2002 Fiscal Year Final Research Report Summary
Molecular Analysis of Stem Cell in Hepatocarcinogenesis
| Project/Area Number |
13670528
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Gastroenterology
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| Research Institution | Nagasaki University School of Medicine |
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Principal Investigator |
OHTSURU Akira Dept. Nature Medicine Nagasaki University School of Medicine, Assistant Professor, 医学部, 助手 (00233198)
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| Co-Investigator(Kenkyū-buntansha) |
YAMASHITA Shunichi Nagasaki Univ. Sch. Med., Professor, 医学部, 教授 (30200679)
TSUKAZAKI Tomoo Graduate School of Biomedical Sciences, Associate Professor, 大学院・医歯薬学総合研究科, 助教授 (50315230)
NAKAO Kazuhiko Nagasaki Univ. Sch. Med., Associate Professor, 保健管理センター, 助教授 (00264218)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Hepatoma / Stem Cell / Carcinogenesis / Apoptosis / MEKK / Radiation |
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| Research Abstract |
We compared the expression profile of RTK genes in rat normal liver and diethylnitrosamine-induced hepatoma tissues using a homology cloning method with degenerated primers. The Tie-2, c-Met, and Flk-1 genes were the most abundant RTK genes cloned in rat hepatoma compared to normal liver. In situ hybridization and immunohistochemical studies showed overexpression of c-Met and Flk-1 in GST-P positive preneoplastic lesions as well as neoplastic lesions. Tie-2 was expressed not only in endothelial cells but also in so-called oval cells, which are thought to be liver stem cells. Tie-2 ligand, angiopointin-1, mRNA was detected in both normal livers and hepatoma cells/tissues. In contrast, angiopoietin-2 mRNA was detected only in hepatoma tissues.
We next aimed to examine the involvement of caspases and calpains in H2O2-induced hepatic cell apoptosis. TUNEL-positive apoptotic cells appeared in parallel with poly(ADP-ribose) polymerase (PARP) cleavage and procaspase-3 proteolysis by H2O2 treatment in a dose-dependent manner (250-1000μM). Bcl-xL and intact Bax expression levels decreased when H2O2 was >250μM. The cleaved form of Bax appeared prior to caspase-3 activation, increasing in a dose-dependent manner. These results indicate that Bax cleavage is upstream signal of caspase-dependent apoptosis in hepatocytes. Molecular analysis of Bax cleavage may allow the mechanism of development of hepatoma cell.
Finally, we acknowledge a support from this grant and a valuable contribution of our post doc fellows and staffs.
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Research Products
(12 results)
