Differentiation Of Acute Myeloid Leukemia Cells Research Articles

Therapeutic Potential of Adina rubella Hance Stem and Picroside III as a Differentiation Inducer in AML Cells via Mitochondrial ROS Accumulation

Acute myeloid leukemia (AML) is characterized by the accumulation of immature myeloid cells and a differentiation block, highlighting the urgent need for novel differentiation-inducing therapies. This study evaluated Adina rubella Hance (ARH) stem as a potent differentiation inducer by systematically screening 200 plant extracts. ARH stem promoted phenotypic differentiation in AML cells. In addition to its differentiation-inducing effects, ARH stem exhibited strong antileukemic activities, such as inhibiting cell proliferation, inducing cell death, and enhancing mitochondrial reactive oxygen species (mtROS) levels, the latter of which is critical for its differentiation-promoting activity. Comparative analysis with the extracts from other parts of the plant confirmed the superior efficacy of the stem extract because of its unique chemical composition. Ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry analysis identified Picroside III as a major active compound within the stem extract, capable of recapitulating ARH stem-induced differentiation and demonstrating significant antileukemic properties. These findings underscore the therapeutic potential of ARH stem and its active component, Picroside III, as promising agents for differentiation-based treatment strategies in AML.

Targeting protein tyrosine phosphatase non-receptor type 6 (PTPN6) as a therapeutic strategy in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by the clonal expansion of myeloid progenitor cells. Despite advancements in treatment, the prognosis for AML patients remains poor, highlighting the need for novel therapeutic targets. Protein Tyrosine Phosphatase Non-Receptor Type 6 (PTPN6), also known as SHP-1, is a critical regulator of hematopoietic cell signaling and has been implicated in various leukemias. This study investigates the therapeutic potential of targeting PTPN6 in AML. We employed both in vitro and in vivo models to evaluate the effects of PTPN6 inhibition on AML cell proliferation, apoptosis, and differentiation. Our results demonstrate that PTPN6 inhibition leads to a significant reduction in AML cell viability, induces apoptosis, and promotes differentiation of leukemic cells into mature myeloid cells. Mechanistic studies revealed that PTPN6 inhibition disrupts key signaling pathways involved in AML pathogenesis, including the JAK/STAT and PI3K/AKT pathways. Furthermore, the combination of PTPN6 inhibitors with standard chemotherapeutic agents exhibited a synergistic effect, enhancing the overall therapeutic efficacy. These findings suggest that PTPN6 is a promising therapeutic target in AML and warrants further investigation into the development of PTPN6 inhibitors for clinical application in AML treatment.

MRNA m5C Alteration in Azacitidine Demethylation Treatment of Acute Myeloid Leukemia.

The DNA demethylating therapy with azacitidine (AZA) is a promising therapeutic strategy for elderly patients with acute myeloid leukemia (AML). AZA primarily inhibits DNA methylation, promotes cell differentiation and apoptosis in AML. However, as a cytosine nucleoside analog, AZA also has the potential to be incorporated into RNA molecules. To assess the impact of AZA on RNA m5C methylation during demethylating therapy, we conducted Nanopore direct-RNA sequencing on samples from three AML patients pre and after demethylating therapy, as well as on HL-60 cells pretreated with AZA. We performed an integrated analysis of the transcriptome and the m5C methylome, contrasting the states of complete remission with those of active disease (AML). Our results revealed an extensive demethylation effect at the RNA level attributable to AZA and found that mRNA m5C modification may play a pivotal role in the progression of AML. Additionally, S100P was identified as a biomarker with significant prognostic implications. We also conducted a conjoint analysis of the transcriptome and the m5C methylome of the full-length transcripts, uncovering several dysregulated mRNA isoforms. Collectively, our findings indicate that mRNA m5C methylation is implicated during AML progression, and AZA exhibits an overall suppressive effect on this process.

APEX1 Polymorphisms Affect Acute Myeloid Leukemia Risk, and Its Expression Is Involved in Cell Proliferation and Differentiation.

The link between DNA repair gene polymorphisms and cancer susceptibility has gained significant attention. Thus, we investigated the impact of base excision repair (BER) gene polymorphisms on acute myeloid leukemia (AML) risk and pathogenesis. In total, 106 patients with AML and 191 healthy controls were included in the study, wherein polymorphisms in four BER genes (APEX1, MUTYH, OGG1, and XRCC1) were examined. Notably, the APEX1-656 T>G polymorphism exhibited a significant association with AML risk in the recessive (TT vs. TG + GG) (p = 0.046) and co-dominant models (TT vs. GG) (p = 0.02). Assessing APEX1 expression levels, APEX1 expression was elevated in the bone marrow of patients with AML compared with that in controls (p = 0.02). Subsequently, we compared the percentages of CD34+ cells between the APEX1 high or low expression groups, revealing a significant difference (high vs. low = 29.9% vs. 11.5%, p = 0.01). Additionally, we observed reduced APEX1 expression in HL60 cells differentiated with all-trans retinoic acid (p < 0.001). We hypothesized that APEX1 expression could correlate with stemness and analyzed its expression in stem and differentiated cells. In the GSE48558 dataset, AML cells and normal CD34+ cells expressed APEX1 at higher levels than did granulocytes (p < 0.01). Functional experiments revealed that APEX1 knockdown led to a reduction in AML cell proliferation. These findings indicated that APEX1 polymorphisms were a potential risk factor for AML and highlighted the important role of APEX1 in regulating AML cell differentiation and proliferation.

Bone marrow stromal cells enhance differentiation of acute myeloid leukemia induced by pyrimidine synthesis inhibitors.

Acute myeloid leukemia (AML) is a heterogeneous group of hematological malignancies characterized by differentiation arrest, high relapse rates, and poor survival. The bone marrow (BM) microenvironment is recognized as a critical mediator of drug resistance and a primary site responsible for AML relapse. Our previous study reported that 5-aminoimidazole-4-carboxamide ribonucleoside (AICAr) induces AML cell differentiation by inhibiting pyrimidine synthesis and activating Checkpoint kinase 1. Although the protective effect of BM stroma on leukemia cells in response to cytotoxic drugs is well-documented, its effect on AML differentiation remains less explored. In this study, we investigated the impact of stromal cell lines and primary mesenchymal stromal cells (MSCs) on AML cell line differentiation triggered by AICAr and brequinar, a known dihydroorotate dehydrogenase (DHODH) inhibitor. Our findings indicate that the mouse MS-5 stromal cell line, known for its cytoprotective effects, does not inhibit AML cell differentiation induced by pyrimidine synthesis inhibitors. Interestingly, AICAr caused morphological changes and growth arrest in MS-5 stromal cells via an AMP-activated protein kinase (AMPK)-dependent pathway. Human stromal cell lines HS-5 and HS-27, as well as primary MSCs isolated from patient bone marrow, were superior in promoting AML differentiation compared with mouse cells in response to AICAr and brequinar, with the inhibitors not significantly affecting the stromal cells themselves. In conclusion, our study highlights the supportive role of human BM MSCs in enhancing the differentiation effects of pyrimidine synthesis inhibitors on AML cells, suggesting that AML treatment strategies focusing on differentiation rather than cell killing may be successful in clinical settings.NEW & NOTEWORTHY This study is the first to demonstrate that human stromal cell lines and primary mesenchymal stromal cells from patients enhance the in vitro differentiation of acute myeloid leukemia (AML) cells induced by pyrimidine synthesis inhibitors, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAr), and brequinar. Furthermore, this is the first report to show that AICAr affects mouse bone marrow stromal cells by activating AMP-activated protein kinase (AMPK) and that human stromal cells are superior to mouse cells for testing the effects of drugs on AML differentiation.

Rapid increase of C/EBPα p42 induces growth arrest of acute myeloid leukemia (AML) cells by Cop1 deletion in Trib1-expressing AML.

Cop1 encodes a ubiquitin E3 ligase that has been well preserved during evolution in both plants and metazoans. In metazoans, the C/EBP family transcription factors are targets for degradation by Cop1, and this process is regulated by the Tribbles pseudokinase family. Over-expression of Tribbles homolog 1 (Trib1) induces acute myeloid leukemia (AML) via Cop1-dependent degradation of the C/EBPα p42 isoform. Here, we induced rapid growth arrest and granulocytic differentiation of Trib1-expressing AML cells using a Cop1 conditional knockout (KO), which is associated with a transient increase in the C/EBPα p42 isoform. The growth-suppressive effect of Cop1 KO was canceled by silencing of Cebpa and reinforced by exogenous expression of the p42 isoform. Moreover, Cop1 KO improved the survival of recipients transplanted with Trib1-expressing AML cells. We further identified a marked increase in Trib1 protein expression in Cop1 KO, indicating that Trib1 is self-degraded by the Cop1 degradosome. COP1 downregulation also inhibits the proliferation of human AML cells in a TRIB1-dependent manner. Taken together, our results provide new insights into the role of Trib1/Cop1 machinery in the C/EBPα p42-dependent leukemogenic activity, and a novel idea to develop new therapeutics.

Overexpression of RBM4 promotes acute myeloid leukemia cell differentiation by regulating alternative splicing of TFEB

Alternative splicing (AS) is an efficient and ubiquitous transcriptional regulatory mechanism that expands the coding capacity of the genome and is associated with the occurrence and progression of cancer. The differentiation-promoting regimen is a potential therapeutic approach in cancer treatment. In this study, we screened NPMc-positive and NPMc-negative AML samples from the Cancer Genome Atlas (TCGA), focusing on the splicing factor RBM4 and its splicing mechanism on the target gene TFEB, which are most relevant to the prognosis of AML. We also investigated the impact of the TFEB-dominant spliceosome on autophagy and differentiation of THP-1 and K562 cells. The results showed that RBM4 recognized the CU-rich sequence in intron 8 of TFEB, increasing the production of the TFEB-L spliceosome, which promoted autophagy. Overexpression of RBM4 increased autophagy and promoted cell differentiation. The combination of TFEB-L with the therapeutic drug rapamycin further promoted the differentiation of leukemia cell lines and primary leukemia cells in AML patients. This study suggested that overexpression of RBM4 could promote cell differentiation by promoting the production of the TFEB-dominant spliceosome, demonstrating the potential of the TFEB-dominant spliceosome combined with chemotherapy drugs to promote leukemia cell differentiation and improve patient prognosis.

In Vivo Chemical Screening in Zebrafish Embryos Identified FDA-Approved Drugs That Induce Differentiation of Acute Myeloid Leukemia Cells.

Acute myeloid leukemia (AML) is characterized by the abnormal proliferation and differentiation arrest of myeloid progenitor cells. The clinical treatment of AML remains challenging. Promoting AML cell differentiation is a valid strategy, but effective differentiation drugs are lacking for most types of AML. In this study, we generated Tg(drl:hoxa9) zebrafish, in which hoxa9 overexpression was driven in hematopoietic cells and myeloid differentiation arrest was exhibited. Using Tg(drl:hoxa9) embryos, we performed chemical screening and identified four FDA-approved drugs, ethacrynic acid, khellin, oxcarbazepine, and alendronate, that efficiently restored myeloid differentiation. The four drugs also induced AML cell differentiation, with ethacrynic acid being the most effective. By an RNA-seq analysis, we found that during differentiation, ethacrynic acid activated the IL-17 and MAPK signaling pathways, which are known to promote granulopoiesis. Furthermore, we found that ethacrynic acid enhanced all-trans retinoic acid (ATRA)-induced differentiation, and both types of signaling converged on the IL-17/MAPK pathways. Inhibiting the IL-17/MAPK pathways impaired ethacrynic acid and ATRA-induced differentiation. In addition, we showed that ethacrynic acid is less toxic to embryogenesis and less disruptive to normal hematopoiesis than ATRA. Thus, the combination of ethacrynic acid and ATRA may have broader clinical applications. In conclusion, through zebrafish-aided screening, our study identified four drugs that can be repurposed to induce AML differentiation, thus providing new agents for AML therapy.

Bi-functional CpG-STAT3 decoy oligonucleotide triggers multilineage differentiation of acute myeloid leukemia in mice

Acute myeloid leukemia (AML) cells resist differentiation stimuli despite high expression of innate immune receptors, such as Toll-like receptor 9 (TLR9). We previously demonstrated that targeting Signal Transducer and Activator of Transcription 3 (STAT3) using TLR9-targeted decoy oligodeoxynucleotide (CpG-STAT3d) increases immunogenicity of human and mouse AML cells. Here, we elucidated molecular mechanisms of inv(16) AML reprogramming driven by STAT3-inhibition/TLR9-activation invivo. At the transcriptional levels, AML cells isolated from mice after intravenous administration of CpG-STAT3d or leukemia-targeted Stat3 silencing and TLR9 co-stimulation, displayed similar upregulation of myeloid cell differentiation (Irf8, Cebpa, Itgam) and antigen-presentation (Ciita, Il12a, B2m)-related genes with concomitant reduction of leukemia-promoting Runx1. Single-cell transcriptomics revealed that CpG-STAT3d induced multilineage differentiation of AML cells into monocytes/macrophages, erythroblastic and B cell subsets. As shown by an inducible Irf8 silencing invivo, IRF8 upregulation was critical for monocyte-macrophage differentiation of leukemic cells. TLR9-driven AML cell reprogramming was likely enabled by downregulation of STAT3-controlled methylation regulators, such as DNMT1 and DNMT3. In fact, the combination of DNA methyl transferase (DNMT) inhibition using azacitidine with CpG oligonucleotides alone mimicked CpG-STAT3d effects, resulting in AML cell differentiation, Tcell activation, and systemic leukemia regression. These findings highlight immunotherapeutic potential of bi-functional oligonucleotides to unleash TLR9-driven differentiation of leukemic cells by concurrent STAT3 and/or DNMT inhibition.

Monocytic Differentiation in Acute Myeloid Leukemia Cells: Diagnostic Criteria, Biological Heterogeneity, Mitochondrial Metabolism, Resistance to and Induction by Targeted Therapies.

We review the importance of monocytic differentiation and differentiation induction in non-APL (acute promyelocytic leukemia) variants of acute myeloid leukemia (AML), a malignancy characterized by proliferation of immature myeloid cells. Even though the cellular differentiation block is a fundamental characteristic, the AML cells can show limited signs of differentiation. According to the French-American-British (FAB-M4/M5 subset) and the World Health Organization (WHO) 2016 classifications, monocytic differentiation is characterized by morphological signs and the expression of specific molecular markers involved in cellular communication and adhesion. Furthermore, monocytic FAB-M4/M5 patients are heterogeneous with regards to cytogenetic and molecular genetic abnormalities, and monocytic differentiation does not have any major prognostic impact for these patients when receiving conventional intensive cytotoxic therapy. In contrast, FAB-M4/M5 patients have decreased susceptibility to the Bcl-2 inhibitor venetoclax, and this seems to be due to common molecular characteristics involving mitochondrial regulation of the cellular metabolism and survival, including decreased dependency on Bcl-2 compared to other AML patients. Thus, the susceptibility to Bcl-2 inhibition does not only depend on general resistance/susceptibility mechanisms known from conventional AML therapy but also specific mechanisms involving the molecular target itself or the molecular context of the target. AML cell differentiation status is also associated with susceptibility to other targeted therapies (e.g., CDK2/4/6 and bromodomain inhibition), and differentiation induction seems to be a part of the antileukemic effect for several targeted anti-AML therapies. Differentiation-associated molecular mechanisms may thus become important in the future implementation of targeted therapies in human AML.

Studying Signaling Pathway Activation in TRAIL-Resistant Macrophage-Like Acute Myeloid Leukemia Cells.

Acute myeloid leukemia (AML) is a malignant neoplasm characterized by extremely low curability and survival. The inflammatory microenvironment and maturation (differentiation) of AML cells induced by it contribute to the evasion of these cells from effectors of antitumor immunity. One of the key molecular effectors of immune surveillance, the cytokine TRAIL, is considered a promising platform for developing selective anticancer drugs. Previously, under in vitro conditions of the inflammatory microenvironment (a three-dimensional high-density culture of THP-1 AML cells), we demonstrated the emergence of differentiated macrophage-like THP-1ad clones resistant to TRAIL-induced death. In the present study, constitutive activation of proinflammatory signaling pathways, associated transcription factors, and increased expression of the anti-apoptotic BIRC3 gene were observed in TRAIL-resistant macrophage-like THP-1ad AML cells. For the first time, a bioinformatic analysis of the transcriptome revealed the main regulator, the IL1B gene, which triggers proinflammatory activation and induces resistance to TRAIL in THP-1ad macrophage-like cells.

Monocytic Differentiation of Human Acute Myeloid Leukemia Cells: A Proteomic and Phosphoproteomic Comparison of FAB-M4/M5 Patients with and without Nucleophosmin 1 Mutations.

Even though morphological signs of differentiation have a minimal impact on survival after intensive cytotoxic therapy for acute myeloid leukemia (AML), monocytic AML cell differentiation (i.e., classified as French/American/British (FAB) subtypes M4/M5) is associated with a different responsiveness both to Bcl-2 inhibition (decreased responsiveness) and possibly also bromodomain inhibition (increased responsiveness). FAB-M4/M5 patients are heterogeneous with regard to genetic abnormalities, even though monocytic differentiation is common for patients with Nucleophosmin 1 (NPM1) insertions/mutations; to further study the heterogeneity of FAB-M4/M5 patients we did a proteomic and phosphoproteomic comparison of FAB-M4/M5 patients with (n = 13) and without (n = 12) NPM1 mutations. The proteomic profile of NPM1-mutated FAB-M4/M5 patients was characterized by increased levels of proteins involved in the regulation of endocytosis/vesicle trafficking/organellar communication. In contrast, AML cells without NPM1 mutations were characterized by increased levels of several proteins involved in the regulation of cytoplasmic translation, including a large number of ribosomal proteins. The phosphoproteomic differences between the two groups were less extensive but reflected similar differences. To conclude, even though FAB classification/monocytic differentiation are associated with differences in responsiveness to new targeted therapies (e.g., Bcl-2 inhibition), our results shows that FAB-M4/M5 patients are heterogeneous with regard to important biological characteristics of the leukemic cells.

A chemically adjustable BMP6-IL6 axis in mesenchymal stem cells drives acute myeloid leukemia cell differentiation

Chemotherapy alone or in combination with allogeneic stem cell transplantation has been the standard of care for acute myeloid leukemia (AML) for decades. Leukemia relapse with limited treatment options remains the main cause of treatment failure. Therefore, an effective and safe approach to improve treatment outcomes is urgently needed for most AML patients. Mesenchymal stem cells (MSCs) have been reported to efficiently induce apoptosis and shape the fate of acute myeloid leukemia cells. Here, we identified LG190155 as a potent compound that enhances the antileukemia efficiency of MSCs. Pretreatment of MSCs with LG190155 significantly provoked differentiation in both AML patient-derived primary leukemia cells and AML cell lines and reduced the tumor burden in the AML mouse model. Using the quantitative proteomic technique, we discovered a pivotal mechanism that mediates AML cell differentiation, in which autocrine bone morphogenetic protein 6 (BMP6) in MSCs boosted IL-6 secretion and further acted on leukemic cells to trigger differentiation. Furthermore, the activity of the BMP6-IL6 axis was dramatically enhanced by activating vitamin D receptor (VDR) in MSCs. Our data illustrated an effective preactivated approach to reinforcing the antileukemia effect of MSCs, which could serve as an effective therapeutic strategy for AML.

Induction of AML cell differentiation using HOXA9/DNA binding inhibitors as a potential therapeutic option for HOXA9-dependent AML.

The mainstay of acute myeloid leukemia (AML) treatment still relies on traditional chemotherapy, with a survival rate of approximately 30% for patients under 65 years of age and as low as 5% for those beyond. This unfavorable prognosis primarily stems from frequent relapses, resistance to chemotherapy, and limited approved targeted therapies for specific AML subtypes. Around 70% of all AML cases show overexpression of the transcription factor HOXA9, which is associated with a poor prognosis, increased chemoresistance, and higher relapse rates. However, direct targeting of HOXA9 in a clinical setting has not been achieved yet. The dysregulation caused by the leukemic HOXA9 transcription factor primarily results from its binding activity to DNA, leading to differentiation blockade. Our previous investigations have identified two HOXA9/DNA binding competitors, namely DB1055 and DB818. We assessed their antileukemic effects in comparison to HOXA9 knockdown or cytarabine treatment. Using human AML cell models, DB1055 and DB818 induced in vitro cell growth reduction, death, differentiation, and common transcriptomic deregulation but did not impact human CD34+ bone marrow cells. Furthermore, DB1055 and DB818 exhibited potent antileukemic activities in a human THP-1 AML in vivo model, leading to the differentiation of monocytes into macrophages. In vitro assays also demonstrated the efficacy of DB1055 and DB818 against AML blasts from patients, with DB1055 successfully reducing leukemia burden in patient-derived xenografts in NSG immunodeficient mice. Our findings indicate that inhibiting HOXA9/DNA interaction using DNA ligands may offer a novel differentiation therapy for the future treatment of AML patients dependent on HOXA9.

Emetine induces oxidative stress, cell differentiation and NF-κB inhibition, suppressing AML stem/progenitor cells

Acute myeloid leukemia (AML) is a fatal malignancy of the blood and bone marrow. Leukemic stem cells (LSCs) are a rare subset of leukemic cells that promote the development and progression of AML, and eradication of LSCs is critical for effective control of this disease. Emetine is an FDA-approved antiparasitic drug with antitumor properties; however, little is known about its potential against LSCs. Herein, we explored the antileukemic potential of emetine, focusing on its effects on AML stem/progenitor cells. Emetine exhibited potent cytotoxic activity both in hematologic and solid cancer cells and induced AML cell differentiation. Emetine also inhibited AML stem/progenitor cells, as evidenced by decreased expression of CD34, CD97, CD99, and CD123 in KG-1a cells, indicating anti-AML stem/progenitor cell activities. The administration of emetine at a dosage of 10 mg/kg for two weeks showed no significant toxicity and significantly reduced xenograft leukemic growth in vivo. NF-κB activation was reduced in emetine-treated KG-1a cells, as shown by reduced phospho-NF-κB p65 (S529) and nuclear NF-κB p65. DNA fragmentation, YO-PRO-1 staining, mitochondrial depolarization and increased levels of active caspase-3 and cleaved PARP (Asp214) were detected in emetine-treated KG-1a cells. Moreover, treatment with the pancaspase inhibitor Z-VAD(OMe)-FMK partially prevented the apoptotic cell death induced by emetine. Emetine treatment also increased cellular and mitochondrial reactive oxygen species, and emetine-induced apoptosis in KG-1a cells was partially prevented by the antioxidant N-acetylcysteine, indicating that emetine induces apoptosis, at least in part, by inducing oxidative stress. Overall, these studies indicate that emetine is a novel potential anti-AML agent with promising activity against stem/progenitor cells, encouraging the development of further studies aimed at its clinical application.

Roles of Glutathione and AP-1 in the Enhancement of Vitamin D-Induced Differentiation by Activators of the Nrf2 Signaling Pathway in Acute Myeloid Leukemia Cells.

Active vitamin D derivatives (VDDs)-1α,25-dihydroxyvitamin D3/D2 and their synthetic analogs-are well-known inducers of cell maturation with the potential for differentiation therapy of acute myeloid leukemia (AML). However, their dose-limiting calcemic activity is a significant obstacle to using VDDs as an anticancer treatment. We have shown that different activators of the NF-E2-related factor-2/Antioxidant Response Element (Nrf2/ARE) signaling pathway, such as the phenolic antioxidant carnosic acid (CA) or the multiple sclerosis drug monomethyl fumarate (MMF), synergistically enhance the antileukemic effects of various VDDs applied at low concentrations in vitro and in vivo. This study aimed to investigate whether glutathione, the major cellular antioxidant and the product of the Nrf2/ARE pathway, can mediate the Nrf2-dependent differentiation-enhancing activity of CA and MMF in HL60 human AML cells. We report that glutathione depletion using L-buthionine sulfoximine attenuated the enhancing effects of both Nrf2 activators concomitant with downregulating vitamin D receptor (VDR) target genes and the activator protein-1 (AP-1) family protein c-Jun levels and phosphorylation. On the other hand, adding reduced glutathione ethyl ester to dominant negative Nrf2-expressing cells restored both the suppressed differentiation responses and the downregulated expression of VDR protein, VDR target genes, as well as c-Jun and P-c-Jun levels. Finally, using the transcription factor decoy strategy, we demonstrated that AP-1 is necessary for the enhancement by CA and MMF of 1α,25-dihydroxyvitamin D3-induced VDR and RXRα protein expression, transactivation of the vitamin D response element, and cell differentiation. Collectively, our findings suggest that glutathione mediates, at least in part, the potentiating effect of Nrf2 activators on VDDs-induced differentiation of AML cells, likely through the positive regulation of AP-1.

The ncBAF Complex Regulates Transcription in AML Through H3K27ac Sensing by BRD9.

The bromodomain-containing protein BRD9 is essential for AML cell viability, but it is unclear whether this requirement is due to the protein's role as an epigenetic reader. We inhibited this activity and identified altered gene-distal chromatin regulation and transcription consistent with a more mature myeloid cell state.

Parbendazole as a promising drug for inducing differentiation of acute myeloid leukemia cells with various subtypes

Acute myeloid leukemia (AML) is a malignancy characterized by differentiation arrest of hematopoietic precursor cells. Differentiation therapy is effective for patients with acute promyelocytic leukemia; however, only a few effective differentiation therapies have been established for patients with other AML subtypes. In this study, seven benzimidazole anthelmintics were examined to determine the effects of differentiation on AML cells. The expression of monocyte markers (CD11b and CD14) was elevated after treatment with most benzimidazole anthelmintics. Among these drugs, parbendazole (PBZ) induced AML cell differentiation at low concentration. PBZ induced the monocyte marker expression, KLF4/DPYSL2A gene expression, and apoptosis for 21 AML cell lines with various subtypes and a primary AML sample. Finally, an in vivo analysis using an AML patient-derived xenograft mouse model showed a significant decrease in the chimerism level and prolonged survival in PBZ-treated mice. These findings could lead to a more effective differentiation therapy for AML.

The Molecular and Biological Function of MEF2D in Leukemia.

Myocyte enhancer factor 2 (MEF2) is a key transcription factor (TF) in skeletal, cardiac, and neural tissue development and includes four isoforms: MEF2A, MEF2B, MEF2C, and MEF2D. These isoforms significantly affect embryonic development, nervous system regulation, muscle cell differentiation, B- and T-cell development, thymocyte selection, and effects on tumorigenesis and leukemia. This chapter describes the multifaceted roles of MEF2 family proteins, covering embryonic development, nervous system regulation, and muscle cell differentiation. It further elucidates the contribution of MEF2 to various blood and immune cell functions. Specifically, in B-cell precursor acute lymphoblastic leukemia (BCP-ALL), MEF2D is aberrantly expressed and forms a fusion protein with BCL9, CSF1R, DAZAP1, HNRNPUL1, and SS18. These fusion proteins are closely related to the pathogenesis of leukemia. In addition, it specifically introduces the regulatory effect of MEF2D fusion protein on the proliferation and growth of B-cell acute lymphoblastic leukemia (B-ALL) cells. Finally, we detail the positive feedback loop between MEF2D and IRF8 that significantly promotes the progression of acute myeloid leukemia (AML) and the importance of the ZMYND8-BRD4 interaction in regulating the IRF8 and MYC transcriptional programs. The MEF2D-CEBPE axis is highlighted as a key transcriptional mechanism controlling the block of leukemic cell self-renewal and differentiation in AML. This chapter starts with the structure and function of MEF2 family proteins, specifically summarizing and analyzing the role of MEF2D in B-ALL and AML, mediating the complex molecular mechanisms of transcriptional regulation and exploring their implications for human health and disease.

Ginsenoside Rd Induces Differentiation of Myeloid Leukemia Cells via Regulating ERK/GSK-3β Signaling Pathway.

To investigate the role of ginsenoside Rd (GRd) in acute myeloid leukemia (AML) cell differentiation. AML cells were treated with GRd (25, 50, 100 and 200 µg/mL), retinoic acid (RA, 0.1g/L) and PD98059 (20 mg/mL) for 72 h, cell survival was detected by methylthiazolyldiphenyl-tetrazolium bromide and colony formation assays, and cell cycle was detected by flow cytometry. Cell morphology and differentiation were observed by Wright-Giemsa staining, peroxidase chemical staining and cellular immunochemistry assay, respectively. The protein expression levels of GATA binding protein 1 (GATA-1), purine rich Box-1 (PU.1), phosphorylated-extracellular signal-related kinase (p-ERK), ERK, phosphorylated-glycogen synthase kinase-3β (p-GSK3β), GSK3β and signal transducer and activator of transcription 1 (STAT1) were detected by Western blot. Thirty-six mice were randomly divided into 3 groups using a random number table: model control group (non-treated), GRd group [treated with 200 mg/(kg·d) GRd] and homoharringtonine (HTT) group [treated with 1 mg/(kg·d) HTT]. A tumor-bearing nude mouse model was established, and tumor weight and volume were recorded. Changes of subcutaneous tumor tissue were observed after hematoxylin and eosin staining. WT1 and GATA-1 expressions were detected by immunohistochemical staining. The cell survival was inhibited by GRd in a dose-dependent manner and GRd caused G0/G1 cell arrest (p<0.05). GRd treatment induced leukemia cell differentiation, showing increased expressions of peroxidase and specific proteins concerning erythrogenic or granulocytic differentiation (p<0.05). GRd treatment elicited upregulation of p-ERK, p-GSK-3β and STAT1 expressions in cells, and reversed the effects of PD98059 on inhibiting the expressions of peroxidase, GATA-1 and PU.1 (P<0.05). After GRd treatment, tumor weight and volume of mice were decreased, and tumor cells underwent massive apoptosis and necrosis (P<0.05). WT1 level was decreased, and GATA-1 level was significantly increased in subcutaneous tumor tissues (P<0.05 or P<0.01). GRd might induce the differentiation of AML cells via regulating the ERK/GSK-3β signaling pathway.