To investigate the relationship between the single nucleotide polymorphism (SNPs) of the bcr and abl gene and chronic myelogeous leukemia (CML), the 9 sequence-tagged sites (STS) in bcr and abl gene were screened by DNA pooling and denaturing high performance liquid chromatography (dHPLC), and the results were varified by sequencing. The results showed that the polymorphism sites were detected in 4 out of the 9 STS fragments and there were 3 bases different from the reference sequence found in 3 fragments. In conclusion, the novel SNP in U07000 fragment shows significantly different frequencies between CML and controled people.
Chromatography, High Pressure Liquid ; methods ; Fusion Proteins, bcr-abl ; genetics ; Genes, abl ; genetics ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; Polymorphism, Single Nucleotide ; Proto-Oncogene Proteins c-bcr ; genetics ; Sequence Analysis, DNA ; Sequence Tagged Sites

This study was aimed to explore the single nucleotide polymorphism (SNPs) of breakpoint cluster region of bcr gene in Chinese people and the relationship between SNPs and chronic myelogenous leukemia (CML). A 3.12 kb region spanning from exon 13 to exon 15 in the bcr region were screened by DNA pooling and denaturing high performance liquid chromatography (dHPLC), and the results were verified by sequencing. The results indicated that 6 novel SNP sites and 2 bases different from reference sequence were confirmed in the region studied, and the frequency of 6 novel SNP sites in studied population was obtained, one SNP of which was found in exon 13 and caused a nonsynonymous mutation. The gene frequencies of novel SNPs had no significant difference between CML and control people. It is concluded that sequence polymorphisms in the major breakpoint cluster region of bcr gene are found, most of which are SNPs, No relationship can be confirmed between SNPs and CML disease.
Base Sequence ; Chromosome Breakage ; Fusion Proteins, bcr-abl ; genetics ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; Molecular Sequence Data ; Polymorphism, Single Nucleotide ; Proto-Oncogene Proteins c-bcr ; genetics

This study was aimed to investigate the effect of SU11248 on proliferation and apoptosis of leukemia cell line K562 in vitro and its mechanism. The inhibitory effect of 3.2 µg/ml SU11248 on K562 proliferation was tested by MTT assay. The ability of SU11248 to induce apoptosis of K562 cells was examined by TUNEL and DNA ladder. The expression of C-MYC, hTERT and BCR-ABL mRNA in K562 cells was detected by RT-PCR. The protein expression of Akt and p-Akt in K562 cells was detected by Western blot. The results showed that the proliferation of K562 cells was obviously inhibited by 3.2 µg/ml SU11248 in a time-dependent manner. SU11248 could induce K562 cells apoptosis in dose-and time-dependent manner. The mRNA expression of C-MYC, hTERT and BCR-ABL was reduced significantly by SU11248 in a time-dependent manner (P < 0.05). Western blot detection showed that the expression of p-Akt protein in K562 cells decreased in dose-and time-dependent manner after SU11248 treatment, but the expression of Akt was not significantly changed. It is concluded that SU11248 can inhibit the growth of K562 cells efficiently through inducing apoptosis, its mechanism may be closely relate with the expression down-regulation of C-MYC, hTERT, BCR-ABL and the inhibition of Akt phosphorylation.
Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; Indoles ; pharmacology ; K562 Cells ; Proto-Oncogene Proteins c-akt ; metabolism ; Proto-Oncogene Proteins c-myc ; metabolism ; Pyrroles ; pharmacology ; RNA, Messenger ; genetics ; Telomerase ; metabolism

The study was purposed to analyze the relationship between the content of T-cell receptor excision DNA circles (TREC) and bcr-abl mRNA levels in CML patients and to evaluate the prognostic significance of recent thymic output function detection in patients with chronic myelogenous leukemia (CML). Quantitative detection of TREC and bcr-abl fusion gene transcripts in peripheral blood from 15 CML patients were preformed by real-time PCR. The change of bcr-abl levels in 6 patients was followed-up for two years. The results showed that there was no significant correlation between TREC and bcr-abl mRNA levels in peripheral blood from CML patients for the first attack. Patients who had higher TREC at diagnosis had a larger reduction of bcr-abl after 2 years of follow-up. While out of 2 patients who underwent haemopoietic stem cell transplantation (HSCT), one patient with higher level of TREC before transplantation was confirmed to express undetectable level of TREC by three consecutive detections after transplantation, other one patient was identified to express low level of bcr-abl. It is concluded that high thymic output function in CML patients can be beneficial for killing the residual CML cells.
Adolescent ; Adult ; Aged ; Female ; Fusion Proteins, bcr-abl ; biosynthesis ; genetics ; Gene Rearrangement ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; immunology ; Male ; Middle Aged ; Proto-Oncogene Proteins c-abl ; biosynthesis ; genetics ; Proto-Oncogene Proteins c-bcr ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Receptors, Antigen, T-Cell ; analysis ; immunology ; T-Lymphocytes ; chemistry ; immunology ; Thymus Gland ; immunology

The aim of this study was to evaluate the value of CD117/CD11b phenotypic analysis to diagnosis and prognosis of acute promyelocytic leukemia (APL). Three- or four-color flow cytometry with a series of 22 monoclonal antibodies and CD45/Side Scatter (SSC) gating strategy were used to identify immunophenotypic characteristics of APL as compared to CML in chronic phase (CML-CP). PML/RAR alpha fusion gene was detected by using reverse-transcription polymerase chain reaction (RT-PCR) technique. The results showed that MPO, CD13 and CD33 were almost expressed in all patients with APL and CML-CP whereas HLA-DR and CD34, the hematopoietic progenitor cell markers, were rarely expressed. The positive rate of CD15 in APL was significantly lower than those in CML-CP (P < 0.01). CD117 was positive in 78.3% of the APL cases and in none of the cases of CML-CP. On the other hand, CD11b was almost positive in all cases of CML-CP, but only 16.9% of the APL cases were found positive for this antigen. The CD117+ CD11b- phenotype was present in 72.3% of APL cases while none of cases with CML-CP with this phenotype. Almost all of the cases with CML-CP had the phenotype of CD117- CD11b+. CD117- CD11b+ phenotype was detected in all patients recovering from APL with CD117+ CD11b- phenotype at diagnosis and after treatment with all-trans-retinoic acid (ARTA) for 2 months. PML/RAR alpha fusion gene was positive in 80.6% (25/31) of the APL cases, of which, 64% of the cases belonged to the type L while only 36% of the cases were showed type S for this fusion gene. The positive rates of CD117 were 87.5%, 44.4% and 33.3% in type L group, S group and negative group respectively. It is concluded that analysis of both CD117 and CD11b phenotype may be helpful to the diagnosis, therapy and prognosis of APL in children and adults and to differentiation of APL from recovering benign myeloid proliferation.
Adolescent ; Adult ; CD11b Antigen ; analysis ; Child ; Female ; Humans ; Immunophenotyping ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; diagnosis ; genetics ; immunology ; Leukemia, Promyelocytic, Acute ; diagnosis ; genetics ; immunology ; Male ; Oncogene Proteins, Fusion ; genetics ; Prognosis ; Proto-Oncogene Proteins c-kit ; analysis

OBJECTIVETo study the effects of anti-ABL tyrosine kinase intrabody on the growth of human chronic myelogenous leukemia (CML) cells in nude mice.

METHODSA recombinant retroviral vector MSCV-ibE-IRES-eGFP was constructed to express intracellular single-chain antibody (intrabody) against ABL tyrosine kinase domain in CML cells. K562 cells were transduced with the retrovirus, eGFP+ cells were then selected by fluorescence-activated cell sorting (FACS). The intrabody mRNA expression was determined by reverse transcription (RT)-polymerase chain reaction (PCR). BCR/ABL and c-ABL protein tyrosine kinase (PTK) activity in the cells was examined. Transduced cells and control group K562 cells were transplanted into nude mice respectively and the tumor sizes were dynamically observed.

RESULTSK562-ibE cell was obtained. Expression of the BCR/ABL and c-ABL protein tyrosine kinase activity of harvested K562-ibE cells were markedly inhibited. At 14, 21 and 28 days after cell injection, the tumor volumes of experimental mice were obviously smaller than that of control mice, about one half of the control groups (P < 0.05).

CONCLUSIONThe growth of K562-ibE cells was significantly inhibited in vivo. It is possible that inhibition of the BCR/ABL protein tyrosine kinase activity by the intrabody blocked BCR/ABL signal transduction pathway, promoted apoptosis and reduced tumorigenicity of K562 cells in vivo.

Animals ; Antibodies ; genetics ; Apoptosis ; Cell Division ; Fusion Proteins, bcr-abl ; biosynthesis ; genetics ; immunology ; Genetic Vectors ; Humans ; K562 Cells ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Protein-Tyrosine Kinases ; immunology ; metabolism ; Proto-Oncogene Proteins c-abl ; genetics ; immunology ; Retroviridae ; genetics

Chronic myelogenous leukemia (CML) is a clonal myeloproliferative disease of transformed hematopoietic progenitor cells. It is now clear that the chimeric bcr/abl P210(bcr/abl) fusion protein, which is generated by the reciprocal translocation t (9; 22), inhibits apoptosis and increase proliferation. P210(bcr/abl) plays a central role in the pathophysiology of CML. The purpose of this study was to construct a cell line model that bcr/abl expression can be regulated by Tet-off inducing-expression-system. The full-length b3a2 bcr/abl cDNA was subcloned into the pTRE2hyg expression vector to construct the pT2-P210 plasmid. 293 cells were firstly transfected with Tet-off plasmid and the clone that the Tet-off system can work effectively after transfected with pTRE2hyg-LUC was selected by luciferase activity assay. The pT2-P210 plasmid was then transfected into the selected clone and cells were then selected for hygromycin B and G418 resistance. The results showed that individual subclones expressing bcr/abl after withdrawing doxycycline were 293pT2-P210 cell line. In conclusion, selected 293pT2-P210 cells are cells that bcr/abl expression can be regulated by Tet-off inducing-expression-system. They are suitable thoroughly to study the function of bcr/abl fusion gene and its signal regulation mechanism.
Base Sequence ; Cell Line, Transformed ; cytology ; physiology ; Chromosomes, Human, Pair 22 ; genetics ; Chromosomes, Human, Pair 9 ; genetics ; Fusion Proteins, bcr-abl ; biosynthesis ; genetics ; Gene Expression Regulation, Neoplastic ; Genes, abl ; genetics ; Humans ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; genetics ; metabolism ; pathology ; Models, Genetic ; Molecular Sequence Data ; Proto-Oncogene Proteins c-bcr ; genetics ; Transfection ; Translocation, Genetic ; Tumor Cells, Cultured

OBJECTIVETo explore the inhibitory effect of alantolactone on the proliferation of adriamycin-resistant human chronic myelogenous leukemia cell line K562/ADR cells and its mechanism.

METHODSK562/ADR cells were treated with various concentrations of alantolactone (0, 1, 2, 4, 6, 8, and 10 μmol/L) for different time points. Cell viability was analyzed with MTT assay. The effect of alantolactone on the apoptosis of K562/ADR cells was measured by flow cytometry. The expression of apoptosis-related proteins after treatment with alantolactone was analyzed using Western blot.

RESULTSAlantolactone could effectively inhibit the proliferation of K562/ADR cells in dose- and time- dependent manner, the IC50 value of alantolactone treatment of K562/ADR cells for 24 h was 4.7 μmol/L (P<0.05). Flow cytometric analysis displayed that the apoptotic rates were 1.35%, 16.91%, 29.61% and 46.26%, respectively, after treatment with alantolactone at 0, 2.5, 5 and 7.5 μmol/L. Meanwhile, the expression of Bcl-2 and BCR-ABL proteins were significantly decreased and that of Bax, cytochrome C, cleaved-caspase-9, cleaved-caspase-3 and cleaved-PARP increased by alantolactone treatment.

CONCLUSIONAlantolactone had obvious inhibitory effect on the proliferation of K562/ADR cells through the caspase dependent mitochondrial(or intrinsic)apoptotic pathway.

Apoptosis ; Caspase 3 ; metabolism ; Caspase 9 ; metabolism ; Cell Proliferation ; drug effects ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; K562 Cells ; Lactones ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Sesquiterpenes, Eudesmane ; pharmacology ; bcl-2-Associated X Protein ; metabolism

The aim of this study was to investigate the effect of suppression of nicotinamide phosphoribosyltransferase (NAMPT) expression on imatinib-sensitivity in chronic myelogenous leukemia (CML) cell line K562 and its mechanisms, NAMPT siRNA was synthesized and transfected into K562 cells. PI/Calcein staining technique was used to determine survival rate of transfected K562 cells at 48th hour after exposure to 1 µmol/L imatinib. MTS method was used to determine the proliferation changes of transfected K562 cell at 48th hour after exposure to different doses of imatinib, then half inhibitory concentration (IC(50)) was calculated. Expression of NAMPT at 3rd-48th hour after exposure to 1 µmol/L imatinib was determined by Western blot. To explore the effect of NAMPT-siRNA and imatinib on the expression of apoptosis-related genes, the microarray data from NCBI GEO Data-Sets was analyzed, then the results were confirmed by Western blot. The luciferase reporter assay was used to determine the effect of NAMPT and imatinib on transcriptional activity of NF-κB transcription factors. The results showed that after exposure to 1 µmol/L imatinib for 3 - 48 h, there was no significant change of NAMPT expression in K562 cells. The expression of NAMPT could be effectively inhibited by the NAMPT-siRNA. After exposure to 1 µmol/L of imatinib for 48 h, the survival rate of NAMPT-siRNA interference group was lower than that of negative control group (P < 0.05), indicating that suppression of NAMPT expression can increase the sensitivity of K562 cells to imatinib and enhance the killing effect of imatinib on K562 cells. The IC(50) of imatinib in NAMPT-siRNA interference group was the lowest compared with that of control group (P < 0.05) after exposure to different concentrations of imatinib for 48 h, the fitted survival curves showed that the slope of NAMPT-siRNA interference group was the largest ranging between 0.01 - 0.1 µmol/L of imatinib. Data mining of expression profiling indicated that the anti-apoptotic factor Bcl-2 decreased in K562 cells treated with either NAMPT-siRNA or imatinib, which was confirmed by Western blot. The inhibitory effect was much more significant when both NAMPT-siRNA and imatinib were used. The results of luciferase reporter assay showed that either NAMPT-siRNA or imatinib decreased transcriptional activity of NF-κB. The decreased effect was much more significant when both NAMPT-siRNA and imatinib were used. It is concluded that survival of K562 cells affected by imatinib may not be due to regulation of expression of NAMPT. When expression of NAMPT decreases, the K562 cells are more sensitive to imatinib, this may be related with the decreased transcriptional activity of NF-κB and its downstream effector Bcl-2.
Benzamides ; Cytokines ; antagonists & inhibitors ; metabolism ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; Imatinib Mesylate ; K562 Cells ; NF-kappa B ; metabolism ; Nicotinamide Phosphoribosyltransferase ; antagonists & inhibitors ; metabolism ; Piperazines ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Pyrimidines ; pharmacology

Studies on chronic myeloid leukemia (CML) have served as a paradigm for cancer research and therapy. These studies involve the identification of the first cancer-associated chromosomal abnormality and the subsequent development of tyrosine kinase inhibitors (TKIs) that inhibit BCR-ABL kinase activity in CML. It becomes clear that leukemia stem cells (LSCs) in CML which are resistant to TKIs, and eradication of LSCs appears to be extremely difficult. Therefore, one of the major issues in current CML biology is to understand the biology of LSCs and to investigate why LSCs are insensitive to TKI monotherapy for developing curative therapeutic strategies. Studies from our group and others have revealed that CML LSCs form a hierarchy similar to that seen in normal hematopoiesis, in which a rare stem cell population with limitless self-renewal potential gives rise to progenies that lack such potential. LSCs also possess biological features that are different from those of normal hematopoietic stem cells (HSCs) and are critical for their malignant characteristics. In this review, we summarize the latest progress in CML field, and attempt to understand the molecular mechanisms of survival regulation of LSCs.
Animals ; DNA-Binding Proteins ; genetics ; metabolism ; Fusion Proteins, bcr-abl ; antagonists & inhibitors ; metabolism ; Humans ; Hypoxia-Inducible Factor 1 ; metabolism ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; metabolism ; pathology ; Lipid Metabolism ; Neoplastic Stem Cells ; drug effects ; metabolism ; Protein Kinase Inhibitors ; pharmacology ; therapeutic use ; Proto-Oncogene Proteins c-bcl-6 ; src-Family Kinases ; metabolism