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*

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 investigate the expression and significance of regulatory T cells (Tregs), FoxP3 and transforming growth factor-β (TGF-β) in different phase of chronic myeloid leukemia (CML). METHODS: Peripheral blood of 73 CML patients in Department of Hematology, Heze Municipal Hospital from March 2018 to March 2021 were collected. According to patient's period in CML, they were divided into ND CML group (newly diagnosed), CP CML group (chronic period), and BP CML group (blast phase). The percentage of Tregs, expression level of FoxP3 mRNA and TGF-β were detected by flow cytometry, RT-qPCR, and ELISA, respecitively. The roles of above indices in clinical pathogenesis of patients with CML were analyzed. RESULTS: The proportion of Treg in the ND CML group was slightly higher than the CP CML group, but the difference was not statistically significant (P =0.695), while the BP CML group was significantly higher than the other two groups (P =0.008, P <0.001). The expression levels of FoxP3 mRNA in ND CML group, CP CML group and BP CML group were 11.61±2.21, 6.46±1.35 and 8.54±2.13, respectively. Significant difference in FoxP3 mRNA levels was observed among patients in different phases of CML (F =55.199, P <0.001). The expression levels of FoxP3 mRNA both in ND CML group and BP CML group were significantly higher than that in CP CML group (P <0.001), and the ND CML group was the highest (P <0.001). However, the expression levels of TGF-β in different phases of CML showed no statistical differences (H =0.634, P =0.728). CONCLUSION The abnormal distribution of Treg subset in different phases of CML and the significant increase of the expression level of FoxP3 mRNA in the new onset and blast phase of CML suggest that Tregs may promote the occurrence and progression of CML through immune regulation.
Humans ; Blast Crisis/metabolism* ; Forkhead Transcription Factors/metabolism* ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics* ; RNA, Messenger/metabolism* ; T-Lymphocytes, Regulatory/metabolism* ; Transforming Growth Factor beta/metabolism*

OBJECTIVE: To investigate the effects of dasatinib on the maturation of monocyte-derived dendritic cells (moDCs) derived from healthy donors (HDs) and chronic myelogenous leukemia (CML) patients. METHODS: Peripheral blood mononuclear cells (PBMCs) were isolated from HDs (n=10) and CML patients (n=10) who had got the remission of MR4.5 with imatinib treatment. The generation of moDCs from PBMCs was completed after 7 days of incubation in DC I culture medium, and another 3 days of incubation in DC II culture medium with or without 25 nmol/L dasatinib. On the 10th day, cells were harvested and expression of molecules of maturation related marker were assessed by flow cytometry. The CD80⁺CD86⁺ cell population in total cells was gated as DCs in the fluorescence-activated cell storting (FACS) analyzing system, then the expression of CD83, CD40 or HLA-DR in this population was analyzed respectively. RESULTS: The proportion of CD80⁺CD86⁺ cells in total cells didn't show a statistical difference between HD group and patient group (89.46%±9.70% vs 87.39%±9.34%, P=0.690). Dasatinib significantly enhanced the expression of the surface marker CD40 (P=0.008) and HLA-DR (P=0.028) on moDCs derived from HDs compared with the control group, while the expression of CD83 on moDCs didn't show a significant difference between dasatinib group and the control group (P=0.428). Meanwhile, dasatinib significantly enhanced the expression of the surface marker CD40 (P=0.023), CD83 (P=0.038) and HLA-DR (P=0.001) on moDCs derived from patients compared with the control group. CONCLUSION For CML patients, the same high proportion of moDCs as HDs can be induced in vitro, which provides a basis for the application of DC-based immunotherapy strategy. Dasatinib at the concentration of 25 nmol/L can efficiently promote the maturation of moDCs derived from HDs and CML patients in vitro. Dasatinib shows potential as a DC adjuvant to be applied in DC-based immunotherapy strategies, such as DC vaccine and DC cell-therapy.
Cell Differentiation ; Cells, Cultured ; Dasatinib/pharmacology* ; Dendritic Cells ; HLA-DR Antigens/pharmacology* ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism* ; Leukocytes, Mononuclear ; Monocytes

OBJECTIVE: To explore the combined pro-apoptosis effect of HSP90 inhibitor BIIB021 and chloroquine (CQ) in chronic myeloid leukemia (CML) cells bearing T315I mutation and its mechanism. METHODS: The p210-T315I cells were divided into 4 groups by different treatment: control, BIIB021, CQ, and BIIB021 + CQ. After treated with BIIB021 or/and CQ for 24 hours, Annexin V/PI binding assay was used to detect apoptosis rates of CML cells. DAPI staining was used to observe nuclear fragmentation, and Western blot was used to detect the expression of caspase 3, PARP (apoptosis related proteins) and p62, LC3-I/II (autophagy related proteins). P210-T315I cells were inoculated subcutaneously into mice and CML mouse models were established. The mice in treatment groups were injected with BIIB021 and/or CQ while mice in control group were treated with PBS and normal saline. The tumor volume of mice was measured every 4 days, and protein level of cleaved-caspase 3 and LC3-II in tumor tissue were detected by immunohistochemistry. RESULTS: The results showed that BIIB021 induced apoptosis of CML cells in a dose-dependent manner ( r=0.91). CQ could enhance the apoptosis-inducing effect of BIIB021. Flow cytometry analysis results showed that the apoptosis rate of p210-T315I cells in combination group was higher than that in BIIB021 or CQ only group (P<0.05). DAPI staining showed nuclear fragmentation in combination group could be observed more obviously. Western blot analysis showed that BIIB021 could induce LC3-I to convert to LC3-II and decrease p62 protein levels (P<0.05). Moreover, the combination group had higher expression of LC3-II, p62 (P<0.05), activated PARP and activated caspase 3 than BIIB021 only group (P<0.05). Besides, experiment in vivo showed the mean tumor volume in co-treatment group was lower than that in single drug group (P<0.01). Immunohistochemistry of tumor tissue also showed the protein level of cleaved-caspase 3 and LC3-II in combined group was higher than that in BIIB021 only group. CONCLUSION HSP90 inhibitor BIIB021 induced significant apoptosis of CML cells bearing T315I both in vivo and in vitro. CQ can enhance this effect probably by autophagy inhibition.
Adenine/analogs & derivatives* ; Animals ; Apoptosis ; Autophagy ; Caspase 3/metabolism* ; Cell Line, Tumor ; Chloroquine/therapeutic use* ; Fusion Proteins, bcr-abl/pharmacology* ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy* ; Mice ; Mutation ; Poly(ADP-ribose) Polymerase Inhibitors/therapeutic use* ; Pyridines

OBJECTIVE: To investigate the effect of silencing DNA methyltransferase 1(DNMT1) to the methylation of the promoter of the tumor suppressor gene wnt-1 (WIF-1) in human chronic myeloid leukemia (CML) cells. METHODS: DNMT1 siRNAi plasmid was constructed and DNMT1 siRNAi was transfected into CML K562 cells. RT-PCR and Western blot were used to detect the expression of DNMT1 gene and related protein, and methylation PCR was used to detect WIF-1 gene promoter methylation level. The trypan blue exclusion and MTT assay were used to detect the cell proliferation, flow cytometry were used to detect the cell apoptosis rate, colony formation assay was used to detect cell colony formation ability. Expression of Wnt/β- catenin and its downstream signaling pathway proteins were detected by Western blot after DNMT1 gene was silenced. RESULTS: The expression level of DNMT1 mRNA and its related protein in the experimental group were significantly lower than those in the control group and negative control group (P<0.05). After 72 hours of successful transfection, the WIF-1 gene in the control group and negative control group were completely methylated, while in the experimental group, the methylation level significantly decreased. The results of MSP showed that the PCR product amplified by the unmethylated WIF-1 primer in the experimental group increased significantly,while by the methylated WIF-1 primer decreased significantly. After 48 h of transfection, the OD value, viable cell number and colony formation of the cells in experimental group were significantly lower than those in the negative control group and the control group (P<0.05). The apoptosis rate of the cells in experimental group was significantly higher than those in the negative control group and control group (P<0.05). The expression levels of β- actin, myc, cyclin D1 and TCF-1 in K562 cells in the experimental group were significantly lower than those in the negative control group and control group (P<0.05). CONCLUSION Silencing DNMT1 gene can inhibit the proliferation and promote the apoptosis of K562 cells. The mechanism may be related to reverse the hypermethylation level of the WIF-1 gene promoter, thereby inhibit the activity of the Wnt/β- catenin signaling pathway.
Adaptor Proteins, Signal Transducing/metabolism* ; DNA Methylation ; Humans ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics* ; Repressor Proteins/metabolism*

OBJECTIVE: To explore the expression of CPEB4 in K562 cells, the biological activity and its possible molecular mechanisms. METHODS: Western blot was used to detect the expression of CPEB4 in normal leukocytes and K562 cells. The overexpression plasmid pcDNA3.1(+)-His-CPEB4 and the silencing plasmid pPLK+Puro-CPEB4 shRNA were transfected into K562 cells to change the expression of CPEB4 in K562 cells, and the transfection efficiency was detected by Western blot. Finally, CCK-8 and flow cytometry were used to detect the proliferation and apoptosis of differently treated cells, and the expression changes of proliferation and apoptosis marker proteins (AKT, p-AKT, caspase-3, BCL-2) were detected by Western blot. RESULTS: Compared with normal leukocytes, the expression of CPEB4 protein in K562 cells was higher (P＜0.01). Compared with the control group, the proliferation of CPEB4-silenced K562 cells significantly increased (P＜0.01), the number of apoptotic cell significantly decreased, and expression of AKT, p-AKT and BCL-2 was significantly increased, the protein expression of caspase-3 was significantly reduced. The proliferation of K562 cells after CPEB4 overexpression was slowed down (P＜0.05), the number of apoptotic cells significantly increased,the expressions of AKT, p-AKT and BCL-2 were significantly down-regulated, and the expression of caspase-3 was up-regulated. CONCLUSION CPEB4 can inhibit the proliferation and promote the apoptosis of K562 cells, the AKT, p-AKT, BCL-2 and caspase-3 are involved in the regulation mechanism.
Apoptosis ; Cell Proliferation ; Humans ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; RNA-Binding Proteins ; metabolism ; Transfection

No abstract available.
Bone Marrow/pathology ; Chromosomes, Human, Pair 12 ; Chromosomes, Human, Pair 9 ; Core Binding Factor Alpha 2 Subunit/*genetics ; DNA/metabolism ; Gene Rearrangement ; Humans ; In Situ Hybridization, Fluorescence ; Karyotyping ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/diagnosis/*genetics ; Male ; Middle Aged ; Oncogene Proteins, Fusion/*genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Translocation, Genetic

No abstract available.
Aged, 80 and over ; Base Sequence ; Bone Marrow/pathology ; DNA/chemistry/metabolism ; Female ; Fusion Proteins, bcr-abl/*genetics ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/diagnosis/*genetics ; Multiplex Polymerase Chain Reaction ; Protein Isoforms/genetics ; Sequence Analysis, DNA

No abstract available.
Aged ; Cytidine Deaminase/*genetics/metabolism ; Dasatinib/therapeutic use ; Disease Progression ; Drug Resistance, Neoplasm ; Fusion Proteins, bcr-abl/genetics/metabolism ; Humans ; Imatinib Mesylate/*therapeutic use ; In Situ Hybridization, Fluorescence ; Karyotype ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/*drug therapy ; Male ; Microfilament Proteins/*genetics/metabolism ; Oncogene Proteins/*genetics/metabolism ; Protein Kinase Inhibitors/*therapeutic use