A small molecule that binds Hedgehog and blocks its signaling in human cells

Abstract

Small-molecule inhibition of extracellular proteins that activate membrane receptors has proved to be extremely challenging. Diversity-oriented synthesis and small-molecule microarrays enabled the discovery of robotnikinin, a small molecule that binds the extracellular Sonic Hedgehog (Shh) protein and blocks Shh-signaling in cell lines, human primary keratinocytes and a synthetic model of human skin. Shh pathway activity is rescued by small-molecule agonists of Smoothened, which functions immediately downstream of the Shh receptor Patched.

Activation of the hedgehog-signaling pathway in human cancer and the clinical implications

“…Recent results from mouse models indicate that the inhibition of Hh signaling has little effects on bone barrow stem cell population, which clears the concern of toxic effects of Hh signaling inhibition on normal stem cells Hofmann et al, 2009). Based on diversity-oriented synthesis and smallmolecule microarrays, a small-molecule robotnikinin is reported to bind Shh protein and blocks Shh signaling in cell lines, human primary keratinocytes and a synthetic model of human skin (Stanton et al, 2009). Robotnikinin inhibits Shh signaling in a concentrationdependent manner but shows no inhibitory activity in a cell line lacking the Ptc1 receptor, does not compete with cyclopamine-Smo interactions and does not show an inhibitory effect in the presence of the well- (Stanton et al, 2009).…”

“…Based on diversity-oriented synthesis and smallmolecule microarrays, a small-molecule robotnikinin is reported to bind Shh protein and blocks Shh signaling in cell lines, human primary keratinocytes and a synthetic model of human skin (Stanton et al, 2009). Robotnikinin inhibits Shh signaling in a concentrationdependent manner but shows no inhibitory activity in a cell line lacking the Ptc1 receptor, does not compete with cyclopamine-Smo interactions and does not show an inhibitory effect in the presence of the well- (Stanton et al, 2009). A few small-molecule inhibitors for Gli1 functions are identified through chemical library screening (Lauth et al, 2007;Hyman et al, 2009).…”

Targeting the CB2 cannabinoid receptor in osteoporosis

“…Similar effects might be afforded by agents that target hedgehog ligand processing and interaction with receptors. Robotnikinin, a drug that blocks the interaction of Shh with receptors [90], is of this class. Further down the pathway, the knowledge that Gli activity may be an important factor in tumor biology, independent of hedgehog signaling, has also driven discovery efforts to identify drugs that can block this activity, and the Gli antagonists (GANTs; -58 and -61) [91], and, more recently, the HPI class of drugs [92] that interfere with Gli trafficking and transcription, may have clinical applicability.…”

Diversity-oriented synthesis as a tool for identifying new modulators of mitosis

“…In 2008, we discovered gemmacin, a small molecule with similar potency to clinically used antibiotics and improved activity against resistant bacterial strains 14 . Other groups have also used this approach effectively; some notable examples include the discovery of the novel Hedgehog pathway modulator robotnikinin 15 , and compounds with interesting antimalarial properties 16 . Another related approach, termed biology-oriented synthesis, has also led to the identification of many useful tool compounds from phenotypic screens [17][18][19] .…”