Tseng Tsui-Hwa, Shen Chien-Heng, Huang Wen-Shih, Chen Cheng-Nan, Liang Wen-Hai, Lin Tseng-Hsi, Kuo Hsing-Chun
Division of Transfusion Medicine, Department of Pathology and Laboratory Medicine; Division of Hematology, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan.
J Biomed Sci. 2014 Jul 5;21(1):61. doi: 10.1186/1423-0127-21-61.
Caffeic acid phenethyl ester (CAPE), a component of propolis, is reported to possess anti-inflammatory, anti-bacterial, anti-viral, and anti-tumor activities. Previously, our laboratory demonstrated the in vitro and in vivo bioactivity of CAPE and addressed the role of p53 and the p38 mitogen-activated protein kinase (MAPK) pathway in regulating CAPE-induced apoptosis in C6 glioma cells.
C6 cancer cell lines were exposed to doses of CAPE; DNA fragmentation and MAPKs and NGF/P75NTR levels were then determined. SMase activity and ceramide content measurement as well as western blotting analyses were performed to clarify molecular changes. The present study showed that CAPE activated neutral sphingomyelinase (N-SMase), which led to the ceramide-mediated activation of MAPKs, including extracellular signal-regulated kinase (ERK), Jun N-terminus kinase (JNK), and p38 MAPK. In addition, CAPE increased the expression of nerve growth factor (NGF) and p75 neurotrophin receptor (p75NTR). The addition of an N-SMase inhibitor, GW4869, established that NGF/p75NTR was the downstream target of N-SMase/ceramide. Pretreatment with MAPK inhibitors demonstrated that MEK/ERK and JNK acted upstream and downstream, respectively, of NGF/p75NTR. Additionally, CAPE-induced caspase 3 activation and poly [ADP-ribose] polymerase cleavage were reduced by pretreatment with MAPK inhibitors, a p75NTR peptide antagonist, or GW4869.
Taken together, N-SMase activation played a pivotal role in CAPE-induced apoptosis by activation of the p38 MAPK pathway and NGF/p75NTR may explain a new role of CAPE induced apoptosis in C6 glioma.
咖啡酸苯乙酯（CAPE）是蜂胶的一种成分，据报道具有抗炎、抗菌、抗病毒和抗肿瘤活性。此前，我们实验室证明了CAPE的体外和体内生物活性，并探讨了p53和p38丝裂原活化蛋白激酶（MAPK）途径在调节CAPE诱导C6胶质瘤细胞凋亡中的作用。
将C6癌细胞系暴露于不同剂量的CAPE；然后测定DNA片段化、MAPKs以及NGF/P75NTR水平。进行鞘磷脂酶（SMase）活性和神经酰胺含量测定以及蛋白质印迹分析以阐明分子变化。本研究表明，CAPE激活中性鞘磷脂酶（N-SMase），导致神经酰胺介导的MAPKs激活，包括细胞外信号调节激酶（ERK）、c-Jun氨基末端激酶（JNK）和p38 MAPK。此外，CAPE增加神经生长因子（NGF）和p75神经营养因子受体（p75NTR）的表达。添加N-SMase抑制剂GW4869证实NGF/p75NTR是N-SMase/神经酰胺的下游靶点。用MAPK抑制剂预处理表明，MEK/ERK和JNK分别在NGF/p75NTR的上游和下游起作用。此外，用MAPK抑制剂、p75NTR肽拮抗剂或GW4869预处理可降低CAPE诱导的半胱天冬酶3激活和聚[ADP-核糖]聚合酶裂解。
综上所述，N-SMase激活通过激活p38 MAPK途径在CAPE诱导的凋亡中起关键作用，NGF/p75NTR可能解释了CAPE诱导C6胶质瘤细胞凋亡的新作用。
