Abstract: Objective To study the effect of urokinase-type plasminogen activator receptor (uPAR) gene expression on the migration and invasion of human bladder cancer cell line T24 in vitro and the possible mechanism. Methods uPAR siRNA, Rictor siRNA, PTEN siRNA and NC siRNA were designed, synthesized and transfected into bladder cancer T24 cells using transient transfection, separately，setting as siuPAR, siRictor, siRictor + siuPAR, siuPAR + siPTEN and NC groups. Expression levels of mRNA and protein were respectively detected by real-time quantitive PCR (RT-qPCR) and Western blot. Cell migration assay and Transwell invasion assay were used to testify the migration and invasion of uPAR-silencing T24 cells. Results uPAR mRNA and protein levels of highly invasive bladder cancer T24 cells showed higher than less aggressive RT4 cells（P < 0.05）. After T24 cells were transfected with uPAR siRNA, phosphorylation of serine-473, an mammalian target of rapamycin complex 2 (mTORC2) target, in extracellular regulated protein kinase B (Akt) was significantly downregulated（P < 0.05）. On the other hand, silencing uPAR also down-regulated migration and invasion of T24 cells（P < 0.05）. Moreover, Akt-S473 was neither phosphorylated by uPAR nor mTORC2 in PTEN-negative T24 cells. Instead, silencing uPAR gene derepressed Akt-S473 phosphorylation（P < 0.05）. Conclusions Silencing uPAR down-regulates migration and invasion of bladder cancer cell. The possible mechanism is proposed that uPAR might work as mTORC2 upstream regulator in T24 cells.

Key words: bladder cancer cell line T24 , migration, invasion, uPAR , mTORC2