Home About us Contact
|
Home About us Contact | ||
|
|
||
Early Apoptosis (early + apoptosi)
Selected AbstractsEarly apoptosis plays an important role in the healing mechanism of cutaneous basal cell carcinomas after photodynamic therapyBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2003F. Prignano No abstract is available for this article. [source] Proteolysis of the tumour suppressor hDlg in response to osmotic stress is mediated by caspases and independent of phosphorylationFEBS JOURNAL, Issue 2 2009Francisco A. Iñesta-Vaquera Human disc-large (hDlg) is a scaffold protein critical for the maintenance of cell polarity and adhesion. hDlg is a component of the p38, MAP kinase pathway, which is important for the adaptation of mammalian cells to changes in environmental osmolarity. Here we report a strong decrease in the levels of hDlg protein in the human epithelial cell line HeLa when exposed to osmotic shock. This is independent of the phosphorylation state of hDlg, is prevented by preincubating the cell with the caspase inhibitor z-VAD and is part of the apoptotic process triggered by cellular stress. Although, both caspase 3 and caspase 6 are strongly activated by osmotic shock, the time course of caspase 6 activation parallels hDlg degradation, suggesting that this caspase may be responsible for the proteolysis. Mutating hDlg Asp747 to Ala abolishes caspase-induced cleavage, but does not affect the early stage of apoptosis or cell attachment. Our findings show that osmotic stress triggers hDlg degradation through a mechanism different from the one mediated by proteasomes, and we identify hDlg as a caspase substrate during the apoptotic process, although its proteolysis may not be implicated in the progression of early apoptosis. [source] Exposure to mixtures of endosulfan and zineb induces apoptotic and necrotic cell death in SH-SY5Y neuroblastoma cells, in vitroJOURNAL OF APPLIED TOXICOLOGY, Issue 5 2007Zhenquan Jia Abstract A number of epidemiological studies have demonstrated a strong association between the incidence of Parkinson's disease and pesticide exposure. Earlier it was demonstrated that exposure to the pesticides endosulfan and zineb, alone and in combination, caused neurodegeneration in vivo. It was hypothesized that these pesticides cause neurotoxicity, in part, by enhancing apoptotic cell death. SH-SY5Y human neuroblastoma cells, which retain a catecholaminergic phenotype, were exposed to endosulfan, zineb or a combination of these chemicals, in vitro. For mixture studies, concentrations of pesticides (100 µm each) were chosen based on LC25 (lethal concentration) that would result in minimum cell death. Exposure to a mixture of pesticides exhibited significantly (P , 0.05) higher toxicity than each one alone. Both pesticides were found to cause apoptotic cell death that was concentration (50,400 µm) dependent. A flow cytometric (7-aminoactinomycin D) assay was used to distinguish live, early apoptotic and late apoptotic/necrotic populations. Exposure to mixtures of the pesticides enhanced both early apoptosis and late apoptosis/necrosis compared with either chemical alone. Visual evaluation using a DNA ladder assay and a fluorescence Annexin V/PI assay confirmed the contribution of both apoptotic and necrotic processes. These findings suggest that the cytotoxicity of endosulfan and zineb, both individually and in mixtures, is associated with the occurrence of early and late apoptotic/necrotic processes in SH-SY5Y human neuroblastoma cells and support the contention that pesticide-induced neuronal cell death leading to neurodegenerative disease may, at least in part, be associated with early and late apoptosis of dopaminergic neurons. Copyright © 2007 John Wiley & Sons, Ltd. [source] Heat shock proteins reduce toxicity of 1-methyl-4-phenylpyridinium ion in SK-N-SH cellsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 4 2005Guo-Hua Fan Abstract The pathology of Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra. However, the pathogenesis of PD remains unclear. Heat shock proteins (HSPs) have many functions, including inhibition of apoptosis and necrosis, protection from oxidative stress, and maintenance of the mitochondrial membrane potential, that are related to neurodegenerative diseases. 1-Methyl-4-phenylpyridinium ion (MPP+) is a neurotoxin that selectively inhibits the mitochondrial functions of DA neurons in the substantia nigra. MPP+ administration is accepted as a model for PD. In the present study, we found that MPP+ induced a concentration- and time-dependent decrease in cell viability. Lower concentrations of MPP+ induced mainly early apoptosis, and, as the concentration increased, the number of late apoptotic and necrotic cells significantly increased. However, treated by heat shock preconditioning or transfection with HDJ-1, a homologue of human Hsp40, cells showed marked improvement in viability after exposure to the same concentrations of MPP+. Compared with heat shock, HDJ-1 appeared to improve cell viability obviously. Similarly, HDJ-1 elicited significantly stronger protective effects against apoptosis and necrosis. In addition, HDJ-1 transfection maintained more injured cells in early apoptotic stages and inhibited the occurrence of late apoptotic/necrotic events. Heat shock and HDJ-1 both ameliorated MPP+ -induced cytotoxicity by maintaining the mitochondrial membrane potential and reducing reactive oxygen species (ROS). Therefore, the effects of HSPs, such as reducing apoptosis and necrosis, preserving mitochondrial functions and decreasing oxidative stress, may bring a novel approach for PD therapy. © 2005 Wiley-Liss, Inc. [source] Cyclic stretching force-induced early apoptosis in human periodontal ligament cellsORAL DISEASES, Issue 3 2008W Zhong Objective:, Human periodontal ligament (PDL) cells occur changes in morphology and express relative protein by stretching force. However, whether stretching force, especially excessive stretching force, induces PDL cell apoptosis is not yet clearly understood. In the present study we investigated the relationship between early apoptosis and stretching force in human PDL cells in vitro. Materials and methods:, The human PDL cells were obtained from healthy premolars. After three to five passages, the cells were stretched by strain 1%, 10% and 20% for 30 min, 1 h, 6 h and 12 h, then early apoptosis were detected through annexin fluorescein isothiocyanate (V-FITC) binding by flow cytometry and confocal laser scanning microscopy. Results:, The experiments indicated that human PDL apoptotic cells in the early stage increased in a time- and force-dependent manner in response to stretching strain within 6 h, and then apoptosis decreased at 12 h. Human PDL cells which stretched inclined parallel to each other and aligned their long axis perpendicular to the stretching force vector, but in the centre of the disc, cells showed minimal deformation and unidirectional alignment of PDL cells. Conclusion:, The overall results suggested that stretching force not only influenced morphology but also induced early apoptosis in human PDL cells. [source] In vitro and in vivo antineoplastic activity of a novel bromopyrrole and its potential mechanism of actionBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2010Sheng Xiong Background and purpose:, Many bromopyrrole compounds have been reported to have in vitro antineoplastic activity. In a previous study, we isolated N-(4, 5-dibromo-pyrrole-2-carbonyl)-L-amino isovaleric acid methyl ester (B6) from marine sponges. Here, we investigated the in vitro and in vivo antineoplastic activity of B6 and its potential mechanism. Experimental approach:, The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine the in vitro antineoplastic activity of B6. Flow cytometry, western blot analysis and morphological observations were used to investigate its mechanism of action. A mouse xenograft model was used to determine its in vivo activity. Key results:, B6 inhibited the proliferation of various human cancer cells in vitro, with highest activity on LOVO and HeLa cells. B6 also exhibited significant growth inhibitory effects in vivo in a xenograft mouse model. Acute toxicity analysis suggested that B6 has low toxicity. B6-treated cells arrested in the G1 phase of the cell cycle and had an increased fraction of sub-G1 cells. In addition, the population of Annexin V-positive/propidium iodide-negative cells increased, indicating the induction of early apoptosis. Indeed, B6-treated cells exhibited morphologies typical of cells undergoing apoptosis. Western blotting showed cleaved forms of caspase-9 and caspase-3 in cells exposed to B6. Moreover, B6-promoted Ca2+ release and apoptosis was associated with elevated intracellular Ca2+concentration. Conclusions and implications:, B6 has significant antineoplastic activity in vitro as well as in vivo. It inhibits tumour cell proliferation by arresting the cell cycle and inducing apoptosis. With its low toxicity, B6 represents a promising antineoplastic, primary compound. [source] Apoptosis and Necrosis in the Ischemic Zone Adjacent to Third Degree BurnsACADEMIC EMERGENCY MEDICINE, Issue 6 2008Adam J. Singer MD Abstract Objectives:, Burns are characterized by a central zone of necrosis surrounded by a zone of potentially reversible ischemia. The authors explored the contribution of necrosis and apoptosis to cell death in the zone of ischemia. Methods:, A previously established rat contact thermal injury model that utilizes a brass comb to produce four distinctive burns sites separated by three "interspaces" of unburned skin was used. The interspaces represent the zone of stasis or ischemia while the burn sites represent the zone of coagulation. With this model, most unburned interspaces progress to necrosis over 2 to 3 days. Full-thickness 3-mm biopsies were obtained from the interspaces, burns, and normal skin controls at 30 minutes, 24 hours, and 48 hours after injury. Slides were stained with hematoxylin and eosin as well as activated cleaved caspase-3 (CC3a) for evidence of apoptosis and high-mobility group box 1 (HMGB1) for evidence of necrosis. Results:, Necrosis was not seen at 30 minutes, but was found in a large number of cells within the epidermis, sebaceous glands, and follicles at 24 and 48 hours. Faint nuclear CC3a staining indicative of apoptosis was present in a minority of cells within the epidermis, dermal fibroblasts, dermal follicles, and dermal sebaceous glands at 30 minutes and to a lesser degree at 24 and 48 hours. Conclusions:, Both early apoptosis and delayed necrosis are present in the zone of ischemia, contributing to injury progression. Necrosis appears to play a larger role than apoptosis in injury progression in the comb burn model. [source] Aurora A selective inhibitor MLN8237 suppresses the growth and survival of HTLV-1-infected T-cells in vitroCANCER SCIENCE, Issue 5 2010Mariko Tomita Aurora A kinase plays an essential role in the proper assembly and function of the mitotic spindle. We have shown previously that Aurora A expression is increased aberrantly in human T-cell leukemia virus type 1 (HTLV-1)-infected T-cell lines and primary adult T-cell leukemia cells, and a pan-Aurora kinase inhibitor, which inhibits both Aurora A and Aurora B kinases, reduces viability and induces apoptosis in these cells. However, the specific effects of Aurora A inhibition on HTLV-1-infected T-cells are poorly understood. In this study, we addressed this question by comparing the effects of MLN8237, a selective inhibitor of Aurora A, on cell viability, cell cycle progression, and induction of apoptosis in HTLV-1-infected and -uninfected T-cell lines. MLN8237 reduced the viability of HTLV-1-infected T-cell lines within 24 h, but its effects on that of HTLV-1-uninfected T-cell lines were moderate. MLN8237 induced early apoptosis of HTLV-1-infected T-cell lines without induction of polyploidy. It induced p53 and p21 expression in HTLV-1-infected but not in -uninfected T-cell lines, suggesting that MLN8237-treated HTLV-1-infected T-cell lines exit from mitosis and activate a p53-dependent postmitotic G1 checkpoint, leading to G1 arrest followed by the induction of apoptosis. Our results suggest that specific inhibition of Aurora A kinase is a potentially useful therapeutic strategy in the treatment of adult T-cell leukemia and that further in vivo exploration is warranted. (Cancer Sci 2010; 101: 1204,1211) [source] Comparison of apoptosis and mortality measurements in peripheral blood mononuclear cells (PBMCs) using multiple methodsCELL PROLIFERATION, Issue 5 2005S. Glisic-Milosavljevic Death through apoptosis is the main process by which aged cells that have lost their function are eliminated. Apoptotic cells are usually detected microscopically by changes in their morphology. However, determination of early apoptotic events is important for in vitro (and ex vivo) studies. The main objective of the present study is to find the most sensitive method for apoptosis detection in human peripheral blood mononuclear cells (PBMCs) by comparing six different methods following five different means of immunological stimulation at 3 and 5 days. Each of six apoptosis quantification methods, except the trypan blue exclusion test, is a combination of two stains, one for the specific detection of apoptotic cells and the other for the unspecific detection of dead cells. Values for apoptosis and mortality were compared with a reference method. The choice of apoptosis detection method is more important following 3 days of stimulation than after 5 days of stimulation (P = 2 × 10,6 versus P = 1 × 10,2). In contrast, we find mortality measurements following the different means of stimulation highly significant at both 3 and 5 days (F2.28 = 7.9, P = 1.4 × 10,6 at 3 days and F2.28 = 8.5, P = 4.5 × 10,7 at 5 days). Variation as a result of the combination of specific PBMC stimulation and the method used to detect apoptosis is reduced considerably with time (F1.58 + 3.7, P + 3 × 10,7 at 3 days to F = (1.58) = 0.97, P = 0.5 at 5 days). Based on Tukey's test, YO-PRO-1 is the most sensitive stain for apoptosis and, when combined with 7-AAD, provides an accurate measure of apoptosis and mortality. In conclusion, we propose YO-PRO-1/7-AAD as a new combination and low-cost alternative for the sensitive detection of early apoptosis. [source] | ||||||||||||||||