Phenotype of apoptotic lymphocytes in children with Down syndrome

<p>Abstract</p> <p>Background</p> <p>Down syndrome (DS) is the most common and best-known chromosomal disorder and is associated with several other pathologic conditions including immunodeficiency which makes a significant contribution to morbidity and mortality. Various immunological theories and observations to explain the predisposition of individuals with DS to various infections have been published, one of which is increased apoptotic cells.</p> <p>Aim</p> <p>The aim of this study was to identify the effect of apoptosis on both types of cells of specific immune response (T and B lymphocytes) in children with DS using Annexin V staining of phosphatidyserine (PS) as a specific marker of early apoptosis.</p> <p>Subjects and methods</p> <p>The study included 17 children with karyotypically ascertained DS (7 males and 10 females). Their ages ranged from 4 months to 14 years with mean age of 5.7 ± 4.35 years. Seventeen age and sex matched healthy children were included in the study as controls. Patients or controls with infections were excluded from the study. Complete blood picture, immunophenotyping, analysis of apoptosis using Annexin V was done at National cancer Institute to all children included in this study.</p> <p>Results</p> <p>Although CBC, differential count, relative and absolute number of CD³⁺and CD¹⁶⁺did not show significant differences between DS children and control group, the relative and the absolute size of apoptotic CD³⁺T lymphocytes, and the relative size of apoptotic CD¹⁹⁺B lymphocytes were significantly higher in DS children than in controls. On the other hand, no significant difference was detected as regards the absolute size of CD¹⁹⁺B lymphocytes in DS children and in controls</p> <p>Conclusion</p> <p>our finding of increased early apoptotic cells (especially T cells) in DS children may emphasize the fact that the function of cells- and not their number- is main mechanism responsible for the impairment of the immune system in DS children and may further add to the known fact that cellular immunity is more severely affected than humoral immunity in these children. Further studies on apoptotic cellular phenotype in larger number of DS are needed</p

Combined effect of sodium selenite and docetaxel on PC3 metastatic prostate cancer cell line

Docetaxel and sodium selenite are well known for their anticancer properties. While resistance to docetaxel remains an obstacle in prostate cancer chemotherapy, sodium selenite, has been exploited as a new therapeutic approach. Currently, development of therapies affecting a multitude of cell targets, have been proposed as a strategy to overcome drug resistance. This association may reduce systemic toxicity counteracting a wide range of side effects. Here we report the effect of docetaxel and sodium selenite combination on the PC3 prostate cancer cell line, derived from bone metastasis. Therefore we evaluate cell growth, cell cycle progression, viability, mitochondria membrane potential, cytochrome C, Bax/Bcl2 ratio, caspase-3 expression and reactive oxygen species production. Our results suggest that sodium selenite and docetaxel combination have a synergistic effect on cell growth inhibition (67%) compared with docetaxel (22%) and sodium selenite (24%) alone. This combination also significantly induced cell death, mainly by late apoptosis vs necrosis, which is correlated with mitochondria membrane potential depletion. On the other hand, cytochrome C, Bax/Bcl2 ratio and caspase-3, known as proapoptotic factors, significantly increased in the presence of sodium selenite alone, but not in the presence of docetaxel in monotherapy or in combination with sodium selenite. These findings suggest that docetaxel and sodium selenite combination may be more effective on prostate cancer treatment than docetaxel alone warranting further evaluation of this combination in prostate cancer therapeutic approach

Effect of Glutathione Depletion on Antitumor Drug Toxicity (Apoptosis and Necrosis) in U-937 Human Promonocytic Cells

9 páginas, 8 figuras -- PAGS nros. 47107-47115Treatment with the DNA topoisomerase inhibitors etoposide, doxorubicin, and camptothecin, and with the alkylating agents cisplatin and melphalan, caused peroxide accumulation and apoptosis in U-937 human promonocytic cells. Preincubation with the reduced glutathione (GSH) synthesis inhibitorl-buthionine-(S,R)-sulfoximine (BSO) always potentiated peroxide accumulation. However, although GSH depletion potentiated the toxicity of cisplatin and melphalan, occasionally switching the mode of death from apoptosis to necrosis, it did not affect the toxicity of the other antitumor drugs. Hypoxia or preincubation with antioxidant agents attenuated death induction, apoptotic and necrotic, by alkylating drugs. The generation of necrosis by cisplatin could not be mimicked by addition of exogenous H2O2 instead of BSO and was not adequately explained by caspase inactivation nor by a selective fall in ATP content. Treatment with cisplatin and melphalan caused a late decrease in mitochondrial transmembrane potential (ΔΨm), which was much greater during necrosis than during apoptosis. The administration of the antioxidant agents N-acetyl-l-cysteine and butylated hydroxyanisole after pulse treatment with cisplatin or melphalan did not affect apoptosis but attenuated necrosis. Under these conditions, both antioxidants attenuated the necrosis-associated ΔΨm decrease. These results indicate that oxidation-mediated alterations in mitochondrial function regulate the selection between apoptosis and necrosis in alkylating drug-treated human promonocytic cells. Apoptosis and necrosis are two different forms of cell death with well defined morphological characteristics (1-3). Among other aspects, during apoptosis the cells undergo nuclear and cytoplasmic shrinkage, the chromatin is condensed and partitioned into multiple fragments, and the cells are finally broken into multiple membrane-surrounded bodies (apoptotic bodies). However, the plasma membrane retains the integrity during the process. By contrast, necrosis is characterized by cell swelling, lysis of intracellular organella, and rapid disintegration of the plasma membrane. Apoptosis seems to be clearly advantageous for the organism, because the elimination of the apoptotic cells or the resulting apoptotic bodies by phagocytosis prevents the release of intracellular content and the consequent damage of the surrounding tissue, as it occurs during necrosis. Hence, it seems very important to elucidate the mechanisms that regulate apoptosis and necrosis and the factors that may decide the selection between one or the other mode of death.One of the most complex aspects in the regulation of cell death is the role of intracellular oxidation. It was initially proposed that oxidation could be a general mediator of apoptosis (4). In fact, (i) exposure to reactive oxygen species (ROS),1 such as hydrogen peroxide (H2O2) or nitric oxide (NO), induces apoptosis in different cell types (5, 6); (ii) many apoptotic inducers, which are not ROS themselves, cause intracellular oxidation,e.g. growth factor deprivation, glucocorticoids, UV irradiation, and some cytotoxic drugs (7-11); and (iii) overexpression of Bcl-2 reduces both ROS generation and apoptosis induction by different stimuli (8, 12). However, the relationship between oxidation and apoptosis is far from being clear. In fact, (i) some forms of apoptosis may take place under very low oxygen tensions, in which ROS generation is expected to be absent or greatly reduced (13, 14), or in the presence of antioxidants (13); (ii) pre-exposure to hyperoxia inhibited H2O2-provoked apoptosis in lung adenocarcinoma cells (15); and (iii) low ROS concentrations may promote proliferation and prevent apoptosis in some cell models (16, and references therein). An additional factor of interest is given by the fact that the intensity of oxidation may be determinant for the mode of death. For instance, treatment with H2O2provoked apoptosis or necrosis, depending on the concentration used (5), and the administration of low concentrations of H2O2 sufficed to inhibit apoptosis and cause necrotic-like death in antitumor drug-treated Burkitt's lymphoma cells (17). It is known that the toxicity of antitumor drugs may largely depend on the intracellular level of reduced glutathione (GSH). Thus, depletion of GSH by prolonged incubation withl-buthionine-(S,R)-sulfoximine (BSO), a specific inhibitor of γ-glutamylcysteine synthetase, increased the lethality of the DNA topoisomerase I inhibitor CPT-11 in V79 hamster lung fibroblasts (18), of the DNA topoisomerase II inhibitor etoposide in K562 human erythroleukemia cells (19), and of the anthracycline doxorubicin in different cell types (20-23). The influence of GSH was particularly evident in the case of alkylating agents, where BSO was occasionally able to change the mode of death from apoptosis to necrosis (24, 25). Because GSH is the main antioxidant system in the cell, a possible explanation is that GSH depletion facilitates ROS accumulation in cells treated with antitumor drugs (26), which in turn increases their lethality.To test the validity of this hypothesis, in the present work we comparatively examined the capacity of BSO to modulate ROS production and cell death in U-937 human promonocytic cells treated with different antitumor drugs. The effects of exogenous H2O2and antioxidant agents, and the possible role of oxidation-related events, such as caspase inactivation, ATP depletion, and mitochondrial dysfunction, were also consideredThis work was supported in part by Grant PB97-0144 from the Dirección General de Enseñanza Superior e Investigación Cientı́fica, Grant 08.1/0027/1997 from the Comunidad Autónoma de Madrid, and Grant 01/0946 from the Fondo de Investigación Sanitaria, Spain.The costs of publication of this article were defrayed in part by the payment of page chargesPeer reviewe