Long non-coding RNA XIST promotes cell proliferation and migration through targeting miR-133a in bladder cancer

The long non-coding RNA (lncRNA) X inactive specific transcript (XIST) has recently been reported to promote the malignant progression of bladder cancer through regulating several microRNAs (miRs), including miR-124, miR-139-5p and miR-200c. However, whether other miRs are also involved in this process has remained to be determined. The present study demonstrated that XIST was significantly upregulated in bladder cancer tissues compared with that in adjacent normal tissues. Furthermore, its expression was reduced in several common bladder cancer cell lines. High expression of XIST was significantly associated with tumour progression and poor prognosis of patients with bladder cancer. An in vitro experiment indicated that knockdown of XIST significantly reduced the proliferation and migration of bladder cancer cells. A luciferase assay suggested that XIST binds to its predicted binding site in miR-133a. In addition, it was identified that miR-133a was significantly downregulated in bladder cancer, and its expression levels were inversely correlated with those of XIST in bladder cancer tissues. Furthermore, loss- and gain-of-function experiments indicated that miR-133a acted as a downstream effector in XIST-mediated bladder cancer cell proliferation and migration. In conclusion, the present study demonstrates that XIST promotes bladder cancer cell proliferation and migration via targeting miR-133a and thus suggests that XIST may be used as a potential therapeutic target for bladder cancer.