Selenium activates p53 and p38 pathways and induces caspase-independent cell death in cervical cancer cells.
The mechanisms of sodium selenite-induced cell death in cervical carcinoma cells were studied during 24 h of exposure in the HeLa Hep-2 cell line. Selenite at the employed concentrations of 5 and 50 micromol/L produced time- and dose-dependent suppression of DNA synthesis and induced DNA damage which resulted in phosphorylation of histone H2A.X. These effects were influenced by pretreatment of cells with the SOD/catalase mimetic MnTMPyP or glutathione-depleting buthionine sulfoximine, suggesting the significant role of selenite-generated oxidative stress. Following the DNA damage, selenite activated p53-dependent pathway as evidenced by the appearance of phosphorylated p53 and accumulation of p21 in the treated cells. Concomitantly, selenite activated p38 pathway but its effect on JNK was very weak. p53- and p38-dependent signaling led to the accumulation of Bax protein, which was preventable by specific inhibitors of p38 (SB 203580) and p53 (Pifithrin-alpha). Mitochondria in selenite-treated cells changed their dynamics (shape and localization) and released AIF and Smac/Diablo, which initiated caspase-independent apoptosis as confirmed by the caspase-3 activity assay and the low effect of caspase inhibitors z-DEVD-fmk and z-VAD-fmk on cell death. We conclude that selenite induces caspase-independent apoptosis in cervical carcinoma cells mostly by oxidative stress-mediated activation of p53 and p38 pathways, but other selenite-mediated effects, in particular mitochondria-specific ones, are also involved.
Rudolf
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Department of Medical Biology and Genetics, Charles University in Prague, Faculty of Medicine in Hradec Králové, Hradec Králové, Czech Republic. rudolf@lfhk.cuni.cz
Rudolf
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Cervinka
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D051033:Apoptosis Inducing Factor / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins; D001973:Bromodeoxyuridine / Q000378:metabolism / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D004249:DNA Damage; D004273:DNA, Neoplasm / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D005978:Glutathione / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008665:Metalloporphyrins; D024101:Mitochondrial Proteins / Q000378:metabolism; D053140:Organelle Shape / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D012643:Selenium / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D002583:Uterine Cervical Neoplasms / Q000201:enzymology* / Q000473:pathology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D051033:Apoptosis Inducing Factor; D051017:Apoptosis Regulatory Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; C412403:DIABLO protein, human; D004273:DNA, Neoplasm; D047908:Intracellular Signaling Peptides and Proteins; D008665:Metalloporphyrins; D024101:Mitochondrial Proteins; D016159:Tumor Suppressor Protein p53; C050950:tetrakis(N-methyl-4-pyridiniumyl)porphine manganese(III) complex; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D053148:Caspase 3; D001973:Bromodeoxyuridine; D005978:Glutathione; D012643:Selenium