Coupling Metastasis to pH-Sensing GPR68 Using a Novel Small Molecule Inhibitor

An acidic milieu is a hallmark of the glycolytic metabolism that occurs in cancerous cells. The acidic environment is known to promote cancer progression, but the underlying signaling and cell biological underpinnings of these phenomena are not well understood. Here, we describe ogremorphin, a first-in-class small-molecule inhibitor of GPR68, an extracellular proton-sensing and mechanosensing G protein–coupled receptor. Ogremorphin was discovered in a chemical genetic zebrafish screen for its ability to perturb neural crest development, which shares basic cell behaviors of migration and invasion with cancer metastasis. Ogremorphin also inhibited migration and invasive behavior of neural crest–derived human melanoma cells in vitro . Furthermore, in phenome-wide association studies (PheWAS), we identified an aberrantly activated variant of GPR68, which is associated with cancer metastasis in vivo and promotes invasive phenotypes of cancer cells in vitro . Thus, extracellular proton-sensing GPR68 signaling promotes cell migration and invasion during embryonic development and may do likewise in cancer progression. ### Competing Interest Statement The authors have declared no competing interest.