Selective and efficient retardation of cancers expressing cytoskeleton-associated protein 2 by targeted RNA replacement.

Human cytoskeleton-associated protein 2 (hCKAP2) is upregulated and highly expressed in various human malignances. hCKAP2 has microtubule-stabilizing characteristics and potentially regulates the dynamics and assembly of the mitotic spindle and chromosome segregation, indicating that hCKAP2 plays important functions during mitosis. In this study, we evaluated hCKAP2 as a plausible anticancer target through development and validation of a targeted cancer gene therapy strategy based on targeting and replacement of hCKAP2 RNA using a trans-splicing ribozyme. This targeted RNA replacement triggered transgene activity via accurate trans-splicing reaction selectively in human cancer cells expressing the hCKAP2 RNA and simultaneously reduced the expression level of the RNA in the cells. Adenoviral vector encoding the hCKAP2-specific trans-splicing ribozyme selectively induced cytotoxicity in tumor cells expressing hCKAP2. Moreover, intratumoral injection of the virus produced selective and efficient regression of tumor that had been subcutaneously inoculated with hCKAP2-positive colon cancer cells in mice with minimal liver toxicity. Furthermore, orthotopically multifocal hCKAP2-positive hepatocarcinoma established in mice were efficiently regressed by systemic delivery of adenoviral vector encoding the specific ribozyme under the control of a liver-selective phosphoenolpyruvate carboxykinase promoter with least hepatotoxicity. The results indicate that hCKAP2 RNA is a promising target for anticancer approach based on trans-splicing ribozyme-mediated RNA replacement.