Molecular genetic alterations in superficial and locally advanced human bladder cancer

We attempted to define the role of tumor suppressor genes in the pathogenesis of human bladder cancer through a combined molecular genetic and immunohistochemical approach. Thirty-four bladder tumors (1 Pis, 6 Pa, 5 P1, 3 P3a, 18 P3b, 1 P4; 8 low grade and 26 high grade tumors) have been analyzed. Restriction fragment length polymorphism analysis directed at 5 suspected or established tumor suppressor gene regions (3p21-25, 11p15, 13q14, 17p11-13, and 18q21) was combined with immunohistochemical using Rb-PMG3-245 monoclonal antibody directed at the retinoblastoma (Rb) gene product. Tumor grade correlated with deletions of 3p (P = 0.004) and 17p (P = 0.063). Tumor stage correlated with deletions of 3p (P = 0.010), 17p (P = 0.015) and altered Rb expression (P = 0.054). Vascular invasion correlated only with deletions of 17p (P = 0.038). No marker correlated with positive lymph nodes. Our results suggest that altered Rb expression occurs in all grades and stages of bladder cancer but is more commonly associated with invasive tumors. Genetic alterations of 3p, 11p, 17p, and 18q are rare events in low grade, superficial tumors, whereas they are more common in high grade and invasive bladder cancer. The role of these genetic alterations in the prognosis of bladder cancer will require additional follow-up and further studies.