Inhibitory effect of pyrvinium pamoate on uveal melanoma cells involves blocking of Wnt/β-catenin pathway

Uveal melanoma is the most common primary intraocular malignancy in adults. And there is an absence of targeted agents for patients with uveal melanoma. Pyrvinium pamoate is an old anthelminthic medicine approved by FDA for the treatment of enterobiasis in 1955, which recently re-attracts attention as an anti-cancer drug due to its inhibition of Wnt/beta-catenin pathway in some types of cancer. But the role of pyrvinium pamoate in uveal melanoma and the potential underlying mechanism remains unknown. In this study, we tested the anti-tumor effects of pyrvinium pamoate on four uveal melanoma cell lines (92.1, Mel270, Omm1, and Omm2.3) and evaluated the Wnt/beta-catenin signaling transduction, cell growth, cell death, cell migration, and invasion accordingly. The results revealed that pyrvinium pamoate treatment repressed the phosphorylation of GSK3 beta at S9 which might be mediated by AKT, and decreased the protein levels of beta-catenin and its downstream targets (c-Myc, cyclin D1). Pyrvinium pamoate remarkably inhibited cell viability and colony formation ability. Treatment with pyrvinium pamoate induced intrinsic pathway-dependent apoptosis accompanied with a decline of anti-apoptotic XIAP and Survivin, and an overt increase of pro-apoptotic Bax. In addition, pyrvinium pamoate significantly inhibited the migration and invasion in vitro. Our studies suggest that pyrvinium pamoate may be a potential therapeutic agent for uveal melanoma.