Effect of Intravesical BCG Instillation on the Expression of Inducible Nitric Oxide Synthase in Mouse

Ryu, Soobang; Jeong, Dongwon; Park, Yangil; Ahn, Kyuyoun

Abstract

PURPOSE: Bacillus Calmette-Guerin(BCG) therapy for superficial bladders carcinoma and carcinoma in situ is believed to exert its antitumor effects through immune mechanisms when BCG is instilled into the bladder, but its detail mechanisms are poorly understood. Recently, intravesical BCG instillation is known to induce nitric oxide(NO) which is revealed to be tumoricidal . This experiment was performed to determine the intravesical localization and alteration of expression of inducible nitric oxide synthase(iNOS) after BCG instillation.
MATERIALS AND METHODS
Normal saline(0.85m1/kg, control group) and BCG(6mg/kg, experimental group) were instilled intravesically in fifty four female mice. After 2 hours, each mouse urinated after removal of urethral ligature, and was sacrificed at 6th, 12th, 18th hour, 1st day, 1.5th, 2th, 3th, 7th and 14th day, respectively. Immunohistochemistry was performed on paraffin embedded bladder tissue using anti-inducible NOS antibody(Transduction Labaratories, USA.).
RESULTS
Inflammatory cells were infiltrated in the bladder wall in the BCG-treated group, but not in the control group. Number of inflammatory cells among BCG-treated group, was the highest in the 18th hour group and was reduced gradually with time elapse thereafter In the control group, immunoreactivity of iNOS to be positive in the all intermediate cell layer and a few basal cell layer of bladder transitional epithelium, which did not change as time passed. In the BCG-treated group, immunoreactivity of iNOS increased from 6 hours after BCG instillation, and gradually decreased from 7 days to restore to the level of the control group. However, some cells of transitional epithelium showed reduced immunoreactivity, focally.
CONCLUSIONS
These results suggest that iNOS is tonically expressed in transitional epithelium of mouse bladder which is further induced by BCG instillation. Also, NOS-mediated NO production is supposed to be one of factors to induce tumoricidal erect by BCG instillation.