Apoptosis: mode of cell death induced in T cell leukemia lines by dexamethasone and other agents

Bansal, Neelam; Houle, Antoinette; Melnykovych, George

doi:10.1096/fasebj.5.2.2004665

Cited by 113 publications

(51 citation statements)

References 21 publications

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“…Inhibition of apoptosis and reduction of c-myc protein by cycloheximide Cycloheximide (CHX) (178 nM) has been shown to partially inhibit glucocorticoid-induced apoptosis in CCRF CEM cells (Bansal et al, 1991). At concentrations > 1 lLM we found it to induce significant (> 50% by 48 h) apoptosis, as has been reported by others (Collins et al, 1991).…”

Section: Kinetics Of Dexamethasone-induced Apoptosissupporting

confidence: 84%

“…This finding contrasts with recent findings that deregulated expression of c-myc in mesenchymal and myeloid cells is a potent inducer of apoptosis (Askew et al, 1991;Evan et al, 1992). Furthermore, the hypothesis that transcriptional suppression by dexamethasone is required to initiate a programmed cell death, and specifically the c-myc gene, had to be reconciled with the finding that CCRF CEM apoptotic cell death was partially inhibited by cycloheximide, an inhibitor of protein synthesis (Bansal et al, 1991 Norman & Thompson (1977) and described further by Yuh & Thompson (1989 Ltd., 1994 were dissolved in absolute ethanol,'the final volume of which was not greater than 0.1% (v/v). Control cultures received the solvent alone.…”

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confidence: 63%

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Changes in c-myc expression and the kinetics of dexamethasone-induced programmed cell death (apoptosis) in human lymphoid leukaemia cells

Wood

Waters²,

Garner³

et al. 1994

Br J Cancer

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The kinetics of dexamethasone-induced death of CCRF CEM clone C7A human lymphoblastic leukaemia cells was determined with respect to changes in the expression of the c-myc protein. Cell death was characterised as being by apoptosis: cells with an intact plasma membrane had condensed chromatin and were characterised as having approximately 300 kbp fragments when DNA integrity was analysed by pulsed-field electrophoresis. Onset of apoptosis required a minimum of 36 h exposure to 5 microM dexamethasone; before this time no apoptotic cells were observed. This 36 h incubation period appeared to be necessary to prime the cells for subsequent death by apoptosis. In the continued presence of dexamethasone the percentage of apoptotic cells increased to 60% apoptotic cells by 54 h. Investigation of changes in c-myc protein showed that it was undetectable after 12 h of incubation with dexamethasone, although cells were not committed to die at this time. Cells were treated with dexamethasone for 54 h and for various pulsed periods with a non-toxic concentration of cycloheximide (200 nM). When cycloheximide was present during the first 36 h priming period of dexamethasone treatment, there was an immediate loss of c-myc protein and apoptosis at 54 h was completely inhibited. In contrast, there was no inhibition of apoptosis when dexamethasone-treated cells were incubated with an 18 h pulse of cycloheximide added after 36 h. Cells exposed to dexamethasone for 36 h ('primed') were given various periods of dexamethasone-free incubation before readdition of dexamethasone for a further 18 h. The longer the cells were free of drug after priming, the less susceptible they became to apoptosis, suggesting a slow decay of their 'memory' of the initial 36 h period of exposure. Cycloheximide inhibited the decay of this memory. Removal of dexamethasone after a 36 h exposure was characterised by a subsequent 24 h suppression of c-myc protein expression. Despite this, 90% of cells became refractory to apoptosis before the reappearance of c-myc protein. The evidence does not support the hypothesis that changes in c-myc expression are required for the engagement of apoptosis of CEM cells. Images Figure 1 Figure 2 Figure 4 Figure 5

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Section: Kinetics Of Dexamethasone-induced Apoptosissupporting

confidence: 84%

mentioning

confidence: 63%

Changes in c-myc expression and the kinetics of dexamethasone-induced programmed cell death (apoptosis) in human lymphoid leukaemia cells

Wood

Waters²,

Garner³

et al. 1994

Br J Cancer

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“…27 Therefore, we tested the effect of knockdown of TNFAIP8 expression in the human leukemic cell line, CEM. 28 CEM cells were transduced with retrovirus expressing shRNAmiRs directed against TNFAIP8 or a Control sequence and sorted on the basis of hCD2 expression. The stably transduced cells were exposed to increasing concentrations of dexamethasone and their viability was assessed after 18 h. CEM cells harboring both TNFAIP8-directed shRNAmiRs showed a pro-survival effect compared with the controls at increasing doses of dexamethasone (Supplementary Figure S4), which is entirely consistent with the protective effect seen on knocking down Tnfaip8 in FTOCs.…”

Section: Resultsmentioning

confidence: 99%

Tnfaip8 is an essential gene for the regulation of glucocorticoid-mediated apoptosis of thymocytes

et al. 2009

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Glucocorticoids have significant immunoregulatory actions on thymocytes and T cells and act by binding and activating cytosolic glucocorticoid receptors, which translocate to the nucleus and control gene expression through binding to specific response elements in target genes. Glucocorticoids promote cell death by activating an apoptotic program that requires transcriptional regulation. We set out to identify genes that are crucial to the process of glucocorticoid-mediated thymocyte apoptosis. Freshly isolated murine primary thymocytes were treated with dexamethasone, mRNA isolated and used to screen DNA microarrays. A set of candidate genes with upregulated expression was identified and selected members assayed in reconstituted fetal thymic organ culture (FTOC). Fetal liver-derived hematopoietic progenitor cells (HPCs) were infected with retroviruses expressing individual genes then used to repopulate depleted fetal thymic lobes. Reconstituted FTOCs expressing the gene Tnfaip8 were treated with dexamethasone and shown to be greatly sensitized to dexamethasone. Retrovirus-mediated RNA interference was applied to knock down Tnfaip8 expression in HPCs and these were used to reconstitute FTOCs. We observed that downregulating the expression of Tnfaip8 alone was sufficient to effectively protect thymocytes against glucocorticoid-induced apoptosis. We propose that Tnfaip8 is crucial in regulating glucocorticoid-mediated apoptosis of thymocytes.

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“…Hickman, 1992;Amenta et al, 1993;Sherwood and Schimke, 1994;Barbiero et al, 1995) or by the HMGCoA reductase inhibitor lovastatin (e.g. Bansal et al, 1991;Pe Â rez-Sala and Molinedo, 1994;Han and Wyche, 1996). Also, neither the action of clofibrate as enzyme inducer (see Introduction) nor the suggestion that PP toxicity may result from PPAR interferring with retinoid action (Green and Wahli, 1994) can be disregarded.…”

Section: Mechanisms Of the Lethal Action Of Clofibrate And Nafenopinmentioning

confidence: 99%

Rapid and extensive lethal action of clofibrate on hepatoma cells in vitro

et al. 1997

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Clofibrate, for a long time in use as a hypolipidemic drug, is a well known peroxisomal proliferator (PP) and hepatocarcinogen in rodents. We show here that in vitro 1 mM clofibrate induces a rapid and massive death of rat AH-130 hepatoma cells. Cell death was prominent already after 4 h of treatment, with a characteristic`apoptotic' pattern by conventional microscopy. This was further supported by the pronounced chromatin condensation detectable on 4',6-diamine-2'-phenylindole dihydrochloride (DAPI) staining, the clearcut internucleosomal DNA fragmentation on agarose-gel electrophoresis (ladder patten), and the accumulation of markedly hypochromic cells observed in flow cytometric DNA histograms. Consistently with the apoptotic features of the process, some parameters commonly used to detect cell death, such as plasma membrane permeabilization to trypan blue or propidium iodide, lack of mitochondrial retention of rhodamine 123, or extracellular release of lactate dehydrogenase, were all virtually negative. However, these same parameters became markedly positive after 24 h of treatment, which was suggestive for the occurrence of`secondary' necrosis among AH-130 cells. By a combination of flow cytometric parameters, after 4 h on 1 mM clofibrate only 41% of the AH-130 cells could still be categorized as viable (i.e., non-apoptotic and non-necrotic), while 46% of cells appeared apoptotic and 13% necrotic. At 24 h, 67% of cells were necrotic, 20% apoptotic and only 13% non-apoptotic and nonnecrotic. Apoptosis was also extensive in AH-130 cells treated with another PP such as nafenopin at 1 mM concentration and in human hepatoma HepG2 cells treated with clofibrate. By contrast, clofibrate did not cause apoptosis on primary rat hepatocyte cultures. These observations indicate that: (i) apart from their well-known cell growth-promoting action, PPs such as clofibrate or nafenopin may exert a substantial cytotoxic action on targets such as the AH-130 or HepG2 hepatoma cells; (ii) this cell death evolves from an initial apoptotic' to an eventual`necrotic' pattern; (iii) detection of cell death requires the adoption of a full panel of tests, adequate to cover the whole evolving death pattern, while such tests may even be substantially misleading whenever applied individually; (iv) the cytotoxicity of clofibrate and similar agents on normal and, particularly, tumoural cells may deserve careful reevaluation.

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Apoptosis: mode of cell death induced in T cell leukemia lines by dexamethasone and other agents

Cited by 113 publications

References 21 publications

Changes in c-myc expression and the kinetics of dexamethasone-induced programmed cell death (apoptosis) in human lymphoid leukaemia cells

Changes in c-myc expression and the kinetics of dexamethasone-induced programmed cell death (apoptosis) in human lymphoid leukaemia cells

Tnfaip8 is an essential gene for the regulation of glucocorticoid-mediated apoptosis of thymocytes

Rapid and extensive lethal action of clofibrate on hepatoma cells in vitro

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