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)

Murine monoclonal antibody (mAb) 7C11 binds to the same cell surface epitope as anti-APO-1 and anti-Fas and reacts specifically with cells transfected with a cDNA encoding the human Fas antigen. Furthermore, incubation with 7C11 causes death of hematopoietic cell lines that express APO-1/Fas but not APO-1/Fas-negative cell lines. 7C11 therefore recognizes the human APO-1/Fas (CD95) antigen, a 40 to 50 kDa cell surface glycoprotein that can trigger apoptosis or programmed cell death. Expression of APO-1/Fas antigen by normal and neoplastic hematopoietic cells was determined by flow cytometry using 7C11. APO-1/Fas is expressed by approximately 30 to 40% of resting peripheral blood T cells, B cells, and monocytes and by approximately 5% of resting NK cells and thymocytes. It was not detected on granulocytes, erythrocytes, or platelets. Approximately 80 to 90% of activated T cells, B cells, and thymocytes express APO-1/Fas, as do the majority of activated NK cells. Perturbation of APO-1/Fas by 7C11 does not affect the viability of resting lymphocytes or monocytes. In contrast, activated T cells and NK cells undergo apoptosis within 3 hours of exposure to 7C11. Other mAb that stimulate T cells or NK cells do not cause rapid induction of programmed cell death. APO-1/Fas antigen is expressed by many cell lines of lymphoid and myeloid lineage. However, this antigen was detected on neoplastic cells from only one of 69 patients with acute myeloid leukemia, acute lymphoblastic leukemia, chronic myelogenous leukemia, chronic lymphocytic leukemia, or multiple myeloma. Only 3 out of 25 tumor samples from patients with non-Hodgkin's lymphoma were found to express APO-1/Fas. All three of these lymphomas harbored the bcl-2-Ig fusion gene associated with the chromosomal translocation t (14;18). Conversely, only 27% of lymphomas that possessed the bcl-2-Ig gene were found to express the APO-1/Fas antigen. Like normal activated lymphocytes, leukemia and lymphoma cells that expressed APO-1/Fas antigen were found to undergo apoptosis in vitro after incubation with 7C11. The APO-1/Fas antigen appears to regulate the growth of normal hematopoietic cells, and the marked upregulation of this antigen on activated normal lymphocytes contrasts sharply with the absence of APO-1/Fas on neoplastic cells of hematopoietic lineage. Defects in the apoptotic signal delivered through this antigen might contribute to the pathogenesis of hematopoietic neoplasms. Thus, the gene encoding APO-1/Fas can be considered a novel type of tumor suppressor gene, just as bcl-2 can be considered a cellular proto-oncogene.
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PMID:Functional consequences of APO-1/Fas (CD95) antigen expression by normal and neoplastic hematopoietic cells. 753 60

Soluble receptors have been identified for most members of the TNF-receptor/NGF receptor superfamily. CD95 (Fas/Apo-1) is of particular importance, since its triggering may induce apoptosis in sensitive cells. Recently, a soluble form of the CD95 molecule was described which interacts with the CD95-CD95 ligand death pathway. Increased concentrations of soluble CD95 (sCD95) were previously detected in some patients with T and B cell leukemias and lymphomas. In the present study we investigated sCD95 in the serum of patients with myeloid leukemias, myeloproliferative and myelodysplastic syndromes. A total of 72 patients was studied (29 AML, 17 MDS, 20 CML and six other myeloproliferative disorders). In AML with active disease, the levels of sCD95 tended to be elevated, but did not correlate with defined clinical or laboratory parameters. In the other disorders, the levels of sCD95 were not generally increased, although some patients had elevated levels. These data strongly suggest that sCD95 in AML patients is not derived from leukemic cells, but is possibly secreted or shed from reactive or stromal cells. This hypothesis is also supported by a group of eight patients with septicemia but not leukemia who had elevated sCD95 (P < 0.05). Furthermore, all three patients with elevated sCD95 who had undergone chemotherapy for AML had major infections. Taken together, this study shows that measuring soluble Fas-receptor in myeloid leukemia is not diagnostically useful, but increased sCD95 may be associated with clinical complications like septicemias.
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PMID:Soluble FAS (CD95) is not elevated in the serum of patients with myeloid leukemias, myeloproliferative and myelodysplastic syndromes. 875 76

Interferon-alpha (IFN-alpha) is an established treatment for chronic myelogenous leukemia (CML) in chronic phase, but the mechanism of its antileukemic activity is not clear. One possible mechanism of action might include the induction of apoptosis, and especially Fas-mediated cell killing may play an important role in the elimination of malignant cells. We investigated Fas receptor (Fas-R) expression and the consequences of Fas-R triggering in CML patients. Using two-color flow cytometry, we found a significantly higher number of Fas-R-expressing CD34+ cells in the bone marrow (BM) of CML patients compared with normal subjects. We have previously shown that IFN-gamma induces Fas-R expression on CD34+ cells; in this study, we investigated whether IFN-alpha induces Fas-R expression on CML progenitor cells. Dose-dependent induction of Fas-R expression was observed after IFN-alpha stimulation of CD34+ cells from CML BM. In methylcellulose culture, IFN-alpha alone at a therapeutic concentration showed only marginal antiproliferative effects on both normal and CML BM progenitors. In contrast, a Fas-R agonist, the anti-CD95 monoclonal antibody CH11, inhibited colony formation from normal progenitors, and the inhibition was even stronger on CML progenitors. When CML BM cells were cultured in the presence of IFN-alpha, Fas-R-mediated inhibition of colony growth was potentiated in a dose-dependent fashion, consistent with IFN-alpha induction of Fas-R expression. This functional effect did not require the presence of accessory cells, since similar results were obtained with purified CD34+ cells. In suspension cultures, we demonstrated that suppression of CML hematopoiesis by IFN-alpha and Fas-R agonist was exerted through Fas-R-mediated induction of apoptosis. Our findings suggest that the Fas-R/Fas-ligand system might be involved in the immunologic regulation of CML progenitor growth and that its effect can be amplified by IFN-alpha.
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PMID:Involvement of Fas-mediated apoptosis in the inhibitory effects of interferon-alpha in chronic myelogenous leukemia. 902 27

Liver infiltrating lymphocytes (LIL) were isolated from HCV-positive (+) and HCV-negative (-) end-stage livers. Phenotypic analysis and functional studies using proliferative and lymphocytotoxic assays were performed with the isolated LIL. Two CD3+ lymphocyte populations were found in LIL using FITC anti-CD3 monoclonal antibodies (mAb). One was a bright fluorescence intensity population (as in PBL), and the other dim. We calculated the number of FITC-anti-CD3 mAbs bound per lymphocyte on PBL and LIL and found 80,040 +/- 4628 and 39,615 +/- 3932, respectively. Therefore, HCV+ and HCV- patient PBL contained approximately twice the number of CD3 molecules per cell than patient CD3+ LIL. LIL also contained approximately a threefold higher concentration of TCR alpha beta +, CD4-CD8-, and CD56,16 (NK) cells than the patient PBL. Thus, a major subset of LIL is phenotypically similar to mouse NK1.1+ "intermediate" T cells. LIL freshly isolated from HCV+ livers exhibited weak CTL activity against EBV- or Con A-transformed lymphoblast targets infected with vaccinia-HCV recombinant virus (rHCV) or primary hepatocyte cultured cells. However, after in vitro coculture of LIL with rHCV, these cells developed a strong cytotoxicity for the above targets. In contrast, LIL from HCV- livers were not cytotoxic against the same targets. Histochemical studies (in situ) demonstrated that these hepatocytes express CD95, and stains demonstrated apoptosis. The HCV+ hepatocytes also express class I MHC molecules and ICAM-1. The addition of mAb specific for these adhesion molecules inhibited CML activity. Short-term cultured hepatocytes (targets) from HCV+ and HCV- patients produced low levels of cytokines IL-1 beta, IL-2, IL-6, TNF alpha, and IFN-gamma but a high level of IL-8. It is speculated that LIL expressing reduced numbers of CD3 molecules may even function as immune regulators as proposed for intermediate T cells in mice.
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PMID:The immune reactivity role of HCV-induced liver infiltrating lymphocytes in hepatocellular damage. 908 90

Drug resistance is a common cause of treatment failure in oncology. In addition to the resistance caused by over-expression of p-glycoprotein and similar molecules other mechanisms are involved in the selection or induction of drug resistant tumor cells. In this study, we characterized a CML cell line made resistant to cyclophosphamide (KBM7-B5-1803) further for the expression of apoptosis promoting and inhibiting molecules. We found that KBM7-B5-1803 has a 3 4-fold over-expression of the receptor CD95 (Fas/Apo-1) compared with the parent line. The regulation of CD95 by cytokines was comparable to other types of cells. Despite the inducibility and over-expression of CD95, CD95 failed to trigger apoptosis in both the parent and the drug resistant line. The drug resistant line has a particular pattern of the expression of bcl-2 family members: bcl-2 protein and message were expressed to a similar extent, however, compared with the parent line, the message for bclx short was decreased. P-glycoprotein was not expressed in either cell line. Taken together we show here in a leukemia cell line that the phenotype of cyclophosphamide resistance is associated with a particular pattern of apoptosis-related molecules.
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PMID:Further characterization of cyclophosphamide resistance: expression of CD95 and of bcl-2 in a CML cell line. 978 11

Fas antigen, also termed APO-1 or CD95, is a transmembrane protein and a member of the tumor necrosis factor receptor/nerve growth factor receptor superfamily which mediates apoptosis upon oligomerization. The Fas/Fas ligand system is considered to be a key regulator of apoptosis. Recently, we have demonstrated that Fas antigen expression is induced by low-dose irradiation of some types of lymphomas, and we also demonstrated that irradiation-induced Fas antigen expression increased with the passage of time until peaking at 48 h after irradiation in CML-C1, CML-C2, DL-40, and DL-95 cell lines. In this study, we also examined the potential cytotoxicity of Fas ligand peptide against several types of lymphoma/leukemia cell lines that showed induction of Fas antigen expression under irradiation. Flow cytometry analysis was performed at 6, 24 and 48 h after irradiation. Samples (1 x10(6) cells/ml) from irradiated and non-irradiated cells of each cell line were incubated with or without 5 microg/ml of Fas ligand peptide for 2 h at 37 degrees C in a humidified atmosphere of 5% carbon dioxide (CO2) in air. The killing effect of Fas ligand against cell lines of CML-C1, DL-40, and DL-95 were clearly identified as the percentage of cells with Fas antigen expression induced by irradiation. Concerning HD-70 cell line, for which soluble Fas antigen has been identified, the killing effects were clearly observed in samples pre-treated with PBS washings. To our knowledge, this is the first report describing a possible application of the Fas/Fas ligand system in treatment of certain types of malignancies in which Fas antigen is inducible by irradiation.
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PMID:Cytotoxicity of Fas ligand against lymphoma cells with radiation-induced Fas antigen. 985 30

We investigated whether inhibition of the BCR-ABL tyrosine kinase by the CGP57418B compound would render chronic myeloid leukaemia (CML) cells susceptible to Fas (CD95, Apo-1)-mediated cell death. Only two (AR230 and SD1) out of 10 BCR-ABL positive cell lines were found to express the CD95 protein. No change in Fas expression was observed in any of the 10 cell lines after 48 h exposure to CGP57418B. AR230 cells were resistant and SD1 cells were partially resistant to Fas-mediated apoptosis induced by ligation of the Fas receptor to an anti-Fas IgM antibody. Pre-incubation with 1 microM CGP57418B did not change the susceptibility of these cell lines to Fas-mediated cell death. Similar results were observed in experiments with CD34+ cells from CML patients and from normal individuals. The data suggest that, in contrast to some cytotoxic drugs, the CGP57148B tyrosine kinase inhibitor utilizes a pathway other than the CD95 system in order to induce apoptosis in CML cells.
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PMID:The susceptibility of Philadelphia chromosome positive cells to FAS-mediated apoptosis is not linked to the tyrosine kinase activity of BCR-ABL. 985 22

The differentiation and apoptosis-sensitizing effects of the Bcr-Abl-specific tyrosine kinase inhibitor CGP57148B, also known as STI-571, were determined in human Bcr-Abl-positive HL-60/Bcr-Abl and K562 cells. First, the results demonstrate that the ectopic expression of the p185 Bcr-Abl fusion protein induced hemoglobin in the acute myeloid leukemia (AML) HL-60 cells. Exposure to low-dose cytosine arabinoside (Ara-C; 10 nmol/L) increased hemoglobin levels in HL-60/Bcr-Abl and in the chronic myeloid leukemia (CML) blast crisis K562 cells, which express the p210 Bcr-Abl protein. As compared with HL-60/neo, HL-60/Bcr-Abl and K562 cells were resistant to apoptosis induced by Ara-C, doxorubicin, or tumor necrosis factor-alpha (TNF-alpha), which was associated with reduced processing of caspase-8 and Bid protein and decreased cytosolic accumulation of cytochrome c (cyt c). Exposure to CGP57148B alone increased hemoglobin levels and CD11b expression and induced apoptosis of HL-60/Bcr-Abl and K562 cells. CGP57148B treatment down-regulated antiapoptotic XIAP, cIAP1, and Bcl-x(L), without affecting Bcl-2, Bax, Apaf-1, Fas (CD95), Fas ligand, Abl, and Bcr-Abl levels. CGP57148B also inhibited constitutively active Akt kinase and NFkappaB in Bcr-Abl-positive cells. Attenuation of NFkappaB activity by ectopic expression of transdominant repressor of IkappaB sensitized HL-60/Bcr-Abl and K562 cells to TNF-alpha but not to apoptosis induced by Ara-C or doxorubicin. Importantly, cotreatment with CGP57148B significantly increased Ara-C- or doxorubicin-induced apoptosis of HL-60/Bcr-Abl and K562 cells. This was associated with greater cytosolic accumulation of cyt c and PARP cleavage activity of caspase-3. These in vitro data indicate that combinations of CGP57148B and antileukemic drugs such as Ara-C may have improved in vivo efficacy against Bcr-Abl-positive acute leukemia.
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PMID:CGP57148B (STI-571) induces differentiation and apoptosis and sensitizes Bcr-Abl-positive human leukemia cells to apoptosis due to antileukemic drugs. 1097 73

Killer lymphocytes play a central therapeutic role in graft-versus-leukemia following allogeneic hematopoietic stem cell transplantation (HSCT). The Perforin/Granzyme and FAS/CD95 pathways are of crucial importance in tumor cell elimination by killer cells. In this study, we have examined whether hematological malignancies are resistant to perforin and anti-FAS antibodies. Leukemic cells were studied from 29 patients suffering either from acute or chronic myeloid leukemia (AML or CML), acute or chronic lymphoid leukemia, or non-Hodgkin's lymphoma. An average of 49 vs 5% of specific cell killing was found when using perforin vs anti-FAS antibodies, respectively. Interestingly, resistance towards both perforin and anti-FAS antibodies was found exclusively in leukemic cells from patients with myeloid leukemia. Analysis of leukemic cells from patients with CML, suffering from leukemia relapse after HSCT and given donor lymphocyte infusion (DLI) to induce remission, indicated that the effectiveness of treatment with DLI was not associated with sensitivity of leukemic cells to perforin. In conclusion, resistance towards anti-FAS antibodies is a common phenomenon in leukemia/lymphoma, whereas perforin resistance occurs only in myeloid leukemia. However, as a single parameter, perforin resistance does not appear to be suitable to predict the outcome of DLI.
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PMID:Prevalence and clinical significance of resistance to perforin- and FAS-mediated cell death in leukemia. 1521 73

Proteasome inhibitors are able to efficiently induce apoptosis in many tumor cells while leaving quiescent, untransformed cells largely unharmed. Here we investigated the further enhancement of proteasome inhibitor-mediated apoptosis induction in Bcr-Abl positive K562 CML cells by simultaneous treatment with different histone deacetylase inhibitors (HDIs). Combining proteasome and HDIs resulted in rapid hyperacetylation of histone H3 and accumulation of polyubiquitinated proteins and the synergistic induction of apoptosis. Apoptosis induction was associated with caspase 8, 3 and 9 activation, Bid processing, destruction of the mitochondrial membrane potential, cleavage of PARP and lamin B and extensive DNA fragmentation. The pan-caspase inhibitor Z-VAD-FMK and the caspase-8 inhibitor Z-IETD-FMK could inhibit K562 cell apoptosis. Apoptosis was also delayed by overexpression of Bcl-xL, as well as by crmA, a known inhibitor of caspases 1 and 8. Caspase 8 activity could still be detected in the presence of ectopic Bcl-xL, but not in crmA transfected cells. The most striking anti-apoptotic effect though was obtained by the translational inhibitor cycloheximide, which abolished caspase 8 processing, blocked Bid cleavage and maintained the mitochondrial transmembrane potential. Apoptosis by the combination treatment occurred independently from CD95/Fas receptor stimulation. These results demonstrated that transcriptional activation by HDIs combined with proteasome inhibitor mediated posttranslational stabilization of protein(s) results in significantly enhanced CML apoptosis which was striktly dependent on uninterrupted protein synthesis.
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PMID:Synergistic apoptosis induction by proteasome and histone deacetylase inhibitors is dependent on protein synthesis. 1613 66


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