Development of Boron-Cluster-Based Progesterone Receptor Antagonists Bearing a Pentafluorosulfanyl (SF5) Group.

The progesterone receptor (PR) plays an important role in various physiological processes, especially in the female reproductive system, and abnormalities of PR function are associated with several diseases, including some types of cancer. Non-steroidal PR ligands are of interest as candidate drugs for treatment of PR-related diseases without the serious adverse effects that may be caused by steroidal ligands. For the development of non-steroidal PR ligands, both a hydrophobic backbone and a polar functional group corresponding to the 3-carbonyl group of progesterone, which interacts with Gln725 and Arg766 of the PR-ligand binding domain, are critically important. We previously showed that carborane is a useful hydrophobic pharmacophore for PR antagonists, and in this work, we introduced the pentafluorosulfanyl (SF5) group as a novel polar functional group of carborane-based non-steroidal PR antagonists. All the synthesized SF5-containing carborane derivatives exhibited PR-antagonistic activity at micromolar or submicromolar concentration. Among them, compounds 11 are potent progesterone antagonists with submicromolar IC50 values.

Characterization of a novel compound that promotes myogenesis via Akt and transcriptional co-activator with PDZ-binding motif (TAZ) in mouse C2C12 cells.

Transcriptional co-activator with PDZ-binding motif (TAZ) plays versatile roles in the regulation of cell proliferation and differentiation. TAZ activity changes in response to the cellular environment such as mechanic and nutritional stimuli, osmolarity, and hypoxia. To understand the physiological roles of TAZ, chemical compounds that activate TAZ in cells are useful as experimental reagents. Kaempferol, TM-25659, and ethacridine are reported as TAZ activators. However, as each TAZ activator has a distinct property in cellular functions, additional TAZ activators are awaiting. We screened for TAZ activators and previously reported IB008738 as a TAZ activator that promotes myogenesis in C2C12 cells. In this study, we have characterized IBS004735 that was obtained in the same screening. IBS004735 also promotes myogenesis in C2C12 cells, but is not similar to IBS008738 in the structure. IBS004735 activates TAZ via Akt and has no effect on TAZ phosphorylation, which is the well-described key modification to regulate TAZ activity. Thus, we introduce IBS004735 as a novel TAZ activator that regulates TAZ in a yet unidentified mechanism.