A high-content chemical screen identifies ellipticine as a modulator of p53 nuclear localization
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p53 regulates apoptosis and the cell cycle through actions in the nucleus and cytoplasm. Altering the subcellular localization of p53 can alter its biological function. Therefore, small molecules that change the localization of p53 would be useful chemical probes to understand the influence of subcellular localization on the function of p53. To identify such molecules, a high-content screen for compounds that increased the localization of p53 to the nucleus or cytoplasm was developed, automated, and conducted. With this image-based assay, we identified ellipticine that increased the nuclear localization of GFP-mutant p53 protein but not GFP alone in Saos-2 osteosarcoma cells. In addition, ellipticine increased the nuclear localization of endogenous p53 in HCT116 colon cancer cells with a resultant increase in the transactivation of the p21 promoter. Increased nuclear p53 after ellipticine treatment was not associated with an increase in DNA double stranded breaks, indicating that ellipticine shifts p53 to the nucleus through a mechanism independent of DNA damage. Thus, a chemical biology approach has identified a molecule that shifts the localization of p53 and enhances its nuclear activity.
KeywordsHigh-throughput screen p53 Ellipticine
SDS-polyacrylamide gel electrophoresis
We thank Dr. Sam Benchimol for helpful advice and discussions. This work was supported by the Canadian Institutes of Health Research (CIHR), and the Ontario Cancer Research Network through funding from the province of Ontario. I.A.M. is the recipient of the Edward Christie Stevens Fellowship in Medical Research. A.D.S. is the recipient of a CIHR Clinician Scientist Award.