A Cox-2 promoter-based replication-selective adenoviral vector to target the Cox-2-expressing human bladder cancer cells

Purpose: Cyclooxygenase-2 (Cox-2), an enzyme that catalyzes the synthesis of prostaglandins, is overexpressed in a variety of premalignant and malignant conditions, including urinary bladder cancer. In the present study, we examined the feasibility of using Cox-2 promoter-based replication-selective adenovirus for targeting bladder cancer cells that express Cox-2 transcriptional activity. Experimental Design: A series of human cancer cell lines, including three bladder cancer cell lines (KK47, T24, and 5637), were evaluated for their Cox-2 and CAR (the Coxsackievirus and adenovirus receptor) mRNA expression levels by quantitative real-time PCR. AdE3-cox2-327, a replication-selective adenovirus in which the expression of E1a is controlled by the Cox-2 promoter, was generated, and its tissue-specific activity was tested in vitro and in vivo. Results: Three bladder cancer cell lines express higher levels of Cox-2 mRNA than does the human prostate cancer cell line PC3, the primary cultured human benign prostatic fibroblast, PF cells, and the human colon cancer cell line Colo320. Relatively higher expression of CAR mRNA was detected in the KK47, 5637, respectively, and Colo320 than in the T24, PC-3, and PF cells. In vitro assays revealed significant growth suppression of both Cox-2- and CAR-expressing bladder cancer cells KK47 and 5637 in comparison with the other cells that lack Cox-2 expression and/or CAR expression. Conclusions: The present study demonstrated both specificity and efficacy of AdE3-cox2-327, a selectively replicated adenovirus, toward the Cox-2-expressing bladder cancer cells in vitro and in vivo. We also found that CAR expression in the target cancer cells is an important factor for the efficacy of selectively replicated adenovirus-based gene therapy.