Disruption of the parvulin family peptidyl prolyl isomerase (PPIase) Pin1 gene delays reentry into the cell cycle when quiescent primary mouse embryo fibroblasts are stimulated with serum. Since Pin1 regulates cell cycle progression, a Pin1 inhibitor would be expected to block cell proliferation. To identify such inhibitors, we screened a chemical compound library for molecules that inhibited human Pin1 PPIase activity in vitro. We found a set of compounds that inhibited Pin1 PPIase activity in vitro with low microM IC50s and inhibited the growth of several cancer lines. Among the inhibitors, PiB, diethyl-1,3,6,8-tetrahydro-1,3,6,8-tetraoxobenzo[lmn] phenanthroline-2,7-diacetate ethyl 1,3,6,8-tetrahydro-1,3,6,8-tetraoxo-benzo[lmn] phenanthroline-(2H,7H)-diacetate, had the least nonspecific toxicity. These results suggest that Pin1 inhibitors could be used as a novel type of anticancer drug that acts by blocking cell cycle progression.

No abstract

No abstract

No abstract

Cyclophilin is a ubiquitous peptidyl prolyl cis/trans isomerase that plays critical roles in many biological processes. A number of cyclophilin inhibitors have been designed based on the structure of the immunosuppressant cyclosporin A. To discover inhibitors that have other structures, the authors established the high-throughput screening (HTS) method using FDSS6000 real-time fluorescence detector. The inhibitors identified with this HTS showed significant correlation with direct interaction as measured by surface plasmon resonance. This high-throughput assay system is a powerful tool for the discovery of peptidylprolyl isomerase inhibitors. (Journal of Biomolecular Screening 2009:419-424)