OBJECTIVETo investigate the effect of steadily down-regulating the expression of VE-cadherin on the chemotheraputic sensitivity of K562 cells, and explore its possible mechanism.

METHODSSpecifically targeting interference sequences carrying human VE-cadherin were designed, the recombinant lentiviral vector containing the IRES-GFP and NEO segment was constructed; recombinant lentivirus was generated by three-plasmids packing system, and transfected into K562 cells, then the cells steadily down-regulated were sorted. CCK-8 assay was performed to evaluate the VE-cadherin of chemotherapeutic (Imatinib) sensitivity of K562 cells. The apoptosis was analyzed by flow cytometry with Annexin V/7-AAD double labeling. The expressions of CD133 and ALDH1 mRNA were determined by real time PCR. The protein expressions of VE-cadherin, BCR-ABL and β-catenin were analyzed by Western blot.

RESULTSThe recombinant lentiviral vector pLB-shVEC-NEO-IRES-GFP was successfully constructed, packed into the lentivirus, then the K562 cells steadily down-regulating VE-cadherin expression was obtained. When VE-cadherin was down-rengulated in K562 cells, the proliferation rate was reduced while the the apoptosis rate was increased; the mRNA levels of CD133 and ALDH1 also were reduced; BCR-ABL fusion protein was not obviously changed; the total β-catenin protein, as well as the nuclear β-catenin protein were decreased in the K562/shVEC cells. Conclution: K562 cells are more susceptible to chemotherapy when VE-cadherin is down-regulated, that may be realized via reducing the stability and the nuclear transfer of β-catenin protein.

Antigens, CD ; metabolism ; Apoptosis ; Cadherins ; metabolism ; Cell Proliferation ; Fusion Proteins, bcr-abl ; Humans ; K562 Cells

This study was aimed to investigate the bcr-abl transcription level and its relationship with the clinical status of patients so as to provide some bases for predicting patient status according to absolute value of bcr-abl transcript. The bcr-abl/abl values (%) of bone marrow samples from 30 newly diagnosed CML patients at the baseline bcr-abl/abl value obtained in CML patients with bcr-abl positive were defined, then 161 bone marrow samples from 82 patients were detected at virions time points, and the bcr-abl/abl value of each sample was compared with baseline value and its relationship with clinical status of patient at same time point was investigated. The results showed that bcr-abl/abl values (%) of 30 patients showed positive skew distribution and a large variation with mean 13.5631 (1.0206 - 98.3159) and mathematical mean of 21.1491 (95% CI: 12.3532 - 29.9450). For strict standard, the baseline value of bcr-abl/abl (%) was set as 1, the lower limit of these values. In the detected results of 161 samples, there were 33 samples' values above the baseline value, in which resistance/relapse/progression (R/R/P) 13 (39.4%, 13/33), no remission (NR) 17 (51.5%, 17/33) and complete hematologic remission (CHR) 3 (9.1%, 3/33) were observed. the values of 26 samples decreased by 0 - 1 order of magnitude (0.1 < or = bcr-abl/abl % < 1), in which R/R/P 6 (23.1%, 6/26), NR 7 (26.9%, 7/26), CHR 7 (26.9%, 7/26) and cytogenetic remission (CyR) 6 (23.1%, 6/26) were observed, the values of 19 samples decreased by 1 - 2 order of magnitude (0.01 < or = bcr-abl/abl % < 0.1), in which NR 2 (10.5%, 2/19), CHR 3 (15.8%, 3/19) and CyR 14 (73.7%, 14/19) were determined. 7 samples decreased by 2 - 3 order of magnitude (0.001 < or = bcr-abl/abl % < 0.01) in which major CyR (MCyR) 2 (28.6%, 2/7) and complete CyR (CCyR) 5 (71.4%, 5/7) were determined, the values of 76 samples decreased by 3 or more order of magnitude (bcr-abl/abl % < 0.001), and all these were CCyR. In conclusion, the using decrease degree of one time point-detected value compared to the baseline could well assess the patient clinical status. The bcr-abl/abl % < 0.01 can reliably reflect CyR obtained by patients at the time point, and bcr-abl/abl % < 0.001 can reflect CCyR obtained by patients. However, exact judgments of patient status relies on dynamic and serial monitoring.
Adolescent ; Adult ; Female ; Fusion Proteins, bcr-abl ; analysis ; metabolism ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; metabolism ; pathology ; physiopathology ; Male ; Middle Aged ; Polymerase Chain Reaction ; methods ; Young Adult

The aim of this study was to investigate the apoptosis-inducing effect of cinnamic aldehyde (CA) on chronic myeloid leukemic (CML) cells and its mechanism. K562 cells and primary bone marrow mononuclear cells (MNC) from patients with CML were treated by various concentrations of CA. Flow cytometry was employed to measure the apoptosis of K562 cells and primary CML bone marrow MNC. Western blot was used to determine the expression of C-MYC and the phosphorylation of CrkL in K562 cells, and real-time polymerase chain reaction (real-time PCR) was used to quantify the expression of BCR-ABL mRNA in K562 cells. The results indicated that CA induced the apoptosis of K562 cells in a time- and dose-dependent manner. CA induced apoptosis of CML MNC dose-dependently. CA inhibited the expression of BCR-ABL mRNA and C-MYC, reduced CrkL phosphorylation levels in K562 cells. It is concluded that CA induces apoptosis of CML cells in vitro. Down-regulation of the expression and function of BCR-ABL may be one of its most important anti-leukemia mechanisms.
Acrolein ; analogs & derivatives ; pharmacology ; Apoptosis ; drug effects ; Fusion Proteins, bcr-abl ; metabolism ; Gene Expression Regulation, Leukemic ; Humans ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; metabolism ; pathology

OBJECTIVETo explore the effects of As(2)O(3) on BCR-ABL protein level and signal transduction in chronic myeloid leukemia (CML) cells.

METHODSImmunoprecipitation, protein tyrosine kinase (PTK) activity assay, real-time Taqman quantitative PCR and Western blot were used.

RESULTSAs(2)O(3) downregulated BCR-ABL protein and STAT1 protein of CML mononuclear cells in the concentrations of 1.0 approximately 2.0 micro mol/L and 0.5 approximately 2.0 micro mol/L after 48 h exposure, respectively. However, p27 protein level was not affected. The PTK activity of BCR-ABL protein was also mildly decreased in CML monouclear cells at 60 h. The bcr-abl mRNA level remained unchanged.

CONCLUSIONAs(2)O(3) downregulats BCR-ABL protein, STAT1 protein, BCR-ABL signal transduction and PTK activity in CML cells.

Fusion Proteins, bcr-abl ; genetics ; Humans ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; Phosphorylation ; drug effects ; Protein-Tyrosine Kinases ; metabolism ; Signal Transduction

OBJECTIVETo detect bcr/abl fusion gene at DNA level in K562 cell line and mononuclear cells from patients with chronic myelogenous leukemia (CML).

METHODSBased on previous research, a set of DNA-PCR primers was redesigned. DNA from K562 cells and mononuclear cells of CML patients was extracted respectively. After DNA-PCR for bcr/abl fusion gene the amplified fragments were then sequenced.

RESULTAt DNA level the bcr/abl fusion gene in K562 cells and mononuclear cells of 2 CML patients was amplified. Furthermore, the DNA breakpoint of fusion gene in the above samples through sequencing of amplified fragments was localized.

CONCLUSIONDNA-PCR offers a new detection technology for bcr/abl fusion without the expression of fusion gene.

Fusion Proteins, bcr-abl ; genetics ; Humans ; K562 Cells ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; Leukocytes, Mononuclear ; metabolism ; Polymerase Chain Reaction ; methods

OBJECTIVETo investigate the possibility of multi-unit ribozymes to purge bone marrow of chronic myelocytic leukemia (CML), its in vitro cleavage ability and the reversal effect on CML cell's malignant phenotype.

METHODSAs bcr-abl fusion gene plays an important role in CML pathology, three single-unit ribozymes were designed and synthesized in 44 base pairs near the fusion point, two enzyme cleavage sites on bcr gene and one on abl gene. Multi-unit ribozymes' in vitro transcription and retroviral vector through gene recombination were constructed. Then, its in vitro cleavage ability was tested and the retroviral vector was transfected into K562 cell. Through MTT assay, the incorporation rate of (3)H-TdR, RT-PCR, Southern and Northern blot hybridization, flow cytometry, transmission and scanning electron microscopy were used to study the effect of multi-unit ribozymes on CML cell proliferation, cell structure, cell cycle and the induction of apoptosis.

RESULTSMulti-unit ribozymes had in vitro cleavage efficiency of 70.8%. After the transfection of multi-unit ribozymes retroviral vector into K562 cell, cell proliferation and DNA synthesis were greatly reduced with an inhibition rate of about 50% after 96 hours of transfection. Multi-unit ribozymes could cleave K562 cell's RNA with a reduction rate about one 1 000 th of the original. By flow cytometry (FCM), 18.4% cells underwent apoptosis after 72 hours transfection with most of the cells blocked in the G phase. Here, the ratio in S phase was lowered by 41.9%. Under transmission and scanning electron microscope, compaction of nuclear chromation and apoptosis bodies were observed in the transfected cells.

CONCLUSIONMulti-unit ribozymes possess high cleavage ability in vitro. The ribozymes, whose retroviral vector being transfected into CML cell, are able to express a lasting ability to cleave the fusion gene, induce apoptosis, reduce cell proliferation, revert the malignant phenotype. It is possible to make use of multi-unit ribozymes to purge CML bone marrow. Therefore, multi-unit ribozymes may very well be valuable in the gene therapy of CML.

Apoptosis ; Cell Division ; drug effects ; Fusion Proteins, bcr-abl ; genetics ; metabolism ; Humans ; K562 Cells ; RNA, Catalytic ; metabolism ; pharmacology

OBJECTIVETo construct a vector containing protein transduction domain (PTD) and bcr/abl fusion gene of chronic myelogenous leukemia and express PTD-bcr/abl fusion protein in E. Coli.

METHODSDNA fragment encoding PTD was synthesized and fused to PCR-amplified bcr/abl gene fragment, then inserted into plasmid pET-16b to get the expression vector pEPb containing PTD-bcr/abl fusion gene, which was transfected and expressed in E. Coli LB21. PTD-bcr/abl fusion protein was purified by affinity chromatography.

RESULTS523 bp bcr/abl fusion gene was effectively amplified. The PTD-bcr/abl gene sequencing showed the same sequence as scheduled. The fusion peptide was successfully expressed in E. Coli and purified.

CONCLUSIONThe results may provide a new PTD-bcr/abl fusion peptide for the immunotherapy of CML.

Electrophoresis, Polyacrylamide Gel ; Escherichia coli ; genetics ; Fusion Proteins, bcr-abl ; genetics ; metabolism ; Gene Expression ; Gene Products, tat ; genetics ; metabolism ; Genetic Vectors ; genetics ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; Recombinant Fusion Proteins ; genetics ; metabolism

Bcr-abl antisense oligodeoxynucleotides (AS-ODNs) have provided evidence of an antileukemia effect when tested in vitro against Philadelphia-positive cells. In order to investigate the efficacy of AS-ODNs as purging agents in chronic myeloid leukemia (CML) patients, K562 cells, a human CML cell line, were treated in vitro with various types of AS-ODNs and interferon-alpha. Cells were treated in vitro for 0 and 36 hr with 40 microgram/mL of AS-ODNs, respectively, and incubated at 37 degrees C for 36 hr. Cytotoxic effects were measured by counting the number of viable cells as well as by MTT test. Clonogenic activities were evaluated by methylcellulose culture for 2 weeks. The effects of purging agents on the rearrangement of bcrabl gene were evaluated by RT-PCR. AS-ODNs inhibited the proliferation of K562 cells with time in cell count assay and MTT test. AS-ODNs were superior to INF-alpha in inhibiting clonogenic activity (recovery rate; 26.3% vs 64.0%). After incubation with bcr-abl AS-ODNs primers and mRNA isolated from K562 cells, positive bands were abolished, especially of b3a2 type and phosphorothioate type. Our results suggest that AS-ODNs mediated purging may be one of the efficient methods and that autograft may be an alternative treatment for allograft in high-risk group patients of CML if they do not have a stem cell donor.
Bone Marrow Purging* ; Colony-Forming Units Assay ; Fusion Proteins, bcr-abl/genetics ; Fusion Proteins, bcr-abl/metabolism ; Hematopoietic Stem Cells/physiology* ; Human ; Leukemia, Myeloid, Chronic/therapy ; Neuroblastoma/therapy* ; Oligonucleotides, Antisense/metabolism* ; Oligonucleotides, Antisense/therapeutic use ; Transplantation, Autologous* ; Tumor Cells, Cultured

Several studies have shown that the tumor endothelial cells are different from the normal tissue endothelial cells. These tumor endothelial cells may contribute to tumor neo-vasculogenesis. This study was purposed to analyze the biologic features and determine the expression level of CD133 and BCR/ABL fusion gene in circulating endothelial cells (CEC) isolated from peripheral blood of CML patients, as well as to investigate the role of CEC in disease progression. Mononuclear cells were isolated from peripheral blood by density gradient centrifugation; CEC were sorted by MACS and harvested in the endothelial growth medium. The morphologic features of CEC were observed by microscopy, the cell growth rate was calculated by cell counting, and the cells were identified by immunofluorescence staining for the expression of CD31,CD34,VWF and CD133. The expression of BCR/ABL fusion gene was examined by FISH in 12 CML patients. The results indicated that the isolated CEC displayed the typical cobble-stone morphology. These cells could be identified by the positive immunofluorescence staining for CD31, CD34 and VWF, and showed more increased proliferative potential as compared to that of healthy donors. It was found that the positive rate of CD133 was 31.29% in CML patients, which was significantly different from that of healthy donors (P < 0.05). In 12 CML patients, CEC carried the same chromosome aberration as the leukemia cells (10.77%). Higher expression level of CD133 and BCR/ABL fusion gene positively correlated with progression of disease. It is concluded that the CEC may participate in invasion and angiogenesis in patients with CML and possibly correlate to the spreading and progression of the disease.
AC133 Antigen ; Adult ; Antigens, CD ; metabolism ; Cell Proliferation ; Endothelial Cells ; metabolism ; Female ; Fusion Proteins, bcr-abl ; genetics ; metabolism ; Glycoproteins ; metabolism ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; metabolism ; pathology ; Male ; Middle Aged ; Neovascularization, Pathologic ; Peptides ; metabolism ; Young Adult

Adenocarcinoma ; complications ; drug therapy ; metabolism ; Aged ; Antineoplastic Agents ; therapeutic use ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; diagnosis ; etiology ; metabolism ; Male ; Organoplatinum Compounds ; therapeutic use ; Stomach Neoplasms ; drug therapy ; metabolism