title: MiR-133b regulates bladder cancer cell proliferation and apoptosis by targeting Bcl-w and Akt1.
abstract: BACKGROUND
  MiR-133b is a muscle-specific microRNA; it has a role in the formation of cardiocytes and the expression of myocardium ion channels by regulating target genes. Many human malignant tumors demonstrate a low expression of miR-133b, as noted in colorectal, lung, esophagus and bladder cancers, but the role of miR-133b in bladder cancer is unknown.
  
  
  METHODS
  The expression of miR-133b in clinical bladder cancer specimens and adjacent normal tissues was confirmed by stem-loop RT-PCR. We also analyzed the relationship between miR-133b expression and clinicopathological factors of bladder cancer. Bcl-w and Akt1 protein expression in 41 bladder cancer specimens and adjacent normal tissues was detected by Western blot. After transfection of miR-133b mimics or inhibitor into a T24 human bladder cancer cell line, Bcl-w and Akt1 protein and mRNA expression were examined by Western blot and RT-PCR, respectively. The effect of miR-133b on T24 cell proliferation and apoptosis was measured by CCK-8 tests and flow cytometry, respectively.
  
  
  RESULTS
  The expression of miR-133b in bladder cancer tissues from 41 patients was significantly down-regulated (P < 0.01); low expression of miR-133b was strongly associated with high-grade bladder cancer (P < 0.01). Bcl-w and Akt1 proteins were significantly overexpressed in bladder cancer tissues versus adjacent normal tissues (P < 0.01 for both). The expression of Akt1 and Bcl-w proteins and Akt1 mRNA, in T24 cells was significantly down-regulated or up-regulated after transfection of miR-133b mimics or inhibitor, respectively; however, there was no significant difference in Bcl-w mRNA expression. Transfection of HEK-293 T cells with miR-133b significantly suppressed a luciferase-reporter containing the Bcl-w or Akt 1 3'-untranslated regions. MiR-133b mimics significantly inhibited T24 cell proliferation, as well as increased T24 cell apoptosis (P < 0.05 and P < 0.01, respectively) while the miR-133b inhibitor increased and decreased these, respectively (P < 0.05 for both).
  
  
  CONCLUSIONS
  MiR-133b may play a very important role in the proliferation and apoptosis of T24 cells by regulating the expression of Bcl-w and Akt1.
authors.affiliation: Department of Urology, Shengjing Hospital of China Medical University, Shenyang 11004, Liaoning, P.R. China.
authors.forename: Xiao-Nan
authors.initials: XN
authors.lastname: Chen
authors.affiliation: Department of Urology, Shengjing Hospital of China Medical University, Shenyang 11004, Liaoning, P.R. China.
authors.forename: Ke-Feng
authors.initials: KF
authors.lastname: Wang
authors.affiliation: Department of Urology, Shengjing Hospital of China Medical University, Shenyang 11004, Liaoning, P.R. China.
authors.forename: Zhen-Qun
authors.initials: ZQ
authors.lastname: Xu
authors.affiliation: Department of Urology, Shengjing Hospital of China Medical University, Shenyang 11004, Liaoning, P.R. China.
authors.forename: Shi-Jie
authors.initials: SJ
authors.lastname: Li
authors.affiliation: Department of Urology, Shengjing Hospital of China Medical University, Shenyang 11004, Liaoning, P.R. China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Urology, Shengjing Hospital of China Medical University, Shenyang 11004, Liaoning, P.R. China.
authors.forename: Dong-Hui
authors.initials: DH
authors.lastname: Fu
authors.affiliation: Department of Urology, Shengjing Hospital of China Medical University, Shenyang 11004, Liaoning, P.R. China.
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Urology, Shengjing Hospital of China Medical University, Shenyang 11004, Liaoning, P.R. China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
keywords: Akt1; Apoptosis; Bcl-w; Bladder cancer; Proliferation; miR-133b