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*

Aged ; Bone Marrow ; diagnostic imaging ; pathology ; Epidural Space ; diagnostic imaging ; pathology ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; diagnostic imaging ; pathology ; Male ; Sarcoma, Myeloid ; diagnostic imaging ; pathology ; Spinal Cord Compression ; diagnostic imaging ; pathology

Platycodin D(PD) has a significantly inhibitory effect on multiple malignant tumors, and can inhibit the proliferation of leukemia cells K562 and induce apoptosis. However, its effect in improving the sensitivity of drug-resistant cells to imatinib and their molecular mechanism remained unclear. To investigate the effect and mechanism of PD alone or combined with imatinib (IM) in inhibiting CML imatinib resistant cell line K562/R, the cell proliferation was examined by CCK8 assay to reveal the effect of PD on the inhibitory function of imatinib. Cell apoptosis was detected by Annexin V-FITC/PI double staining. Protein expressions of cleaved caspase-3, cleaved caspase-9, PARP, cleaved PARP, Bcr/abl, p-AKT and p-mTOR were detected by Western blot. The results showed that the inhibitory effect of PD combined with imatinib on the proliferation and apoptosis of K562/R cells was significantly higher than that of the control group and the single drug group. Protein expressions of cleaved caspase-3, cleaved caspase-9 and cleaved PARP were significantly up-regulated in the combination group, and protein expressions of PARP, Bcr/abl, p-AKT and p-mTOR were down-regulated. The results indicated that PD increased the sensitivity of drug-resistant cells to imatinib, and the inhibitory effect of PD combined with imatinib was significantly better than the single drug on cell proliferation, induction of apoptosis, inhibition of Bcr/abl protein and PI3K/AKT/mTOR signaling pathway.
Antineoplastic Agents ; pharmacology ; Apoptosis ; Cell Proliferation ; Drug Resistance, Neoplasm ; Humans ; Imatinib Mesylate ; pharmacology ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; pathology ; Saponins ; pharmacology ; Signal Transduction ; Triterpenes ; pharmacology

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.
Base Sequence ; Bone Marrow/pathology ; Fusion Proteins, bcr-abl/*genetics ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/diagnosis/*genetics ; Male ; Middle Aged ; Real-Time Polymerase Chain Reaction

OBJECTIVETo explore the effect of a novel emodin derivative E19 on proliferation inhibition and apoptosis induction of human chronic myelogenous leukemia (CML) cell line K562 and imatinib-resistant CML cell line (K562/G01), and to clarify the involved mechanisms.

METHODSMTT and colony formation test were used to detect the cell proliferation. Apoptotic induction effects were examined by DAPI staining method and DNA ladder assay. Western blot was performed to detect the changes of P210(Bcr-Abl) protein.

RESULTSThe emodin derivative E19 could efficiently inhibit proliferation and induce apoptosis in K562 and K562/G01 cells. IC50 of K562 cells and IC50 of K562/G01 cells were (1.20 ± 0.19) µmol/L and (1.22 ± 0.16) µmol/L, respectively. DNA fragmentation in K562 cells and K562/G01 cells confirmed that the E19 induced apoptosis in dose-dependent manner. Western blot showed that emodin derivative inhibited phosphorylation of P210 protein in K562 cells and K562/G01 cells and down-regulated the expression level of P210 in dose- and time-dependent manners.

CONCLUSIONThe emodin derivative E19 can efficiently inhibit growth and induce apoptosis of K562 cells and K562/G01 cells, while the inhibition of phosphorylation of P210 protein and down-regulation of P210 protein expression may be involved in these processes.

Apoptosis ; drug effects ; Cell Proliferation ; Down-Regulation ; Drug Resistance, Neoplasm ; Emodin ; analogs & derivatives ; pharmacology ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; Imatinib Mesylate ; pharmacology ; K562 Cells ; drug effects ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; pathology ; Phosphorylation

No abstract available.
Aged ; Antineoplastic Agents/therapeutic use ; Bone Marrow/pathology ; Fusion Proteins, bcr-abl/genetics/metabolism ; Humans ; Imatinib Mesylate/therapeutic use ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/complications/*diagnosis/drug therapy ; Leukocyte Count ; Male ; Multiple Myeloma/complications/*diagnosis/drug therapy ; Platelet Count ; Polymerase Chain Reaction ; Thrombocytosis/etiology

To study the pathogenesis of hearing loss in chronic myelogenous leukemia (CML). To report one case with CML whose first sign was sudden unilateral hearing loss. Sudden hearing loss in CML was presented with dramatic high white blood cell count in peripheral blood. Some cases of sudden hearing loss in CML may be improved or even cured by leukapheresis and intrathecal chemotherapy. The proposed pathogenesis for deafness in leukemia is due to hyperleukocytosis, hyperviscosity syndrome, leukemic infiltration and the inner ear hemorrhage. In treatment, clinicians should quickly reduce the number of white blood cells to lighten the tumor burden. Intrathecal injection of MTX and plasmapheresis is commonly used.
Ear, Inner ; pathology ; Hearing Loss, Sudden ; etiology ; Hearing Loss, Unilateral ; etiology ; Hemorrhage ; pathology ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; complications ; Leukocyte Count

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder characterized by a chromosome translocation that generates the Bcr-Abl oncogene encoding a constitutive kinase activity. Despite remarkable success in controlling CML at chronic phase by Bcr-Abl tyrosine kinase inhibitors (TKIs), a significant proportion of CML patients treated with TKIs develop drug resistance due to the inability of TKIs to kill leukemia stem cells (LSCs) that are responsible for initiation, drug resistance, and relapse of CML. Therefore, there is an urgent need for more potent and safer therapies against leukemia stem cells for curing CML. A number of LSC-associated targets and corresponding signaling pathways, including CaMKII-γ, a critical molecular switch for co-activating multiple LSC-associated signaling pathways, have been identified over the past decades and various small inhibitors targeting LSC are also under development. Increasing evidence shows that leukemia stem cells are the root of CML and targeting LSC may offer a curable treatment option for CML patients. This review summarizes the molecular biology of LSC and its-associated targets, and the potential clinical application in chronic myeloid leukemia.
Animals ; Chemokines ; metabolism ; Epigenesis, Genetic ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; metabolism ; pathology ; Neoplastic Stem Cells ; metabolism ; pathology ; Transcription Factors ; metabolism ; Tumor Microenvironment