Conditionally replicating adenovirus-mediated gene therapy in bladder cancer: An orthotopic in vivo model

IntroductionThe effects of a conditionally replicating adenovirus on various bladder cancer lines were explored, a truncated bone sialoprotein (BSP) promoter controlling the E1a/b lytic-regulating sequence was used, since BSP protein is found in many osteotropic neoplasms, including bladder cancer.MethodsReverse transcriptase polymerase chain reaction analysis was used to determine expression patterns of BSP and Coxsackie adenovirus receptor, a receptor known to interact with adenovirus, on multiple lines of bladder cancer (253J, 253J B-V, RT4, transitional cell carcinoma, T24, UMUC3, and WH). Ad-BSP-E1a was tested in vitro for lytic activity on 4 of these cell lines. The 253J B-V cell line was used and inoculated into female nude mice either subcutaneously in the flank or orthotopically into the bladder, and treated with control or Ad-BSP-E1a virus.ResultsBSP is expressed in RT4, transitional cell carcinoma, and WH. Meanwhile, Coxsackie adenovirus receptor was expressed in all lines except T24. Ad-BSP-E1a had the most impact on 253J and 253J B-V cells; cell density declined significantly when compared to phosphate-buffered saline and Ad-BSP-TK “dummy” virus-treatment groups. The 253J B-V tumors treated with Ad-BSP-E1a revealed a decreased percent change of size in the subcutaneous model when compared to controls at week 3. The orthotopic murine model showed decreased end tumor mass in the Ad-BSP-E1a treated group over controls. Histologic examination of in vivo tumors showed evidence of fibrosis and apoptosis in the Ad-BSP-E1a treated groups using hematoxylin-eosin, trichrome, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining. Control groups only had viable tumor in in vivo models.ConclusionAdenovirus therapy of orthotopic murine bladder tumors is feasible. Ad-BSP-E1a is effective in treating very aggressive yet sensitive bladder tumor cells. Further study of this conditionally replicating adenovirus treatment (Ad-BSP-E1a) with chemotherapeutic combination is warranted, and future translation of such combination therapy into human beings is a possibility.