Piperlongumine (PL), a natural alkaloid isolated from longer pepper plants, is recently found to be a potent selective anti-cancer compound. We first tested its anti-cancer effects on bladder cancer, the fifth most common and aggressive cancer worldwide, to further explore the therapeutic spectrum and molecular mechanisms of PL. PL significantly suppressed bladder cancer cell proliferation, the transition of G2/M phase to next phase, migration/invasion in vitro and bladder cancer growth/development in vivo. PL markedly elevated reactive oxygen species (ROS) and the administration of antioxidants abolished PL induced cell proliferation inhibition, G2/M phase arrest and migration suppression on bladder cancer cells. In vivo studies demonstrated that PL inhibited epithelial mesenchymal transition with profoundly decreased level of Slug, beta-catenin, ZEB1 and N-Cadherin. Further, we first reported PL effects on cytoskeleton with prominently reduced lamellipodia formation and decreased F-actin intensity in bladder cancer cells. Taken together, our results first revealed that PL suppressed bladder cancer proliferation and migration in vivo and in vitro, suggesting novel mechanism underlying PL's anti-cancer effect and providing a new anticancer drug strategy for bladder cancer therapy. (C) 2017 Elsevier Inc. All rights reserved.