Genipin-induced apoptosis in hepatoma cells is mediated by reactive oxygen species/c-Jun NH2-terminal kinase-dependent activation of mitochondrial pathway.
Genipin, the aglycone of geniposide, exhibits anti-inflammatory and anti-angiogenic activities. Here we demonstrate that genipin induces apoptotic cell death in FaO rat hepatoma cells and human hepatocarcinoma Hep3B cells, detected by morphological cellular changes, caspase activation and release of cytochrome c. During genipin-induced apoptosis, reactive oxygen species (ROS) level was elevated, and N-acetyl-l-cysteine (NAC) and glutathione (GSH) suppressed activation of caspase-3, -7 and -9. Stress-activated protein kinase/c-Jun NH2-terminal kinase 1/2(SAPK/JNK1/2) but neither MEK1/2 nor p38 MAPK was activated in genipin-treated hepatoma cells. SP600125, an SAPK/JNK1/2 inhibitor, markedly suppressed apoptotic cell death in the genipin-treated cells. The FaO cells stably transfected with a dominant-negative c-Jun, TAM67, was less susceptible to apoptotic cell death triggered by genipin. Diphenyleneiodonium (DPI), an inhibitor of NADPH oxidase, inhibited ROS generation, apoptotic cell death, caspase-3 activation and JNK activation. Consistently, the stable expression of Nox1-C, a C-terminal region of Nox1 unable to generate ROS, blocked the formation of TUNEL-positive apoptotic cells, and activation of caspase-3 and JNK in FaO cells treated with genipin. Our observations imply that genipin signaling to apoptosis of hepatoma cells is mediated via NADPH oxidase-dependent generation of ROS, which leads to downstream of JNK.
Kim
Byung-Chul
BC
Division of Life Sciences, College of Natural Sciences, Kangwon National University, 192-1 Hyoja-2-dong, Chuncheon 200-701, Korea.
Kim
Hong-Gyum
HG
Lee
Sin-Ae
SA
Lim
Seunghwan
S
Park
Eun-Hee
EH
Kim
Seong-Jin
SJ
Lim
Chang-Jin
CJ
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D020169:Caspases / Q000502:physiology; D002460:Cell Line; D006801:Humans; D057889:Iridoid Glycosides; D039823:Iridoids; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology*; D020935:MAP Kinase Signaling System; D008928:Mitochondria / Q000502:physiology*; D048055:Mitogen-Activated Protein Kinase 8 / Q000502:physiology; D019255:NADPH Oxidases / Q000502:physiology; D011714:Pyrans / Q000494:pharmacology*; D051381:Rats; D017382:Reactive Oxygen Species
D057889:Iridoid Glycosides; D039823:Iridoids; D011714:Pyrans; D017382:Reactive Oxygen Species; C007834:genipin; D019255:NADPH Oxidases; D048031:JNK Mitogen-Activated Protein Kinases; D048055:Mitogen-Activated Protein Kinase 8; D020169:Caspases