Mechanism Of Acute Myeloid Leukemia Research Articles

DNMT3A-R882: a mutation with many paradoxes.

Understanding the underlying mechanism of acute myeloid leukemia (AML) has led to the discovery of novel biomarkers to help predict, treat and monitor leukemia. DNA (cytosine-5)-methyltransferase 3A (DNMT3A) is considered a prognostic and therapeutic epigenetic target in AML patients with a hotspot mutation of R882. R882 mutation is associated with impaired differentiation of Hematopoietic stem cells in the bone marrow and disease progression. The prevalence of R882 mutation varied in different ethnicities and countries, and similarly, its prognostic impact differed among numerous studies. Nevertheless, the co-occurrence of mutations in R882 with NPM1 and FLT3 has been reported more frequently and is associated with a worse prognosis. These studies also suggest diverse results regarding bone marrow transplantation response as a treatment, while chemoresistance is reached as a conclusive outcome These findings highlight the crucial need for an in-depth discussion on the significance of the R882 mutation in AML patients. Understanding its impact on leukemic transformation, prognosis, and treatment is vital for advancing clinical implications.

Biomarker development from functional precision medicine datasets via explainable machine learning.

10061 Background: Genomics precision medicine, deployed via tumor panel sequencing, now assists in deploying targeted therapies to cancer patients. Numerous clinical trials have investigated the utility and benefit of genomics precision medicine in multiple cancer indications. Current large-scale studies report actionability rates from ~35% to ~60%, although clinical benefit rates have been shown to be closer to 10%. While this has positively impacted patients in need, the gap between actionability and benefit remains a clinical challenge attributed to multiple factors including the complex, multi-factorial relationship between molecular status and response to therapy. These differences go beyond simple disease states and may be reflective of multiple clinically relevant features including age, sex, and race/ethnicity. Methods: We implemented a functional precision medicine (FPM) program where patients with advanced pediatric cancers were prospectively profiled via high-throughput drug sensitivity testing (DST) of FDA-approved agents on patient-derived tumor cells as well as genomics testing. The objective was to investigate the clinical utility and benefit of FPM guidance in the treatment of pediatric cancer and elucidate the relationship between molecular status of patients’ diseases and treatment responses. We generated DST data (n = 21 patients) and genomic profiling data (n = 20 patients) on pediatric cancer patients in Miami, FL, as well as post-hoc whole exome and transcriptome sequencing data (n = 13 patients) and investigated three specific relationships. Results: We analyzed the relationship between racial/ethnic background and functional response to anti-cancer agents, determining potential differences in response to therapeutic classes. Next, we examined relationships between functional response and cancer type, identifying an unanticipated lack of clustering between disease indications in patients with advanced pediatric cancers. Finally, we applied an explainable machine learning (xML) framework to the functional genomic dataset to develop multi-omics biomarker hypotheses for the chemotherapy agent idarubicin, pinpointing a potential multi-cancer relationship between response to idarubicin and known disease mechanisms in acute myeloid leukemia (AML), the sole indication where idarubicin is approved. We further present additional proof-of-concept studies generating biomarker hypotheses via xML, demonstrating a framework for development of multi-omics biomarkers. Conclusions: We are now expanding our pan-pediatric cancer functional genomics dataset through an NIMHD-funded expansion cohort (NCT05857969, n = 65 patients) to further investigate multi-omics relationships between functional and molecular characteristics and understand the role of race/ethnicity in the complex relationship.

P200CUX1-regulated BMP8B inhibits the progression of acute myeloid leukemia via the MAPK signaling pathway.

The full-length p200CUX1 protein encoded by the homology frame CUT-like protein (CUX1) plays an important role in tumors as a pro-oncogene or oncogene. However, its role and mechanism in acute myeloid leukemia remain unknown. p200CUX1 regulates several pathways, including the MAPK signaling pathway. Our data showed that p200CUX1 is lowly expressed in THP1 and U937 AML cell lines. Lentiviral overexpression of p200CUX1 reduced proliferation and promoted apoptosis and G0/G1 phase blockade, correlating with MAPK pathway suppression. Additionally, p200CUX1 regulated the expression of bone morphogenetic protein 8B (BMP8B), which is overexpressed in AML. Overexpression of p200CUX1 downregulated BMP8B expression and inhibited the MAPK pathway. Furthermore, BMP8B knockdown inhibited AML cell proliferation, enhanced apoptosis and the sensitivity of ATRA-induced cell differentiation, and blocked G0/G1 transition. Our findings demonstrate the pivotal function of the p200CUX1-BMP8B-MAPK axis in maintaining the viability of AML cells. Consequently, targeting p200CUX1 could represent a viable strategy in AML therapy.

Dinaciclib inhibits the growth of acute myeloid leukemia cells through either cell cycle-related or ERK1/STAT3/MYC pathways

Although immature differentiation and uncontrolled proliferation of hematopoietic stem cells are thought to be the primary mechanisms of acute myeloid leukemia (AML), the pathophysiology in most cases remains unclear. Dinaciclib, a selective small molecule targeting multiple cyclin-dependent kinases (CDKs), is currently being evaluated in oncological clinical trials. Despite the proven anticancer potential of dinaciclib, the differential molecular mechanisms by which it inhibits the growth of different AML cell lines remain unclear. In the current study, we treated HL-60 and KG-1 AML cell lines with dinaciclib and investigated the potential mechanisms of dinaciclib-induced AML cell growth inhibition using flow cytometry and western blotting assays. Data from HL-60 and KG-1 AML cells were validated using human primary AML cells. The results showed that the growth inhibitory effect of dinaciclib was more sensitive in HL-60 cells (IC50: 8.46 nM) than in KG-1 cells (IC50: 14.37 nM). The protein decline in Cyclin A/B and CDK1 and cell cycle arrest in the G2/M phase were more profound in HL-60 cells, corresponding to its growth inhibition. Although the growth inhibition of KG-1 cells by dinaciclib was still pronounced, the cell cycle-associated proteins were relatively insensitive. In addition to cell cycle regulation, the activation/expression of ERK1/STAT3/MYC signaling was significantly reduced by dinaciclib in KG-1 cells compared with that in HL-60 cells. Regarding the results of primary AML cells, we observed ERK1/STAT3/MYC inhibition and cell cycle regulation in different patients. These findings suggest that the cell cycle-associated and ERK1/STAT3/MYC signaling pathways might be two distinct mechanisms by which dinaciclib inhibits AML cells, which could facilitate the development of combination therapy for AML in the future.

Glucose Metabolism in Acute Myeloid Leukemia Cell Line Is Regulated via Combinational PI3K/AKT/mTOR Pathway Inhibitors.

Metabolism reprogramming is a survival mechanism in acute myeloid leukemia (AML) cells in the tumor microenvironment. Therefore, we investigated the effect of signaling pathway inhibitors on the expression of genes rewired in the metabolic pathway of AML cells. HL-60 cells were treated with Idelalisib, MK-2206, and Everolimus, which respectively are selective inhibitors of phosphatidylinositol-3-kinase (PI3K), AKT, and the mammalian target of rapamycin (mTOR), either individually or in combination. The relative expressions of glucose transporter 1, hexokinase 2, pyruvate kinase, pyruvate dehydrogenase E1, citrate synthase, isocitrate dehydrogenase 2, and hypoxia inducible factor 1 subunit alpha were determined by real-time PCR. The combined treatment of HL-60 cells with Idelalisib, MK-2206, and Everolimus decreased the expression of glucose transporter 1, hexokinase 2, pyruvate kinase M2, pyruvate dehydrogenase E1, citrate synthase, isocitrate dehydrogenase 2, and hypoxia inducible factor 1 subunit alpha. A combination of PI3K/AKT/mTOR pathway inhibitors regulates the expression of genes involved in glycolysis, pyruvate dehydrogenase complex (PDH), and the tricarboxylic acid (TCA) cycle and interferes with metabolic reprogramming and immune evasion mechanisms of AML leukemic cells. Combinational therapy approaches to block these pathways might be a promising and novel therapeutic strategy for targeting the metabolic requirements of AML cells.

AKT inhibition interferes with the expression of immune checkpoint proteins and increases NK-induced killing of HL60-AML cells.

To determine the role of the AKT pathway in the regulating of natural Killer-induced apoptosis of acute myeloid leukemia cells and to characterize the associated molecular mechanisms. BALB/c nude mice were injected with HL60 cells to induce a xenogenic model of subcutaneous leukemic tumors. Mice were treated with perifosine, and their spleens were analyzed using biometry, histopathology, and immunohistochemistry. Gene expression analysis in leukemia cells was performed by real-time PCR. Protein analysis of leukemia and natural Killer cells was performed by flow cytometry. AKT inhibition in HL60 cells, followed by co-culture with natural Killer cells was performed to assess cytotoxicity. Apoptosis rate was quantified using flow cytometry. Perifosine treatment caused a reduction in leukemic infiltration in the spleens of BALB/c nude mice. In vitro , AKT inhibition reduced HL60 resistance to natural Killer-induced apoptosis. AKT inhibition suppressed the immune checkpoint proteins PD-L1, galectin-9, and CD122 in HL60 cells, but did not change the expression of their co-receptors PD1, Tim3, and CD96 on the natural Killer cell surface. In addition, the death receptors DR4, TNFR1, and FAS were overexpressed by AKT inhibition, thus increasing the susceptibility of HL60 cells to the extrinsic pathway of apoptosis. The AKT pathway is involved in resistance to natural Killer-induced apoptosis in HL60 cells by regulating the expression of immune suppressor receptors. These findings highlight the importance of AKT in contributing to immune evasion mechanisms in acute myeloid leukemia and suggests the potential of AKT inhibition as an adjunct to immunotherapy.

A perspective of immunotherapy for acute myeloid leukemia: Current advances and challenges.

During the last decade, the underlying pathogenic mechanisms of acute myeloid leukemia (AML) have been the subject of extensive study which has considerably increased our understanding of the disease. However, both resistance to chemotherapy and disease relapse remain the principal obstacles to successful treatment. Because of acute and chronic undesirable effects frequently associated with conventional cytotoxic chemotherapy, consolidation chemotherapy is not feasible, especially for elderly patients, which has attracted a growing body of research to attempt to tackle this problem. Immunotherapies for acute myeloid leukemia, including immune checkpoint inhibitors, monoclonal antibodies, dendritic cell (DC) vaccines, together with T-cell therapy based on engineered antigen receptor have been developed recently. Our review presents the recent progress in immunotherapy for the treatment of AML and discusses effective therapies that have the most potential and major challenges.

Abstract 5013: Effects of PP2A-activating drugs on FLT3 inhibitor resistance mediated by diverse mechanisms in acute myeloid leukemia with FLT3-ITD

Abstract Internal tandem duplication (ITD) of the fms-like tyrosine kinase 3 (FLT3) receptor tyrosine kinase is present in AML cells in 25% of patients, causing constitutive activation and aberrant signaling. FLT3-ITD+ AML patients have a high relapse rate following chemotherapy and short disease-free and overall survival. Incorporation of FLT3 inhibitors (FLT3is) into therapy for FLT3-ITD+ AML has improved outcomes, but FLT3i efficacy is limited by onset of resistance, which occurs by diverse mechanisms. The tumor suppressor protein phosphatase 2A (PP2A) is inactivated in FLT3-ITD+ AML, and we previously showed that PP2A-activating drugs (PADs), including DT-061 and FTY720, enhance FLT3i efficacy through enhanced proteasomal degradation of c-Myc and Pim-1, mediated by activation of the serine/threonine kinase GSK-3β (Mol Cancer Ther 20:676, 2021). Here we sought to determine whether concurrent treatment with PADs overcomes resistance to FLT3is. We studied MOLM-14 human AML cells, with heterozygous FLT3-ITD, and FLT3i-resistant MOLM-14 cells with D835Y tyrosine kinase domain and F691L gatekeeper FLT3 mutations and M14(R)701 MOLM-14 cells (from Dr. Donald Small, Johns Hopkins) with a G12D NRAS activating mutation. IC50s, determined by WST-1 cytotoxicity assays, of Type 1 FLT3i gilteritinib in MOLM-14, D835Y, F691L and M14(R)701 cells were 9.2, 18.6, 56 and 57.5 nM, and the Type II FLT3i quizartinib, 2.8, 211, 659 and >4,000 nM. Both DT-061 and FTY720 sensitized MOLM-14 D835Y cells to quizartinib (IC50s <10 nM) but not to gilteritinib in cytotoxicity assays and showed synergy with quizartinib (combination indexes 0.6, 0.5), but not with gilteritinib in drug combination studies using Chou-Talalay analysis. In contrast, DT-061 and FTY720 did not sensitize to or synergize with quizartinib or gilteritinib in MOLM-14 F691L cells. Finally, FTY720 markedly sensitized M14(R)701 cells to both quizartinib and gilteritinib and showed substantial synergy (combination indexes <0.1), while DT-061 did not. In mechanistic studies, quizartinib alone did not decrease phospho-FLT3 expression by western blot analysis in MOLM-14 D835Y cells, but DT-061 or FTY720 and quizartinib co-treatment markedly decreased phospho-FLT3, but not FLT3, expression. Thus PADs resensitize cells with D835Y to quizartinib by inactivating FLT3-ITD, thereby enabling the binding of quizartinib to FLT3-ITD. Additionally, while FTY720, but not DT-061, markedly sensitized M14(R)701 cells to quizartinib and gilteritinib, FTY720 and DT-061 increased phosphatase activity similarly in a PP2A immunoprecipitation phosphatase assay, indicating that sensitization by FTY720 likely occurs by a mechanism other than PP2A activation. Potential induction of ceramide accumulation by FTY720, a sphingolipid analog, in M14(R)701 cells is being studied. Citation Format: Moaath Mustafa Ali, Aditi Chatterjee, Jonelle K. Lee, Mario Scarpa, Maria R. Baer. Effects of PP2A-activating drugs on FLT3 inhibitor resistance mediated by diverse mechanisms in acute myeloid leukemia with FLT3-ITD. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5013.

The clinical impact of the molecular landscape of acute myeloid leukemia

Research into the underlying pathogenic mechanisms of acute myeloid leukemia (AML) has led to remarkable advances in our understanding of the disease. Mutations now allow us to explore the enormous diversity among cytogenetically defined subsets of AML, particularly the large subset of cytogenetically normal AML. Despite the progress in unraveling the tumor genome, only a small number of recurrent mutations have been incorporated into risk-stratification schemes and have been proven to be clinically relevant, targetable lesions. The current World Health Organization Classification of myeloid neoplasms and leukemia includes eight AML categories defined by recurrent genetic abnormalities as well as three categories defined by gene mutations. We here discuss the utility of molecular markers in AML in prognostication and treatment decision-making. New therapies based on targetable markers include IDH inhibitors (ivosidenib, enasidenib), venetoclax-based therapy, FLT3 inhibitors (midostaurin, gilteritinib, and quizartinib), gemtuzumab ozogamicin, magrolimab and menin inhibitors.

Pathogenic Mechanisms in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) is the most common form of leukemia in adults, leading to the highest number of annual leukemia-associated deaths in the USA. Although most AML patients initially enter remission following induction therapy, most eventually relapse, underscoring the unmet need for more effective therapies. In recent years, novel high-throughput sequencing techniques, and mouse and human models of disease have increased our understanding of the molecular mechanisms that lead to AML. Leukemogenic mechanisms can be broadly classified into two types-cell-intrinsic and cell-extrinsic. Cell-intrinsic mechanisms include an array of genetic and epigenetic alterations that lead to dysregulated gene expression and function in hematopoietic stem/progenitor cells, leading to their increased fitness and ultimately, malignant transformation. Extrinsic mechanisms include both hematopoietic and non-hematopoietic stromal components of the leukemic microenvironment that interact with pre-leukemic and leukemic clones to promote their survival, self-renewal, and/or resistance to therapy. Through the individual and concerted action of these factors, pre-leukemic clones acquire the changes necessary for leukemic transformation. In addition, following therapy, specific leukemic clones are selected for that eventually re-initiate disease. Improving our understanding of these cell-intrinsic and cell-extrinsic mechanisms will provide novel opportunities to treat AML as well as prevent the development of disease.

RNA m6A modification: Mapping methods, roles, and mechanisms in acute myeloid leukemia

N6-Methyladenosine (m6A) is the most abundant modification in eukaryotic mRNA, and plays important biological functions via regulating RNA fate determination. Recent studies have shown that m6A modification plays a key role in hematologic malignancies, including acute myeloid leukemia. The current growth of epitranscriptomic research mainly benefits from technological progress in detecting RNA m6A modification in a transcriptome-wide manner. In this review, we first briefly summarize the latest advances in RNA m6A biology by focusing on writers, readers, and erasers of m6A modification, and describe the development of high-throughput methods for RNA m6A mapping. We further discuss the important roles of m6A modifiers in acute myeloid leukemia, and highlight the identification of potential inhibitors for AML treatment by targeting of m6A modifiers. Overall, this review provides a comprehensive summary of RNA m6A biology in acute myeloid leukemia.

The Effects of PI3K/Akt/mTOR Signaling Pathway Inhibitors on the Expression of Immune Checkpoint Ligands in Acute Myeloid Leukemia Cell Line.

Up-regulation of immune checkpoint ligands is considered as one of the most important immune escape mechanisms in acute myeloid leukemia (AML). Herein, we investigate a relationship between the inhibition of PI3K/Akt/mTOR signaling pathways and the regulation of immune checkpoint ligands in AML cells. The HL-60 cell line was treated with idelalisib as PI3K inhibitor, MK-2206 as Akt inhibitor, and everolimus as mTOR inhibitor either in a single or combined format. Cell viability and apoptosis were evaluated using MTT and flow cytometry assays, respectively. The relative expression of PD-L1, galectin-9, and CD155 was determined by real-time PCR. Our findings demonstrated decreased proliferation and increased apoptosis of HL-60 cells after treatment with idelalisib, MK-2206, and everolimus. As expected, the combined treatment showed a more inhibiting effect than the single treatment. Interestingly, our results elucidated that the expression of PD-L1 and Gal-9 but not MK-2206 decreased after treatment with idelalisib and everolimus. Regarding CD155, the expression of this molecule was downregulated after treatment with everolimus, but not idelalisib and MK-2206. However, combined treatment of HL-60 cells with two or three inhibitors decreased the expression levels of PD-L1, Gal-9, and CD155 checkpoint ligands. We showed that PI3K/Akt/mTOR pathway inhibitors not only serve as cytotoxic drugs but also regulate the expression of immune checkpoint ligands and interfere with the immune evasion mechanisms of AML leukemic cells. Combinational treatment approaches to block these pathways might be a promising and novel therapeutic strategy for AML patients via interfering in immune escape mechanisms.

Expression and Regulation Network of HDAC3 in Acute Myeloid Leukemia and the Implication for Targeted Therapy Based on Multidataset Data Mining.

Background Histone deacetylase 3 (HDAC3) plays an important role in the development and progression of a variety of cancers, but its regulatory mechanism in acute myeloid leukemia (LAML) is not entirely understood. Methods We analyzed the expression of HDAC3 in normal and cancerous tissues using Oncomine, UALCAN, and GEO databases. Changes of the HDAC3 gene were analyzed by cBioPortal. The genes coexpressed with HDAC3 were analyzed by WebGestalt, and the predicted signaling pathways in KEGG were discussed. Results We discovered that the expression of HDAC3 was elevated in some types of acute myeloid leukemia. The HDAC3 gene has a strong positive correlation with SLC25A5, NDUFA2, Cox4I1, and EIF3K, which regulate cell growth and development. HDAC3 transcription is higher in patients with FLT3 mutation than in healthy people. HDAC3 can be directly involved in regulating the thyroid hormone signaling pathway. MEF2D is directly involved in the cGMP-PKG signaling pathway, and the HDAC3 gene has a strong synergistic relationship with MEF2D. HDAC3 is indirectly involved in the cGMP-PKG signaling pathway, thereby indirectly regulating the expression levels of p53 and p21 genes in patients with LAML. Genomics of Drug Sensitivity in Cancer (GDSC) database analysis revealed that the application of the HDAC3 inhibitor can inhibit the proliferation of leukemia cells. Conclusions Therefore, our data suggest that HDAC3 may be a possible therapeutic target for acute myeloid leukemia.

The Bone Marrow Microenvironment Mechanisms in Acute Myeloid Leukemia.

Bone marrow (BM) is a highly complex tissue that provides important regulatory signals to orchestrate hematopoiesis. Resident and transient cells occupy and interact with some well characterized niches to produce molecular and cellular mechanisms that interfere with differentiation, migration, survival, and proliferation in this microenvironment. The acute myeloid leukemia (AML), the most common and severe hematological neoplasm in adults, arises and develop in the BM. The osteoblastic, vascular, and reticular niches provide surface co-receptors, soluble factors, cytokines, and chemokines that mediate important functions on hematopoietic cells and leukemic blasts. There are some evidences of how AML modify the architecture and function of these three BM niches, but it has been still unclear how essential those modifications are to maintain AML development. Basic studies and clinical trials have been suggesting that disturbing specific cells and molecules into the BM niches might be able to impair leukemia competencies. Either through niche-specific molecule inhibition alone or in combination with more traditional drugs, the bone marrow microenvironment is currently considered the potential target for new strategies to treat AML patients. This review describes the cellular and molecular constitution of the BM niches under healthy and AML conditions, presenting this anatomical compartment by a new perspective: as a prospective target for current and next generation therapies.

Single-Cell Multi-Omic Analysis Uncovers Comprised Immune Function and Primary Resistance Mechanism in Acute Myeloid Leukemia

Background: Approximately 20% of AML patients do not respond to induction chemotherapy (primary resistance) and 40-60% of patients develop secondary resistance, eventually leading to relapse followed by refractory disease (RR-AML). Diversified molecular mechanisms have been proposed for drug resistance and RR phenotype. However, we still cannot predict when relapse will occur, nor which patients will become resistant to therapy.Single-cell multi-omic (ScMo) profiling may provide new insights into our understanding of hematopoietic stem cell (HSC) differentiation trajectories, tumor heterogeneity and clonal evolution. Here we applied ScMo to profile bone marrow (BM) from AML patients and healthy controls.Methods: AML samples were collected at diagnosis with institutional IRB approval. Cells were stained with a panel of 62 DNA barcoded antibodies and 10x Genomics Single Cell 3' Library Kit v3 was used to generate ScMo data. After normalization, clusters were identified using Uniform Manifold Approximation and Projection (UMAP) and annotated using MapCell (Koh and Hoon, 2019). We analyzed 23,933 cells from 4 adult AML BM samples, and 39,522 cells from 2 healthy adults and 3 sorted CD34+ normal BM samples. Gene set enrichment analysis (GSEA) and Enrichr program were used to examine underlying pathways among differentially expressed genes between healthy and AML samples.Results: We identified 16 cell types between the AML and normal samples (Fig 1a) amongst 45 clusters in the UMAP projection (Fig 1b). Comparative analysis of the T cell clusters in AML samples with healthy BM cells identified an “AML T-cell signature” with over-expression of genes such as granzymes, NK/T cell markers, chemokine and cytokine, proteinase and proteinase inhibitor (Fig 2a). Among them, IL32 is known to be involved in activation-induced cell death in T cells and has immunosuppressive role, while CD8+ GZMB+ and CD8+ GZMK+ cells are considered as dysfunctional or pre-dysfunctional T cells. Indeed, Enrichr analysis showed the top rank of phenotype term - “decreased cytotoxic T cell cytolysis”.We next examined whether NK cells, are similarly dysfunctional in the AML ecosystem. The “AML NK cell signature” includes Fc Fragment family, IFN-stimulated genes (ISGs), the effector protein-encoding genes and other genes when compared to normal NK cells (Fig 2b). GSEA analysis revealed “PD-1 signalling” among the top 5 ranked pathways in AML-NK cells, though no increase in PD-1 protein nor PDCD1 gene were identified in these cells. Inhibitory receptor CD160 was expressed higher in AML samples along with exhaustion (dysfunction) associated genes TIGIT, PRF1 and GZMB (Fig 2c). Enrichr analysis uncovered enrichment of “abnormal NK cell physiology and ”impaired natural killer cell mediated cytotoxicity“. Similarly, the ”AML monocyte signature“ was significantly enriched with genes in ”Tumor Infiltrating Macrophages in Cancer Progression and Immune Escape“ and ”Myeloid Derived Suppressor Cells in Cancer Immune Escape“.We also analyzed HSPC component in one pair of cytogenetically matched, untreated complete remission (CR) /RR AML pair (Fig 2d). Notably, half of the 10 genes overexpressed in RR-AML, CXCR4, LGALS1, S100A8, S100A9, SRGN (Serglycin), regulate cell-matrix interaction and play pivotal roles in leukemic cells homing bone marrow niche. The first 4 of these genes have been demonstrated as prognostic indicators of poor survival and associated with chemo-resistance and anti-apoptotic function. Furthermore, single-cell trajectory analysis of this CR/RR pair illustrated a change in differentiation pattern of HSPCs in CR-AML to monocytes in RR-AML. We are currently analyzing more AML samples to validate these findings.Conclusions: Our ScMo analysis demonstrates that the immune cells are systematically reprogrammed and functionally comprised in the AML ecosystem. Upregulation of BM niche factors could be the underlying mechanism for RR-AML. Thus, reversing the inhibited immune system is an important strategy for AML therapy and targeting leukemic cell-BM niche interaction should be considered for cases with high expression of these molecules on AML HSPCs.Note: J.Z. and J.A.S. share co-first authorship. [Display omitted] DisclosuresScolnick: Proteona Pte Ltd: Current holder of individual stocks in a privately-held company. Xu: Proteona Pte Ltd: Current Employment. Ooi: Jansen: Honoraria; Teva Pharmaceuticals: Honoraria; GSK: Honoraria; Abbvie: Honoraria; Amgen: Honoraria. Lovci: Proteona Pte Ltd: Current Employment. Chng: Aslan: Research Funding; Takeda: Honoraria; Johnson & Johnson: Honoraria, Research Funding; BMS/Celgene: Honoraria, Research Funding; Amgen: Honoraria; Novartis: Honoraria, Research Funding; Antengene: Honoraria; Pfizer: Honoraria; Sanofi: Honoraria; AbbVie: Honoraria.

CTCF: A novel fusion partner of ETO2 in a multiple relapsed acute myeloid leukemia patient

ETO2 is a nuclear co-repressor, which plays a critical role in the regulation of the cell cycle, self-renewal capacity, and differentiation of hematopoietic progenitor cells. We identified novel fusion transcripts involving ETO2 and CTCF by RNA-seq in a multiple relapsed AML case. The CTCF-ETO2 and ETO2-CTCF chimeric genes were validated by RT-PCR and Sanger sequencing. In addition, both transcripts apparently promoted cell proliferation via JAK/STAT3 pathway that is sensitive to STAT3 inhibitors. The novel fusions may have prognostic value and pathogenic mechanisms in acute myeloid leukemia.

MAP4K1 functions as a tumor promotor and drug mediator for AML via modulation of DNA damage/repair system and MAPK pathway.

Background: Acute myeloid leukemia (AML) is a group of heterogeneous hematologic malignancies correlates with poor prognosis. It is important to identify biomarkers for effective treatment of AML. Kinases participate in many regulatory pathways and biological activities in AML. Previous studies demonstrated that MAP4K1, a serine/threonine kinase, was associated with immune regulation and cancer progression. However, its role and mechanism in acute myeloid leukemia (AML) have not been explored.Methods: RNA-seq profiling was performed for Homoharringtonine (HHT)-resistant and Homoharringtonine (HHT)-sensitive cell lines. Bioinformatic tools were used for differential analysis. Cell culture and transfection, Cell proliferation, apoptosis and Cell cycle assay, Quantitative RT-PCR, and Western blotting analysis were used to explore biological phenotypes in vitro.Findings: We found that MAP4K1 was highly expressed in HHT-induced resistant AML cell lines. In addition, overexpression of MAP4K1 in AML cells induced resistance of AML cells against HHT. Not only that, the findings of this study showed that overexpression of MAP4K1 was an independent risk factor that predicts poor prognosis of AML. Further, In vitro studies showed that MAP4K1 modulated cell cycle through MAPK and DNA damage/repair pathways. Therefore, MAP4K1 is a potential target for developing therapies for AML.Interpretation: This study demonstrates that MAP4K1 not only regulates HHT resistance but also independently predicts AML prognosis. In addition, understanding the regulatory mechanism of MAP4K1 reveals novel treatment strategies for resistant and refractory AML.Fundings: This work was supported by the National Natural Science Foundation of China (NSFC) (Grant No.81800199, 81670124, 82070118) and the Natural Science Foundation of Zhejiang Province (LY20H080008).

Study on the Immune Escape Mechanism of Acute Myeloid Leukemia With DNMT3A Mutation.

DNA (cytosine-5)-methyltransferase 3A (DNMT3A)-mutated acute myeloid leukemia (AML) has a poor prognosis, but the exact mechanism is still unclear. Here, we aimed to explore the mechanism of immune escape in AML with DNMT3A mutation. We constructed a DNMT3A knockout clone and DNMT3A-R882H-mutated clones. RNA-seq results showed that transcription factors and macrophage inflammatory proteins were significantly downregulated in the DNMT3A mutant clones. KEGG enrichment and gene set enrichment analysis (GSEA) showed that a large number of genes were enriched in inflammatory immune-related pathways, such as the toll-like receptor signaling pathway. Therefore, we co-cultured AML cells with macrophages. The DNMT3A-mutated AML cells attenuated M1 macrophage polarization and resisted its killing effect in vitro and in vivo. In xenografts, the tumor volumes in the experimental group were significantly larger than those in the control group, and the proportion of M2 macrophages was significantly higher. After the co-culture, the increase in pro-inflammatory cytokine expression in the mutant cells was significantly lower than that in the control group, while that in immunosuppressive factors was not significantly different. In co-cultivated supernatants, the concentration of inflammatory factors in the experimental group was significantly lower than that in the control group, while that of immunosuppressive factors was significantly higher. Resistin significantly promoted the expression of inflammatory proteins in AML cells. It relieved the inhibitory effect of DNMT3A mutation, promoted the phenotypic recovery of the co-cultured macrophages, eliminated resistance, and regulated the immune microenvironment. Thus, resistin may serve as an ancillary drug for patients with DNMT3A-mutated AML.

LncRNA RAET1K Promotes the Progression of Acute Myeloid Leukemia by Targeting miR-503-5p/INPP4B Axis.

BackgroundAlthough long non-coding RNA (lncRNA) RAET1K has been observed to be abnormally expressed in patients with various cancers, its role and molecular mechanism in acute myeloid leukemia (AML) remain unclear.MethodsThe expression of RAET1K and miR-503-5p in bone marrow tissues and cell lines was detected by qRT-PCR. Cell proliferation was evaluated by cell counting kit-8 and 5-ethynyl-20-deoxyuridine (EdU) staining assay. Cell invasion and migration were detected by transwell assay. Cell apoptosis was evaluated by flow cytometry. The relationship between RAET1K and miR-503-5p, as well as miR-503-5p and INPP4B, was determined by luciferase reporter assay and RNA immunoprecipitation (RIP) assay. In addition, the tumorigenesis of leukemia cells was evaluated by using a xenograft mouse model in vivo.ResultsRAET1K was significantly upregulated and miR-503-5p was markedly downregulated in bone marrow tissues and cell lines (HL-60 and THP-1). Silencing of RAET1K (si-RAET1K) and overexpression of miR-503-5p inhibited cell proliferation, migration, and invasion but promoted apoptosis of HL-60 and THP-1 cells. RAET1K functioned as a sponge of miR-503-5p, and miR-503-5p inhibitor obviously attenuated the effect of si-RAET1K on AML progression in vitro. INPP4B was identified as a target of miR-503-5p, and INPP4B overexpression obviously reversed the effect of miR-503-5p mimics on cell proliferation, migration, invasion, and apoptosis of HL-60 and THP-1 cells in vitro. Knockdown of RAET1K effectively inhibited the tumorigenesis of leukemia cells in vivo.ConclusionOur results demonstrated that RAET1K/miR-503-5p/INPP4B axis contributed to AML progression, suggesting that RAET1K might be a potential target for the treatment of AML.

Immune evasion mechanisms in acute myeloid leukemia: A focus on immune checkpoint pathways.

Immune surveillance mechanisms comprising of adaptive and innate immune systems are naturally designed to eliminate AML development. However, leukemic cells apply various immune evasion mechanisms to deviate host immune responses resulting tumor progression. One of the recently well-known immune escape mechanisms is over-expression of immune checkpoint receptors and their ligands. Introduction of blocking antibodies targeting co-inhibitory molecules achieved invaluable success in tumor targeted therapy. Moreover, several new co-inhibitory pathways are currently studying for their potential impacts on improving anti-tumor immune responses. Although immunotherapeutic strategies based on the blockade of immune checkpoint molecules have shown promising results in a number of hematological malignances, their effectiveness in AML patients showed less remarkable success. This review discusses current knowledge about the involvement of co-inhibitory signaling pathways in immune evasion mechanisms of AML and potential application of immune checkpoint inhibitors for targeted immunotherapy of this malignancy.