Objective        To investigate the effect of CRE-dependent RNA interference targeting STAT3 on the invasion and migration of human bladder cancer BIU-87 cells.       Methods        RNA interfering vectors pSico was used to construct CRE-dependent shRNA expression plasmids targeting STAT3

and pLVX-CRE was used as an expression vector of CRE. BIU-87 cells were divided into 4 groups and were transfected with pSico-shNeg

pSico-shNeg/CRE

pSico-shSTAT3 and pSico-shSTAT3/CRE

respectively. RT-PCR and Western blot analysis were carried out to assess the efficiency of RNA interference. The abilities of invasion and migration of BIU-87 cells after CRE-dependent RNA interference of STAT3 were detected by Transwell chamber assay and wound-healing assay.       Results      Restriction analysis and DNA sequencing proved that the recombinant plasmid pSico-shSTAT3 was constructed successfully. CRE-dependent green fluorescent cells were detected after the transfection. The shRNA against STAT3 significantly inhibited STAT3 mRNA expression

and CRE and shSTAT3 transfection down-regulated the expression levels of STAT3 in BIU87 cells significantly (P0.05). The number of migrating cells were significantly less in the pSico-shSTAT3 /CRE group (42.00±3.00) than in the pSico-shNeg (203.33±12.42)

pSico-shNeg/CRE (196.33±11.85) and pSico-shSTAT3 (201.00±16.64) groups (P0.01).       Conclusion      RNA interference of STAT3 mediated by CRE-dependent shRNA expression plasmid can down-regulate intracellular STAT3 signal level and reduce the abilities of invasion and migration of BIU-87 cells.