| Project/Area Number |
11670514
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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)
NAKAO Kazuhiko Nagasaki Univ.Sch.Med., Assistant Professor, 保健管理センター, 講師 (00264218)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2000: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1999: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | Hepatoma / Suicide Gene Therapy / Radiation / Apoptosis / Angiogenesis / Dormancy |
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| Research Abstract |
The therapeutic efficiency of tumor specific promoter controlled gene therapy for cancer is rather weak. To improve the efficiency of gene therapy for hepatoma, we examined the synergistic effect of radiation therapy combined with suicide gene therapy. Radio-inducible suicide gene (Egr-tk) was constructed by insertion of Egr-1 promoter upstream of HSV-tk gene, and AFP enhancer/promoter region was ligated to HSV-tk (AFP-tk) to create a tumor specific suicide gene construct. In vitro gene therapy was assessed in hepatoma cells with high AFP-producing characteristics that were sensitive to GCV after the transient gene transduction with HVJ-liposome vehicle. Combined with radiation therapy, the AFP-tk transduced cells became more sensitive to the GCV treatment. On the other hand, Egr-tk-transduced hepatoma cells became highly sensitive to GCV after irradiation, but not without irradiation. In vivo, the combined radiation/gene therapy of HuH7 or PLC/PRF/5 tumors implanted to in nude mice resulted in a significant decrease of tumor size and complete regression was observed in 67% or 50% of case with the respective cell line over a 6-month follow-up. Histochemical studies showed that the number of apoptotic cells in tissues of mice received the combined therapy was five-times greater than after gene therapy or irradiation alone and 27 times greater than control. The increased Fas-staining intensity was observed in radiation and combined therapy groups. Our data indicate that radiation potentiated the effectiveness of the AFP enhancer/promoter controlled gene therapy of hepatomas irrespective of the AFP level produced by tumor cells. This synergistic effect may be partly due to the enhanced Fas-mediated apoptosis occurring as a bystander effect.
Finally, we acknowledge a support from this grant and a valuable contribution of our post doc fellows and staffs.
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