Role of heat shock protein 90 inhibition with 17-(allylamino)-17 (demethoxygeldenamycin) in muscle-invasive bladder cancer cells.

Abstract

273 Background: Muscle invasive bladder cancer portends a poor long term prognosis. Platinum based therapy is the mainstay of treatment but more effective agents are needed for management of this disease. Heat shock protein 90 (Hsp90) is a ubiquitous protein that has been shown to be overexpressed in tumor cells. It functions as a molecular chaperone responsible for the stability and function of a number of proteins critical to the oncogenic process. 17-(allylamino)-17 demethoxygeldanamycin (17 AAG) is a Hsp90 inhibitor that is currently in phase III trials in several tumor models. The purpose of this study was to evaluate the role of 17 AAG treatment for bladder cancer in vitro. Methods: Seven bladder cancer cell lines representing muscle invasive bladder cancer were treated in the presence and absence of 17 AAG. Both short term and long term treatments were evaluated for their effects on growth, motility and invasion of the cancer cells. Expression of proteins involved in cell growth, survival and metastasis were evaluated with Western blotting. Results: Our data demonstrated that 17 AAG treatment resulted in induction of apoptosis, inhibition of cell cycle progression through inhibition of MAP kinase pathway and cyclin D1 expression. Decreased tumor cell motility and invasion was observed with 17 AAG treatment. Several intracellular signaling pathways involved in cell proliferation, invasion and metastasis were inhibited. Conclusions: Hsp90 inhibition in muscle invasive bladder cancer cells impacts growth, motility and invasiveness by inhibiting numerous intracellular signaling pathways. Taken together, these findings suggest a possible role for Hsp90 inhibitors in bladder cancer tumorigenesis. No significant financial relationships to disclose.