Carnosic Acid, a Rosemary Phenolic Compound, Induces Apoptosis Through Reactive Oxygen Species-Mediated p38 Activation in Human Neuroblastoma IMR-32 Cells

• Published in: Neurochemical research 2011-12, Vol.36 (12), p.2442-2451
• Main Authors: Tsai, Chia-Wen, Lin, Chia-Yuan, Lin, Hui-Hsuan, Chen, Jing-Hsien
• Format: Article
• Language: English
• Subjects: Acetylcysteine - pharmacology; Apoptosis - drug effects; Biochemistry; Biomedical and Life Sciences; Biomedicine; Caspase 3 - metabolism; Cell Biology; Cell Line, Tumor; Diterpenes, Abietane - pharmacology; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases - metabolism; Humans; JNK Mitogen-Activated Protein Kinases - metabolism; Neuroblastoma - pathology; Neuroblastoma - physiopathology; Neurochemistry; Neurology; Neurosciences; Original Paper; p38 Mitogen-Activated Protein Kinases - metabolism; Plant Extracts - pharmacology; Proto-Oncogene Proteins c-bcl-2 - biosynthesis; Reactive Oxygen Species - metabolism; Rosmarinus
• ISSN: 0364-3190; 1573-6903
• DOI: 10.1007/s11064-011-0573-4

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.