Novel Gap Junction Molecules, Connexin 37, Enhances the Bystander Effect in HSVtk/GCV Gene Therapy

ABSTRACT

PURPOSE: Gap junction intercellular communication(GJIC) is an important mechanism of the bystander effect in herpes simplex thymidine kinase/ganciclovir(HSVtk/GCV) gene therapy Therefore, we attempted to enhance the bystander effect in vitro by exogenous overexpressing connexin 37(Cx37) in cells to increase GJIC. METHODS: NIH3T3 cells were transfected with the Cx37 and HSVtk gene or the HSVtk gene alone by the calcium phosphate method, and we detected their expression from these cells by RT-PCR. GCV-mediated cytotoxicity and the bystander effect of each transfectant was then assessed and compared. RESULTS: Cells transfected with HSVtk became sensitive to low concentration of GCV. We found significantly increased cytotoxicity in HSVtk/GCV gene therapy after introduction of the HSVtk and Cx37 genes together compared with the cytotoxicity seen after introduction of the HSVtk gene in vitro. Co-expression of the HSVtk and Cx37 genes potentiates HSVtk/GCV gene therapy through the bystander effect. CONCLUSION: These results indicated that the increase of GJIC using Cx37 have potentiated the by stander effect of HSVtk/GCV therapy, and may be a new approach to improve response in suicidal cancer gene therapy.