Purpose: siRNA has been used successfully in loss-of-function studies in vitro, but neither in vivo nor in clinical applications. The aims of the present study were (1) to establish rat models for in vivo delivery of siRNA to bladder cancer, and (2) to identify potential targets for siRNA.
Methods: The rat models of human urinary carcinoma and rat urinary carcinoma cell line (AY-27) were induced by tobacco-related chemical carcinogens, either N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) or N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). A syngeneic orthotopic bladder cancer model was established by inoculation of AY-27 cells. A fluorescence-labelled negative control siRNA with cationic and neutral liposomes was tested both in vitro (AY-27 cells) and in vivo.
Results: siRNA was highly accumulated in the cancer cells as early as 12 h and remained at least for 24 h after a single dose in vivo. Numerous CD3+ T cells appeared mainly in the periphery area of the tumour. Bioinformatics analysis revealed a list of concordantly highly expressed genes, possible siRNA targets, in the animal models as well as human urinary carcinoma. Literature search on siRNA and bladder cancer provided a list of genes used as siRNA targets.
Conclusion: The methodology and data presented in the present study provide a number of opportunities for basic research on urinary carcinogenesis and for translational research on evaluation of siRNA therapeutic strategies for urinary carcinoma in the native organ, where hormonal, neural and immunological processes more closely resemble the clinical situation.