title: Effect of herpes simplex virus thymidine kinase expression levels on ganciclovir-mediated cytotoxicity and the "bystander effect".
abstract: Transfer of the herpes simplex virus type-1 thymidine kinase (HSV-tk) gene into tumor cells followed by ganciclovir (GCV) administration, will provide selective tumor cell killing. We studied the effect of herpes simplex virus thymidine kinase (HSV-tk) expression level on the HSV-tk/GCV-mediated "bystander effect." Clones of HSV-tk-transduced rat glioma cells (9L) were isolated that stably expressed with different levels of HSV-tk. All clones studied had similar sensitivity to ganciclovir with IC50 values ranging from 0.45 to 1.3 microM. Within certain enzyme level thresholds, in vitro evaluation of the bystander effect has shown that clones with higher level of HSV-tk expression exhibited a better bystander effect. Interestingly, the bystander effect was observed between different cell types. Both the transduction efficiency and bystander effect are essential factors for the success of the antitumor effect by the HSV-tk/prodrug GCV suicide gene system.
authors.affiliation: Genetic Therapy, Inc., Gaithersburg, MD 20878, USA.
authors.forename: C Y
authors.initials: CY
authors.lastname: Chen
authors.forename: Y N
authors.initials: YN
authors.lastname: Chang
authors.forename: P
authors.initials: P
authors.lastname: Ryan
authors.forename: M
authors.initials: M
authors.lastname: Linscott
authors.forename: G J
authors.initials: GJ
authors.lastname: McGarrity
authors.forename: Y L
authors.initials: YL
authors.lastname: Chiang
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002460:Cell Line; D002999:Clone Cells; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D015774:Ganciclovir / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic; D005822:Genetic Vectors; D005910:Glioma; D018259:Herpesvirus 1, Human / Q000201:enzymology*; D006801:Humans; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D012190:Retroviridae / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics* / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D012333:RNA, Messenger; D013937:Thymidine Kinase; D015774:Ganciclovir