title: 5-Azacytidine induces toxicity in PC12 cells by apoptosis.
abstract: 5-Azacytidine (5 Az)is a potent inhibitor of DNA methylation, and it may allow inactive genes to become expressed. In a previous study, we demonstrated that 5 Az administered to the dam induced apoptosis in the brains of fetal mice. In this study, the 5 Az-induced apoptosis was further characterized in differentiated PC 12 cells as a model for neuronal apoptosis. Cell death, determined by the activity of released lactate dehydrogenase (LDH) into the medium, occurred from 24 to 48 hrs after 5 Az treatment. Toxicity for differentiated PC 12 cells was observed on treatment with more than 10(-1) micrograms/ml of 5 Az, and it reached the maximal level at 10 micrograms/ml. Cycloheximide, an inhibitor of protein synthesis, prevented 5 Az toxicity, suggesting that this cell death required protein synthesis which could be related to the activation of a dormant gene(s). Electrophoresis of DNA from 5 Az-treated cells evoked ladder formation, indicating the cleavage of DNA into nucleosomes. Scanning electron microscopy demonstrated bleb formation, the so-called apoptotic bodies on the cell surface. The biochemical and morphological findings indicated that 5 Az-induced cell death occurred in the form of apoptosis. 5 Az-induced cell death was prevented by treatment with cAMP but not by treatment with high K+ or deoxycytidine. These results suggest that a cAMP-sensitive mechanism is involved in 5 Az-induced cell death. PC 12 cells should be of value in elucidating the molecular mechanism of 5 Az-induced neuronal apoptosis.
authors.affiliation: Department of Veterinary Pathology, Faculty of Agriculture, University of Tokyo, Japan.
authors.forename: M M
authors.initials: MM
authors.lastname: Hossain
authors.forename: A
authors.initials: A
authors.lastname: Takashima
authors.forename: H
authors.initials: H
authors.lastname: Nakayama
authors.forename: K
authors.initials: K
authors.lastname: Doi
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic; D017209:Apoptosis; D001374:Azacitidine / Q000494:pharmacology*; D003994:Bucladesine / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D019175:DNA Methylation; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D016716:PC12 Cells / Q000187:drug effects*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats
chemical_list: D000964:Antimetabolites, Antineoplastic; D011500:Protein Synthesis Inhibitors; D003994:Bucladesine; D003513:Cycloheximide; D007770:L-Lactate Dehydrogenase; D001374:Azacitidine