The loss of retinoblastoma gene in association with c-myc and transforming growth factor-beta 1 gene expression in human bladder cancer.

Abstract

We investigate the roles and possible interactions of the retinoblastoma, transforming growth factor-beta 1 and c-myc genes in bladder cancer. The expression of these 3 genes was examined in 38 biopsy specimens of human bladder cancer by immunohistochemical analysis or Northern blotting. Loss of the retinoblastoma protein expression was most significantly correlated with high grade cancer. Over expression of c-myc or expression of transforming growth factor-beta 1 was less associated with tumor grade or stage, although c-myc over expression defined stage Ta against other stage tumors, since no stage Ta lesions had increased c-myc expression. Finally, loss of retinoblastoma gene function did not correlate with either c-myc or transforming growth factor-beta 1 expression. These results further support that retinoblastoma gene inactivation is an important factor in the progression of bladder cancer, and suggest that transforming growth factor-beta 1 and c-myc are not regulators or are not regulated by retinoblastoma gene expression.