OBJECTIVE: To investigate the synergistic effect and its mechanism of ginsenoside-Rg5 in combination with imatinib in inhibiting proliferation of chronic myeloid leukemia K562 cells. METHODS: K562 cells were treated with ginsenoside-Rg5 and imatinib. Cell survival was detected by CCK-8 assay, and IC₅₀ were calculated separately for each drug. Based on the value of IC₅₀ of ginsenoside-Rg5 and imatinib, an appropriate concentration gradient was selected for the combination. The synergistic effect of the two drug was analyzed using the online software synergy finder. The effects of single or combination therapy on apoptosis rate and the cell cycle distribution of K562 cells were analyzed by flow cytometry. Western blot was used to detect the expression of PI3K/AKT/mTOR signaling pathway related proteins and apoptosis related proteins in K562 cells after single or combination therapy. RESULTS: Ginsenoside-Rg5 and imatinib were able to inhibit the proliferative activity of K562 cells in a dosedependent manner(r =-0.991， r =-0.942). The synergy score ZIP >10 was measured by Synergy Finder online software, indicating that ginsenoside-Rg5 and imatinib act synergistically on K562 cells. The apoptotic rates of K562 cells after single treatments with ginsenoside-Rg5 and imatinib were 11.96% and 8.13%, respectively, while the rate increased to 21.35% with the combination of two drugs, the apoptosis rate in the combination group was higher than that in the single-drug group ( P <0.05). The proportion of K562 cells in the G₀/G₁ phase was significantly increased with the combined treatment of two drugs( P <0.05). The protein expression levels of p-PI3K, p-AKT, p-mTOR in K562 cells treated with the combination were significantly decreased, with noticeable downregulation of BCL-2 and upregulation of BAX, leading to a decreased Bcl-2/BAX ratio, while no significant changes were observed in the non-phosphorylated forms of PI3K, AKT, and mTOR proteins. CONCLUSION The combination of ginsenoside-Rg5 and imatinib can inhibit the proliferation of CML cells and induce apoptosis, and the mechanism may act through PI3K/AKT/mTOR signaling pathways.
Humans ; Ginsenosides/pharmacology* ; Imatinib Mesylate ; K562 Cells ; TOR Serine-Threonine Kinases/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Signal Transduction/drug effects* ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism* ; Drug Synergism ; Apoptosis/drug effects* ; Phosphatidylinositol 3-Kinases/metabolism* ; Cell Proliferation/drug effects*

OBJECTIVE: To investigate the metabolic characteristics of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) in myeloid leukemia by in vitro culture of myeloid leukemia cells and construction of tumor-bearing nude mouse model. METHODS: U937, THP-1, HL60 and K562 cells were cultured in vitro. The cells in logarithmic growth phase (l×10 ⁵ cells/well) were added with ¹⁸F-FDG, and the uptake rate of ¹⁸F-FDG was measured at 15, 30, 60 and 120 min after addation, respectively. The four kinds of cells were inoculated subcutaneously into the hind limbs of nude mice to establish a tumor-bearing nude mouse model. When the tumor size was about 500 mm³, ¹⁸F-FDG was injected through the tail vein of the mice, and positron emission tomography/computed tomography was performed at 60 min after injection. The morphology of tumor-bearing cells was observed by hematoxylin-eosin (HE) staining in serial pathological sections. RESULTS: After co-incubation with ¹⁸F-FDG, the ¹⁸F-FDG uptake rates of U937 cells were significantly higher than THP-1, HL60 and K562 cells at 4 time points (all P <0.05), and THP-1 cells were higher than K562 cells (all P <0.05). The uptake rate of ¹⁸F-FDG by leukemia cells was rapid in the first 60 min, then tended to be stable. Pathological analysis showed that subcutaneous inoculation of U937, THP-1, HL60 and K562 cells could successfully establish tumor-bearing nude mouse models of myeloid leukemia. The ¹⁸F-FDG uptake value in U937 tumor-bearing nude mice was significantly higher than THP-1, HL60 and K562 tumor-bearing nude mice (all P <0.01). The ¹⁸F-FDG uptake values in THP-1 and HL60 tumor-bearing nude mice were significantly higher than that in K562 tumor-bearing nude mice (both P <0.01). CONCLUSION The tumor-bearing nude mouse model of myeloid leukemia can be successfully constructed by subcutaneous inoculation. The ¹⁸F-FDG uptake rate of acute myeloid leukemia (AML) cells is higher in cells cultured in vitro and tumor-bearing nude mouse model. ¹⁸F-FDG may have better clinical application value for AML.
Animals ; Fluorodeoxyglucose F18/metabolism* ; Mice, Nude ; Mice ; Humans ; Leukemia, Myeloid/diagnostic imaging* ; HL-60 Cells ; K562 Cells ; Cell Line, Tumor ; U937 Cells

OBJECTIVE: To investigate the effect of piperlongumine(PL) on the proliferation and ferroptosis of human adriamycin-resistant chronic myeloid leukemia K562/ADR cells, and to explore its possible molecular mechanism. METHODS: CCK-8 assay was used to detect the effect of PL on the survival rate of K562/ADR cells and to screen the appropriate drug concentration. After K562/ADR cells were treated with low, medium and high concentrations of PL(2, 4, and 6 μmol/L), EdU proliferation assay and plate colony formation assay were used to detect cell proliferation and colony formation ability. CCK-8 assay was used to detect the effects of different inhibitors (Fer-1, Z-VAD, Nec-1) combined with PL on cell proliferation. The intracellular Fe²⁺, ROS, malondialdehyde(MDA) and glutathine(GSH) contents were respectively detected by iron ion colorimetry, DCFH-DA fluorescent probe, MDA and GSH kits. RT-qPCR and Western blot were respectively used to detect the expression level of GPX4 mRNA and protein in cells. Bioinformatics websites predicted miRNA that could target and regulate GPX4 . RT-qPCR was used to detect the effects of different concentrations of PL on the expression levels of the predicted miRNA. Dual luciferase gene reporter assay was used to verify the targeting relationship between miR-214-3p and GPX4 . After treating cells with PL or PL+miR-214-3p inhibitor, the Fe²⁺, ROS, MDA, GSH centents and GPX4 protein expression levels in cells were detected. RESULTS: PL inhibited K562/ADR cell proliferation in a concentration-dependent manner（r =0.979）. Compared with the blank control group, the survival rate, EdU positive cells rate in low, medium and high concentration PL groups were significantly decreased (P < 0.01). Compared with the PL group alone, the survival rate of cells in the Z-VAD+PL group was increased slightly (P < 0.05). The cell survival rate was significantly increased in medium or high concentration PL+Fer-1 group (P < 0.01). Compared with blank control group, ROS expression level in low concentration PL group was slightly increased (P < 0.05), and GSH content was slightly decreased (P < 0.05). In medium and high concentration PL groups, the contents of Fe²⁺, ROS and MDA were significantly increased (P < 0.01), while the contents of GSH, expression of GPX4 mRNA and protein were significantly decreased(P < 0.01). Bioinformatics prediction and double luciferase reporter gene experiment confirmed the targeting relationship between GPX4 and miR-214-3p. Compared with the blank control group, the expression level of miR-214-3p in cells of medium and high concentration PL groups was significantly increased (P < 0.01). Compared with PL group alone, the intracellular Fe²⁺, ROS and MDA contents in PL+miR-214-3p inhibitor group were all decreased (P < 0.01), while GSH content and GPX4 protein expression levels were significantly increased (P < 0.01). CONCLUSION Medium and high concentrations of PL can inhibit the proliferation of K562/ADR cells by inducing ferroptosis, which is related to the regulation of miR-214-3p pathway.
Humans ; Ferroptosis/drug effects* ; MicroRNAs/metabolism* ; Dioxolanes/pharmacology* ; Cell Proliferation/drug effects* ; K562 Cells ; Phospholipid Hydroperoxide Glutathione Peroxidase ; Reactive Oxygen Species ; Doxorubicin/pharmacology* ; Signal Transduction ; Piperidones

OBJECTIVES: To investigate the role of METTL3 and FOXO3 in anthracycline resistance in acute myeloid leukemia (AML) cells. METHODS: Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and transcriptome sequencing (RNA-seq) were performed in anthracycline-resistant and sensitive HL60 and K562 cells with lentivirus-mediated knockdown or overexpression of METTL3 and FOXO3. TCGA and GSE6891 datasets were used for analysis of the clinical and gene expression data of AMI patients. FOXO3 expressions at the mRNA and protein levels in the transfected cells were detected with RT-qPCR and Western blotting, and the changes in cell proliferation and apoptosis were evaluated using CCK8 assay and flow cytometry; the expression of m⁶A-modified mRNA and mRNA stability of FOXO3 was detected analyzed using MeRIP-qPCR and RT-qPCR. Functional enrichment analysis of the differential genes in the transfected cells was performed. RESULTS: Differential gene analysis in anthracycline-resistant versus sensitive AML cells and in cells with METTL3 knockdown revealed the enrichment in FoxO and autophagy pathways (P<0.05), and the anthracycline-resistant cells showed significantly increased m⁶A modification of FOXO3. FOXO3 expression was positively correlated with METTL3 expression. METTL3 knockdown significantly reduced FOXO3 mRNA stability and its protein levels in anthracycline-resistant AML cells, which exhibited higher m6A-modified FOXO3 expression levels than their sensitive counterparts. Database analysis, Kaplan-Meier analysis and RT-qPCR results suggested that a high FOXO3 expression was associated with a poor prognosis of AML patients. In anthracycline-resistant AML cells expressing higher FOXO3 levels than the sensitive cells, lentivirus-mediated overexpression of FOXO3 significantly enhanced cell proliferation and suppressed cell apoptosis. Inhibiting autophagy using an autophagy inhibitor (Baf.A1) obviously enhanced the inhibitory effect of adriamycin on resistant AMI cells and cells overexpressing FOXO3. CONCLUSIONS METTL3 promotes FOXO3 expression via m6A modification, and FOXO3-driven autophagy contributes to anthracycline resistance in AML cells by enhancing cell proliferation and suppressing cell apoptosis.
Humans ; Forkhead Box Protein O3/genetics* ; Leukemia, Myeloid, Acute/genetics* ; Drug Resistance, Neoplasm ; Methyltransferases/genetics* ; Autophagy ; Anthracyclines/pharmacology* ; HL-60 Cells ; Apoptosis ; Cell Proliferation ; K562 Cells

OBJECTIVE: To investigate the effect of Cyr61 on imatinib (IM) resistance in chronic myeloid leukemia (CML) and its mechanism. METHODS: Cyr61 level in cell culture supernatant was determined by enzyme-linked immunosorbent assay. The expression of Cyr61 and Bcl-xL were measured by real-time PCR and Western blot. Cell apoptosis was analyzed using an Annexin V-APC Kit. Expression of signal pathways related proteins was determined by Western blot. RESULTS: The level of Cyr61 obviously increased in K562G cells (IM resistance to CML cell line K562). Down-regulating the expression of Cyr61 decreased the resistance of K562G cells to IM and promoted IM induced apoptosis. In CML mouse model, down-regulating the expression of Cyr61 could increase the sensitivity of K562G cells to IM. The mechanism studies showed that Cyr61 mediated IM resistance in CML cells was related to the regulation of ERK1/2 pathways and apoptosis related molecule Bcl-xL by Cyr61. CONCLUSION Cyr61 plays an important role in promoting IM resistance of CML cells. Targeting Cyr61 or its related effectors pathways may be one of the ways to overcome IM resistance of CML cells.
Animals ; Humans ; Mice ; Apoptosis ; Drug Resistance, Neoplasm ; Imatinib Mesylate/pharmacology* ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism* ; Signal Transduction

OBJECTIVE: To explore the expression pattern and clinical significance of Integral membrane protein 2A（ITM2A） in drug resistant patients with chronic myeloid leukemia (CML). METHODS: The expression of ITM2A in CML was evaluated by qRT-PCR, Western blot and immunocytochemistry. In order to understand the possible biological effects of ITM2A, apoptosis, cell cycle and myeloid differentiation antigen expression of CML cells were detected by flow cytometry after over-expression of ITM2A. The nuderlying molecular mechanism of its biological effect was explored. RESULTS: The expression of ITM2A in bone marrow of CML resistant patients was significantly lower than that of sensitive patients and healthy donors（P<0.05）. The CML resistant strain cell K562R was successfully constructed in vitro. The expression of ITM2A in the resistant strain was significantly lower than that in the sensitive strain(P<0.05). Overexpression of ITM2A in K562R cells increased the sensitivity of K562R cells to imatinib and blocked the cell cycle in G₂ phase(P<0.05), but did not affect myeloid differentiation. Mechanistically, up-regulation of ITM2A reduced phosphorylation in ERK signaling (P<0.05). CONCLUSION The expression of ITM2A was low in patients with drug resistance of CML, and the low expression of ITM2A may be the key factor of imatinib resistance in CML.
Humans ; Antineoplastic Agents/pharmacology* ; Apoptosis ; Drug Resistance, Neoplasm ; Imatinib Mesylate/therapeutic use* ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy* ; Signal Transduction

OBJECTIVE: To explore the effect of dichloromethane extraction phase of ethanol extract from stem of Patrinia scabiosaefolia Fisch.(DPSS) on proliferation and differentiation of K562 cells and its related mechanism. METHODS: MTT assay was used to detect the effects of DPSS at 0, 25, 50, 100 and 200 μg/ml on the proliferation of K562 cells at 24, 48 and 72 hours. Flow cytometry was used to analyze the changes of cell cycle and apoptosis at 24 and 48 hours. Wright-Giemsa staining was used to observe the morphological changes of K562 cells. The cell surface antigens CD33 and CD11b were detected by flow cytometry. RESULTS: The proliferation of K562 cells treated with different concentrations of DPSS was inhibited in a time-dose dependent manner (r=-0.96). Cell cycle analysis showed that with the increase of DPSS concentration, cells in G₂/M phase increased (r=0.88), and cells were blocked in G₂/M phase. Flow cytometry results showed that with the apoptosis rate of K562 cells was the highest when treated with 200 μg/ml DPSS for 48 h. Morphological observation showed that the K562 cell body increased, the amount of cytoplasm increased, the ratio of nucleus to cytoplasm decreased, and the nuclear chromatin was rough after DPSS treatment. Cell differentiation antigen, CD33 and CD11b, were positively expressed after treated with DPSS. CONCLUSION DPSS can induce apoptosis through cell cycle arrest, inhibit the proliferation of K562 cells, and induce K562 cells to differentiate into monocytes, which has a potential anti-leukemia effect.
Humans ; K562 Cells ; Patrinia ; Methylene Chloride/pharmacology* ; Apoptosis ; Cell Proliferation ; Cell Differentiation

OBJECTIVE: To investigate the effects of miR-144-3p on cell proliferation, cell cycle and apoptosis of blast phase chronic myelogenous leukemia (CML) K562 cells. METHODS: K562 cells were cultured in vitro and mimics negative control, hsa-miR-144-3p mimics, inhibitor negative control and miR-144-3p inhibitor were respectively transfected into K562 cells with transfection reagents. The cells were divided into five groups including blank control, mimics negative control, miR-144-3p mimics, inhibitor negative control and miR-144-3p inhibitor. After transfection, the cell proliferation activity was detected by CCK-8 assay. The cell cycle distribution and apoptosis were detected by flow cytometry. RESULTS: Compared with the blank control and mimics negative control groups, the proliferation rate of miR-144-3p mimics group was significantly decreased (P<0.05), the proportion of S phase cells was markedly increased (P<0.05), while the proportion of G₁ phase cells was obviously decreased (P<0.05), and the apoptosis rate was significantly increased (P<0.05). Compared with the blank control and inhibitor negative control groups, the proliferation rate of miR-144-3p inhibitor group was obviously increased (P<0.05), the proportion of S phase cells was markedly decreased (P<0.05), while the proportion of G₁ phase cells was obviously increased (P<0.05), and the apoptosis rate was significantly decreased (P<0.05). CONCLUSION miR-144-3p can inhibit the proliferation and promote apoptosis of K562 cells, affect the cell cycle, and block K562 cells in S phase, which indicates that miR-144-3p is involved in the cell cycle activity of CML during blastic phase.
Humans ; Apoptosis/genetics* ; Cell Cycle/genetics* ; Cell Line, Tumor ; Cell Proliferation/genetics* ; K562 Cells ; MicroRNAs/metabolism*

OBJECTIVE: To investigate the effect and underlying mechanism of hispidulin on the proliferation and apoptosis of leukemia K562 cells. METHODS: K562 cells were cultured in vitro and treated with 0, 5, 25 or 100 μmol/L hispidulin for 24 h. Cell proliferation and apoptosis were detected by CCK-8 and flow cytometry, respectively. Western blot was used to assess the expression of Bax, Bcl-2 and interleukin (IL)-37 proteins. Bone marrow mononuclear cells were extracted from 17 chronic myeloid leukemia patients and 21 healthy individuals by Ficoll-Hypaque density gradient method, and the expression of IL-37 protein was measured by Western blot. K562 cells with IL-37 overexpression or knockdown were constructed, and then treated with 0 or 100 μmol/L hispidulin for 24 h. Cell proliferation, apoptosis and protein expression of Bax and Bcl-2 were determined in the same way as above. RESULTS: After K562 cells were treated with hispidulin, the cell inhibition rate, apoptosis rate, and the protein expression of Bax and IL-37 were significantly increased (P <0.05), but the cell proliferation and expression of Bcl-2 protein were decreased (P <0.05). The expression of IL-37 protein in bone marrow mononuclear cells of the leukemia patient was 0.24±0.03, which was significantly lower than 0.91±0.05 of healthy controls (P <0.05). Overexpression of IL-37 significantly promoted inhibition rate, apoptosis rate, and expression of Bax protein in K562 cells (P <0.05), but suppressed the expression of Bcl-2 protein (P <0.05). In addition, knockdown of IL-37 could reverse the effects of hispidulin on proliferation and apoptosis of K562 cells. CONCLUSION Hispidulin inhibits the proliferation and induces apoptosis of leukemia K562 cells, which may be related to the up-regulation of IL-37 protein in cells.
Humans ; K562 Cells ; bcl-2-Associated X Protein/pharmacology* ; Apoptosis ; Leukemia ; Proto-Oncogene Proteins c-bcl-2 ; Cell Proliferation

BACKGROUND: Imatinib mesylate (IM) resistance is an emerging problem for chronic myeloid leukemia (CML). Previous studies found that connexin 43 (Cx43) deficiency in the hematopoietic microenvironment (HM) protects minimal residual disease (MRD), but the mechanism remains unknown. METHODS: Immunohistochemistry assays were employed to compare the expression of Cx43 and hypoxia-inducible factor 1α (HIF-1α) in bone marrow (BM) biopsies of CML patients and healthy donors. A coculture system of K562 cells and several Cx43-modified bone marrow stromal cells (BMSCs) was established under IM treatment. Proliferation, cell cycle, apoptosis, and other indicators of K562 cells in different groups were detected to investigate the function and possible mechanism of Cx43. We assessed the Ca 2+ -related pathway by Western blotting. Tumor-bearing models were also established to validate the causal role of Cx43 in reversing IM resistance. RESULTS: Low levels of Cx43 in BMs were observed in CML patients, and Cx43 expression was negatively correlated with HIF-1α. We also observed that K562 cells cocultured with BMSCs transfected with adenovirus-short hairpin RNA of Cx43 (BMSCs-shCx43) had a lower apoptosis rate and that their cell cycle was blocked in G0/G1 phase, while the result was the opposite in the Cx43-overexpression setting. Cx43 mediates gap junction intercellular communication (GJIC) through direct contact, and Ca 2+ is the key factor mediating the downstream apoptotic pathway. In animal experiments, mice bearing K562, and BMSCs-Cx43 had the smallest tumor volume and spleen, which was consistent with the in vitro experiments. CONCLUSIONS Cx43 deficiency exists in CML patients, promoting the generation of MRD and inducing drug resistance. Enhancing Cx43 expression and GJIC function in the HM may be a novel strategy to reverse drug resistance and promote IM efficacy.
Animals ; Humans ; Mice ; Apoptosis ; Bone Marrow Cells ; Cell Communication ; Connexin 43/genetics* ; Gap Junctions/metabolism* ; Imatinib Mesylate/therapeutic use* ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology* ; Mesenchymal Stem Cells/metabolism* ; Tumor Microenvironment ; Calcium/metabolism*