miR-221 facilitates the TGFbeta1-induced epithelial-mesenchymal transition in human bladder cancer cells by targeting STMN1.
BACKGROUND
Distant metastasis is the major cause of cancer-related death, and epithelial-to-mesenchymal transition (EMT) has a critical role in this process. Accumulating evidence indicates that EMT can be regulated by microRNAs (miRNAs). miR-221, as oncogenes in several human cancers, was significantly up-regulated in bladder cancers. However, the role of miR-221 in the progression of bladder cancer metastasis remains largely unknown.


METHODS
We used qRT-PCR and western blot to accurately measure the levels of miR-221, STMN1 and EMT markers in TGFβ1 induced EMT of bladder cancer cells. miR-221 inhibitors were re-introduced into bladder cancer cells to investigate its role on tumor metastasis which was measured by MTT, wound healing, transwell invasion and adherent assays. Luciferase reporter assay was used to reveal the target gene of miR-221.


RESULTS
miR-221 expression was greatly increased by TGFβ1 in bladder cancer cell. miR-221 inhibition reversed TGFβ1 induced EMT by sharply increasing the expression of the epithelial marker E-cadherin and decreasing the expression of the mesenchymal markers vimentin, Fibroactin and N-cadherin. Furthermore, miR-221 expression is positively correlated with malignant potential of bladder cancer cell through promoting loss of cell adhesion and prometastatic behavior. Luciferase reporter assay revealed that miR-221 negatively regulates STMN1 expression by direct targeting to the 3'UTR region of STMN1.


CONCLUSIONS
Our study demonstrated that miR-221 facilitated TGFβ1-induced EMT in human bladder cancer cells by targeting STMN1 and represented a promising therapeutic target in the process of metastasis.
Department of Urology, 2nd xiangya Hospital, Central South University, NO.139 Middle Renmin Road, 410011, Changsha, Hunan, China. liujun2010_good@163.com.
Jun
J
Liu
Department of Urology, 2nd xiangya Hospital, Central South University, NO.139 Middle Renmin Road, 410011, Changsha, Hunan, China. caojian356288404@sina.com.
Jian
J
Cao
Department of Urology, 2nd xiangya Hospital, Central South University, NO.139 Middle Renmin Road, 410011, Changsha, Hunan, China. xiaokunzhao2014@163.com.
Xiaokun
X
Zhao
D018450:Disease Progression; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D006801:Humans; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009361:Neoplasm Invasiveness; D050777:Stathmin / Q000187:drug effects*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000503:physiopathology* / Q000556:secondary; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology
D035683:MicroRNAs; D050777:Stathmin; D053773:Transforming Growth Factor beta1; C525709:MIR221, human; C493995:STMN1 protein, human