Glycogen Synthase Kinase-3β: A Prognostic Marker and a Potential Therapeutic Target in Human Bladder Cancer

• Published in: Clinical cancer research 2010-11, Vol.16 (21), p.5124-5132
• Main Authors: NAITO, Sei, BILIM, Vladimir, YUUKI, Kaori, UGOLKOV, Andrey, MOTOYAMA, Teiichi, NAGAOKA, Akira, KATO, Tomoyuki, TOMITA, Yoshihiko
• Format: Article
• Language: English
• Subjects: Antineoplastic agents; Biological and medical sciences; Medical sciences; Nephrology. Urinary tract diseases; Pharmacology. Drug treatments; Tumors of the urinary system; Urinary system involvement in other diseases. Miscellaneous; Urinary tract. Prostate gland
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-10-0275

Purpose: Although recent studies have shown glycogen synthase kinase-3β (GSK-3β), a serine/threonine kinase, as a positive regulator of pancreatic, colon, and kidney cancer cell survival and proliferation, the role of GSK-3 in bladder cancer remains unknown. Our objectives were to determine the subcellular localization of GSK-3β and to evaluate the effect of GSK-3 inhibition in bladder cancer. Experimental Design: We used immunohistochemical staining and nuclear/cytosolic fractionation to determine the expression pattern of GSK-3β in human urothelial carcinomas. To study the effect of GSK-3 inhibition on bladder cancer cell proliferation and survival, we used pharmacologic inhibitors of GSK-3, RNA interference, MTS assay, bromodeoxyuridine incorporation assay, quantitative reverse transcriptase-PCR, and Western blotting. Results: We found aberrant nuclear accumulation of GSK-3β in 62% (43 of 69) and 91% (21 of 23) of noninvasive and invasive human urothelial carcinomas, respectively. GSK-3β nuclear staining was significantly associated with high-grade tumors (P < 0.001), advanced stage of bladder cancer (P < 0.05), metastasis (P < 0.05), and worse cause-specific survival (P < 0.05) in bladder cancer patients. Moreover, we found that pharmacologic inhibition or genetic depletion of GSK-3β resulted in decreased viability of bladder cancer cells. Conclusions: Our results suggest nuclear accumulation of GSK-3β as a novel prognostic marker in bladder cancer, show that GSK-3 contributes to urothelial cancer cell proliferation and survival, and identify GSK-3 as a potential therapeutic target in human bladder cancer. Clin Cancer Res; 16(21); 5124–32. ©2010 AACR.