Synergistic antitumor activity by combined treatment with gemcitabine and antisense oligodeoxynucleotide targeting clusterin gene in an intravesical administration model against human bladder cancer KoTCC-1cells

Purpose: We investigated whether antisense (AS) oligodeoxynucleotide (ODN) targeting the clusterin gene enhances the cytotoxic effect of gemcitabine in human bladder cancer KoTCC-1 cells in vitro and in vivo, and evaluated the usefulness of the combined administration of AS clusterin ODN and gemcitabine using an intraperitoneal tumor cell injection model. Materials and Methods: The cytotoxic effect of combined treatment with AS clusterin ODN and gemcitabine on in vitro KoTCC-1 growth was examined using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The in vivo growth inhibitory effects of combined AS clusterin ODN and gemcitabine therapy on subcutaneous KoTCC-1 tumor was also examined. The intraperitoneal tumor cell injection model, which mimics intravesical administration therapy against bladder cancer, was used to evaluate the efficacy of combined AS clusterin ODN and gemcitabine therapy. Results: AS clusterin ODN treatment of KoTCC-1 cells significantly enhanced gemcitabine chemosensitivity in a dose dependent manner, decreasing gemcitabine IC50 by approximately 90%. In vivo systemic administration of AS clusterin ODN and gemcitabine significantly decreased subcutaneous KoTCC-1 tumor volume compared with scramble control ODN plus gemcitabine. Furthermore, combined administration of AS clusterin ODN plus gemcitabine resulted in significantly delayed formation of hemorrhagic ascites compared with scramble control ODN plus gemcitabine in an intraperitoneal tumor cell injection model. Conclusions: These findings suggest that AS clusterin ODN may be useful for enhancing the cytotoxicity of gemcitabine in patients with bladder cancer, particularly as a novel therapeutic strategy for intravesical instillation therapy.