Targeting gene expression of the mouse uroplakin II promoter to human bladder cells.

Differential expression of the desired gene product in the target tissue is central to the concept of gene therapy. One approach is to use a tissue-specific promoter to drive therapeutic genes. To investigate the feasibility of tissue-specific gene therapy for bladder cancer using the mouse uroplakin II (UPII) promoter and its transcriptional control, the efficacy of this promoter as well as fragments in regulating gene expression were qualitatively and quantitatively analyzed in bladder and non-bladder tissue cell lines using DNA transfection. Our results demonstrate that the mouse UPII promoter actively drives gene expression in BIU-87, a bladder cancer cell line. Little promoter activity was detected in the non-bladder tissue cell lines. Furthermore, deleting the 5' end 1.5 kb of the UPII promoter by PCR, the activity was significantly decreased but was bladder-specific. However, deleting the 3' end 143-bp of the UPII promoter, the activity was hardly detected in any tissue cell lines. The activity of the 3' end 143-bp of the UPII promoter was detected in both bladder cancer and stomach cancer cell lines. These data demonstrate that the mouse UPII promoter has a high activity in human bladder cells and a low basal activity in human non-bladder cells. This suggests that targeting the gene expression of the mouse UPII promoter could be used to treat human bladder cancer. The enhancer was contained in the region of the 1.5 kb of the 5' end of the mouse UPII promoter. The core promoter was located in the region of the 143 bp of the 3' end.