Background and purpose: Bladder cancer is common. Current treatment for patients with superficial bladder cancer involves transurethral resection followed by adjuvant bacillus Calmette-Guérin (BCG) administration. Adjuvant BCG has been reported to be effective in 38% to 68% of patients; however, more than 30% of patients do not respond. Because p53 mutations are common among superficial bladder cancers, we tested the feasibility of using p53 as a gene therapy agent for targeting superficial tumors, which are easily accessible using an intravesical approach.
Materials and methods: Wild-type p53 was transduced into various human and murine bladder cancer cell lines (HTB9, KU-1, and MBT-2) using a recombinant adenoviral vector (Ad5CMV-p53) in vitro. Also, subcutaneous tumors were established and then treated with intratumoral injection of Ad5CMV-p53 or control viruses.
Results: In vitro assays revealed significant growth suppression of target cells by Ad5CMV-p53 in comparison with those receiving the control Ad5-CMV-PA vector or untreated control cells. In vivo studies using subcutaneous bladder tumor models established in syngeneic mice demonstrated that the rate of tumor growth and volume was reduced to a greater extent by 14 days of intratumoral injection of Ad5CMV-p53 rather than Ad5CMV-PA. Furthermore, the survival of host animals bearing tumors that were infected with Ad5CMV-p53 was significantly longer than that of the control group treated with Ad5CMV-PA (P < 0.01).
Conclusion: Our data suggest that Ad5CMV-p53 is effective in suppressing bladder cancer growth and improving host survival.