High Expression of Long Noncoding RNA MALAT1 Indicates a Poor Prognosis and Promotes Clinical Progression and Metastasis in Bladder Cancer

Bladder cancer is the second most common malignancy of the urinary system, after prostate cancer. The expression of long noncoding RNA MALAT1 can promote cancer cell proliferation, invasion, and metastasis in many tumor types. High MALAT1 expression could serve as an independent prognostic factor for bladder cancer and could be a potential therapeutic target of bladder cancer. Background: Recent studies have demonstrated that the expression of long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) promotes cancer cell proliferation, invasion, and metastasis in many tumor types, but the association between bladder cancer and MALAT1 remains unknown. Materials: The expression of MALAT1 was tested by in situ hybridization (ISH) in 120 bladder cancer specimens. The association between MALAT1 expression and clinicopathological features and prognosis of the patients with bladder cancer was analyzed. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to verify the relationship between the expression of MALAT1 and progression and metastasis of bladder cancer. Results: ISH showed that high MALAT1 expression was associated with advanced histological grade, high tumor stage, and positive lymph nodes. Kaplan-Meier survival analysis and Cox regression analysis indicated that high tumor stage, positive lymph nodes, and high MALAT1 expression were independent prognostic indicators for overall survival (OS) of patients with bladder cancer. qRT-PCR showed that the expression of MALAT1 in bladder cancer tissues was 2.85 times higher than those measured in adjacent normal tissues (P < .001). The expression of MALAT1 was 2.673 +/- 0.254 in non-muscle-invasive bladder cancer and 2.987 +/- 0.381 in muscle-invasive bladder cancer (P = .018). In bladder cancer specimens with positive lymph nodes, MALAT1 expression was 3.167 +/- 0.297 versus 2.896 +/- 0.329 in bladder cancer specimens with negative lymph nodes (P = .020). Conclusion: High MALAT1 expression could serve as an independent prognostic factor for OS of patients with bladder cancer and could be considered as a potential therapeutic target of bladder cancer. (C) 2017 Elsevier Inc. All rights reserved.