OBJECTIVE: To study the expression of SPOP in patients with acute myeloid leukemia (AML) and its effect on proliferation, apoptosis and cycle of AML cells. METHODS: RT-qPCR was used to detect the expression of SPOP mRNA in bone marrow samples of patients with newly diagnosed AML and normal controls. The stable overexpression of SPOP in AML cell lines THP-1 and U937 were constructed by liposome transfection. The effect of SPOP on cell proliferation was detected by CCK-8, and the effect of SPOP on apoptosis and cell cycle was detected by flow cytometry. The expressions of anti-apoptotic protein Bcl-2 and apoptotic protein Bax, Caspase3 were detected by Western blot. RESULTS: The median expression level of SPOP mRNA in normal control group was 0.993 1(0.6303, 1.433), while that in AML group was 0.522 1(0.242 2, 0.723 7). The expression level of SPOP in AML group was significantly lower than that in normal control group ( P < 0.001). After the overexpression of SPOP, the proportion of apoptotic cells in the U937 overexpression group and THP-1 overexpression group was 10.9%±0.3% and 4.6%±015%, which were higher than 8.9%±0.3% and 3.0%±0.30% in the Empty Vector group, respectively (both P < 0.05). The expression of Caspase3 in U937 overexpression group and THP-1 overexpression group was 1.154±0.086 and 1.2±0.077, which were higher than 1 in Empty Vector group, respectively (both P < 0.05). The ratio of Bax/Bcl-2 in U937 overexpression group and THP-1 overexpression group was 1.328±0.057 and 1.669±0.15, which were higher than 1 in Empty Vector group, respectively (both P < 0.05). In the cell proliferation experiment, the number of cells in the U937 overexpression group and THP-1 overexpression group were both slightly lower than those in the Empty Vector group, but the differences were not statistically significant (P >0.05). In the cell cycle experiment, the proportion of G₁ cells in the U937 overexpression group and THP-1 overexpression group were both slightly higher than those in the Empty Vector group, but the differences were not statistically significant (P >0.05). CONCLUSION SPOP can promote the apoptosis of leukemic cells, and its mechanism may be related to down-regulation of Bcl-2 expression and up-regulation of Bax and Caspase3 expression.
Humans ; Leukemia, Myeloid, Acute/pathology* ; Apoptosis ; Repressor Proteins/genetics* ; Cell Proliferation ; Nuclear Proteins/genetics* ; Cell Cycle ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; Caspase 3/metabolism* ; bcl-2-Associated X Protein/metabolism* ; U937 Cells ; Cell Line, Tumor ; RNA, Messenger/genetics*

OBJECTIVE: To investigate the role of nucleolin (NCL) in acute myeloid leukemia (AML) Kasumi-1 cells and its underlying mechanism. METHODS: The Kasumi-1 cells were infected with lentivirus carrying shRNA to downregulate NCL expression. Cell proliferation was detected by CCK-8 assay, and cell apoptosis and cell cycle were determined by flow cytometry. Transcriptome next-generation sequencing (NGS) was performed to predict associated signaling pathways, the expression levels of related genes were measured by RT-PCR. RESULTS: Down-regulation of NCL expression significantly inhibited the proliferation of Kasumi-1 cells (P <0.01) and markedly increased the apoptosis rate (P <0.001). Cell cycle analysis showed significant changes in the distribution of cells in the G₁ and S phases after NCL knockdown (P <0.05), while no significant difference was observed in the G₂ phase (P >0.05). Transcriptome sequencing analysis demonstrated that differentially expressed genes in Kasumi-1 cells with low expression of NCL were primarily enriched in key signaling pathways, including ribosome, spliceosome, RNA transport, cell cycle, and amino acid biosynthesis. qPCR validation showed that the expression of BAX, CASP3, CYCS, PMAIP1, TP53 , and CDKN1A was significantly upregulated after NCL downregulation (P <0.05), with CDKN1A exhibiting the most pronounced difference. CONCLUSION NCL plays a critical role in regulating the proliferation, apoptosis, and cell cycle progression of Kasumi-1 cells. The mechanism likely involves suppressing cell cycle progression through activation of the TP53-CDKN1A pathway and promoting apoptosis by upregulating apoptosis-related genes.
Humans ; Leukemia, Myeloid, Acute/pathology* ; Down-Regulation ; Cell Proliferation ; Apoptosis ; RNA-Binding Proteins/genetics* ; Nucleolin ; Cell Line, Tumor ; Phosphoproteins/metabolism* ; Cell Cycle ; Signal Transduction ; RNA, Small Interfering

The objective of the present study was to investigate the role and mechanism of bone marrow microenvironmental cells in regulating the mitochondrial mass of leukemia cells, and to uncover the mechanism of leukemia progression at the metabolic level. A mouse model of acute myeloid leukemia (AML) induced by the overexpression of the MLL-AF9 (MA9) fusion protein was established, and the bone marrow cells of AML mice were transplanted into mitochondrial fluorescence reporter mice expressing the Dendra2 protein (mito-Dendra2 mice). The proportion of Dendra2⁺ cells in bone marrow leukemia cells at different stages of AML was quantified by flow cytometry. The effects of transferred mitochondria on leukemia cells were studied by fluorescence-activated cell sorting (FACS), followed by functional experiments and bulk RNA sequencing. Finally, components within the bone marrow niche, such as mesenchymal stromal cells (MSCs) and endothelial cells (ECs), were co-cultured with leukemia cells in vitro. The proportion of leukemia cells that underwent mitochondrial transfer and the apoptosis level of leukemia cells were then detected by flow cytometry. The results showed that mitochondria from bone marrow cells were transferred to leukemia cells in the AML mouse model, and the proportion of mitochondrial transfer decreased with AML progression. The proportion of mitochondria transferred to leukemia stem cells (LSCs) was lower than that of mature AML cells. In AML cells receiving Dendra2⁺ mitochondria, there was a significant increase in the levels of intracellular reactive oxygen species (ROS) and apoptosis, while the levels of protein translation and their colony-forming capacities were decreased. The transplantation of Dendra2⁺ AML cells resulted in an extension of the survival of mice. RNA sequencing analysis demonstrated a significant downregulation of pathways related to translation, aerobic respiration and mitochondrial organization in AML cells that had received mitochondria. In vitro co-culture experiments indicated that MSCs within the bone marrow niche tended to transfer their mitochondria to leukemia cells and promoted the apoptosis of leukemia cells. These results indicate that in the MA9-induced AML mouse model, bone marrow niche cells can transfer mitochondria to leukemia cells, resulting in a reduction in the overall survival and function of the leukemia cells. Mitochondrial transfer in the bone marrow microenvironment may serve as a self-defensive mechanism of the host bone marrow niche cells, inhibiting the progression of AML.
Animals ; Mice ; Mitochondria/metabolism* ; Disease Progression ; Leukemia, Myeloid, Acute/genetics* ; Apoptosis ; Mesenchymal Stem Cells/metabolism* ; Bone Marrow Cells/metabolism* ; Humans ; Tumor Microenvironment ; Mice, Inbred C57BL

Obesity-associated protein (FTO) is an important m6A demethylase that regulates RNA methylation modification and can promote the proliferation of acute myeloid leukemia(AML) cells. FTO regulates the methylation level of AML through multiple cellular signaling pathways such as FTO/RARA/ASB2, FTO/m6A/CEBPA, and PDGFRB/ERK, and participates in the occurrence, development, treatment and prognosis of AML. At present, studies have found that a variety of inhibitors targeting FTO have shown good anti-leukemia effects, and the study of FTO will provide new ideas for the treatment of AML. This review focus on the mechanism of action of FTO in AML and the research progress of FTO inhibitors in AML.
Humans ; Methylation ; Leukemia, Myeloid, Acute/genetics* ; Prognosis ; Alpha-Ketoglutarate-Dependent Dioxygenase FTO/metabolism*

OBJECTIVE: To investigate the effect of long non-coding RNA LINC01268 on apoptosis of acute myeloid leukemia (AML) cells and related mechanisms. METHODS: The expression levels of LINC01268 and miR-217 in peripheral blood samples from AML patients and AML cell lines HL-60 and KG-1 were detected by qRT-PCR. HL-60 cells were divided into pcDNA3.1-NC, pcDNA3.1-LINC01268, si-NC, si-LINC01268, miR-NC, miR-217 mimics, si-LINC01268 + inhibitor-NC and si-LINC01268+ miR-217 inhibitor groups. The mRNA expressions of LINC01268 and miR-217 were detected by qRT-PCR. The targeting relationship between LINC01268 and miR-217 was detected by dual-luciferase reporter assay. Cell viability was detected by CCK-8 assay. Cell cycle distribution and apoptosis were detected by flow cytometry. The expression of cell cycle and apoptosis-related proteins p21, Bcl-2, Bax, caspase-3 and PI3K/AKT signaling pathway-related proteins were detected by Western blot. RESULTS: The expression of LINC01268 in peripheral blood samples of AML patients and AML cell lines HL-60 and KG-1 was increased (P < 0.05), and the expression of miR-217 was decreased (P < 0.05). Compared with si-NC group and miR-NC group, the viability of HL-60 cells was decreased in si-LINC01268 group and miR-217 mimics group (P < 0.05), the proportion of cells in G₁ phase and apoptosis rate were increased (P < 0.05), the protein expression levels of p21, Bax and caspase-3 were increased (P < 0.05), while the protein expression level of Bcl-2 was decreased (P < 0.05). LINC01268 targeted and negatively regulated the expression of miR-217, and inhibiting the expression of miR-217 partially reversed the effects of LINC01268 interference on the viability, cell cycle and apoptosis of HL-60 cells. Interference with LINC01268 could inhibit the activity of PI3K/AKT signaling pathway. Inhibiting the expression of miR-217 could partially reverse the inhibition of LINC01268 interference on PI3K/AKT signaling pathway. CONCLUSION LINC01268 is highly expressed and miR-217 is lowly expressed in AML cells. LINC01268 can promote the activity of PI3K/AKT signaling pathway, increase the survival rate and inhibit the apoptosis of AML cells by targeting miR-217 expression.
Humans ; Apoptosis ; bcl-2-Associated X Protein/metabolism* ; Caspase 3 ; Cell Line, Tumor ; Cell Proliferation ; Leukemia, Myeloid, Acute/metabolism* ; MicroRNAs/metabolism* ; Phosphatidylinositol 3-Kinases/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; RNA, Long Noncoding/genetics*

Objective To investigate the effects of miR-181b-5p on cells proliferation and apoptosis in acute myeloid leukemia (AML) by targeting paired box 9 (PAX9). Methods The relationship between expression level of PAX9 and prognosis in AML patients was analyzed by gene expression profiling interactive analysis (GEPIA) database and The Cancer Genome Atlas (TCGA) database. Kasumi-1 and AML5 cells were transfected with empty vector (Vector group) or PAX9 (PAX9 group). The proliferation activity was detected by CCK-8 assay, and cells cycle and apoptosis were detected by flow cytometry. Expressions of cyclin-dependent kinase 2 (CDK2), cyclin B1 (CCNB1), B-cell lymphoma 2 (Bcl2) and Bcl2-associated X protein (BAX) were detected by Western blot analysis. The targeted microRNA (miRNA) by PAX9 was predicted by bioinformatics analysis, and the targeted effect was verified by luciferase reporter assay. The level of PAX9 mRNA was detected by real-time quantitative PCR, and expression of PAX9 protein was detected by Western blot analysis. Kasumi-1 and AML5 cells were transfected with miR-NC (miR-NC group) or miR-181b-5p (miR-181b-5p group). The cells were further transfected with PAX9 (miR-181b-5p combined with PAX9 group) in miR-181b-5p group. The proliferation, cycle and apoptosis of cells were detected by the above methods.Results GEPIA and TCGA databases showed that the expression of PAX9 was down-regulated in AML patients, which was correlated with poor prognosis. In Kasumi-1 and AML5 cells, compared with Vector group, proliferation activity of cells, percentage of cells in S phase, and expressions of CDK2, CCNB1 and Bcl2 proteins were decreased, while percentage of cells in G0/G1 phase, apoptosis rate and the expression of BAX protein were increased in PAX9 group. It was confirmed by double luciferase reporter assay that PAX9 was the target gene of miR-181b-5p. Compared with miR-NC group, proliferation activity of cells, percentage of cells in S phase, and expressions of CDK2, CCNB1 and Bcl2 proteins were increased, while percentage of cells in G0/G1 phase, apoptosis rate and the expression of BAX protein were decreased in miR-181b-5p group. Compared with miR-181b-5p group, proliferation activity of cells, percentage of cells in S phase, and expressions of CDK2, CCNB1 and Bcl2 proteins were decreased, while percentage of cells in G0/G1 phase, apoptosis rate and the expression of BAX protein were increased in miR-181b-5p combined with PAX9 group. Conclusion The miR-181b-5p can promote the proliferation of AML cells and delay apoptosis by inhibiting PAX9.
Humans ; Apoptosis/genetics* ; bcl-2-Associated X Protein ; Cell Line, Tumor ; Cell Proliferation/genetics* ; Leukemia, Myeloid, Acute/pathology* ; Luciferases ; MicroRNAs/metabolism* ; PAX9 Transcription Factor/genetics*

Objective: To investigate the prognostic significance of interferon regulatory factor 9 (IRF9) expression and identify its role as a potential therapeutic target in acute promyelocytic leukemia (APL) . Methods: The gene expression profile and survival data applied in the bioinformatic analysis were obtained from The Cancer Genome Atlas and Beat acute myeloid leukemia (AML) cohorts. A dox-induced lentiviral system was used to induce the expression of PML-RARα (PR) in U937 cells, and the expression level of IRF9 in U937 cells treated with or without ATRA was examined. We then induced the expression of IRF9 in NB4, a promyelocytic leukemia cell line. In vitro studies focused on leukemic phenotypes triggered by IRF9 expression. Results: ①Bioinformatic analysis of the public database demonstrated the lowest expression of IRF9 in APL among all subtypes of AML, with lower expression associated with worse prognosis. ②We successfully established a PR-expression-inducible U937 cell line and found that IRF9 was downregulated by the PR fusion gene in APL, with undetectable expression in NB4 promyelocytic cells. ③An IRF9-inducible NB4 cell line was successfully established. The inducible expression of IRF9 promoted the differentiation of NB4 cells and had a synergistic effect with lower doses of ATRA. In addition, the inducible expression of IRF9 significantly reduced the colony formation capacity of NB4 cells. Conclusion: In this study, we found that the inducible expression of PR downregulates IRF9 and can be reversed by ATRA, suggesting a specific regulatory relationship between IRF9 and the PR fusion gene. The induction of IRF9 expression in NB4 cells can promote cell differentiation as well as reduce the colony forming ability of leukemia cells, implying an anti-leukemia effect for IRF9, which lays a biological foundation for IRF9 as a potential target for the treatment of APL.
Cell Differentiation ; Humans ; Interferon-Stimulated Gene Factor 3, gamma Subunit/metabolism* ; Leukemia, Myeloid, Acute/drug therapy* ; Leukemia, Promyelocytic, Acute/genetics* ; Oncogene Proteins, Fusion/metabolism* ; Phenotype ; Tretinoin/therapeutic use* ; U937 Cells

: AbstractObjective: To identify the expression and methylation patterns of lncRNA CASC15 in bone marrow (BM) samples of acute myeloid leukemia (AML) patients, and further explore its clinical significance. METHODS: Eighty-two de novo AML patients and 18 healthy donors were included in the study. Meanwhile, seven public datasets from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) were included to confirm the expression and methylation data of CASC15. Receiver operating characteristic (ROC) curve analysis was applied to determine the discriminative capacity of CASC15 expression to identify AML. The patients were divided into CASC15high group and CASC15low group by X-tile method, and the prognostic value of CASC15 was identified by Kaplan-Meier method and univariate and multivariate Cox regression analysis. RESULTS: The expression level of CASC15 was significantly decreased in BM cells of AML patients compared with healthy donors (P<0.001). ROC curve analysis suggested that CASC15 expression might be a potential biomarker to discriminate AML from controls. The expression of CASC15 was high at the early stage of hematopoiesis, and reached a peak at the stage of multipotent progenitors differentiation, then decreased rapidly, and was at a range of low level fluctuations in the subsequent process. Among FAB subtypes, CASC15 expression in M0 was significantly higher than that in M1-M7. Clinically, CASC15low patients were more likely to have NPM1 mutations than CASC15high patients (P=0.048), while CASC15high patients had a significantly higher frequency of IDH1 and RUNX1 mutations (P=0.021 and 0.014, respectively). Moreover, CASC15low group had a shorter overall survival (OS) in patients with NPM1 mutations. Furthermore, multivariate analysis confirmed that CASC15 expression was a significant independent risk factor for OS in NPM1 mutated AML patients. In addition, CASC15 methylation level in BM samples of AML patients was significantly decreased compared with healthy donors. Patients with CASC15 high methylation had poor OS and disease-free survival. CONCLUSION The expression of CASC15 is decreased in AML, and low CASC15 expression may predict adverse prognosis in AML patients with NPM1 mutations. Moreover, CASC15 methylation level in AML is significantly decreased, and high CASC15 methylation may predict poor prognosis in AML.
Humans ; Leukemia, Myeloid, Acute/metabolism* ; Mutation ; Nuclear Proteins/genetics* ; Nucleophosmin/genetics* ; Prognosis ; RNA, Long Noncoding/genetics*

OBJECTIVE: To explore the expression patterns, prognostic implications, and biological role of leukotriene B4 receptor (LTB4R) in patients with acute myeloid leukemia (AML). METHODS: We collected the data of mRNA expression levels and clinical information of patients with AML from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database for mRNA expression analyses, survival analyses, Cox regression analyses and correlation analyses using R studio to assess the expression patterns and prognostic value of LTB4R. The correlation of LTB4R expression levels with clinical characteristics of the patients were analyzed using UALCAN. The co-expressed genes LTB4R were screened from Linkedomics and subjected to functional enrichment analysis. A protein-protein interaction network was constructed using STRING. GSEA analyses of the differentially expressed genes (DEGs) were performed based on datasets from TCGA-LAML stratified by LTB4R expression level. We also collected peripheral blood mononuclear cells (PBMCs) from AML patients and healthy donors for examination of the mRNA expression levels of LTB4R and immune checkpoint genes using qRT-PCR. We also examined serum LTB4R protein levels in the patients using ELISA. RESULTS: The mRNA expression level of LTB4R was significantly increased in AML patients (4.898±1.220 vs 2.252±0.215, P < 0.001), and an elevated LTB4R expression level was correlated with a poor overall survival (OS) of the patients (P=0.004, HR=1.74). LTB4R was identified as an independent prognostic factor for OS (P=0.019, HR=1.66) and was associated with FAB subtypes, cytogenetic risk, karyotype abnormalities and NPM1 mutations. The co- expressed genes of LTB4R were enriched in the functional pathways closely associated with AML leukemogenesis, including neutrophil inflammation, lymphocyte activation, signal transduction, and metabolism. The DEGs were enriched in differentiation, activation of immune cells, and cytokine signaling. Examination of the clinical serum samples also demonstrated significantly increased expressions of LTB4R mRNA (P=0.044) and protein (P=0.008) in AML patients, and LTB4R mRNA expression was positively correlated with the expression of the immune checkpoint HAVCR2 (r= 0.466, P=0.040). CONCLUSION LTB4R can serve as a novel biomarker and independent prognostic indicator of AML and its expression patterns provide insights into the crosstalk of leukemogenesis signaling pathways involving tumor immunity and metabolism.
Humans ; Leukemia, Myeloid, Acute/metabolism* ; Leukocytes, Mononuclear/metabolism* ; Prognosis ; RNA, Messenger/metabolism* ; Receptors, Leukotriene B4/genetics*

OBJECTIVE: To investigate the relationship between AML1-ETO (AE) fusion gene and intracellular N6-methyladenosine (m6A) modification pattern in t(8;21) acute myeloid leukemia (AML). METHODS: RNA m6A sequencing was performed in SKNO-1 and AE knockdown SKNO-1 (SKNO-1 siAE) cells using RNA-protein co-immunoprecipitation and high-throughput sequencing (methylated RNA immunoprecipitation sequencing, MeRIP-Seq) to analyze the changes in m6A modification of the entire transcriptome. Transcriptome sequencing (RNA-seq) was performed using high-throughput sequencing. The differentially modified mRNAs were further functionally annotated by Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The changes in m6A-related enzyme expressions were detected using real-time PCR. RESULTS: A total of 26 441 genes were identified in AE knockdown AML cells and AE-expressing cells, containing 72 036 m6A peaks. AE knockdown caused a reduction of the number of intracellular m6A peaks from 37 042 to 34 994, among which 1278 m6A peaks were significantly elevated and 1225 were significantly decreased; 1316 genes with newly emerged m6A modification were detected and 1830 genes lost m6A modification after AE knockdown. The differential peaks were mainly enriched in pathways involving cancer and human T-lymphocytic leukemia virus I. RNA-seq results showed that 2483 genes were up-regulated and 3913 genes were down-regulated after AE knockdown. The combined analysis of MeRIP-Seq and RNA-Seq results revealed relatively high expression levels of m6A-modified genes as compared with the genes without m6A modification (SKNO-1: 0.6116±1.263 vs 2.010±1.655, P < 0.0001; SKNO-1 siAE: 0.5528±1.257 vs 2.067±1.686, P < 0.0001). The m6A modified genes located in the 3'UTR or 5 'UTR had significantly higher expression levels than those located in exonic regions (SKNO-1: 2.177± 1.633 vs 1.333 ± 1.470 vs 2.449 ± 1.651, P < 0.0001; SKNO-1 siAE: 2.304 ± 1.671 vs 1.336 ± 1.522 vs 2.394 ± 1.649, P < 0.05). Analysis of RNA-seq data identified 3 m6A-related enzymes that showed significantly elevated mRNA expression after AE knockdown, namely WTAP, METTL14, and ALKBH5 (P < 0.05), but the results of real-time PCR showed that the expressions of WTAP and ALKBH5 were significantly increased while the expression of METTL14 was lowered after AE knockdown (P < 0.05). CONCLUSION AE knockdown results in differential expressions of m6A-associated enzymes, suggesting that the AE fusion gene regulates the expression of one or more m6A-associated enzymes to control cellular methylation levels.
Adenosine/analogs & derivatives* ; Humans ; Leukemia, Myeloid, Acute/genetics* ; RNA, Messenger/metabolism* ; Transcriptome