The objective of this project is to discover and characterize molecules that inhibit breast cancer cell proliferation by maintaining activity of the retinoblastoma protein (Rb). Rb is inactivated to drive proliferation in normal and cancer cells by phosphorylation, which dissociates the E2F transcription factor from Rb. Our goal is to find and characterize molecules that stabilize the complex between phosphorylated Rb and E2F.In this first year of the project period, we successfully optimized a fluorescence polarization assay for Rb-E2F binding suitable for high-throughput screening. Together with scientists at the Sanford Burnham Institute, we then screened 350,000 compounds for activity stabilizing the complex. 236 hit compounds were found in the primary screen, of which 108compounds repeated in a dose response assay. We are now in position to follow these lead compounds in secondary assays and characterize their mechanism of action.
