Correlation of Increased Expression of MicroRNA-155 in Bladder Cancer and Prognosis

Objective: To investigate the expression level and clinical significance of microRNA-155 (miR-155) in bladder cancer. Methods: We collected 102 pairs of tissue specimens from patients with primary bladder cancer and adjacent normal bladder specimens between March 2008 and May 2013. Quantitative real-time polymerase chain reaction (QRT-PCR) was performed to detect the expression levels of miR-155. We performed univariate survival analyses using the Kaplan-Meier method and assessed statistical significance between survival curves via the log-rank test. Results: The mean (SD) level of miR-155 expression in tissues with bladder cancer was 13.78 (4.80), which was significantly higher on average than that in adjacent normal bladder tissues (6.14 [2.26], P<.001). Progression-free survival (PFS) was significantly lower for patients with bladder cancer who had a high expression level of miR-155 (5-year survival rate, 23.0%) than those with a low miR-155 expression level (5-year survival rate, 48.9%; P<.001). Conclusions: We found that elevated expression of miR-155 is correlated with a poor outcome for patients with bladder cancer; this suggests that miR-155 is a potential biomarker for bladder cancer prognosis.