HUMAN LUNG AND BLADDER-CARCINOMA TUMORS AS COMPARED TO THEIR ADJACENTNORMAL TISSUE HAVE ELEVATED AP-1 ACTIVITY ASSOCIATED WITH THE RETINOBLASTOMA GENE PROMOTER

Examination of the nucleotide sequence of the retinoblastoma (Rb) prom oter revealed the presence of a DNA region highly homologous to the re cognition site for the cellular transcription factor AP-1. A pair of c omplementary oligonucleotides containing the AP-1 site was synthesized and used in gel retardation assays to determine the role of the AP-1 protein in the regulation of the Rb gene expression. Using nuclear ext racts from Hela cells as well as from lung and bladder tumors, we foun d specific binding of the AP-1 protein to this oligonucleotide. This b inding is elevated in Hela cells, in 10113 lung and 318 bladder tumors as compared to adjacent normal tissue. These results suggest that AP- 1 could be implicated in Rb gene transcriptional regulation through it s interaction with the AP-1 binding site of the Rb gene promoter.