Abstract: Objective:To observe the inhibition effect and mechanism of siRNA-Gli-1 and BCNU on the expression of Hedgehog(Hh) signal pathway and the proliferation and aptosis in glioma 251 cell. Methods:　Five groups were divided : BCNU group( BCNU),siRNA-Gli-1 group (si RNA- Gli -1)、combination group（siRNA-Gli-1 + BCNU）、transfection reagents group (transfection reagents）and blank control group(RPMI1640). siRNA-Gli-1 was transfected into U251 glioma cells, the mRNA and protein expression of Gli-1 gene were assessed by real- time quantitative poly merase chain reaction ( RT-PCR) and western blotting. After being treated by BCNU and siRNA-Gli-1,the proliferation and apoptosis of U251cells were examined by MTT, Flow Cyto- metry , Annexin V methods . RT-PCR and Western blotting was used to detect the mRNA and protein expression of Bcl-2、CyclinD1 and Bax in Hh signal pathway. Results:　 The expression of Gli-1 in siRNA- Gli-1 and combination group declined distinctly,as compared with other three groups (P<0.05) ; Flow Cytometry analysis showed that the proliferation and apoptosis of U251 cells in BCNU group、siRNA- Gli-1 group and combination group was inhibited and increased respectively , and G0/G1 phase rate increased and S phase rate decreased, as compared with transfection reagents group and blank control group(P < 0. 05)；In siRNA-Gli-1 group and com- bination group , especially in combination group , the expression of Bcl-2 and CyclinD1 decrea- sed obviously and the expression of Bax increased or had no change(P < 0. 05). Conclusion　: Combine application of siRNA-Gli-1 and BCNU can enhance the effect of inhibition to U251cell , it may be related to the inhibitory to the expression of Gli-1,as well as Bcl-2 and CyclinD1 in Hh pathway ,and the expression Bax may be increased.This effect can be achieved by cell cycle arrest and decreasing the ratio of Bax/Bcl-2..

Key words: glioma, Gli-1, RNAi, BCNU, signal pathway