Overexpression of Pim-1 in bladder cancer

Expression and localization of Pim-1 in human normal and malignant bladder specimens were examined by Immunohistochemistry and Pim-1 staining score was compared with several clinicopathologic parameters. To further demonstrate the biological function of Pim-1 in bladder cancer, its expression was validated in five bladder cancer cell lines by western blot and immunohistochemistry analyses. Subsequent knockdown of Pim-1 was achieved by lentivirus encoding small interfering RNA, and the effect of Pim-1 on bladder cell survival and drug sensitivity were further assessed by colony formation and cell proliferation assays.When compared with normal epithelium, Pim-1 was overexpressed in bladder cancer epithelium, and the expression level was higher in invasive bladder cancer than Non-invasive bladder cancer specimens. Pim-1 was also detected in all the bladder cancer cell lines examined in our study. Moreover, the knockdown of Pim-1 significantly inhibited bladder cancer cell growth and also sensitized cells to chemotherapeutic drugs in vitro.Our results in this study suggest that Pim-1 may play a role in bladder cancer initiation and progression. Since Pim-1 is also involved in bladder cancer cell survival and drug resistance, Pim-1 is a potential candidate for targeted therapy in bladder cancer.Bladder cancer is one of the most common types of cancer globally, with approximately 75% of the diagnosed tumors classified as Non-invasive tumor (Ta, Tis, or T1). Treatment of Non-invasive tumor includes transurethral resection (TUR) with or without intravesical instillation therapy, but the recurrence rate is high, ranging from 50% to 70%. In addition, an average of 10% to 20% for Non-invasive tumors may further progress to muscle-invasive disease, thus lead to eventual radical Cystectomy and urinary diversion [1-3]. In this context, clinicians face challenges to identify the novel therapeutic targets for bladder cancer.Pim-1 is overexpressed in several types of cancer, includi