Discovery of a small molecule that selectively destabilizes Cryptochrome 1 and enhances life span in p53 knockout mice

Cryptochromes are negative transcriptional regulators of the circadian clock in mammals. It is not clear how reducing the level of endogenous level of the CRY1 in mammals will affect circadian rhythm and the relation of such a decrease with apoptosis is unknown. Here, we discovered a molecule that destabilizes Cryptochrome 1 (CRY1) both in vitro and in vivo. The small molecule, called M47, selectively enhanced the degradation rate of CRY1 by increasing its ubiquitination and the period of U2OS Bmal1-dLuc cells. In addition, subcellular fractionation studies from mice liver indicated that M47 enhanced degradation rate of the CRY1 level in the nucleus. Furthermore, M47-mediated CRY1 reduction enhanced cisplatin-induced apoptosis in Ras-transformed p53 null fibroblast cells. Finally, systemic repetitive administration of M47 increased the median lifespan of p53-/- mice by ~25%. Collectively our data suggest that M47 is a very promising molecule to treat forms of cancer depending on the p53 mutation.