Objective: To investigate the effect of the AML1-ETO (AE) fusion gene on the biological function of U937 leukemia cells by establishing a leukemia cell model that induces AE fusion gene expression. Methods: The doxycycline (Dox) -dependent expression of the AE fusion gene in the U937 cell line (U937-AE) were established using a lentivirus vector system. The Cell Counting Kit 8 methods, including the PI and sidanilide induction, were used to detect cell proliferation, cell cycle-induced differentiation assays, respectively. The effect of the AE fusion gene on the biological function of U937-AE cells was preliminarily explored using transcriptome sequencing and metabonomic sequencing. Results: ①The Dox-dependent Tet-on regulatory system was successfully constructed to regulate the stable AE fusion gene expression in U937-AE cells. ②Cell proliferation slowed down and the cell proliferation rate with AE expression (3.47±0.07) was lower than AE non-expression (3.86 ± 0.05) after inducing the AE fusion gene expression for 24 h (P<0.05). The proportion of cells in the G(0)/G(1) phase in the cell cycle increased, with AE expression [ (63.45±3.10) %) ] was higher than AE non-expression [ (41.36± 9.56) %] (P<0.05). The proportion of cells expressing CD13 and CD14 decreased with the expression of AE. The AE negative group is significantly higher than the AE positive group (P<0.05). ③The enrichment analysis of the transcriptome sequencing gene set revealed significantly enriched quiescence, nuclear factor kappa-light-chain-enhancer of activated B cells, interferon-α/γ, and other inflammatory response and immune regulation signals after AE expression. ④Disorder of fatty acid metabolism of U937-AE cells occurred under the influence of AE. The concentration of the medium and short-chain fatty acid acylcarnitine metabolites decreased in cells with AE expressing, propionyl L-carnitine, wherein those with AE expression (0.46±0.13) were lower than those with AE non-expression (1.00±0.27) (P<0.05). The metabolite concentration of some long-chain fatty acid acylcarnitine increased in cells with AE expressing tetradecanoyl carnitine, wherein those with AE expression (1.26±0.01) were higher than those with AE non-expression (1.00±0.05) (P<0.05) . Conclusion: This study successfully established a leukemia cell model that can induce AE expression. The AE expression blocked the cell cycle and inhibited cell differentiation. The gene sets related to the inflammatory reactions was significantly enriched in U937-AE cells that express AE, and fatty acid metabolism was disordered.目的： 通过建立可诱导表达AML1-ETO（AE）融合基因的白血病细胞模型，研究AE融合基因对U937白血病细胞生物学功能的影响。 方法： 利用慢病毒载体系统，构建强力霉素（Dox）依赖的可诱导表达AE融合基因的U937细胞系（U937-AE）。在AE融合基因表达前后，分别采用CCK-8法、流式细胞术进行细胞增殖、周期、诱导分化检测，并进行转录组学测序和代谢组学测序分析，初步探讨AE融合基因对白血病细胞生物学功能的影响。 结果： ①成功构建Dox依赖的Tet-on调控系统，调控AE融合基因在U937-AE细胞中稳定表达。②诱导AE融合基因表达24 h后，表达AE的U937-AE细胞增殖倍率为3.47±0.07，低于AE阴性组的3.86±0.05（P<0.05）；处于G(0)/G(1)期的细胞比例为（63.45±3.10）%，明显高于AE阴性组的（41.36±9.56）%（P<0.05）；表达CD13、CD14的细胞比例较AE阴性组明显下降（P<0.05）。③转录组学测序进行基因集富集分析显示，与静息相关、NF-κB和干扰素α/γ应答相关的炎症反应和免疫调节的基因集被明显富集在表达AE的U937-AE细胞。④U937-AE细胞表达AE融合基因后脂肪酸代谢发生紊乱，AE阳性组细胞的部分中、短链脂肪酸酰基肉碱的代谢物浓度降低[丙酰基-L-肉碱：AE阳性组0.46±0.13，AE阴性组1.00±0.27（P<0.05）]；部分长链脂肪酸酰基肉碱的代谢物浓度升高[十四烷酰肉碱：AE阳性组1.26±0.01，AE阴性组1.00±0.05（P<0.05）]。 结论： 成功建立可诱导表达AE融合基因的白血病细胞模型。AE融合基因表达使U937-AE细胞增殖变慢、周期阻滞、分化受抑，炎症反应和免疫调节的相关基因集被明显富集，细胞的脂肪酸代谢发生紊乱。.
Chimeric antigen receptor-engineered T (CAR-T) cells have extraordinary effect in treating lymphoblastic leukemia. However, treatment of acute myeloid leukemia (AML) using CAR-T cells remains limited to date. Leukemogenesis always relates with the abnormalities of cytogenetics, and nearly one third of AML patients have activating mutations in Fms-like tyrosine kinase 3 (FLT3) which reminded poor prognosis. Considering the FLT3 expressed in AML patients' blast cells, it may be a new candidate target for CAR-T therapy to treat FLT3+ AML, especially patients harboring FLT3-ITD mutation. The FLT3L CAR-T using FLT3 ligand as recognizing domain was constructed. The specific cytotoxicity against FLT3+ leukemia cell lines, primary AML cells, and normal hematopoietic progenitor stem cells (HPSCs) in vitro were evaluated. In addition, FLT3+ AML mouse model was used to assess the effect of FLT3L CAR-T therapy in vivo. FLT3L CAR-T cells could specifically kill FLT3+ leukemia cell lines and AML patients' bone marrow mononuclear cells in vitro (with or without FLT3 mutation) and have more potent cytotoxicity to FLT3-ITD cells. In a human FLT3+ AML xenograft mouse model, FLT3L CAR-T cells could significantly prolong the survival of mice. Furthermore, it was found that FLT3L CAR-T cells could activate the FLT3/ERK signaling pathway of FLT3+ leukemia cells with wild-type FLT3; meanwhile, it had no inhibitory effects on the colony formation of CD34+ stem cells derived from normal human umbilical cord blood. The ligand-based FLT3L CAR-T cells could be a promising strategy for FLT3+ AML treatment, especially those carried FLT3 mutation.
<div>Abstract<p>Metabolism plays a key role in the maintenance of normal hematopoietic stem cells (HSC) and in the development of leukemia. A better understanding of the metabolic characteristics and dependencies of preleukemic cells could help identify potential therapeutic targets to prevent leukemic transformation. As AML1–ETO, one of the most frequent fusion proteins in acute myeloid leukemia that is encoded by a RUNX1::RUNX1T1 fusion gene, is capable of generating preleukemic clones, in this study, we used a conditional Runx1::Runx1t1 knockin mouse model to evaluate preleukemic cell metabolism. AML1–ETO expression resulted in impaired hematopoietic reconstitution and increased self-renewal ability. Oxidative phosphorylation and glycolysis decreased significantly in these preleukemic cells accompanied by increased HSC quiescence and reduced cell cycling. Furthermore, HSCs expressing AML1–ETO exhibited an increased requirement for fatty acids through metabolic flux. Dietary lipid deprivation or loss of the fatty acid transporter FATP3 by targeted deletion using CRISPR/Cas9 partially restored differentiation. These findings reveal the unique metabolic profile of preleukemic cells and propose FATP3 as a potential target for disrupting leukemogenesis.</p><p><b>Significance:</b> Fatty acid metabolism is required for maintenance of preleukemic cells but dispensable for normal hematopoiesis, indicating that dietary lipid deprivation or inhibiting fatty acid uptake may serve as potential strategies to prevent leukemogenesis.</p></div>
To explore the signal transduction pathway in the differentiation and apoptosis of leukemia cells induced by heat shock protein 90 (HSP90) inhibitor 17-Allyl amide-17-demethoxygeldanamycin (17AAG).Kasumi-1 cells were treated with increasing concentrations or exposure time of 17AAG. The total kit protein (CD117), phosphorylated kit protein and its downstream signaling molecules were measured by Western blot analysis. Mutated kit protein from control and 17AAG-treated Kasumi-1 cells was immunoprecipitated and immunoblotted for associated chaperones.Total kit protein and kit activity were decreased in 17AAG treated cells, but c-kit mRNA level was not. Total AKT protein and phospho-AKT, as well as phospho-STAT3 were rapidly down-regulated in Kasumi-1 cell after treatment with 17AAG. There was no change in total STAT3 protein. Immunoprecipitation showed that 1 microM 17AAG treatment for 1 hour caused kit associated HSP90 decrease and HSP70 increase.17AAG-induced apoptosis of Kasumi-1 cells is associated with a decline in Asn822Lys mutated kit protein level and phosphorylated kit, and with a downregulation in its downstream activated signaling molecules involved in proliferation. AKT is a client protein of HSP90. The changes of kit associated HSP90 and HSP70 satisfy the circulation mode of molecular chaperone complex.
Wt1 is a dual-function gene involved in hematopoiesis, leukemogenesis and prognosis for leukemia. This gene is highly expressed in acute myeloid leukemia (AML) and the progression of chronic myelogenous leukemia (CML). It was reported elsewhere that high level of wt1 expression indicated worse prognosis for leukemia. Wt1 gene functions are different due to its subcellular localization. This study was aimed to investigate the expression and localization of wt1 mRNA and WT1 protein, and explore the effects of wt1 inhibitor, curcumin, on K562 cell proliferation, cell cycle and its possible mechanisms. MTT method was used to detect cell proliferation; flow cytometry was used to analyze the alteration of cell cycle, and the immunofluorescence and Western blot technology were performed to observe the subcellular localization of WT1 protein. The transcripts of wt1 and bcr/abl p210 was analyzed by real-time PCR. The results showed that wt1 mRNA and its protein were both highly expressed in K562 cells. The curcumin and imatinib (Glevec) both inhibit the cell proliferation resulting in the G(2)/M and G(0)/G(1) phase arrest respectively. Meanwhile, the transcripts of wt1 and bcr/ablp210 genes decreased greatly after being treated with the two inhibitors above. It is concluded that the alteration of wt1 gene affects the biological characteristics of Ph(+) K562 cells, such as cell proliferation, cell cycle and so on. Gene wt1 is expected to be further studied as a new therapy target in Ph(+) leukemias.
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