OBJECTIVETo discover BCR-ABL tyrosine kinase inhibitors through structure based virtual screening.

METHODSDocking screening against the distinctive inactive conformation of the catalytic domain of BCR-ABL tyrosine kinase was performed on 3D database. The MTT assay was performed to assess the viability of the tumor cells treated with selected compounds. The amount and kinase activity of BCR-ABL protein were detected in the presence of compounds by Western blot analysis and immunoprecipitation.

RESULTSFrom the top 1,000 compounds with the best DOCK energy score, 15 compounds were selected for biological assay. Eight out of 15 compounds showed notable inhibitory activity against Ph+ human K562 cells with IC50 values ranging from 10 to 200 micromol/L. In cell-based assays of ABL tyrosine phosphorylation, the ability of two kinds of novel, structurally diverse, lead compounds to inhibit ABL kinase activity was observed. However, no significant differences in the amount of BCR-ABL protein were noted on the ABL immunoblot in the presence of these lead compounds.

CONCLUSIONSTwo promising lead compounds were discovered to inhibit BCR-ABL tyrosine kinase activity. Virtual screening technique has been proven to narrow down the size of screening compound libraries to the most prospective drug candidates with high success rates.

Computer Simulation ; Drug Evaluation, Preclinical ; Enzyme Inhibitors ; chemical synthesis ; Fusion Proteins, bcr-abl ; Humans ; K562 Cells ; Models, Molecular ; Molecular Conformation ; Phosphorylation ; Protein-Tyrosine Kinases ; antagonists & inhibitors ; chemistry ; genetics

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

Chronic myeloid leukemia (CML) is a myeloproliferative disease characterized by the overproduction of granulocytes, which leads to high white blood cell counts and splenomegaly in patients. Based on clinical symptoms and laboratory findings, CML is classified into three clinical phases, often starting with a chronic phase, progressing to an accelerated phase and ultimately ending in a terminal phase called blast crisis. Blast crisis phase of CML is clinically similar to an acute leukemia; in particular, B-cell acute lymphoblastic leukemia (B-ALL) is a severe form of acute leukemia in blast crisis, and there is no effective therapy for it yet. CML is induced by the BCR-ABL oncogene, whose gene product is a BCR-ABL tyrosine kinase. Currently, inhibition of BCR-ABL kinase activity by its kinase inhibitor such as imatinib mesylate (Gleevec) is a major therapeutic strategy for CML. However, the inability of BCR-ABL kinase inhibitors to completely kill leukemia stem cells (LSCs) indicates that these kinase inhibitors are unlikely to cure CML. In addition, drug resistance due to the development of BCRABL mutations occurs before and during treatment of CML with kinase inhibitors. A critical issue to resolve this problem is to fully understand the biology of LSCs, and to identify key genes that play significant roles in survival and self-renewal of LSCs. In this review, we will focus on LSCs in CML by summarizing and discussing available experimental results, including the original studies from our own laboratory.
5-Lipoxygenase-Activating Proteins ; metabolism ; Animals ; Benzamides ; Disease Models, Animal ; Fusion Proteins, bcr-abl ; antagonists & inhibitors ; chemistry ; metabolism ; Humans ; Imatinib Mesylate ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; enzymology ; genetics ; pathology ; Male ; Mice ; Neoplastic Stem Cells ; enzymology ; pathology ; PTEN Phosphohydrolase ; metabolism ; Philadelphia Chromosome ; Piperazines ; therapeutic use ; Point Mutation ; Protein Structure, Tertiary ; Protein-Tyrosine Kinases ; antagonists & inhibitors ; chemistry ; metabolism ; Pyrimidines ; therapeutic use

Philadelphia (Ph) chromosome at (9; 22) reciprocal chromosomal translocation producing BCR-ABL fusion gene, emerges in almost all patients with chronic myeloid leukemia (CML). The protein product of BCR-ABL is a constitutively active tyrosine kinase that drives the abnormal proliferation of CML cells. Blast crisis (BC) is the terminal phase of CML, which is often associated with additional chromosomal and molecular secondary changes. Although the mechanisms responsible for transition of CML chronic phase (CP) into BC remain poorly understood, ample evidence suggests that it depends on synergy of BCR/ABL with other genes dysregulated during disease progression, and signaling pathways are abnormally activated by BCR/ABL. With the application of imatinib, a ABL-specific tyrosine kinase inhibitor, its remarkable therapeutic effects suggest that blast crisis transition will be postponed in most patients with CML. Rate of cumulative best response in CML-CP patients from the IRIS trial after 5 years are 98% for complete hematologic response, 92% for major cytogenetic response and 87% for complete cytogenetic response. However, a minority of CML-CP patients and most patients in progression either fail or respond suboptimally to imatinib. There are many distinct patterns of resistance, and ABL kinase mutations is a common finding associated with clinical resistance. Dasatinib and nilotinib can restore hematologic and cytogenetic remission in the majority of patients with primary failure or acquired resistance in chronic phase. This review illustrates the molecular mechanisms underlying transition to CML-BC, also addresses oneself to how and why imatinib resistance occurs.
Benzamides ; Blast Crisis ; drug therapy ; genetics ; Dasatinib ; Drug Resistance, Neoplasm ; drug effects ; Fusion Proteins, bcr-abl ; antagonists & inhibitors ; genetics ; Genes, abl ; drug effects ; Humans ; Imatinib Mesylate ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; genetics ; pathology ; Philadelphia Chromosome ; Piperazines ; pharmacology ; therapeutic use ; Protein Kinase Inhibitors ; pharmacology ; therapeutic use ; Pyrimidines ; pharmacology ; therapeutic use ; Thiazoles ; pharmacology ; therapeutic use ; Translocation, Genetic

In order to investigate the molecular mechanisms of SARI expression regulation in chronic myeloid leukemia (CML), 46 patients with CML and 40 healthy volunteers were recruited in this study. SARI expression in the peripheral blood mononuclear cells (PBMNC) of CML patients and healthy volunteers was assayed by using real-time quantitative PCR. K562 cells were in vitro incubated with the BCR-ABL inhibitor STI571 (imatinib) at 37°C and 5% CO2 for 24 hours, then SARI expression was detected by using real-time quantitative PCR. All experiments were repeated three times. The results showed that as compared with healthy volunteers, the expression of SARI mRNA in PBMNC of CML patients presented a lower level (p < 0.001). After exposure of K562 cells to STI571 (2.5 µmol/L) for 24 hours, the SARI expression was higher than that in K562 cells treated without STI571 (p < 0.001). It is concluded that the suppression of SARI expression is involved in CML pathogenesis, and BCR-ABL mediates the down-regulation of SARI mRNA expression in K562 cells. These findings suggest a new orientation for gene therapy in CML patients.
Basic-Leucine Zipper Transcription Factors ; genetics ; Benzamides ; Fusion Proteins, bcr-abl ; antagonists & inhibitors ; Gene Expression Regulation, Leukemic ; drug effects ; Humans ; Imatinib Mesylate ; K562 Cells ; Piperazines ; pharmacology ; Pyrimidines ; pharmacology ; Tumor Suppressor Proteins ; genetics

OBJECTIVETo investigate the antitumor efficacy and mechanism of HSP90 inhibitor FW-04-806 against Bcr/Abl(+) leukemia K562 and HL60 cells and their mechanisms of action.

METHODSMTT assay was used to assess the proliferation-inhibiting effect of FW-04-806. Cell cycle was analyzed with propidium iodide by flow cytometry. Cell apoptosis was determined using the FITC mV apoptosis detection kit. Western blot was applied to reveal the protein expression of related proliferative and apoptotic signaling pathways. The changes of mitochondrial membrane potential were detected by flow cytometry. Protein-protein interactions was shown by co-immunoprecipitation. The level of mRNA was assessed by real-time RT-PCR.

RESULTSFW-04-806 obviously inhibited cell proliferation in the HL60, K562 and HL60/Bcr-Abl cell lines, with an IC50 of (30.89 ± 0.12) µmol/L, (9.76 ± 0.19) µmol/L and (8.03 ± 0.26) µmol/L, respectively (P<0.001). Compared with the vehicle group, the two increasing doses of FW-04-806 showed inhibition of tumor growth at a rate of (17.40 ± 0.34)% and (34.33 ± 5.00)%, respectively, in the K562 cell line groups (P=0.003), and (18.90 ± 1.45)% and (35.60 ± 3.55)% (P=0.001) in the HL60/Bcr-Abl cell line groups. FW-04-806 dissociated Hsp90/Cdc37 chaperon/co-chaperon complex, followed by degradation of the Hsp90 proteins through proteasome pathway without affecting mRNA expression. FW-04-806 induced apoptosis and led to G2/M arrest.

CONCLUSIONOur findings indicate that FW-04-806 displays potential antitumor effect by suppressing the proliferation and apoptosis in Bcr/Abl(+) leukemia cells in vivo.

Apoptosis ; drug effects ; Cell Cycle ; Cell Proliferation ; drug effects ; Fusion Proteins, bcr-abl ; HL-60 Cells ; HSP90 Heat-Shock Proteins ; antagonists & inhibitors ; Humans ; K562 Cells ; Leukemia ; drug therapy ; metabolism ; pathology ; Membrane Potential, Mitochondrial ; Oxazoles ; pharmacology ; RNA, Messenger ; metabolism ; Signal Transduction

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

This study was aimed to compare HHGV678 with imatinib (IM) in growth inhibition of Bcr-Abl wild type and IM-resistant cell lines, investigate the possibility of replacing IM with HHGV678 in treatment of chronic myeloid leukemia (CML) and IM-resistant CML patients. Viability of two Bcr-Abl wild type cell lines (K562 and 32Dp210) and 16 IM-resistant cell lines (K562R and 15 Bcr-Abl point mutant cell lines) treated with HHGV678 and IM was analyzed by MTT. The apoptosis of those cells was identified by flow cytometry with Annexin V staining and DNA ladder analysis. Western blot was applied for detecting the expression of Bcr-Abl and phosphotyrosine protein levels. The results indicated that HHGV678 significantly inhibited the growth of two Bcr-Abl wild types and IM-resistant cell lines in dose-dependent manner except cell line of T315I point mutant. IC(50) results showed that the growth inhibition of HHGV678 was 15.5 and 28-fold higher than that of IM in K562, 32Dp210 and 1.4 to 124.3-fold higher than that of IM in 15 IM-resistant cell lines respectively. Compared with IM, HHGV678 more significantly inhibited phosphotyrosine kinase protein of the cells mentioned above at different concentrations. With most importance, HHGV678 of 10.0 micromol/L induced cell apoptosis of 40.06% and 33.32% in K562R and 32Dp210(T315I) cell lines, which were much higher than that of IM (19.77% and 10.68%). It is concluded that HHGV678 is more effective than IM in the growth inhibition of Bcr-Abl wild type cell lines and IM-resistant cell lines, especially in strongest IM-resistant cell lines. Further studies are needed to show whether HHGV678 may be a novel targeting drug in treatment of CML and IM-resistant CML patients.
Aminopyridines ; Apoptosis ; drug effects ; Benzamides ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Drug Resistance, Neoplasm ; drug effects ; Fusion Proteins, bcr-abl ; metabolism ; Humans ; Imatinib Mesylate ; Piperazines ; pharmacology ; Protein Kinase Inhibitors ; pharmacology ; Protein-Tyrosine Kinases ; antagonists & inhibitors ; Pyrimidines ; pharmacology

No abstract available.
Adult ; Antineoplastic Agents/therapeutic use ; *Chromosome Deletion ; *Chromosomes, Human, Pair 9 ; Cytogenetic Analysis ; DNA Mutational Analysis ; Fusion Proteins, bcr-abl/*antagonists & inhibitors/genetics/metabolism ; Gene Expression Regulation ; Humans ; Incidental Findings ; Klinefelter Syndrome/complications/diagnosis/*genetics ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/complications/diagnosis/*drug therapy/enzymology/genetics ; Male ; Molecular Targeted Therapy ; Protein Kinase Inhibitors/*therapeutic use ; Remission Induction ; Time Factors ; Treatment Outcome

Animals ; Antineoplastic Agents ; therapeutic use ; Benzamides ; Dasatinib ; Drug Resistance, Neoplasm ; drug effects ; Fusion Proteins, bcr-abl ; genetics ; metabolism ; Humans ; Imatinib Mesylate ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; genetics ; metabolism ; Piperazines ; therapeutic use ; Protein-Tyrosine Kinases ; antagonists & inhibitors ; Pyrimidines ; pharmacology ; therapeutic use ; Thiazoles ; pharmacology ; therapeutic use