2004 Fiscal Year Final Research Report Summary
TOPOISOMERASE INHIBITORS ENHANCE THE CYTOCIDAL EFFECT OF AAV-HSVTK/GANCICLOVIR ON CANCER CELLS
| Project/Area Number |
14571627
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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 |
Otorhinolaryngology
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
SHINHAMA Akihiko University of the Ryukyus, Faculty of Medicine, Department of Otorhinolaryngology-Head and Neck Surgery, Instructor, 医学部, 助手 (60284973)
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| Co-Investigator(Kenkyū-buntansha) |
KOUCHI Ayako University of the Ryukyus, Faculty of Medicine, Department of Otorhinolaryngology-Head and Neck Surgery, Instructor, 医学部, 助手 (30264500)
GANAHA Akira University of the Ryukyus, Faculty of Medicine Hospital, Department of Otorhinolaryngology, Instructor, 医学部附属病院, 助手 (00347155)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Adeno-associated virus vector / Head and Neck Cancer / Chemotherapy / Suicide Gene / Combined Therapy |
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| Research Abstract |
Adeno-associated virus(AAV) is a nonpathogenic virus with a single-strand DNA genome. AAV vectors have several unique properties suited for gene therapy applications. However, an obstacle to their application is a low efficiency of transgene expression, mainly due to a limited second-strand synthesis. In the present study, we investigated whether topoisomerase inhibitors (etoposide and camptothecin) enhance the AAV vector-mediated transgene expression and the killing effect by AAVtk/GCV system. The enhancement of transgene expression was observed in a concentration-dependent manner on human laryngeal carcinoma cells (HEp-2 cells) and HeLa cells. Southern analysis confirmed that etoposide enhanced the double-strand synthesis of the AAV vector genome in HEp-2 cells and HeLa cells. The cells were efficiently killed by AAVtk/GCV system, as expected. More importantly, both etoposide and camptothecin augmented the cytocidal effect of the AAVtk/GCV system. Following the in vitro experiments, we evaluated the transgene expression and the antitumor activity of the AAV vectors in nude mice inoculated with HEp-2 subcutaneously. The LacZ expression was observed in the xenografted tumors and the AAVtk/GCV system suppressed the tumors growth compared with any other control such as AAVLacZ/GCV, AAVtk/PBS. These findings suggest that the combination of AAV-mediated suicide gene therapy and treatment with topoisomerase inhibitors may have synergistic therapeutic effects in the treatment of cancers.
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