• Williams CH, Hempel JE, Hao J, Frist AY, Williams MM, Fleming JT, Sulikowski GA, Cooper MK, Chiang C, Hong CC. An in vivo chemical genetic screen identifies phosphodiesterase 4 as a pharmacological target for hedgehog signaling inhibition. Cell reports. 2015 Apr 7;11(1). 43-50. PMID: 25818300 [PubMed]. PMCID: PMC4394042. NIHMSID: NIHMS669677.


Hedgehog (Hh) signaling plays an integral role in vertebrate development, and its dysregulation has been accepted widely as a driver of numerous malignancies. While a variety of small molecules target Smoothened (Smo) as a strategy for Hh inhibition, Smo gain-of-function mutations have limited their clinical implementation. Modulation of targets downstream of Smo could define a paradigm for treatment of Hh-dependent cancers. Here, we describe eggmanone, a small molecule identified from a chemical genetic zebrafish screen, which induced an Hh-null phenotype. Eggmanone exerts its Hh-inhibitory effects through selective antagonism of phosphodiesterase 4 (PDE4), leading to protein kinase A activation and subsequent Hh blockade. Our study implicates PDE4 as a target for Hh inhibition, suggests an improved strategy for Hh-dependent cancer therapy, and identifies a unique probe of downstream-of-Smo Hh modulation.