Objective      To investigate the effects of down-regulating human ribonuclease inhibitor (RI) on cell proliferation

invasion and tumor growth in human bladder cancer BIU-87 cells.       Methods      Two specific siRNA RI expression vectors and a non-homologous vector negative control were transfected into noninvasive bladder cancer BIU-87 cells

then screened and identified. Cell proliferation was measured by Am-blue assay

and the expression of MMP-2 and MMP-9 were detected by Western blotting. Tumor cells at  2×10

6

inclu

ding the BIU-87 siRNA3 cells and the BIU-87 vector cells were respectively injected subcutaneously into the back of BALB/c nude mice to observe tumor growth and microvessel density. Immunohistochemical assays for RI

CD31

nm23-H1 and E-cadherin were performed to detect the effect of RI expressions on angiogenesis and metastasis potential of the tumor mass.       Results      Silencing RI expression in BIU-87 cells obviously enhanced cell proliferation

and increased MMP-2 and MMP-9 expression. BALB/c nude mice receiving an injection of RI siRNA transfected BIU-87 cells showed a significant facilitation of the tumor with heavier tumor weight

higher density of microvessel

lower nm23-H1 and E-Cadherin expression than those in the control group.       Conclusion      Silencing RI promotes growth and metastasis potentials of BIU-87 cells. The results show that RI may be a therapeutic target protein for bladder cancer.