Alterations in antigen expression in superficial bladder cancer.

Bladder cancer can be viewed as a prototype for carcinogen-induced neoplasia. This has been demonstrated experimentally in a variety of systems and in man through epidemiological studies of occupational exposure to putative carcinogens. The natural history of this neoplasm demonstrates recurrence in time and space, i.e., multifocal disease. This clinical scenario is precisely what would be expected if a target tissue, e.g., urothelium, was continuously exposed to a weak carcinogen. The detection of gross disease is clinically easy. However, the ability to intervene at early stages and monitor the success of this treatment requires the definition of early markers for bladder cancer. Integrins are a family of cell surface proteins, many of which function as receptors for extracellular matrix components. Normal epithelial cells express the integrin alpha 6 beta 4 in association with an anchoring structure known as the hemidesmosome. Urothelium expresses alpha 6 beta 4 on the basal layer of cells similar to the distribution seen on other epithelial surfaces. Even early stages of bladder cancer demonstrate an alteration in the expression of this integrin. Low-stage bladder tumors express alpha 6 beta 4 diffusely throughout the tumor as well as at the invading margin. Altered expression of alpha 6 beta 4 may be an early marker for bladder cancer which may contribute to an invasive phenotype. A second potential marker is detected by DD23, an IgG1 murine monoclonal antibody triggered by the immunization of a BALB/c mouse with a fresh human bladder tumor specimen. The antigen detected by DD23 is not present on normal urothelial specimens.(ABSTRACT TRUNCATED AT 250 WORDS)