A Novel Zebrafish Model of Metastasis Identifies the HSD11β1 Inhibitor Adrenosterone as a Suppressor of Epithelial-Mesenchymal Transition and Metastatic Dissemination

Metastasis of Cancer cells is multi-step process and dissemination is an initial step. Here we report a tamoxifen-controllable Twist1a-ER^T2 transgenic zebrafish line as a new animal model for metastasis research, and demonstrate that this model can serve as a novel platform for discovery of antimetastasis drugs targeting metastatic dissemination of Cancer cells. By crossing Twist1a-ER^T2 with xmrk (a homolog of hyperactive form of EGFR) transgenic zebrafish, which develops hepatocellular carcinoma, approximately 80% of the double transgenic zebrafish showed spontaneous cell dissemination of mCherry-labeled hepatocytes from the liver to the entire abdomen region and the tail region. The dissemination is accomplished in 5 days through induction of an epithelial-to-mesenchymal transition. Using this model, we conducted in vivo drug screening and identified three hit drugs. One of them, adrenosterone, an inhibitor for hydroxysteroid (11-beta) dehydrogenase 1 (HSD11β1), has a suppressor effect on cell dissemination in this model. Pharmacologic and genetic inhibition of HSD11β1 suppressed metastatic dissemination of highly metastatic human cell lines in a zebrafish xenotransplantation model. Through downregulation of Snail and Slug, adrenosterone-treated cells recovered expression of E-cadherin and other epithelial markers and lost partial expression of mesenchymal markers compared with vehicle-treated cells. Taken together, our model offers a useful platform for the discovery of antimetastasis drugs targeting metastatic dissemination of Cancer cells. IMPLICATIONS: This study describes a transgenic zebrafish model for liver tumor metastasis and it has been successfully used for identification of some drugs to inhibit metastatic dissemination of human Cancer cells.