Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is commonly accepted that mitochondria undergo major changes early during the apoptotic process and that these alterations are critical for the death/life decision. Here we report that Jurkat T cell leukemia cells exhibit a perturbed incorporation of potential-sensitive fluorochromes. After 6 h of CD95/Fas/APO-1 crosslinking, a significant fraction of still normal-sized Jurkat cells exhibit a decreased incorporation of three different cationic lipophilic dyes commonly used for the quantitation of the mitochondrial transmembrane potential (deltapsi(m)): DiOC6(3), chloromethyl-X-rosamine, and tetramethylrhodaminemethylester. In contrast, upon induction of apoptosis, cells tend to exhibit an increase in the fluorescence obtained with rhodamine 123. The increased rhodamine 123 fluorescence into cells undergoing apoptosis is not affected by labeling in the presence of the protonophore m-chlorophenylhydrazone and thus cannot be attributed to a change in the deltapsi(m). Six hours after CD95 ligation no changes are found among normal-sized cells in the incorporation of mitotracker green and nonylacridine orange, which both measure mitochondrial mass. However, a fraction of cells exhibit an increased staining with the Apo2.7 antibody which detects a mitochondrial antigen generated during apoptosis. These findings underline the importance of using adequate fluorochromes for the quantitation of mitochondrial changes occurring during early apoptosis. Moreover, they cast doubts on those studies that, using rhodamine 123, hypothesized that apoptosis would be associated with a stable or increased deltapsi(m).
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PMID:Cytofluorometric detection of mitochondrial alterations in early CD95/Fas/APO-1-triggered apoptosis of Jurkat T lymphoma cells. Comparison of seven mitochondrion-specific fluorochromes. 965 69

We have previously reported that vitamin K2 (VK2) but not VK1 has a potent apoptosis-inducing effect on freshly isolated leukemia cells from patients with various types of leukemia. By multi-color flow cytometric analysis using monoclonal antibody (mAb), APO2.7, which detects mitochondrial 7A6 antigen specifically expressed by cells undergoing apoptosis, we further investigated the apoptosis-inducing effect of VK2 on minor populations of leukemic blast cells in bone marrow from patients with myelodysplastic syndrome (MDS) and overt myeloid leukemia (post-MDS AML). Limiting dilution of CD95 (anti-Fas) mAb-treated apoptotic Jurkat cells with nonapoptotic CTB-1 cells revealed that APO2.7-positive Jurkat cells were consistently detectable by flow cytometry when present at levels of at least 5% in the CTB-1 suspension. In patient samples the gating area for leukemic clone was determined using cell surface antigen-specific mAbs conjugated with either fluorescein isothionate (FITC) or phycoerythrin (PE) and subsequently the cells stained with phycoerythrin cyanine (PE-Cy5)-conjugated APO2.7 mAb were assessed within the gating area of the leukemic clone for monitoring apoptosis. Treatment of the bone marrow mononuclear cells with 3-10 microM of VK2 (menaquinone-3, -4 and -5) in vitro potently induced apoptosis of the leukemic blast cells as compared with the untreated control cells in all 15 MDS patients tested. This effect was more prominent on blastic cells than that on mature myeloid cells such as CD34-/CD33+ gated cells. In addition, VK2 performed much less effectively on CD3-positive lymphoid cells. In contrast to VK2, VK1 did not show apoptosis-inducing activity. These data suggest that VK2 may be used for treatment of patients with MDS in blastic transformation.
Leukemia 1998 Sep
PMID:Vitamin K2 selectively induces apoptosis of blastic cells in myelodysplastic syndrome: flow cytometric detection of apoptotic cells using APO2.7 monoclonal antibody. 973 87

The interaction of Fas with Fas ligand (FasL) mediates activation-induced cell death (AICD) of T hybridomas and of mature T lymphocytes. The TNF/TNF receptor system also plays a significant role in AICD of mature T cells and in the maintenance of peripheral tolerance. We previously demonstrated that in human Jurkat leukemia cells, AICD is triggered mainly by the rapid release of preformed FasL upon TCR stimulation. In the present work, we show that the cytotoxic cytokine APO2 ligand (APO2L; also known as TRAIL) is constitutively expressed as an intracytoplasmic protein in Jurkat T cells and derived sublines. APO2L is also detected in fresh human peripheral blood mononuclear cells (PBMC) from a significant number of donors, and the amount of both FasL and APO2L substantially increases upon blast generation. A neutralizing anti-APO2L monoclonal antibody (mAb) partially suppresses the cytotoxicity induced by supernatants of phytohemagglutinin (PHA)-prestimulated Jurkat or human PBMC on non-activated Jurkat cells, indicating that APO2L is released by these cells and contributes to AICD. A combination of neutralizing anti-APO2L and anti-Fas mAb blocks around 60 % of the toxicity associated with supernatants from PHA-activated human PBMC. These results show that FasL and APO2L account for the majority of cytotoxic activity released during AICD, and suggest that additional uncharacterized factors may also contribute to this process.
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PMID:Involvement of APO2 ligand/TRAIL in activation-induced death of Jurkat and human peripheral blood T cells. 975 59

Activation-induced cell death is a process by which overactivated T cells are eliminated, thus preventing potential autoimmune attacks. Two known mediators of activation-induced cell death are Fas(CD95) ligand (FasL) and APO2 ligand (APO2L)/TNF-related apoptosis-inducing ligand (TRAIL). We show here that upon mitogenic stimulation, bioactive FasL and APO2L are released from the T cell leukemia Jurkat and from normal human T cell blasts as intact, nonproteolyzed proteins associated with a particulate, ultracentrifugable fraction. We have characterized this fraction as microvesicles of 100-200 nm in diameter. These microvesicles are released from Jurkat and T cell blasts shortly (</=1 h) after PHA stimulation, well before the cell enters apoptosis. FasL- and APO2L-containing vesicles are also present in supernatants from PHA-activated fresh human PBMC. These observations provide the basis for a new and efficient mechanism for the rapid induction of autocrine or paracrine cell death during immune regulation.
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PMID:Activated human T cells release bioactive Fas ligand and APO2 ligand in microvesicles. 1041 24

Transforming growth factor beta (TGF-beta) enhanced the growth-inhibitory activities of dexamethasone (Dex) and 1alpha,25-dihydroxyvitamin D3 (VD3) on human monocytoid leukemia U937 cells. TGF-beta and VD3 synergistically increased the expression of differentiation-associated markers such as the CD11b and CD14 antigens, whereas TGF-beta and Dex did not. On the other hand, TGF-beta and Dex synergistically increased the number of Apo2.7-positive cells, which represents the early stage of apoptosis, whereas TGF-beta and VD3 did not, suggesting that TGF-beta enhanced apoptosis with Dex and enhanced monocytic differentiation with VD3. In the presence of TGF-beta, the retinoblastoma susceptibility gene product, pRb, was synergistically dephosphorylated by Dex as well as VD3. TGF similarly enhanced the expression of the p21Waf1 gene in U937 cells treated with Dex and VD3. TGF-beta dose-dependently increased the expression of Bcl-2 and Bad and decreased the expression of Bcl-X(L) in U937 cells. Dex enhanced the down-regulation of Bcl-X(L) expression in TGF-beta-treated cells, whereas VD3 blocked this down-regulation of Bcl-X(L). However, the down-regulation of Bcl-X(L) by treatment with the antisense oligomer did not affect the apoptosis or differentiation of U937 cells. The apoptosis of CD14-positive cells was suppressed in the VD3 plus TGF-beta-treated cultures. These results suggest that the expression of CD14 is involved in the survival of differentiated cells.
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PMID:Role of CD14 expression in the differentiation-apoptosis switch in human monocytic leukemia cells treated with 1alpha,25-dihydroxyvitamin D3 or dexamethasone in the presence of transforming growth factor beta1. 1054 74

Arsenic trioxide (As2O3) effectively induces remissions in relapsed acute promyelocytic leukaemia (APL), but the safety of its long-term administration is unknown. The anthracycline idarubicin is highly active alone or in combination chemotherapy for the treatment of APL. To minimize arsenic exposure and based on the high sensitivity of APL cells to anthracyclines, we conducted a prospective study to evaluate induction with As2O3 followed by consolidation with idarubicin in the treatment of APL in relapse. Eight patients were treated with As2O3 at a daily dose of 10 mg until remission, followed by three monthly courses of idarubicin, at 6 mg/m(2)/day for 5 days in the first course and 6 mg/m(2)/day for 2 days in the subsequent two courses. All patients achieved morphological but not molecular remission after As2O3 treatment. During As2O3 therapy, an increase in white cell count peaking at a median of 17 days occurred in all the cases. Serial flow cytometric analysis of apoptosis, with mitochondrial APO2.7 antigen expression and the sub-G1 cell fraction on DNA histogram as markers, showed induction of apoptosis of APL cells in vivo. With both qualitative and real-time quantitative polymerase chain reaction, all patients were shown to attain molecular remission after subsequent idarubicin treatment. With a median follow up of 13 months, seven of eight patients have remained in complete clinical remission, with six patients in molecular remission as well. One patient who was in third remission became PCR-positive after being transiently negative. One patient died from an intracranial extramedullary relapse after achieving marrow molecular remission. We conclude that As2O3 induction followed by idarubicin consolidation is an effective therapy for APL in relapse. This regimen avoids the possible long-term toxicities of As2O3 and mutagenicity of combination chemotherapy, a strategy that might be suitable for this potentially curable leukaemia.
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PMID:Arsenic trioxide- and idarubicin-induced remissions in relapsed acute promyelocytic leukaemia: clinicopathological and molecular features of a pilot study. 1127 39

TNF-related apoptosis-inducing ligand (TRAIL) shares significant homology with CD95 (Fas) ligand and has the ability to induce apoptosis in sensitive cells through a caspase-mediated pathway. We have evaluated the activity of purified human recombinant soluble TRAIL (S-TRAIL, comprising residues 114-281; Biomol, Plymouth Meeting, PA, USA) and a leucine zipper construct of TRAIL (LZ-TRAIL; Immunex, Seattle WA, USA) against myeloma cell lines NCI H929, U266, RPMI 8226, the FasL-sensitive Jurkat T cell ALL line, the lymphoblastoid cell line MC/CAR and primary tumour cells from 16 myeloma patients. Furthermore, we examined the relationship between TRAIL-induced apoptosis and TRAIL receptor expression utilising RT-PCR and flow cytometry. Two of three myeloma cell lines and Jurkat were TRAIL sensitive whereas MC/CAR was relatively resistant. Five of 16 (31%) primary tumours demonstrated > or =20% reduction in myeloma cells following TRAIL incubation (20-59%). This did not correlate with prior therapy. Four cell lines (two sensitive) and five primary tumours (two sensitive) demonstrated mRNA expression of the intra-cellular death domain containing TRAIL-R1. Variable expression of the two decoy (TRAIL-R3 and R4) and soluble (osteoprotegerin) receptors was seen and this did not correlate with TRAIL resistance. We conclude that myeloma cell expression of death effector receptors for TRAIL is insufficient to confer sensitivity to TRAIL-induced apoptosis but that in a significant minority of patients, irrespective of prior therapy, tumour cells are sensitive to TRAIL. The further investigation of TRAIL as an adjunct to presently available therapies for myeloma is justified.
Leukemia 2001 Oct
PMID:TRAIL-induced eradication of primary tumour cells from multiple myeloma patient bone marrows is not related to TRAIL receptor expression or prior chemotherapy. 1158 25

Monoclonal antibody 2E12 was prepared by immunization of mice with fresh cells of chronic myeloid leukemia cell line MOLM-7. A panel of 15 leukemic cell lines (myeloid, promyelocytic, erythroid, B and T lymphoid) and numerous cultured patient's leukemia and myeloma cells were tested for reactivity with 2E12 antibody. A subset of cells in all cell lines and various number of patient's cells cultivated for 10 days or more were 2E12 positive. KG-1 and HL-60 cell lines were treated by camptothecin (CAM) (5 microg/ml, 4 h), washed and further cultivated without CAM. After 24 and 48 h in culture a considerable increase of 2E12 positivity was detected both in KG-1 and HL-60 cells, which well correlated with the increase of APO2.7 positivity and the sub-G1 peaks. The 2E12 positive cells were morphologically the same as cells in PCD, possibly apoptosis. We suggest that the 2E12 antibody detects a strong antigen on apoptotic cells which could be a part of the signaling process for ingestion by phagocytes.
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PMID:Monoclonal antibody to human chronic myeloid leukemia cell line MOLM-7 specifically reacts with an antigen of apoptotic cells. 1173 3

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent activator of the cell death pathway and exerts tumoricidal activity in vivo with minimal toxicity. In order to investigate the therapeutic potential of TRAIL in B chronic lymphocytic leukemia (B-CLL) we have analyzed the expression of TRAIL receptors (TRAIL-Rs) in leukemic cells from B-CLL patients and their in vitro sensitivity to apoptosis induced by recombinant human TRAIL. We have found TRAIL-R1 and -R2 death receptor, and TRAIL-R3 and -R4 decoy receptor mRNA expression in most of the 57 B-CLL patients studied (R1 82%, R2 100%, R3 96% and R4 82%). TRAIL-R1 and R2 proteins were expressed on the surface and within the cells, whereas R3 and R4 decoy receptors were almost exclusively expressed in the cytoplasm. Despite TRAIL death receptor expression, B-CLL cells were relatively resistant to induction of apoptosis by recombinant human TRAIL (300 ng/ml). However, the susceptibility to TRAIL-induced apoptosis was increased by treatment of B-CLL cells with actinomycin D (Act D). Western blot analysis showed higher constitutive expression of the long form of FLICE-inhibitory protein (FLIP(L)) in B-CLL as compared to normal tonsillar B cells. Act D treatment down-regulated both long and short FLIP expression, which was correlated with the increase in B-CLL sensitivity to TRAIL. Although the surface TRAIL death receptor expression was up-regulated both by cell culture and by Act D treatment, the changes were not correlated with a gain in susceptibility to TRAIL. In addition, neither decoy receptors nor Bcl-2 expression were affected by Act D. Our findings suggest the possible involvement of FLIP in regulating TRAIL-mediated apoptosis in B-CLL.
Leukemia 2001 Dec
PMID:Sensitization to TRAIL-induced apoptosis and modulation of FLICE-inhibitory protein in B chronic lymphocytic leukemia by actinomycin D. 1175 7

BCR-ABL fusion proteins exhibit elevated tyrosine kinase activity and transforming properties. Genetic and biochemical data suggest that Ras activation plays a central role in leukemogenic transformation by BCR-ABL. Imatinib (Novartis, Basel, Switzerland) is a potent and selective inhibitor of the tyrosine kinase activity of BCR-ABL. Although imatinib has shown promise against Ph-positive leukemia in human clinical trials, the emergence of imatinib resistance in patients with acute forms of Ph-positive leukemia has highlighted the need for combination chemotherapy to eradicate this disease. In the present study, combined use of a farnesyl transferase inhibitor, SCH66336 (lonafarnib), with the antileukemic agents imatinib, daunorubicin, cytosine arabinoside, or etoposide was investigated by cell proliferation assays. The effects of the combination of SCH66336 and imatinib were also investigated by apoptosis assay and colony-forming assay. In proliferation assays with BCR-ABL-expressing cells, combination of SCH66336 with imatinib or cytosine arabinoside showed enhanced antiproliferative activity, whereas combination of SCH66336 with daunorubicin or etoposide demonstrated an antagonistic effect. The combination of imatinib plus SCH66336 more effectively inhibited hematopoietic colony formation by primary human chronic myelogenous leukemia cells. SCH66336 combined with imatinib was shown to induce apoptosis in imatinib-resistant BCR-ABL cells by flow cytometric analysis with an APO2.7 monoclonal antibody. These results indicate that SCH66336 is a promising candidate for use in the treatment of patients with imatinib-resistant, Ph-positive leukemia and that the combination of SCH66336 plus imatinib may be useful to circumvent resistance.
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PMID:Efficacy of SCH66336, a farnesyl transferase inhibitor, in conjunction with imatinib against BCR-ABL-positive cells. 1265 16


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