Expression and activation of apoptosis-related molecules involved in interferon-alpha-mediated apoptosis in human liver cancer cells.
Interferon (IFN)-alpha directly inhibits proliferation of liver cancer cells by inducing apoptosis, but the molecular mechanisms by which IFN-alpha induces apoptosis in these cells are not fully understood. We examined the effect of broad spectrum caspase inhibitor, Z-VAD-fmk, and the caspase activation in IFN-alpha-mediated apoptosis by using 4 liver cancer cell lines that were sensitive or resistant to IFN-alpha-mediated apoptosis. Involvement of apoptosis-related mitochondrial proteins and Bcl-2 family proteins in IFN-alpha-mediated apoptosis was further examined in 1 sensitive cell line (KIM-1). The Z-VAD-fmk completely or moderately inhibited IFN-alpha-mediated apoptosis in the sensitive cells. IFN-alpha induced time-dependent activation of caspase-3 in the sensitive cells, while the resistant cells showed mild or no activation. Activation of caspase-9, caspase-8, and caspase-7, and the cleavage of poly(ADP-ribose)polymerase were identified in either or both of the sensitive cell lines, but not in the resistant cells. In KIM-1 cells, the release of cytochrome c and Smac/DIABLO from mitochondria to cytosole was confirmed. Meanwhile, Bcl-xL was upregulated, and Bid activation or translocation, or conformational changes of Bax were not identified. In conclusion, our results suggest IFN-alpha-mediated apoptosis in liver cancer cells involves the mitochondrial apoptotic pathway and is induced by activating various caspases.
Yano
Hirohisa
H
Department of Pathology, Kurume University School of Medicine, Research Center of Innovative Cancer Therapy of the 21st Century COE Program for Medical Science, Kurume, Fukuoka 830-0011, Japan. hiroyano@med.kurume-u.ac.jp
Ogasawara
Sachiko
S
Momosaki
Seiya
S
Akiba
Jun
J
Nishida
Naoyo
N
Kojiro
Sakiko
S
Ishizaki
Hironori
H
Kojiro
Masamichi
M
D017209:Apoptosis / Q000187:drug effects*; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000032:analysis; D020169:Caspases / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology*; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D002352:Carrier Proteins; D016898:Interferon-alpha; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051020:bcl-X Protein; D020169:Caspases