José C. Diez

Ganoderma lucidum induced apoptosis in NB4 human leukemia cells: Involvement of Akt and Erk

AIM OF THE STUDY The final goal of this work was to study the toxic and apoptosis effects induced by fractions from Ganoderma lucidum [Ganoderma lucidum (Curtis) P. Karst.; Ganodermataceae Donk] on NB4 human leukemia cells. MATERIALS AND METHODS Two aqueous extracts and a methanol-extracted column-chromatography semipurified fraction were obtained from Ganoderma lucidum fruiting body. Flow cytometry analyses were used to measure cell viability, cell cycle and DNA fragmentation and to quantify apoptosis. Western-blot analyses were used to quantify changes in apoptosis proteins and intracellular kinases. RESULTS Aqueous extracts slightly reduce cell viability and induce DNA fragmentation in NB4 cells. Methanol-extracted semipurified fraction at dilutions down to 15% or 40% of the initial fraction concentration reduced significantly the viability of these leukemia cells (treated for 19h) with induction of DNA fragmentation and induction of apoptosis. Overmore, the dilution down to 15% of the initial E3 concentration induced a reduction of p53 levels, of the Bcl2/Bax relationship as well as reduced levels of both unphosphorylated and phosphorylated Akt (Protein kinase Akt, protein kinase B) and Erk (Erk1 and 2). CONCLUSIONS Induction of apoptosis and alterations in signal transduction kinases (Akt and Erk) are produced by active fractions from Ganoderma lucidum on human leukemia cells. These data could be of important relevance from the viewpoint of antitumor actions of compounds from Ganoderma lucidum. Eventual therapy applications in leukemia cells might be developed.

Delivery to macrophages and toxic action of etoposide carried in mouse red blood cells

Erythrocytes could be used as physiological carriers of active compounds. Several substances can be loaded into erythrocytes by hypotonic dialysis methods. Furthermore, carrier erythrocyte membrane can be chemically modified in order to promote increased arrival of the loaded compound to macrophages. In this work, we have prepared erythrocytes loaded with etoposide. We found conditions to obtain high etoposide encapsulation yields with minor alteration of some cell parameters of these carrier erythrocytes. Etoposide loaded into erythrocytes is mainly localised in the cytoplasmic compartment. Membrane modification of etoposide-loaded erythrocytes with band 3 crosslinkers produces an increased incorporation of the drug into macrophages mainly by phagocytosis process. The toxic effect of etoposide conveyed in these carrier erythrocytes determined as DNA fragmentation in macrophages was higher than that shown by free etoposide added at the same concentration in the culture medium to macrophages. These results seem to indicate the usefulness of this model to deliver this anti-tumour compound to macrophages, which might be useful in therapy.

In vitro phagocytosis of carrier mouse red blood cells is increased by Band 3 cross-linking or diamide treatment

Chemical alteration of red blood cells (RBCs) can induce increased phagocytosis of modified cells by macrophages. In this study we have used different chemical treatments for the modification of the mouse red‐blood‐cell membrane surface, namely oxidant compounds, such as ascorbate/Fe+2 and diamide [azodicarboxylic acid bis(dimethylamide)], or Band 3‐cross‐linking reagents. We monitored the phagocytosis of oxidized or Band 3‐cross‐linked mouse red blood cells by peritoneal macrophages. The extent of phagocytosis of RBCs is not affected by oxidation with ascorbate/Fe3+, but it is increased (up to 10%) by oxidation with 2 mM diamide. Furthermore, phagocytosis is greatly increased (up to 40%) as a result of cross‐linking with either of two Band 3 bifunctional reagents [bis(sulphosuccinimidyl) suberate (BS3) and 3,3′‐dithiobis(sulphosuccinimidyl propionate) (DTSSP)]. To evaluate targeting towards macrophages of such modified RBCs for therapeutical purposes, we have determined the phagocytosis of Band 3 carrier RBCs loaded with carbonic anhydrase. In this case phagocytosis is high enough (25%) to deliver the enzyme into macrophages. We have also assayed the influence of serum components and IgG on the efficiency of phagocytosis and discuss the possible phagocytosis mechanisms. In the case of BS3‐cross‐linked carrier RBCs, phagocytosis is markedly enhanced (from 12% up to 25%) by serum components. This opens a way for therapeutic application of these carrier RBCs, with special relevance in short‐term delivery to cells of the mononuclear phagocytic system.

Human acute promyelocytic leukemia NB4 cells are sensitive to esculetin through induction of an apoptotic mechanism.

Acute promyelocytic leukemia (APL) is a type of cancer, in which immature cells called promyelocytes proliferate abnormally. Human NB4 cell line appears to be a suitable in vitro model to express the characteristics of APL. In this work, we have investigated the effects of esculetin, a coumarin derivative with antioxidant properties, on the viability, the induction of apoptosis and the expression of apoptotic factors in NB4 cells. Cells treated with esculetin at several concentrations (20-500 μM) and for different times (5-24 h) showed a concentration- and time-dependent viability decrease with increased subdiploid DNA production. Esculetin inhibited cell cycle progression and induced DNA fragmentation. Moreover, annexin-V-FITC cytometry assays suggested that increased toxicity is due to both early and late apoptosis. This apoptosis process is be mediated by activation of caspase-3 and caspase-9. Treatments with progressively increasing concentrations (from 100 μM to 500 μM) of esculetin produced a reduction of Bcl2/Bax ratio in NB4 cells at 19 h, without affecting p53 levels. Proapoptotic action of esculetin involves the ERK MAP kinase cascade since increased levels of phosphorylated ERK were observed after those treatments. Increments in the levels of phosphorylated-Akt were also observed. Additionally, esculetin induced the loss of mitochondrial membrane potential with a release of cytochrome c into the cytosol which starts at 6 h of treatment with esculetin and increases up to 24 h. Esculetin induced an increase in superoxide anion at long times of treatment and a reduction of peroxides at short times (1 h) with an observed increase at 2-4 h of treatment. No significant changes in NO production was observed. Esculetin reduced the GSH levels in a time-dependent manner. In summary, the present work shows the cytotoxic action of esculetin as an efficient tool to study apoptosis mechanism induction on NB4 cell line used as a relevant model of APL disease.

Dequalinium induces apoptosis in peripheral blood mononuclear cells isolated from human chronic lymphocytic leukemia

SummaryB-cell chronic lymphocytic leukemia (B-CLL) is an abnormal neoplasic proliferation of B cells, which accumulate mainly in the bone marrow and blood preventing both B cells development in the lymph nodes and the ability to fight against infection. The antitumor agents used in chemotherapy are aimed at inducing malignant cell death, thus limiting the growth and spreading of these cells. However, the lack of specificity for tumor cells exhibited by these agents causes undesirable side effects that have led to the investigation of new therapeutic strategies designed to specifically target malignant cells and thus trigger selective cell destruction. Dequalinium (DQA) is an antitumoral agent that selectively accumulates in the mitochondria and has been shown to display anticancer activity in cells from different malignancies. In the present study, the DQA-induced cytotoxicity in B-CLL cells was analyzed by measuring cell viability and cell death, either by necrosis or apoptosis. Our results support the importance of DQA as a selective and potential antileukemic drug with a higher cytotoxic effect on peripheral blood mononuclear cells from B-CLL patients than in those from healthy donors and encourage the performance of further studies in combination with other agents.

Delivery to macrophages of interleukin 3 loaded in mouse erythrocytes.

Mouse carrier erythrocytes containing 125I-interleukin 3 have been prepared and treated with band 3 crosslinking reagents. The incorporation of interleukin 3 by hypotonic treatment into mouse erythrocytes reached levels of about 15% of the interleukin 3 added to the medium being predominantly present in the cytosolic fraction (73%). Uptake fell to about 7.4% when using the same conditions but omitting hypotonic shock. The interaction of band 3 crosslinked interleukin 3 loaded erythrocytes with macrophages was also studied. A high level of incorporation of interleukin 3 into macrophages was observed either from band 3 crosslinked, interleukin 3-loaded erythrocytes or from interleukin 3 loaded erythrocytes. The observations encourage the view that the system may be able to deliver and target cytokines and other growth factors to macrophages.

CYTOTOXIC ACTION OF GANODERMA LUCIDUM ON INTERLEUKIN-3 DEPENDENT LYMPHOMA DA-1 CELLS: INVOLVEMENT OF APOPTOSIS PROTEINS

Aqueous extracts and a semipurified fraction obtained by methanol extraction and column chromatography were isolated from Ganoderma lucidum [Ganoderma lucidum (Curtis) P. Karst.; Ganodermataceae Donk] and their effects on interleukin 3‐dependent lymphoma cells (DA‐1) were studied. Cell viability was reduced by the action of unboiled aqueous extract and by the methanol‐extracted column‐chromatography semipurified fraction, producing DNA fragmentation in DA‐1 cells. Treatments with aqueous extracts showed increments of Bax after 13 h, increments of p53 and Mdm2 after 19 h and a reduction of these three proteins after 24 h. The methanol‐extracted semipurified fraction also induced increments of p53 and Mdm2 factors at 19 h with a reduction after 24 h. The methanol‐extracted column‐chromatography semipurified fraction from Ganoderma lucidum produced minor changes in the level of Akt after treatments for 19 h in DA‐1 cells with a slight reduction in the levels of NFkB‐p65 factor. Both the unboiled aqueous extract and the methanol‐extracted column‐chromatography semipurified fraction produced cleavage of inactive caspase 3, as a clear indication of induction of apoptosis by compounds present in Ganoderma lucidum. Copyright

Differential In vitro and In vivo Behavior of Mouse Ascorbate/Fe3+ and Diamide Oxidized Erythrocytes

Chemical oxidation of mouse erythrocytes has been carried out using two different oxidizing systems namely: Diamide and Ascorbate/Fe3+ together with different concentrations of the oxidant. These oxidation treatments produced different extents of modification in membrane proteins as was observed by electrophoretic analyses that showed a possible formation of high molecular weight aggregates. Lipid peroxidation was also observed as the result of these chemical treatments. The action of these two oxidation treatments produced different extents of lipid peroxidation in which the effect Ascorbate/Fe3+ reached higher values than that shown by diamide treatments. To study the resulting in vitro behavior of such oxidized erythrocytes, we have evaluated the recognition of oxidized erythrocytes by peritoneal macrophages. In the conditions used, diamide oxidized erythrocytes were more highly recognized by macrophages than Ascorbate/Fe3+ treated erythrocytes. However, in both cases an influence of serum factors in the recognition process can be inferred. Additionally, we have correlated on one side the action of different oxidation systems on mouse erythrocytes with different in vivo behavior and organ uptake of the oxidized erythrocytes. On the other side, differential targeting of oxidized erythrocytes to a liver or spleen was observed on dependence of the oxidant used.

Band‐3 crosslinking‐induced targeting of mouse carrier erythrocytes

Mouse band‐3 crosslinked carrier erythrocytes have been prepared. [125I]Carbonic anhydrase (CA) has been encapsulated into mouse erythrocytes. Then, loaded erythrocytes were labelled with 51Cr. Eventually, these doubly labelled cells were crosslinked with band‐3 crosslinking reagents. [125I]CA was shown to have cytosolic localization in crosslinked carrier erythrocytes. Estimation of the action of band‐3 crosslinkers on mouse carrier‐erythrocyte membranes rendered values around 17–21% of band‐3 monomer reduction. Crosslinked carrier erythrocytes were in vivo targeted to liver, as shown by chromium‐labelling localization. Also, encapsulated CA radioactivity was localized in vivo predominantly in liver, which is clearly in contrast with the behaviour shown by free CA injected into animals. These results support this model as a feasible system for the analysis of carrier‐erythrocyte survival and targeting as well as the in vivo efficacy of release and targeting of encapsulated compounds.

JNK and NFκB dependence of apoptosis induced by vinblastine in human acute promyelocytic leukaemia cells

The relationship between the mitogen‐activated protein kinase response, nuclear factor‐κB (NFκB) expression and the apoptosis in human acute promyelocytic leukaemia NB4 cells treated with vinblastine was investigated in this work. Cell viability, subdiploid DNA and cell cycle were analysed by propidium iodide permeability and flow cytometry analyses. Apoptosis was determined by annexin V‐Fluorescein isothiocyanate assays. Western‐blot analysis was used for determination of expression levels of apoptotic factors (p53, Bax and Bcl2), intracellular kinases [serine/threonine‐specific protein kinase, extracellular signal‐regulated kinase and c‐Jun N‐terminal kinase (JNK)], NFκB factor and caspases. Electrophoretic mobility shift assay was usefully applied to study DNA‐NFκB interaction. In NB4 cells, vinblastine produces alteration of p53 and DNA fragmentation. Vinblastine treatment had an antiproliferative effect via the induction of apoptosis producing Bax/Bcl‐2 imbalance. Vinblastine treatment suppressed NFκB expression and depressed NFκB‐DNA binding activity while maintaining JNK activation that subsequently resulted in apoptotic response through caspase‐dependent pathway. Our study provides a possible anti‐cancer mechanism of vinblastine action on NB4 cells by deregulation of the intracellular signalling cascade affecting to JNK activation and NFκB expression. Moreover, JNK activation and NFκB depression can be very significant factors in apoptosis induction by vinblastine. Copyright