A zebrafish embryo screen utilizing gastrulation for identification of anti-metastasis drugs

Few models exist that allow for rapid and effective screening of anti-metastasis drugs. Here, we present a phenotype-based chemical screen utilizing gastrulation of zebrafish embryos for identification of anti-metastasis drugs. Based on the evidence that metastasis proceeds through utilizing the molecular mechanisms of gastrulation, we hypothesize that chemicals which interrupt zebrafish gastrulation might suppress metastasis of cancer cells. Thus, we developed a drug screening protocol which uses epiboly, the first morphogenetic movement in gastrulation, as a marker. The screen only needs zebrafish embryos and enables hundreds of chemicals to be tested in five hours through observing epiboly progression of a test chemical-treated embryos. In the screen, embryos at the two-cell stage are firstly corrected and then developed to the sphere stage. The embryos are treated with a test chemical and incubated in the presence of the chemical until vehicle-treated embryos develop to 90% epiboly stage. Finally, positive hit chemicals that interrupt epiboly progression are selected through comparing epiboly progression of the chemical-treated embryos with that of vehicle-treated embryos under a stereoscopic microscope. Previous study subjected 1,280 FDA-approved drugs to the screen and identified Adrenosterone and Pizotifen as epiboly-interrupting drugs. These drugs were validated to suppress metastasis of breast cancer cells in mice models of metastasis. Furthermore, 11{beta}-Hydroxysteroid Dehydrogenase 1 (HSD11{beta}1) and serotonin receptor 2C (HTR2C), which are primary target of Adrenosterone and Pizotifen respectively, promotes metastasis through induction of epithelial-mesenchymal transition (EMT). That indicates the screen could be diverted to a chemical genetic screening platform for identification of metastasis-promoting genes.