title: p38 MAPK signaling mediates mitochondrial apoptosis in cancer cells induced by oleanolic acid.
abstract: Oleanolic acid (OA) is a nutritional component widely distributed in various vegetables. Although it has been well recognized for decades that OA exerts certain anti-tumor activity by inducing mitochondria-dependent apoptosis, it is still unclear that what molecular signaling is responsible for this effect. In this study, we employed cancer cell lines, A549, BXPC-3, PANC-1 and U2OS to elucidate the molecular mechanisms underlying OA anti- tumor activity. We found that activation of MAPK pathways, including p-38 MAPK, JNK and ERK, was triggered by OA in both a dose and time-dependent fashion in all the tested cancer cells. Activation was accompanied by cleavage of caspases and PARP as well as cytochrome C release. SB203580 (p38 MAPK inhibitor), but not SP600125 (JNK inhibitor) and U0126 (ERK inhibitor), rescued the pro-apoptotic effect of OA on A549 and BXPC- 3 cells. OA induced p38 MAPK activation promoted mitochondrial translocation of Bax and Bim, and inhibited Bcl-2 function by enhancing their phosphorylation. OA can induce reactive oxygen species (ROS)-dependent ASK1 activation, and this event was indispensable for p38 MAPK-dependent apoptosis in cancer cells. In vivo, p38 MAPK knockdown A549 tumors proved resistant to the growth-inhibitory effect of OA. Collectively, we elucidated that activation of ROS/ASK1/p38 MAPK pathways is responsible for the apoptosis stimulated by OA in cancer cells. Our finding can contribute to a better understanding of molecular mechanisms underlying the antitumor activity of nutritional components.
authors: Institutes of Oceanology, Chinese Academy of Sciences, Qingdao, China E-mail : zhenglanhong@126.com, linxiukun@yahoo.com.
authors: Jia
authors: J
authors: Liu
authors: Ning
authors: N
authors: Wu
authors: Lei-Na
authors: LN
authors: Ma
authors: Jia-Teng
authors: JT
authors: Zhong
authors: Ge
authors: G
authors: Liu
authors: Lan-Hong
authors: LH
authors: Zheng
authors: Xiu-Kun
authors: XK
authors: Lin
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D006801:Humans; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism*; D009828:Oleanolic Acid / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; D009828:Oleanolic Acid; D045304:Cytochromes c; D011065:Poly(ADP-ribose) Polymerases; D048051:p38 Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; C482858:MAP3K5 protein, human