Curcumin inhibits cell proliferation and motility via suppression of TROP2 in bladder cancer cells

Bladder cancer (BC) has become a serious health problem and represents the second most commonly diagnosed urological tumor. Curcumin is a principal active natural component of turmeric and has long been used in Asia as a traditional herbal medicine. Curcumin suppresses cell growth in various types of cancer, including BC, by regulating numerous molecular signaling pathways. The human trophoblast cell surface antigen 2 (Trop2) belongs to the tumor-associated calcium signal transducer gene family. Trop2 has been described as a cancer driver and is deregulated in various types of cancer. However, whether Trop2 is involved in curcumin-induced BC cell inhibition remains to be elucidated. The present study hypothesized that Trop2 may be a promising target of curcumin in BC cells. It was found that Trop2 was closely involved in curcumin-induced cell proliferation suppression, mobility inhibition, apoptosis, and cell cycle arrest in BC cells. Curcumin decreased the expression of Trop2 and its downstream target cyclin E1, and increased the level of p27. The overexpression of Trop2 enhanced the oncogenic activity of BC cells, whereas downregulation of the expression of Trop2 suppressed cell proliferation and mobility, increased apoptosis, and sensitized BC cells to curcumin treatment. Therefore, Trop2 may be a promising target of curcumin in BC cells and the inhibition of Trop2 may be an important method for the therapeutic management of patients with BC.