The presence of an antibacterial glycoprotein in a spectrum of transitional gel carcinomas

The mucin lining of the bladder is thought to serve as a primary defense mechanism against bacterial colonization, and has recently been implicated in the urothelial resistance to carcinogenic insult. We have isolated a unique glycoprotein fraction (GP1) of this lining from the normal rabbit bladder which may have a function in preventing bacterial adherence and colonization in the urinary tract. This glycoprotein has been shown to bind to a wide range of uropathic bacteria. The present study examines changes in the bladder's antibacterial defense mechanisms as measured by GP1 expression in the neoplastic state. Using an anti-GP1 serum, immunohistochemical staining was performed on 20 paraffinized and fresh frozen transitional cell carcinomas ranging from low grade, superficial tumors to high grade, invasive tumors. The presence of GP1 was seen throughout the mucosal layer in normal specimens with increased amounts noted towards the mucosal surface. Progressively decreased expression was noted with increasing grades of all transitional carcinoma specimens. Mucosal field changes in GP1 expression were not noted in any of the patients. Intestinal mucosal controls failed to detect the presence of GP1. These studies suggest that the expression of GP1 decreases with tumor dedifferentiation and that bladder tumorogenesis may serve a role in handicapping the bladder's primary antibacterial defense mechanism.