Identification of a Potent Antagonist of Smoothened in Hedgehog Signaling

Abstract

Background Hedgehog signaling is essential to the regulation of embryonic development, tissue homeostasis, and stem cell self-renewal, making it a prime target for developing cancer therapeutics. Given the close link between aberrant Hedgehog signaling and cancers, many small molecular compounds have been developed to inhibit this pathway for treating cancer and several of such compounds have been approved by FDA (GDC-0449 and LDE-225). As we known, acquired drug resistance is the main obstacle of first generation of Smoothened inhibitors. Therefore, new Smoothened inhibitors that could inhibit wild-type and mutant receptors are essential for refractory cancers. ResultsWe established the Smoothened β arrestin 2 GFP high throughput screening platform based on the mechanistic discovery of Hedgehog signaling pathway, and discovered several active small molecules targeting Smoothened including 0025A 0025A. Here we show that 0025A can block the translocation of β arrestin 2 GFP to Smoothened , displace Bodipycyclopamine binding to wild type Smoothened or mutant Smoothened D473H and reduce the expression of Gli upon Hedgehog stimulation. In addition, we reveal that 0025A can effectively suppress hair follicle morphogenesis and hair growth in mice. Conclusions Thus, our results demonstrate that 0025A is a potent antagonist targeting Smoothened wild-type and mutant type and mutant receptors in the Hreceptors signaling pathway and may provide a new new therapy for refractory cancers.