. In diseased mice, restoration of CUX1 expression was sufficient to reverse the disease. CUX1 knockdown bone marrow transplant recipients exhibited a transient hematopoietic expansion, followed by a reduction of hematopoietic stem cells (HSCs), and fatal bone marrow failure, in a dose-dependent manner. RNA-sequencing after CUX1 knockdown in human CD34+ cells identified a -7/del(7q) MDS gene signature and altered differentiation, proliferative, and phosphatidylinositol 3-kinase (PI3K) signaling pathways. In functional assays, CUX1 maintained HSC quiescence and repressed proliferation. These homeostatic changes occurred in parallel with decreased expression of the PI3K inhibitor, Pik3ip1, and elevated PI3K/AKT signaling upon CUX1 knockdown. Our data support a model wherein CUX1 knockdown promotes PI3K signaling, drives HSC exit from quiescence and proliferation, and results in HSC exhaustion. Our results also demonstrate that reduction of a single 7q gene, Cux1, is sufficient to cause MDS in mice.
Subject(s)
Gene Dosage , Hematopoiesis , Hematopoietic Stem Cells/pathology , Homeodomain Proteins/genetics , Myelodysplastic Syndromes/genetics , Myelodysplastic Syndromes/pathology , Nuclear Proteins/genetics , Repressor Proteins/genetics , Anemia/genetics , Anemia/pathology , Anemia/physiopathology , Animals , Cell Proliferation , Cellular Senescence , Disease Models, Animal , Gene Knockdown Techniques , Humans , Mice , Myelodysplastic Syndromes/physiopathologyABSTRACT
One third of tumor suppressors are haploinsufficient transcriptional regulators, yet it remains unknown how a 50% reduction of a transcription factor is translated at the cis-regulatory level into a malignant transcriptional program. We studied CUX1, a haploinsufficient transcription factor that is recurrently mutated in hematopoietic and solid tumors. We determined CUX1 DNA-binding and target gene regulation in the wildtype and haploinsufficient states. CUX1 binds with transcriptional activators and cohesin at distal enhancers across three different human cell types. Haploinsufficiency of CUX1 altered the expression of a large number of genes, including cell cycle regulators, with concomitant increased cellular proliferation. Surprisingly, CUX1 occupancy decreased genome-wide in the haploinsufficient state, and binding site affinity did not correlate with differential gene expression. Instead, differentially expressed genes had multiple, low-affinity CUX1 binding sites, features of analog gene regulation. A machine-learning algorithm determined that chromatin accessibility, enhancer activity, and distance to the transcription start site are features of dose-sensitive CUX1 transcriptional regulation. Moreover, CUX1 is enriched at sites of DNA looping, as determined by Hi-C analysis, and these loops connect CUX1 to the promoters of regulated genes. We propose an analog model for haploinsufficient transcriptional deregulation mediated by higher order genome architecture.
Subject(s)
Enhancer Elements, Genetic , Homeodomain Proteins/physiology , Nuclear Proteins/physiology , Promoter Regions, Genetic , Repressor Proteins/physiology , Transcription, Genetic , Base Sequence , Cell Cycle Proteins/metabolism , Cell Survival , Chromosomal Proteins, Non-Histone/metabolism , Consensus Sequence , Haploinsufficiency , Hep G2 Cells , Humans , K562 Cells , Nucleic Acid Conformation , Protein Binding , Transcription Factors , Transcriptional Activation , CohesinsABSTRACT
A fundamental tenet of the immune system is the requirement for lymphocytes to respond to transformed or infected cells while remaining tolerant of normal cells. Natural killer (NK) cells discriminate between self and non-self by monitoring the expression of MHC class I molecules. According to the 'missing-self' hypothesis, cells that express self-MHC class I molecules are protected from NK cells, but those that lack this self-marker are eliminated by NK cells. Recent work has revealed that there is another system of NK-cell inhibition, which is independent of MHC class I molecules. Newly discovered NK-cell inhibitory receptors that have non-MHC-molecule ligands broaden the definition of self as seen by NK cells.
Subject(s)
Killer Cells, Natural/immunology , Self Tolerance/immunology , Animals , Antigens, Neoplasm/immunology , Autoimmunity/immunology , Cell Adhesion Molecules/immunology , Histocompatibility Antigens Class I/immunology , Humans , Lectins/metabolism , Receptors, Antigen/immunology , Sialic Acids/metabolismABSTRACT
Loss of chromosome 7 and del(7q) [-7/del(7q)] are recurring cytogenetic abnormalities in hematologic malignancies, including acute myeloid leukemia and therapy-related myeloid neoplasms, and associated with an adverse prognosis. Despite intensive effort by many laboratories, the putative myeloid tumor suppressor(s) on chromosome 7 has not yet been identified.We performed transcriptome sequencing and SNP array analysis on de novo and therapy-related myeloid neoplasms, half with -7/del(7q). We identified a 2.17-Mb commonly deleted segment on chromosome band 7q22.1 containing CUX1, a gene encoding a homeodomain-containing transcription factor. In 1 case, CUX1 was disrupted by a translocation, resulting in a loss-of-function RNA fusion transcript. CUX1 was the most significantly differentially expressed gene within the commonly deleted segment and was expressed at haploinsufficient levels in -7/del(7q) leukemias. Haploinsufficiency of the highly conserved ortholog, cut, led to hemocyte overgrowth and tumor formation in Drosophila melanogaster. Similarly, haploinsufficiency of CUX1 gave human hematopoietic cells a significant engraftment advantage on transplantation into immunodeficient mice. Within the RNA-sequencing data, we identified a CUX1-associated cell cycle transcriptional gene signature, suggesting that CUX1 exerts tumor suppressor activity by regulating proliferative genes. These data identify CUX1 as a conserved, haploinsufficient tumor suppressor frequently deleted in myeloid neoplasms.
Subject(s)
Chromosome Deletion , Chromosomes, Human, Pair 7/genetics , Homeodomain Proteins/genetics , Leukemia, Myeloid/genetics , Nuclear Proteins/genetics , Repressor Proteins/genetics , Acute Disease , Animals , Blotting, Western , Cell Line, Tumor , Drosophila melanogaster/genetics , Gene Expression Profiling , Haploinsufficiency , HeLa Cells , Homeodomain Proteins/metabolism , Humans , Interleukin Receptor Common gamma Subunit/deficiency , Interleukin Receptor Common gamma Subunit/genetics , K562 Cells , Leukemia, Myeloid/metabolism , Leukemia, Myeloid/pathology , Mice , Mice, Inbred NOD , Mice, Knockout , Mice, SCID , Nuclear Proteins/metabolism , RNA Interference , Repressor Proteins/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Transcription Factors , Translocation, Genetic , Tumor Suppressor Proteins/genetics , Tumor Suppressor Proteins/metabolism , U937 Cells , Xenograft Model Antitumor AssaysABSTRACT
-7/del(7q) occurs in half of myeloid malignancies with adverse-risk cytogenetic features and is associated with poor survival. We identified the spectrum of mutations that co-occur with -7/del(7q) in 40 patients with de novo or therapy-related myeloid neoplasms. -7/del(7q) leukaemias have a distinct mutational profile characterized by low frequencies of alterations in genes encoding transcription factors, cohesin and DNA-methylation-related proteins. In contrast, RAS pathway activating mutations occurred in 50% of cases, a significantly higher frequency than other acute myeloid leukaemias and higher than previously reported. Our data provide guidance for which pathways may be most relevant in the treatment of adverse-risk myeloid leukaemia.
Subject(s)
Chromosome Deletion , Chromosomes, Human, Pair 7/genetics , Leukemia, Myeloid, Acute/genetics , Homeodomain Proteins/genetics , Humans , Nuclear Proteins/genetics , Repressor Proteins/genetics , Risk Factors , Transcription FactorsABSTRACT
Many transcription factors (TFs) function as tumor suppressor genes with heterozygous phenotypes, yet haploinsufficiency generally has an underappreciated role in neoplasia. This is no less true in myeloid cells, which are normally regulated by a delicately balanced and interconnected transcriptional network. Detailed understanding of TF dose in this circuitry sheds light on the leukemic transcriptome. In this review, we discuss the emerging features of haploinsufficient transcription factors (HITFs). We posit that: (a) monoallelic and biallelic losses can have distinct cellular outcomes; (b) the activity of a TF exists in a greater range than the traditional Mendelian genetic doses; and (c) how a TF is deleted or mutated impacts the cellular phenotype. The net effect of a HITF is a myeloid differentiation block and increased intercellular heterogeneity in the course of myeloid neoplasia.
Subject(s)
Haploinsufficiency , Neoplasms , Humans , Gene Regulatory Networks , Transcription FactorsABSTRACT
CUX1 is a homeodomain-containing transcription factor that is essential for the development and differentiation of multiple tissues. CUX1 is recurrently mutated or deleted in cancer, particularly in myeloid malignancies. However, the mechanism by which CUX1 regulates gene expression and differentiation remains poorly understood, creating a barrier to understanding the tumor-suppressive functions of CUX1. Here, we demonstrate that CUX1 directs the BAF chromatin remodeling complex to DNA to increase chromatin accessibility in hematopoietic cells. CUX1 preferentially regulates lineage-specific enhancers, and CUX1 target genes are predictive of cell fate in vivo. These data indicate that CUX1 regulates hematopoietic lineage commitment and homeostasis via pioneer factor activity, and CUX1 deficiency disrupts these processes in stem and progenitor cells, facilitating transformation.
Subject(s)
Chromatin , Hematopoietic Stem Cells , Homeodomain Proteins , Repressor Proteins , Humans , Homeodomain Proteins/metabolism , Homeodomain Proteins/genetics , Hematopoietic Stem Cells/metabolism , Hematopoietic Stem Cells/cytology , Chromatin/metabolism , Repressor Proteins/metabolism , Repressor Proteins/genetics , Transcription Factors/metabolism , Transcription Factors/genetics , Animals , Mice , Nuclear Proteins/metabolism , Nuclear Proteins/genetics , Cell Lineage , Chromatin Assembly and Disassembly , Cell Differentiation , DNA-Binding Proteins/metabolism , DNA-Binding Proteins/genetics , Enhancer Elements, Genetic/geneticsABSTRACT
Current therapies for high-grade TP53-mutated myeloid neoplasms (≥10% blasts) do not offer a meaningful survival benefit except allogeneic stem cell transplantation in the minority who achieve a complete response to first line therapy (CR1). To identify reliable pre-therapy predictors of complete response to first-line therapy (CR1) and outcomes, we assembled a cohort of 242 individuals with TP53-mutated myeloid neoplasms and ≥10% blasts with well-annotated clinical, molecular and pathology data. Key outcomes examined were CR1 & 24-month survival (OS24). In this elderly cohort (median age 68.2 years) with 74.0% receiving frontline non-intensive regimens (hypomethylating agents +/- venetoclax), the overall cohort CR1 rate was 25.6% (50/195). We additionally identified several pre-therapy factors predictive of inferior CR1 including male gender (P = 0.026), ≥2 autosomal monosomies (P < 0.001), -17/17p (P = 0.011), multi-hit TP53 allelic state (P < 0.001) and CUX1 co-alterations (P = 0.010). In univariable analysis of the entire cohort, inferior OS24 was predicated by ≥2 monosomies (P = 0.004), TP53 VAF > 25% (P = 0.002), TP53 splice junction mutations (P = 0.007) and antecedent treated myeloid neoplasm (P = 0.001). In addition, mutations/deletions in CUX1, U2AF1, EZH2, TET2, CBL, or KRAS ('EPI6' signature) predicted inferior OS24 (HR = 2.0 [1.5-2.8]; P < 0.0001). In a subgroup analysis of HMA +/-Ven treated individuals (N = 144), TP53 VAF and monosomies did not impact OS24. A risk score for HMA +/-Ven treated individuals incorporating three pre-therapy predictors including TP53 splice junction mutations, EPI6 and antecedent treated myeloid neoplasm stratified 3 prognostic distinct groups: intermediate, intermediate-poor, and poor with significantly different median (12.8, 6.0, 4.3 months) and 24-month (20.9%, 5.7%, 0.5%) survival (P < 0.0001). For the first time, in a seemingly monolithic high-risk cohort, our data identifies several baseline factors that predict response and 24-month survival.
Subject(s)
Mutation , Tumor Suppressor Protein p53 , Humans , Male , Female , Aged , Tumor Suppressor Protein p53/genetics , Middle Aged , Aged, 80 and over , Adult , Prognosis , Treatment OutcomeABSTRACT
-7/del(7q) is prevalent across subtypes of myeloid neoplasms. CUX1, located on 7q22, encodes a homeodomain-containing transcription factor, and, like -7/del(7q), CUX1 inactivating mutations independently carry a poor prognosis. As with loss of 7q, CUX1 mutations often occur early in disease pathogenesis. We reported that CUX1 deficiency causes myelodysplastic syndrome in mice but was insufficient to drive acute myeloid leukemia (AML). Given the known association between -7/del(7q) and RAS pathway mutations, we mined cancer genome databases and explicitly linked CUX1 mutations with oncogenic RAS mutations. To determine if activated RAS and CUX1 deficiency promote leukemogenesis, we generated mice bearing NrasG12D and CUX1-knockdown which developed AML, not seen in mice with either mutation alone. Oncogenic RAS imparts increased self-renewal on CUX1-deficient hematopoietic stem/progenitor cells (HSPCs). Reciprocally, CUX1 knockdown amplifies RAS signaling through reduction of negative regulators of RAS/PI3K signaling. Double mutant HSPCs were responsive to PIK3 or MEK inhibition. Similarly, low expression of CUX1 in primary AML samples correlates with sensitivity to the same inhibitors, suggesting a potential therapy for malignancies with CUX1 inactivation. This work demonstrates an unexpected convergence of an oncogene and tumor suppressor gene on the same pathway.
Subject(s)
Leukemia, Myeloid, Acute , Phosphatidylinositol 3-Kinases , Mice , Animals , Phosphatidylinositol 3-Kinases/metabolism , Transcription Factors/genetics , Transcription Factors/metabolism , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/metabolism , Mutation , Hematopoietic Stem Cells/metabolismABSTRACT
Therapy-related myeloid neoplasms (t-MNs) share many clinical and molecular characteristics with AML de novo in the elderly. One common factor is that they arise in the setting of chronic inflammation, likely because of advanced age or chemotherapy-induced senescence. Here, we examined the effect of haploinsufficient loss of the del(5q) tumor suppressor gene, EGR1, commonly deleted in high-risk MNs. In mice, under the exogenous stress of either serial transplant or successive doses of the alkylating agent N-ethyl-nitrosourea (ENU), Egr1-haploinsufficient hematopoietic stem cells (HSCs) exhibit a clonal advantage. Complete loss of EGR1 function is incompatible with transformation; mutations of EGR1 are rare and are not observed in the remaining allele in del(5q) patients, and complete knockout of Egr1 in mice leads to HSC exhaustion. Using chromatin immunoprecipitation sequencing (ChIP-seq), we identified EGR1 binding sites in human CD34+ cord blood-derived stem and progenitor cells (HSPCs) and found that EGR1 binds genes critical for stem cell differentiation, inflammatory signaling, and the DNA damage response. Notably, in the chromosome 5 sequences frequently deleted in patients, there is a significant enrichment of innate and inflammatory genes, which may confer a fitness advantage in an inflammatory environment. Short hairpin RNA (shRNA)-mediated silencing of EGR1 biases HSPCs toward a self-renewal transcriptional signature. In the absence of EGR1, HSPCs are characterized by upregulated MYC-driven proliferative signals, downregulated CDKN1A (p21), disrupted DNA damage response, and downregulated inflammation-adaptations anticipated to confer a relative fitness advantage for stem cells especially in an environment of chronic inflammation.
Subject(s)
Haploinsufficiency , Hematopoietic Stem Cells , Humans , Mice , Animals , Aged , Hematopoietic Stem Cells/metabolism , Antigens, CD34/metabolism , Ethylnitrosourea/metabolism , Inflammation/metabolism , Early Growth Response Protein 1/genetics , Early Growth Response Protein 1/metabolismABSTRACT
CUX1, encoding a homeodomain-containing transcription factor, is recurrently deleted or mutated in multiple tumor types. In myeloid neoplasms, CUX1 deletion or mutation carries a poor prognosis. We have previously established that CUX1 functions as a tumor suppressor in hematopoietic cells across multiple organisms. Others, however, have described oncogenic functions of CUX1 in solid tumors, often attributed to truncated CUX1 isoforms, p75 and p110, generated by an alternative transcriptional start site or post-translational cleavage, respectively. Given the clinical relevance, it is imperative to clarify these discrepant activities. Herein, we sought to determine the CUX1 isoforms expressed in hematopoietic cells and find that they express the full-length p200 isoform. Through the course of this analysis, we found no evidence of the p75 alternative transcript in any cell type examined. Using an array of orthogonal approaches, including biochemistry, proteomics, CRISPR/Cas9 genomic editing, and analysis of functional genomics datasets across a spectrum of normal and malignant tissue types, we found no data to support the existence of the CUX1 p75 isoform as previously described. Based on these results, prior studies of p75 require reevaluation, including the interpretation of oncogenic roles attributed to CUX1.
Subject(s)
Genomics , Hematopoietic Stem Cells/metabolism , Homeodomain Proteins/genetics , Repressor Proteins/genetics , Transcription Factors/genetics , Animals , HL-60 Cells , Homeodomain Proteins/metabolism , Humans , K562 Cells , MCF-7 Cells , Mice , NIH 3T3 Cells , Protein Isoforms , RNA Processing, Post-Transcriptional , Repressor Proteins/metabolism , Transcription Factors/metabolism , Transcription Initiation Site , Transcription, Genetic , Transcriptional Activation , U937 CellsSubject(s)
Intracellular Signaling Peptides and Proteins , Leukemia, Myeloid, Acute , Mutagenesis, Insertional , Myelodysplastic Syndromes , Neoplasm Proteins , Peptide Termination Factors , Proteins , Retroviridae , Wnt Signaling Pathway/genetics , Animals , DNA-Binding Proteins , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Leukemia, Myeloid, Acute/genetics , Leukemia, Myeloid, Acute/metabolism , Leukemia, Myeloid, Acute/pathology , Mice , Mice, Mutant Strains , Myelodysplastic Syndromes/genetics , Myelodysplastic Syndromes/metabolism , Myelodysplastic Syndromes/pathology , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Peptide Termination Factors/genetics , Peptide Termination Factors/metabolism , Proteins/genetics , Proteins/metabolism , Transcription FactorsABSTRACT
BH3 mimetics are increasingly used as anti-cancer therapeutics either alone or in conjunction with other chemotherapies. However, mounting evidence has also demonstrated that BH3 mimetics modulate varied amounts of apoptotic signaling in healthy immune populations. In order to maximize their clinical potential, it will be essential to understand how BH3 mimetics affect discrete immune populations and to determine how BH3 mimetic pressure causes immune system adaptation. Here we focus on the BCL-2 specific inhibitor venetoclax (ABT-199) and its effects following short-term and long-term BCL-2 blockade on T cell subsets. Seven day "short-term" ex vivo and in vivo BCL-2 inhibition led to divergent cell death sensitivity patterns in CD8+ T cells, CD4+ T cells, and Tregs resulting in shifting of global T cell populations towards a more memory T cell state with increased expression of BCL-2, BCL-XL, and MCL-1. However, twenty-eight day "long-term" BCL-2 blockade following T cell-depleted bone marrow transplantation did not lead to changes in the global T cell landscape. Despite the lack of changes in T cell proportions, animals treated with venetoclax developed CD8+ and CD4+ T cells with high levels of BCL-2 and were more resistant to apoptotic stimuli following expansion post-transplant. Further, we demonstrate through RNA profiling that T cells adapt while under BCL-2 blockade post-transplant and develop a more activated genotype. Taken together, these data emphasize the importance of evaluating how BH3 mimetics affect the immune system in different treatment modalities and disease contexts and suggest that venetoclax should be further explored as an immunomodulatory compound.
Subject(s)
Antineoplastic Agents/therapeutic use , Bridged Bicyclo Compounds, Heterocyclic/therapeutic use , Cell Death/drug effects , Memory T Cells/drug effects , Sulfonamides/therapeutic use , Animals , Antineoplastic Agents/pharmacology , Apoptosis , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Cell Line, Tumor , Humans , Mice , Sulfonamides/pharmacologyABSTRACT
Natural killer (NK) cells are critical in the immune response to tumor cells, virally infected cells, and bone marrow allografts. 2B4 (CD244) is expressed on all NK cells and the ligand for 2B4, CD48, is expressed on hematopoietic cells. Cross-linking 2B4 on NK cells with anti-2B4 monoclonal antibody leads to NK cell activation in vitro. Therefore, 2B4 is considered to be an activating receptor. Surprisingly, we have found, using antibody-blocking and 2B4-deficient NK cells, that NK lysis of CD48(+) tumor and allogeneic targets is inhibited by 2B4 ligation. Interferon gamma production by NK cells is also inhibited. Using a peritoneal tumor clearance assay, it was found that 2B4(-/-) mice have increased clearance of CD48(+) tumor cells in vivo. Retroviral transduction of 2B4 was sufficient to restore inhibition in 2B4(-/-) primary NK cells. It was found that although mature NK cells express SH2D1A, in vitro-derived NK cells do not. However, both populations are inhibited by 2B4 ligation. This indicates that 2B4 inhibitory signaling occurs regardless of the presence of SH2D1A. These findings reveal a novel role for 2B4 as a non-major histocompatibility complex binding negative regulator of NK cells.
Subject(s)
Antigens, CD/immunology , Killer Cells, Natural/immunology , Major Histocompatibility Complex , Membrane Glycoproteins/immunology , Receptors, Immunologic/immunology , Animals , Antigens, CD/genetics , CD48 Antigen , Cytotoxicity, Immunologic/immunology , Membrane Glycoproteins/deficiency , Membrane Glycoproteins/genetics , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , Mice, SCID , Receptors, Immunologic/deficiency , Receptors, Immunologic/genetics , Signaling Lymphocytic Activation Molecule FamilyABSTRACT
Therapy-related myeloid neoplasms (t-MNs) following treatment with alkylating agents are characterized by a del(5q), complex karyotypes, alterations of TP53, and a dismal prognosis. To decipher the molecular pathway(s) leading to the pathogenesis of del(5q) t-MN and the effect(s) of cytotoxic therapy on the marrow microenvironment, we developed a mouse model with loss of two key del(5q) genes, EGR1 and APC, in hematopoietic cells. We used the well-characterized drug, N-ethyl-N-nitrosurea (ENU) to demonstrate that alkylating agent exposure of stromal cells in the microenvironment increases the incidence of myeloid disease. In addition, loss of Trp53 with Egr1 and Apc was required to drive the development of a transplantable leukemia, and accompanied by the acquisition of somatic mutations in DNA damage response genes. ENU treatment of mesenchymal stromal cells induced cellular senescence, and led to the acquisition of a senescence-associated secretory phenotype, which may be a critical microenvironmental alteration in the pathogenesis of myeloid neoplasms.
Subject(s)
Antineoplastic Agents, Alkylating , Bone Marrow , Leukemia, Myeloid , Neoplasms, Second Primary , Animals , Antineoplastic Agents, Alkylating/adverse effects , Antineoplastic Agents, Alkylating/therapeutic use , Chromosome Deletion , Genes, p53 , Leukemia, Myeloid/chemically induced , Leukemia, Myeloid/genetics , Mice , Neoplasms, Second Primary/chemically induced , Neoplasms, Second Primary/genetics , Stromal Cells , Tumor Microenvironment/geneticsABSTRACT
In this phase 1 study, azacitidine (AZA) was given before high-dose cytarabine (HiDAC) and mitoxantrone (mito) based on the hypothesis that epigenetic priming with a hypomethylating agent before cytotoxic chemotherapy would improve response rates in patients with high-risk acute myeloid leukemia (AML), including relapsed/refractory disease. The primary objective was to establish the recommended phase 2 dose of AZA given before standard HiDAC/mito. In a dose escalation scheme, 46 patients (median age, 66 years) received AZA at 37.5, 50, or 75 mg/m2 subcutaneously or IV once daily on days 1 to 5 followed by HiDAC (3000 mg/m2) and mitoxantrone (30 mg/m2) once each on days 6 and 10 (the HiDAC/mito dose was reduced 33% in elderly subjects). Two dose-limiting toxicities occurred (both in the same patient): acute liver failure and kidney injury at the 50 mg/m2 dose. The 30-day induction death rate was 2.2% (1 of 46). The overall response rate, including complete remission and complete remission with incomplete count recovery, was 61% (28 of 46). Previously untreated patients aged ≥60 years with therapy-related AML and de novo AML were more likely to respond than untreated patients with AML progressing from an antecedent hematologic disorder (myelodysplastic syndrome and chronic myelomonocytic leukemia). Patients with favorable European Leukemia Network risk (P = .008), NPM1 mutations (P = .007), or IDH2 mutations (P = .03) were more likely to respond, and those with TP53 mutations (P = .03) were less likely to respond. The recommended phase 2 dose of AZA is 75 mg/m2 per day on days 1 to 5 followed by HiDAC (3000 mg/m2) and mitoxantrone (30 mg/m2) once each on days 6 and 10. This trial was registered at www.clinicaltrials.gov as #NCT01839240.
Subject(s)
Leukemia, Myeloid, Acute , Mitoxantrone , Aged , Azacitidine/adverse effects , Cytarabine/adverse effects , Humans , Leukemia, Myeloid, Acute/drug therapy , Nucleophosmin , Remission InductionABSTRACT
Clonal hematopoiesis of indeterminate potential (CHIP) describes clonal selection of a hematopoietic stem cell with a somatic mutation that confers increased fitness, influenced by a selective environment such as aging, inflammation, or therapeutic exposure. In this issue of Cell Stem Cell, Hsu et al. (2018) explore the role of cytotoxic therapy in disease-relevant CHIP.