Acute myelogenous leukemia in a patient with Li-Fraumeni syndrome treated with valproic acid, theophyllamine and all-trans retinoic acid: a case report.
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Aminophylline↗
Biomedical subjects
B T Gjertsen
Publications and source records attributed to B T Gjertsen.
CaM-kinaseII-dependent commitment to microcystin-induced apoptosis is coupled to cell budding, but not to shrinkage or chromatin hypercondensation.
The protein phosphatase inhibitor microcystin-LR (MC) induced hepatocyte apoptosis mediated by the calcium-calmodulin-dependent multifunctional protein kinase II (CaMKII). CaMKII antagonists were added at various times after MC to define for how long the cells depended on CaMKII activity to be committed to execute the various parameters of death. Shrinkage and nonpolarized budding were reversible and not coupled to commitment. A critical commitment step was observed 15-20 min after MC (0.5 microM) addition. After this, CaMKII inhibitors no longer protected against polarized budding, DNA fragmentation, lost protein synthesis capability, and cell disruption. Commitment to chromatin hypercondensation occurred 40 min after MC addition. In conclusion, irreversible death commitment was coupled to polarized budding, but not to shrinkage or chromatin condensation. Antioxidant prevented chromatin condensation when given after the CaMKII-dependent commitment point, suggesting that CaMKII had mediated the accumulation of a second messenger of reactive oxygen species nature.
Amino Acid Chloromethyl Ketones↗
Animal models of acute myelogenous leukaemia - development, application and future perspectives.
From the early inception of the transplant models through to contemporary genetic and xenograft models, evolution of murine leukaemic model systems have been critical to our general comprehension and treatment of cancer, and, more specifically, disease states such as acute myelogenous leukaemia (AML). However, even with modern advances in therapeutics and molecular diagnostics, the majority of AML patients die from their disease. Thus, in the absence of definitive in vitro models which precisely recapitulate the in vivo setting of human AMLs and failure of significant numbers of new drugs late in clinical trials, it is essential that murine AML models are developed to exploit more specific, targeted therapeutics. While various model systems are described and discussed in the literature from initial transplant models such as BNML and spontaneous murine leukaemia virus models, to the more definitive genetic and clinically significant NOD/SCID xenograft models, there exists no single compendium which directly assesses, reviews or compares the relevance of these models. Thus, the function of this article is to provide clinicians and experimentalists a chronological, comprehensive appraisal of all AML model systems, critical discussion on the elucidation of their roles in our understanding of AML and consideration to their efficacy in the development of AML chemotherapeutics.
Animals↗
Khat (Catha edulis)-induced apoptosis is inhibited by antagonists of caspase-1 and -8 in human leukaemia cells.
Khat chewing is a widespread habit that has a deep-rooted sociocultural tradition in Africa and the Middle East. The biological effects of khat are inadequately investigated and controversial. For the first time, we show that an organic extract of khat induces a selective type of cell death having all morphological and biochemical features of apoptotic cell death. Khat extract was shown to contain the major alkaloid compounds cathinone and cathine. The compounds alone and in combination also induced apoptosis. Khat-induced apoptosis occurred synchronously in various human cell lines (HL-60, NB4, Jurkat) within 8 h of exposure. It was partially reversed after removal of khat and the effect was dependent on de novo protein synthesis, as demonstrated by cotreatment with cycloheximide. The cell death was blocked by the pan-caspase inhibitor Z-VAD-fmk, and also by submicromolar concentrations of Z-YVAD-fmk and Z-IETD-fmk, inhibitors of caspase-1 and -8, respectively. The 50% inhibition constant (IC(50)) for khat (200 microg ml(-1))-induced apoptosis by Z-VAD-fmk, Z-YVAD-fmk and Z-IETD-fmk was 8 x 10(-7) M as compared to 2 x 10(-8) M and 8 x 10(-8) M, respectively. Western blot analysis showed a specific cleavage of procaspase-3 in apoptotic cells, which was inhibited by Z-VAD-fmk. The cell death by khat was more sensitively induced in leukaemia cell lines than in human peripheral blood leukocytes. It is concluded that khat induces a rather swift and sensitive cell death by apoptosis through mechanisms involving activation of caspase-1, -3 and -8.
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Caspase-dependent, geldanamycin-enhanced cleavage of co-chaperone p23 in leukemic apoptosis.
Co-chaperone p23 is a component of the heat-shock protein (Hsp)90 multiprotein-complex and is an important modulator of Hsp90 activity. Hsp90 client proteins involved in oncogenic survival signaling are frequently mutated in leukemia, and the integrity of the Hsp90 complex could therefore be important for leukemic cell survival. We demonstrate here that p23 is cleaved to a stable 17 kDa fragment in leukemic cell lines treated with commonly used chemotherapeutic drugs. The cleavage of p23 paralleled the activation of procaspase-7 and -3 and was suppressed by the caspase-3/-7 inhibitor DEVD-FMK. In vitro translated 35S-p23 (in reticulocyte lysate) was cleaved at D142 and D145 by caspase-7 and -3. Cleavage of p23 occurred in caspase-3-deficient MCF-7 cells, suggesting a role for caspase-7 in intact cells. The Hsp90 inhibitor geldanamycin enhanced caspase-dependent p23 cleavage both in vitro and in intact cells. Geldanamycin also enhanced anthracycline-induced caspase activation and apoptosis. We conclude that p23 is a prominent target in leukemic cell apoptosis. Geldanamycin enhanced p23 cleavage both by rendering p23 more susceptible to caspases and by enhancing chemotherapy-induced caspase activation. These findings underscore the importance of the Hsp90-complex in antileukemic treatment, and suggest that p23 may have a role in survival signaling.
Apoptosis↗
Catha edulis (Khat) induces cell death by apoptosis in leukemia cell lines.
Khat is the Celastraceus edulis plant, a flowering evergreen tree or large shrub, which grows in the Horn of Africa and southwestern Arabia. Khat use has been associated with development of oral cancer, but its molecular effects remain controversial. This study describes a novel cytotoxic effect of whole khat extract on three leukemia cell lines. Cells were exposed to khat extract and harvested for analysis by fluorescent and electron microscopy, trypan blue exclusion, as well as immunoblotting to characterize the mode of cell death. In a separate series, cells were pretreated with a panel of caspase inhibitors for possible inhibitory effects. Khat induced a rapid cell death effect in HL-60, Jurkat, and NB4 cells that occurred within 2 h of exposure. The treated cells retained their ability to exclude trypan blue dye, a key feature in the apoptotic process. Exposed cells consistently developed morphological features of manifest apoptosis. Z-VAD, a pan-caspase inhibitor, completely inhibited toxic activity for up to 8 h, with partial inhibition by other caspase-specific agents. Western blot analysis showed specific cleavage of caspase-3 in khat-exposed cells. This study shows that khat induces cell death by apoptosis in a process sensitive to inhibition by caspase inhibitors, suggesting that subcellular interactions could be of particular relevance for the biological effects of khat in the cell death process and possibly carcinogenesis.
Apoptosis↗
Expression of Fc(epsilon)-receptors by human acute myelogenous leukemia (AML) blasts: studies of high- and low- (CD23) affinity receptor expression and the effects of IgE-mediated receptor ligation on functional AML blast characteristics.
Acute myelogenous leukemia (AML) blasts derived from 20 patients were examined for expression of high- (Fc(epsilon)RI) and low-affinity (Fc(epsilon)RII, CD23) IgE Fc(epsilon)-receptors. Fc(epsilon)RI expression was not detected for any patient. In contrast, expression of CD23 (at least 15% of the blasts stained positive) was detected for 6 out of the 20 patients. Acute lymphoblastic leukemia (ALL) blasts derived from 12 patients did not express CD23 (<1% positive cells for all patients). The functional effects of Fc(epsilon)R-receptor ligation were also examined for 20 patients, including the five patients with highest CD23 expression (30-55% positive cells) and five patients with verified low CD23 expression (<or=7% positive cells). The presence of IgE during in vitro culture altered the functional characteristics (spontaneous and cytokine-dependent proliferation, colony formation, cytokine secretion, or spontaneous in vitro apoptosis) of AML blasts for a subset of both CD23-positive patients and certain patients with very low CD23 expression. This last observation suggests that Fc(epsilon)R are either expressed at a very low level or receptors are expressed only by a minor cell subset for these patients. We conclude that functional Fc(epsilon)R can be expressed by human AML cells.
Apoptosis↗
Flow cytometric measurement of apoptosis and necrosis in cryopreserved PBPC concentrates from patients with malignant diseases.
The number of viable precursor cells actually reinfused into patients after high-dose chemotherapy is one of the most clinically important variables determining graft success or failure. A modified, previously described flow cytometric method based on annexin V staining was therefore applied to assess the degree of apoptosis and necrosis in cryopreserved PBPC concentrates from patients with malignant diseases. Twenty-two samples of unmanipulated cryopreserved PBPC concentrates were analyzed by flow cytometry. The samples were triple-stained with anti-CD34 PE, annexin V-FITC and actinomycin D, which enabled the separation of viable, early apoptotic and late apoptotic/necrotic CD34(+) precursor cells. Apotosis and necrosis were also measured in the total cell population of the concentrates. Eighty-one percent (range 49-97) of the CD34(+) cells were viable, while 7% (range 1-15) were early apoptotic and 12% (range 2-36) were late apoptotic/necrotic after freeze/thaw. There was no difference in apoptosis and necrosis in CD34(+) cells harvested from mildly pretreated patients with multiple myeloma and heavily pre-treated patients with non-Hodgkin's lymphoma. Apoptosis and necrosis were higher in the total mature cell population of the concentrates. Thirty-two percent (range 7-69) of the cells were apoptotic and 33% (range 12-60) were necrotic. We conclude that flow cytometric analysis of annexinV/actinomycin D binding in PBPC concentrates is a simple technique that can give additional information of the viability status of the cells post thaw. The present study confirms the relative robustness of human CD34(+) precursor cells concerning the freeze/thaw procedure, which are carried out in daily clinical practice.
Adult↗
Favourable response to therapy with the anti-CD20 monoclonal antibody rituximab in primary chronic cold agglutinin disease.
The 'primary' form of chronic cold agglutinin disease is a clonal B-cell lymphoproliferative disorder that is notoriously difficult to treat with drugs, including corticosteroids, alkylating agents, alpha-interferon and purine analogues. We performed a small, open, uncontrolled, prospective study to evaluate the effect of therapy with the monoclonal anti-CD20 antibody rituximab. Six patients with clonal CD20(+)kappa(+) B-cell proliferation received seven courses of rituximab 375 mg/m(2), d 1, 8, 15, and 22. One patient achieved a complete response. Four partial responses were observed, including a response to re-treatment in one patient. Two patients were categorized as non-responders. Haemoglobin levels increased by a median of 4.1 g/dl in the total group and 4.7 g/dl in the responders, who also experienced a substantial improvement of clinical symptoms. The treatment was well tolerated. We discuss the effect of rituximab therapy compared with other treatment options, and try to explain why two individual patients did not respond. Despite the small numbers, the results are very encouraging. Further studies of rituximab therapy for chronic cold agglutinin disease are warranted.
Aged↗
[The mechanism of apoptosis--therapeutic possibilities in cancer].
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Apoptosis↗
Patterns of cell death induced by eluates from denture base acrylic resins in U-937 human monoblastoid cells.
The purpose of this study was to investigate in vitro the apoptosis- and necrosis-inducing potential of eluates from three heat-polymerized and four autopolymerized poly(methyl methacrylate)-based denture base resins. Our hypothesis was that the rate of cell death by apoptosis and/or necrosis induced by such denture base resins could be an important indicator of their cytotoxicity degree. U-937 human monoblastoid cells were exposed for 24 h and 48 h to eluates of 0.1 g/ml, 0.2 g/ml, 0.4 g/ml, and 0.8 g/ml extracted for 24 h and 48 h. The characteristics of apoptosis and necrosis were evaluated by flow cytometry and light and electron microscopy. Eluates from all resins enhanced cell death by apoptosis and necrosis in U-937 cells in a dose- and time-dependent fashion. Eluates from autopolymerized resins yielded higher percentages of apoptosis and necrosis than the heat-polymerized ones. The results support our hypothesis that eluates of poly(methyl methacrylate)-based denture base acrylic resins activate death-signaling pathways, and that the extent of this process reflects their biocompatibility degree.
Annexin A5↗
The effect of heat- and auto-polymerized denture base polymers on clonogenicity, apoptosis, and necrosis in fibroblasts: denture base polymers induce apoptosis and necrosis.
Eluates from poly(methyl methacrylate)-based denture base polymers have recently been found to enhance death by apoptosis and necrosis in U-937 human monoblastoid cells. The present study investigated the potential of such polymers to induce apoptosis and/or necrosis and to alter clonogenicity in L929 murine fibroblasts. A fibroblast cell line was chosen because the impairment of fibroblasts subjacent to denture bases may result in a weaker or more permeable mucosa. Two aspects were addressed: the effect of direct contact with the denture base polymers and the effect of eluates extracted from the polymers. For this purpose L929 fibroblasts were seeded on disks manufactured from three heat-polymerized and four autopolymerized denture base polymers or in different concentrations of their eluates. The effects were evaluated by light, fluorescent, confocal and electron microscopy, counting of colonies, and flow cytometry. Disks and eluates of all polymers enhanced cell death by apoptosis and necrosis in L929 cells and decreased their clonogenic potential in a dose-dependent manner. Apoptosis was the main form of cell death. In general, the deleterious effects were stronger when cells were plated directly on the polymer disks than in the eluates. The autopolymerized polymers, except one, yielded higher percentages of apoptosis and necrosis than the heat-polymerized polymers. The results of the study indicated that poly(methyl methacrylate)-based denture base polymers trigger death-signals in L929 fibroblasts and open doors for possible modulation of the cell/biomaterial interaction.
Animals↗
Autologous stem cell transplantation as post-remission therapy in adult acute myelogenous leukemia: does platelet contamination of peripheral blood mobilized stem cell grafts influence the risk of leukemia relapse?
Conventional chemotherapy of acute myelogenous leukemia (AML) results in an overall long-term disease-free survival of less than 50%, but for selected subsets of younger patients the prognosis can be improved by allogeneic stem cell transplantation. The use of autologous stem cell transplantation is now investigated as an alternative to allotransplantation due to its lower risk of serious complications. However, autotransplantation is associated with a relatively high risk of post-transplant AML relapse that can be derived from contaminating leukemia cells in the autograft. Peripheral blood mobilized stem cell (PBSC) grafts usually contain a higher number of platelets. The degree of platelet contamination is determined by the peripheral blood platelet count at the time of harvesting, and the platelets become activated and release soluble mediators during the ex vivo handling of PBSC grafts. Many of these platelet-derived mediators can bind to specific receptors expressed by AML blasts, and the platelet contamination may then alter AML blast survival and thereby influence the risk of post-transplant leukemia relapse. Therefore, we conclude that the platelet contamination of autologous stem cell grafts is possibly of clinical importance, but the effect of this nonstandardized parameter is difficult to predict in individual patients because the number of graft-contaminating platelets, the degree of platelet activation, and the effects of platelet-derived mediators on AML blasts differ between patients.
Adult↗
In vitro culture of human acute myelogenous leukemia (AML) cells in serum-free media: studies of native AML blasts and AML cell lines.
The functional characteristics were compared for acute myelogenous leukemia (AML) cells (native blasts and AML cell lines) cultured in three serum-free media (X-vivo 10, X-vivo 15, [Bio-Whitacker, Walkersville, MD] and StemSpan [Stem Cell Technologies, Vancouver, BC, Canada]) and in medium containing 10% inactivated fetal calf serum (FCS). For native AML blasts the following functions were compared: (1) autonomous and cytokine-dependent proliferation; (2) frequency of clonogenic cell; and (3) constitutive cytokine secretion. AML blast proliferation differed between patients independent of the culture medium used, and clonogenic cells were maintained after in vitro culture in all media. In contrast, constitutive cytokine secretion was higher for cells cultured in StemSpan and FCS-containing medium than for cells cultured in the X-vivo media. Native AML blasts incubated in StemSpan also showed a low frequency of apoptotic cells. The three serum-free media could also be used for long-term expansion of well-characterized AML cell lines, but the optimal medium for cell expansion and cytokine secretion differed between cell lines. We conclude that standardized serum-free culture conditions can be used for in vitro studies of native AML blasts and AML cell lines.
Adult↗
New strategies for the treatment of acute myelogenous leukemia: differentiation induction--present use and future possibilities.
A differentiation block and an accumulation of immature myeloid cells characterize acute myelogenous leukemia (AML). However, native AML cells usually show some morphological signs of differentiation that allow a classification into different subsets, and further differentiation may be induced by exposure to various soluble mediators, for example, all-trans retinoic acid (ATRA) and several cytokines. Combination therapy with ATRA and chemotherapy should now be regarded as the standard treatment of the acute promyelocytic leukemia (APL) variant of AML. Although several agents can also induce leukemic cell differentiation for other AML subgroups, in vitro studies as well as clinical data have demonstrated that these agents often have heterogeneous effects on the leukemic progenitors. This makes the clinical impact of differentiation induction therapy for individual patients difficult to predict. However, differentiation induction should be regarded as a promising therapeutic approach, especially as a part of immunotherapy or in combination with intensive chemotherapy to increase the susceptibility of AML blasts to drug-induced apoptosis. Although the morphology-based French-American-British classification was used to identify APL as an AML subset that required a special treatment, it seems unlikely that this classification alone can be used to identify new subsets of AML patients with special therapeutic requirements. Future studies on differentiation induction in AML should therefore focus on A) the identification of therapeutic agents with more predictable effects; B) the use of clinical and laboratory parameters to define new subsets of AML patients in which differentiation induction has a predictable and beneficial effect, and C) the characterization of how AML blast sensitivity to drug-induced apoptosis is altered by differentiation induction.
Apoptosis↗
New strategies in the treatment of acute myelogenous leukemia: mobilization and transplantation of autologous peripheral blood stem cells in adult patients.
During the last decade high-dose Ara-C (HIDAC; single doses of 3 g/m(2)) and autologous stem cell transplantation have been increasingly used as postremission therapy in adult acute myelogenous leukemia (AML). Controlled clinical trials have demonstrated a long-term disease-free survival of 40%-50% for patients treated with at least two courses of HIDAC. Other studies have demonstrated that postremission autologous bone marrow transplantation results in a disease-free survival equal to or better than conventional chemotherapy. However, autotransplantation with mobilized peripheral blood stem cells (PBSC) would now be preferred instead of autologous bone marrow, due to the shorter hematopoietic reconstitution period. The results reviewed in the present article suggest that HIDAC and autologous PBSC transplantation can be combined in the postremission treatment of adult AML, and this combination therapy may also reduce minimal residual disease and the risk of posttransplant relapse. From the available studies it cannot be concluded whether graft purging further reduces the relapse risk. However, the possible advantage of combination therapy with repeated courses of HIDAC and autologous PBSC transplantation needs to be demonstrated in prospective clinical trials before it can be recommended as a part of the routine treatment in AML.
Adult↗
Induction of differentiation and apoptosis- a possible strategy in the treatment of adult acute myelogenous leukemia.
A differentiation block with accumulation of immature myeloid cells characterizes acute myelogenous leukemia (AML). However, native AML cells often show some morphological signs of differentiation that allow a classification into different subsets, and further differentiation may be induced by exposure to various soluble mediators, e.g., all trans-retinoic acid (ATRA) and several cytokines. Combination therapy with ATRA and chemotherapy should now be regarded as the standard treatment for the acute promyelocytic leukemia variant of AML. Several agents can induce leukemic cell differentiation for other AML subtypes, although these effects differ between patients. Differentiation may then be associated with induction of apoptosis, and differentiation-inducing therapy may therefore become useful in combination with intensive chemotherapy to increase the susceptibility of AML blasts to drug-induced apoptosis. However, it should be emphasized that differentiation and apoptosis can occur as separate events with different regulation in AML cells, and future studies in AML should therefore focus on: A) the identification of new agents with more predictable effects on differentiation and apoptosis; B) the use of clinical and laboratory parameters to define new subsets of AML patients in which differentiation/apoptosis induction has a predictable and beneficial effect, and C) further characterization of how AML blast sensitivity to drug-induced apoptosis is modulated by differentiation induction.
Adult↗
Caspase I-related protease inhibition retards the execution of okadaic acid- and camptothecin-induced apoptosis and PAI-2 cleavage, but not commitment to cell death in HL-60 cells.
We have previously reported that the putative cytoprotective protease inhibitor, plasminogen activator inhibitor type 2 (PAI-2), is specifically cleaved during okadaic acid-induced apoptosis in a myeloid leukaemic cell line (Br J Cancer (1994) 70: 834-840). HL-60 cells exposed to okadaic acid and camptothecin underwent morphological and biochemical changes typical of apoptosis, including internucleosomal DNA fragmentation and PAI-2 cleavage. Significant endogenous PAI-2 cleavage was observed 9 h after exposure to okadaic acid; thus correlating with other signs of macromolecular degradation, like internucleosomal DNA fragmentation. In camptothecin-treated cells, PAI-2 cleavage was an early event, detectable after 2 h of treatment, and preceding internucleosomal DNA fragmentation. The caspase I selective protease inhibitor, YVAD-cmk, inhibited internucleosomal DNA fragmentation and PAI-2 cleavage of okadaic acid and camptothecin-induced apoptotic cells. YVAD-cmk rather sensitively and non-toxically inhibited camptothecin-induced morphology, but not okadaic acid-induced morphology. In in vitro experiments recombinant PAI-2 was not found to be a substrate for caspase I. The results suggest that caspase I selective protease inhibition could antagonize parameters coupled to the execution phase of okadaic acid- and camptothecin-induced apoptosis, but not the commitment to cell death.
Amino Acid Chloromethyl Ketones↗