Topoisomerase inhibitors enhance the cytocidal effect of AAV-HSVtk/ganciclovir on head and neck cancer cells.
Adeno-associated virus (AAV) is a non-pathogenic 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. Previously, we reported that gamma-rays enhanced the transduction efficiency and cytocidal effect of AAV vector harboring the herpes simplex virus-thymidine kinase (AAVtk) and ganciclovir (GCV) system. 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. 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.
Kanazawa
Takeharu
T
Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical School, 3311-1 Yakushiji Minamikawachi, Tochigi 329-0498, Japan.
Mizukami
Hiroaki
H
Nishino
Hiroshi
H
Okada
Takashi
T
Hanazono
Yutaka
Y
Kume
Akihiro
A
Kitamura
Ken
K
Ichimura
Keiichi
K
Ozawa
Keiya
K
D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D002166:Camptothecin / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000229:Dependovirus / Q000187:drug effects / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D005047:Etoposide / Q000494:pharmacology; D015774:Ganciclovir / Q000627:therapeutic use*; D015870:Gene Expression; D041722:Genes, Transgenic, Suicide; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000628:therapy*; D006801:Humans; D013937:Thymidine Kinase / Q000235:genetics* / Q000378:metabolism; D059004:Topoisomerase I Inhibitors
D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; D059004:Topoisomerase I Inhibitors; D005047:Etoposide; D013937:Thymidine Kinase; D015774:Ganciclovir; D002166:Camptothecin