Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

PD180970 is a novel pyrido[2,3-d]pyrimidine class of ATP-competitive inhibitor of protein tyrosine kinases. We found that PD180970 inhibited in vivo tyrosine phosphorylation of p210Bcr-Abl (IC50 = 170 nM) and the p210BcrAbl substrates Gab2 and CrkL (IC50 = 80 nM) in human K562 chronic myelogenous leukemic cells. In vitro, PD180970 potently inhibited autophosphorylation of p210Bcr-Abl (IC50 = 5 nM) and the kinase activity of purified recombinant Abl tyrosine kinase (IC50 = 2.2 nM). Incubation of K562 cells with PD180970 resulted in cell death. Results of nuclear staining, apoptotic-specific poly(ADP-ribose) polymerase cleavage, and annexin V binding assays indicated that PD180970 induced apoptosis of K562 cells. In contrast, PD180970 had no apparent effects on the growth and viability of p210Bcr-Abl-negative HL60 human leukemic cells. Thus, PD180970 is among the most potent inhibitors of the p210Bcr-Abl tyrosine kinase, which is present in almost all cases of human chronic myelogenous leukemia. These findings indicate that PD180970 is a promising candidate as a novel therapeutic agent for Bcr-Abl-positive leukemia.
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PMID:The pyrido[2,3-d]pyrimidine derivative PD180970 inhibits p210Bcr-Abl tyrosine kinase and induces apoptosis of K562 leukemic cells. 1086 98

Dexrazoxane (DEX) prevents the formation of free radical, lipid peroxidation and cardiotoxicity caused by anthracyclines. Due to a concern about its possible interference with anthracyclin cytotoxicity, the in vitro effect of DEX on daunorubicin (DNR) cytotoxicity, cell cycle and induction of apoptosis by annexin-V was investigated. The sensitivity to DEX, DNR and their combination was tested by the MTT assay in human promyelocytic leukemia HL-60, the erythroid blast crisis CML K562 cell lines and in 45 children with ALL and AML. Cell cycle analysis and annexin-V expression were performed by flow cytometry. It has been observed that DEX itself weakly, but significantly caused cytotoxicity in both cell lines and in patient samples, especially in initial ALL samples. DEX sensitized K562 and HL60, but not patient samples, to cytotoxicity of DNR. The percentage of necrotic/apoptotic cells, as detected in cell cycle analysis and annexin V staining, was higher after exposure to DEX +/- DNR, when compared to respective samples not treated with DEX, in both cell lines but not in patient samples. Expression of annexin V induced by DEX in both cell lines was enlarged, regardless of the presence of DNR. This difference was not observed in patient samples, however, the number of cells expressing annexin V was higher after exposure to DEX +/- DNR in comparison to respective samples not treated with DEX. In conclusion, it seems that DEX possibly has no impact on the sensitivity of childhood leukemic blasts to DNR, however, has weak cytotoxic properties itself.
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PMID:Dexrazoxane has no impact on sensitivity of childhood leukemic blasts to daunorubicin. 1198 42

Clonal expansion of leukemic cells is thought to be due to proliferation in excess of apoptosis. To define and compare proliferation and apoptosis between various leukemias and myelodysplastic syndrome (MDS), we measured proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine (BrdU) incorporation as surrogate markers for proliferation and caspase 3 activity and annexin V surface binding as surrogate markers for activation of the apoptotic cascade in patients with MDS, chronic myelomonocytic leukemia (CMML), acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML). We found high proliferation in bone marrow cells from MDS and CMML as measured by PCNA and BrdU incorporation. The lowest level of proliferation was found in CLL. Apoptosis was also highest in MDS and CMML as measured by annexin V and caspase 3 activity. Unexpectedly, we found no significant difference in proliferation in bone marrow CD34+ cells from various leukemias or MDS. Apoptosis was significantly higher in bone marrow CD34+ cells from MDS and CML in chronic phase as compared to CD34+ cells from AML patients. Our results illustrate differences in proliferation and apoptosis between acute and chronic leukemias and MDS. These differences may have diagnostic and therapeutic implications.
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PMID:Proliferation and apoptosis in acute and chronic leukemias and myelodysplastic syndrome. 1200 3

The leukemogenic property of BCR-ABL in chronic myeloid leukemia (CML) is critically dependent on its protein tyrosine kinase activity. STI571 inhibits the BCR-ABL kinase activity, the growth and the viability of BCR-ABL expressing cells. In this study, we report the apoptotic effect of STI571 in combination with daunorubicin (DNR) on peripheral blood mononuclear cells from 11 CML patients and four BCR-ABL-positive cell lines: AR230, LAMA84, K562 and KCL22. Primary blast cells were identified by flow cytometry on the basis of their low CD45 expression. Nucleus fragmentation, exposure of phosphatidylserines and decrease in mitochondrial membrane potential were measured using acridine orange, FITC-annexin V and DiOC6(3), respectively, to evaluate apoptosis. On cell lines, the effect of DNR was negligible, whereas STI571 induced 10 to 35% of apoptosis in 18 h. STI571 sensitized AR230, LAMA84 and K562 cells to DNR when apoptosis was measured at the mitochondrial and membrane but not the nuclear levels. On CML blast cells, phosphatidyl serine exposure was significantly induced by both DNR and STI571 and was higher when these drugs were used in combination (P < 0.0003). However, the effects of this drug combination were only additive and no sensitization of blast cells to DNR by STI571 was observed. Interestingly, sensitization was evidenced in CML but not normal lymphocytes. These results suggest that other mechanisms additional to Bcr-Abl tyrosine kinase activity could be responsible for DNR resistance, and further investigations are needed to understand its origin.
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PMID:Resistance to daunorubicin-induced apoptosis is not completely reversed in CML blast cells by STI571. 1204 Apr 47

In this study, the underlying antileukemic mechanisms of homoharringtonine (HHT) were investigated. K562 cell line was used to observe the effects of HHT on the induction of apoptosis and on the expression of the specific chimeric protein P210(bcr/abl), as evaluated by flow cytometric annexin V-PI dual labeling technique and Western blot. The results showed that HHT induced K562 cells to apoptotic death at the concentrations of 5 - 20 ng/ml, and some of the cells became necrotic when exposed to a higher concentration. The amount of P210(bcr/abl) oncoprotein was decreased by approximately 70% when the cells were exposed to HHT for 48 hours, however, that of its partner P145(c-abl) proto-oncoprotein was not affected. It is clear from the study that HHT is an inhibitor of P210(bcr/abl) oncoprotein and therefore promotes the apoptosis of CML cells. It could be promising that HHT be used extensively in the chemotherapy of patients with CML.
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PMID:[Homoharringtonine Induces Apoptosis of K562 Cells through Inhibition of P210(bcr/abl)] 1257 68

Interest in exploiting traditional medicines for prevention or treatment of cancer is increasing. Extracts from the herb Tripterygium wilfordii hook F have been used in China for centuries to treat immune-related disorders. Recently it was reported that triptolide, a purified compound from Tripterygium, possessed antitumor properties and induced apoptosis in a variety of malignant cell lines. K562 cells are usually resistant to apoptosis induction, probably because of the expression of bcr-abl, the hybrid gene characteristic of the Philadelphia chromosome t (9;22). Present studies demonstrate that triptolide inhibited K562 cells proliferation and induced apoptosis in a dose and time-dependent manner. The growth-inhibitory IC50 value for triptolide treatment was 40 ng/ml. Characteristic apoptotic features were confirmed by morphology, internucleosomal DNA fragmentation, and Annexin V Staining. Significantly, triptolide-induced apoptosis of K562 cells was associated with a decline in bcr-abl expression levels, at the concentrations of 20 ng/ml, 40 ng/ml and 80 ng/ml, triptolide was able to decrease the expression of bcr-abl down to 50%, 30% and 20% respectively of the basal value after 72 h. Our findings strongly suggest that triptolide might be an effective therapeutic agent against CML cells.
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PMID:Triptolide down-regulates bcr-abl expression and induces apoptosis in chronic myelogenous leukemia cells. 1510 26

Imatinib (STI571, Gleevec) is a tailored drug for chronic myelogenous leukemia (CML), whereas arsenic compounds were used as ancient remedies for CML with certain efficacy. The aim of this study was to investigate the potential benefit of combination therapy with imatinib and arsenic sulfide (As(4)S(4)). Analysis of cell proliferation and clonogenic ability showed that As(4)S(4) and imatinib exerted synergistic effects on both K562 cells and fresh CML cells. The effective concentrations on fresh CML cells were pharmacokinetically available in vivo but had much less inhibitory effect on CD34(+) cells from the nonleukemic donors. Examination of cell cycles showed that As(4)S(4) induced G(2)/M arrest whereas imatinib induced G(1) arrest. Using a number of parameters such as morphology, annexin V/propidium iodide (PI), mitochondrial transmembrane potential, caspase-3 activity, and Fas/Fas-L, the synergistic effects were revealed on induction of cell apoptosis, largely through the mitochondrial pathway. The 2 drugs also exhibited a synergistic effect in targeting BCR-ABL protein. While As(4)S(4) triggered its degradation and imatinib inhibited its tyrosine kinase activity, combined use of the 2 led to lower protein/enzymatic activity levels of BCR-ABL. Our in vitro data thus strongly suggest a potential clinical application of imatinib and As(4)S(4) combination on CML.
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PMID:Combined effects of As4S4 and imatinib on chronic myeloid leukemia cells and BCR-ABL oncoprotein. 1533 52

Arsenic trioxide (As2O3) is an effective drug for treatment of acute promyelocytic leukemia (APL) and malignant tumors. However, it is not commonly known to researchers that sensitivity has been associated with As2O3 concentration in target cells. Cell lines and cell strains of leukemia and solid cancer cells were treated with different concentrations of As2O3, and the concentrations were compared to apoptosis detected by FITC-annexin V and propidium iodide (PI) double staining. Results showed that intracellular and intercellular concentrations of arsenic in different cell lines differed. Our study noted that the cell lines had concentrations of arsenic trioxide in decreasing order, as follows: APL primary cell > K562 > CML primary cell > HL-60 > AML-M2 primary cell > HeLa > H-22. Higher intracellular As2O3 concentrations in cell lines APL, NB4, and K562 can be obtained by treating in culture medium with lower As2O3 concentration for longer times than the transient higher concentration. These results indicate that different leukemia and solid carcinoma cell lines have different intracellular arsenic concentrations, which correlate with different sensitivities to As2O3 in clinical treatment. The intracellular As2O3 concentration is higher; in addition, we note apoptosis, a very important observation in our study. As2O3 inhibited the growth of these cell lines significantly. Novel techniques by maintaining continuous low but effective arsenic levels inside the target leukemic cells in APL may improve the complete remission rate and overall survival with minimum cost and drug toxicity.
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PMID:Significance of intracellular arsenic trioxide for therapeutic response in acute promyelocytic leukemia. 1568 19

Monoclonal antibody 2E12 was prepared by immunization of mice with cells of a chronic myeloid leukemia cell line MOLM-7. Human hematopoietic cell lines JURKAT, HPB-ALL, RC2A and MOLM-7 were induced to receptor mediated apoptosis by the treatment with anti-Fas monoclonal antibody 7C11 and subsequently tested for reactivity with 2E12 antibody in comparison to staining with annexin V-FITC and PI in the two-color immunofluorescence and flow cytometry. After 2, 5, 24, and 48 hours of induction, a gradual increase of the percentage of 2E12 positive cells in all cell lines was observed, which partially correlated with an increase of annexin V-FITC binding with a delay of about 12 hours. In the two- color fluorescence microscopy the 2E12 antibody positivity was restricted to the annexin V positive cells, but their number was lower. The binding of 2E12 did not induce apoptosis nor influenced the binding of annexin V. We suppose that the antibody 2E12 detects an antigen expressed on a subpopulation of cells in death. Therefore it can be useful as a new marker for further dissection between living, apoptotic and necrotic cellular populations in vitro.
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PMID:An antigen recognized on cells in apoptosis detected by monoclonal antibody 2E12. 1573 21

Overexpression of BCR-ABL and P-glycoprotein (Pgp) are two of the known mechanisms of imatinib resistance. As combination therapy may allow to overcome drug resistance, we investigated the effect of combination treatment with imatinib and 17-allylamino-17-demethoxygeldanamycin (17-AAG), a heat-shock protein 90 (Hsp90) inhibitor, on different imatinib-sensitive and imatinib-resistant CML cell lines. In imatinib-sensitive cells, combination index (CI) values obtained using the method of Chou and Talalay indicated additive (CI=1) or marginally antagonistic (CI>1) effects following simultaneous treatment with imatinib and 17-AAG. In imatinib-resistant cells both drugs acted synergistically (CI<1). In primary chronic-phase CML cells additive or synergistic effects of the combination of imatinib plus 17-AAG were discernible. Annexin V/propidium iodide staining showed that the activity of imatinib plus 17-AAG is mediated by apoptosis. Combination treatment with imatinib plus 17-AAG was more effective in reducing the BCR-ABL protein level than 17-AAG alone. Monotherapy with 17-AAG decreased P-glycoprotein activity, which may increase intracellular imatinib levels and contribute to the sensitization of CML cells to imatinib. The results suggest that combination of imatinib and 17-AAG may be useful to overcome imatinib resistance in a clinical setting.
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PMID:Synergistic activity of imatinib and 17-AAG in imatinib-resistant CML cells overexpressing BCR-ABL--Inhibition of P-glycoprotein function by 17-AAG. 1590 98


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