The selection between apoptosis and necrosis is differentially regulated in hydrogen peroxide-treated and glutathione-depleted human promonocytic cells

10 páginas, 7 figuras -- PAGS nros. 889-898Treatment with 0.2 mM hydrogen peroxide (H2O2) or with 0.5 mM cisplatin caused caspase-9 and caspase-3 activation and death by apoptosis in U-937 human promonocytic cells. However, treatment with 2 mM H2O2, or incubation with the glutathione suppressor DL-buthionine-(S,R)-sulfoximine (BSO) prior to treatment with cisplatin, suppressed caspase activation and changed the mode of death to necrosis. Treatment with 2 mM H2O2 caused a great decrease in the intracellular ATP level, which was partially prevented by 3-aminobenzamide (3-ABA). Correspondingly, 3-ABA restored the activation of caspases and the execution of apoptosis. By contrast, BSO plus cisplatin did not decrease the ATP levels, and the generation of necrosis by this treatment was not affected by 3-ABA. On the other hand, while all apoptosis-inducing treatments and treatment with 2 mM H2O2 caused Bax translocation from the cytosol to mitochondria as well as cytochrome c release from mitochondria to the cytosol, treatment with BSO plus cisplatin did not. Treatment with cisplatin alone caused Bid cleavage, while BSO plus cisplatin as well as 0.2 and 2 mM H2O2 did not. Bcl-2 overexpression reduced the generation of necrosis by H2O2, but not by BSO plus cisplatin. These results indicate the existence of different apoptosis/necrosis regulatory mechanisms in promonocytic cells subjected to different forms of oxidative stressThis work was supported in part by Grant SAF-2001-1219 from the Plan Nacional de Investigacion Científica, Desarrollo e Investigación Tecnológica, Ministerio de Ciencia y Tecnología; by Grant 01/0946 from the Fondo de Investigación Sanitaria, Ministerio de Sanidad y Consumo; and by Grant 08.3/0011.3/2001 from the Comunidad Autónoma de Madrid, Spain, to PA; by the Associazione Italiana per la Ricerca sul Cancro (AIRC, Italy) to PB; and by the Program of Cooperation between the CSIC (Spain) and the CNR (Italy). AT and CF are recipients of predoctoral fellowships from the Ministerio de Ciencia y Tecnología, and PS of a predoctoral fellowship from the Ministerio de Educación, Cultura y Deporte, SpainPeer reviewe

miR-874 regulates myocardial necrosis by targeting caspase-8

Cardiomyocyte death is an important reason for the cardiac syndromes, such as heart failure (HF) and myocardial infarction (MI). In the heart diseases, necrosis is one of the main forms of cell death. MicroRNAs (miRNAs) are a class of small non-coding RNAs that mediate post-transcriptional gene silencing. Hitherto, it is not yet clear whether miRNA can regulate necrosis in cardiomyocyte. In this work, we performed a microarray to detect miRNAs in response to H(2)O(2) treatment, and the results showed that miR-874 was substantially increased. We further studied the function of miR-874, and observed that knockdown of miR-874 attenuated necrosis in the cellular model and also MI in the animal model. We searched for the downstream mediator of miR-874 and identified that caspase-8 was a target of miR-874. Caspase-8 was able to antagonize necrosis. When suppressed by miR-874, caspase-8 lost the ability to repress necrotic program. In exploring the molecular mechanism by which miR-874 expression is regulated, we identified that Foxo3a could transcriptionally repress miR-874 expression. Foxo3a transgenic or knockout mice exhibited a low or high expression level of miR-874, and a reduced or enhanced necrosis and MI. Our present study reveals a novel myocardial necrotic regulating model, which is composed of Foxo3a, miR-874 and caspase-8. Modulation of their levels may provide a new approach for tackling myocardial necrosis

Biphasic ROS production, p53 and BIK dictate the mode of cell death in response to DNA damage in colon cancer cells

Necrosis, apoptosis and autophagic cell death are the main cell death pathways in multicellular organisms, all with distinct and overlapping cellular and biochemical features. DNA damage may trigger different types of cell death in cancer cells but the molecular events governing the mode of cell death remain elusive. Here we showed that increased BH3-only protein BIK levels promoted cisplatin-and UV-induced mitochondrial apoptosis and biphasic ROS production in HCT-116 wild-type cells. Nonetheless, early single peak of ROS formation along with lysosomal membrane permeabilization and cathepsin activation regulated cisplatin-and UV-induced necrosis in p53-null HCT-116 cells. Of note, necrotic cell death in p53-null HCT-116 cells did not depend on BIK, mitochondrial outer membrane permeabilization or caspase activation. These data demonstrate how cancer cells with different p53 background respond to DNA-damaging agents by integrating distinct cell signaling pathways dictating the mode of cell death