title: Carnosic acid, a rosemary phenolic compound, induces apoptosis through reactive oxygen species-mediated p38 activation in human neuroblastoma IMR-32 cells.
abstract: Carnosic acid (CA), a rosemary phenolic compound, has been shown to display anti-cancer activity. We examined the apoptotic effect of CA in human neuroblastoma IMR-32 cells and elucidated the role of the reactive oxygen species (ROS) and mitogen-activated protein kinase (MAPK) associated with carcinogenesis. The result indicated that CA decreased the cell viability in a dose-dependent manner. Further investigation in IMR-32 cells revealed that cell apoptosis following CA treatment is the mechanism as confirmed by flow cytometry, hoechst 33258, and caspase-3/-9 and poly(ADP-ribose) polymerase (PARP) activation. Immunoblotting suggested a down-regulation of anti-apoptotic Bcl-2 protein in the CA-treated cells. In flow cytometric analysis, CA caused the generation of reactive oxygen species (ROS); however, pretreatment with the antioxidant N-acetylcysteine (NAC) attenuated the CA-induced generation of ROS and apoptosis. This effect was accompanied by increased activation of p38 and by decreased activation of extracellular signal-regulated kinase (ERK) as well as activation of c-Jun NH(2)-terminal kinase (JNK). Moreover, NAC attenuated the CA-induced phosphorylation of p38. Silencing of p38 by siRNA gene knockdown reduced the CA-induced activation of caspase-3. In conclusion, ROS-mediated p38 MAPK activation plays a critical role in CA-induced apoptosis in IMR-32 cells.
authors.affiliation: Department of Nutrition, China Medical University, 91 Hsueh-Shih Rd, Taichung 404, Taiwan. cwtsai@mail.cmu.edu.tw
authors.forename: Chia-Wen
authors.initials: CW
authors.lastname: Tsai
authors.forename: Chia-Yuan
authors.initials: CY
authors.lastname: Lin
authors.forename: Hui-Hsuan
authors.initials: HH
authors.lastname: Lin
authors.forename: Jing-Hsien
authors.initials: JH
authors.lastname: Chen
mesh_terms: D045784:Abietanes / Q000494:pharmacology*; D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D009447:Neuroblastoma / Q000473:pathology* / Q000503:physiopathology*; D010936:Plant Extracts / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D045784:Abietanes; D010936:Plant Extracts; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D053148:Caspase 3; C018381:salvin; D000111:Acetylcysteine