title: Cinnamaldehyde-induced apoptosis in human PLC/PRF/5 cells through activation of the proapoptotic Bcl-2 family proteins and MAPK pathway.
abstract: Cinnamaldehyde (Cin) has been shown to be effective in inducing apoptotic cell death in a number of human cancer cells. However, the intracellular death signaling mechanisms by which Cin inhibits tumor cell growth are poorly understood. In this study, we investigated the effect of mitogen-activated protein kinases (MAPKs) inhibitors [namely SP600125 (a specific JNK inhibitor), SB203580 (a specific p38 inhibitor) and PD98059 (a specific ERK inhibitor)] on the stress-responsive MAPK pathway induced by Cin in PLC/PRF/5 cells. Trypan blue staining assay indicated that Cin was cytotoxic to PLC/PRF/5 cells. Cin caused cell cycle perturbation (S-phase arrest) and triggered apoptosis as revealed by the externalization of annexin V-targeted phosphatidylserine and accumulation of sub-G1 peak. It down-regulated the Bcl-2 and Mcl-1 expression, and up-regulated Bax protein in a time-response manner. Treatment with 1 microM Cin resulted in an activation of caspase-8 and cleavage of Bid to its truncated form in a time-dependent pattern. JNK, ERK and p38 kinases in cells were activated and phosphorylated after Cin treatment. Pre-incubation with SP600125 and SB203580 markedly suppressed the effect of Cin-induced apoptosis, but not PD98059. Both SP600125 and SB203580 significantly prevented the phosphorylation of JNK and p38 proteins, but not ERK. These results conclude that Cin triggers apoptosis in PLC/PRF/5 cells could be through the activation of pro-apoptotic Bcl-2 family (Bax and Bid) proteins and MAPK signaling pathway.
authors.affiliation: Graduate Institute of Natural Products, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan, ROC.
authors.forename: Shu-Jing
authors.initials: SJ
authors.lastname: Wu
authors.forename: Lean-Teik
authors.initials: LT
authors.lastname: Ng
authors.forename: Chun-Ching
authors.initials: CC
authors.lastname: Lin
mesh_terms: D000171:Acrolein / Q000031:analogs & derivatives* / Q000494:pharmacology*; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D017304:Annexin A5; D004791:Enzyme Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D000171:Acrolein; D048031:JNK Mitogen-Activated Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases; C012843:cinnamaldehyde