RESUMO
BACKGROUND: MicroRNAs (miRNAs) are single-stranded, endogenous, non-coding RNAs that are increased or decreased in almost all cancer types, and they paly crucial roles in the tumorigenesis as well as development. MATERIALS AND METHODS: 90 patients diagnosed with bladder cancer were enrolled in the present study. The bladder cancer tissues or adjacent normal tissues were obtained from the tumor area or adjacent normal zone. The expression level of miR-133b was examined by quantitative real-time polymerase chain reaction assay (qRT-PCR). Survival curves were displayed by the Kaplan-Meier method, and differences between two survival curves were calculated by the log-rank test. RESULTS: The expression levels of miR-133b in bladder tissues were significantly decreased when compared with the matched adjacent normal bladder tissues (P < 0.05). Moreover, miR-133b expression levels are significantly associated with lymphatic invasion (P = 0.026), distant metastasis (P = 0.025), tumor grade (P = 0.038), as well as the muscle invasion status (P < 0.001). The log-rank test indicated that patients with decreased miR-133b expression underwent poorer overall survival (P = 0.007). Furthermore, multivariate Cox regression analysis showed that the expression level of miR-133b (P = 0.024) was an independent factor for predicting the overall survival in patients with bladder cancer. CONCLUSIONS: The present study showed that miR-133b might be associated with bladder cancer progression, and its down-regulation might be a biomarker for poor prognosis of bladder cancer.