| Co-Investigator(Kenkyū-buntansha) |
TAKAKI Akinobu Okayama University, University Hospital of Medicine and Dentistry, Assistant, 医学部・歯学部附属病院, 助手 (80359885)
SHIRATORI Yasushi Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Professor, 大学院・医歯薬学総合研究科, 教授 (70196624)
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| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2003: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Interferon (IFN) combined with 5-Fluorouracil (5-FU) treatment is recently reported to show marked effects in patients with advanced hepatocellular carcinoma (HCC). IFN alpha 2 is widely provided for chronic liver diseases. But IFN alpha 8 is the most effective subtype to induce apoptosis in several cancer cell lines. In this study, we investigated the molecular mechanisms of apoptosis induction in hepatoma cell lines with IFN alpha 2 or alpha 8 in combination with 5-FU. Five hepatoma cell lines (Hep3B, Huh7, HLE, PLC/PRL/5, and HepG2) were tested for apoptosis inducibility by IFN alpha in the absence or presence of 5-FU. Hep3B was the most apoptosis sensitive to IFN plus 5-FU treatment. Caspases-3, -9, and especially caspase-8 activities were higher with IFN alpha plus 5-FU than IFN or 5-FU alone. The JAK-STAT pathway transcriptional factor ISRE was activated more synergistically when 5-FU was added to both IFN alpha treatments. Inhibition of caspase-3,-8,9,c-Jun N-terminal kinase (JNK), phosphatidylinositide 3-kinase (PI3K), and p38 mitogen-activated protein kinase (p38 MAPK) revealed that caspase-8 inhibition was the most effective treatment to decrease apoptotic effects of IFN and/or 5-FU. In JAK1, and ISGF3g-silenced Hep3B cells, the apoptosis induction and caspase-8 activation levels by IFN, even in combination with 5-FU, were abrogated. Although IFN alpha 8 induced apoptosis more effectively than alpha 2 and showed different cluster in microarray analysis, the JAK-STAT and caspase activation status were similar.
We conclude that caspase-8 is the most important factor that controls IFN-and 5-FU- induced apoptosis in hepatoma cell lines.
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