Down- regulation of Notch- 1 gene expression inhibits growth of TJ- 905 glioblastoma

Objective To study the inhibitory effect of siRNA on glioblastoma (GBM) Notch-1 gene expression in addition to the growth of TJ- 905 glioblastoma.Methods Three Small interference RNAs (siRNAs) targeting Notch- 1 gene named siRNA1,siRNA2,siRNA3 were synthesized chemically in vitro with gene bank BLAST.TJ-905 cells were transfectedtwice with the siRNA by using OligofectamineTM2000.The nontransfected cells and nonspecific siRNAs transfected cells were taken as blank and nonsense controls.Down - regulation of Notch- 1 was demonstrated by real- time RT- PCR,according to the result of QRT- PCR we therefore selected the most effective siRNA for further study.Cell proliferation was measured by MTT analysis.Male Balb/C nude mice were injected subcutaneously with Notch- 1 siRNA- or nonsense siRNA- transfected TJ-905 cells,tumor sizes were measured every 4 days.HE stain was used to determine the property of tumor.Resuts(1) The expression of Notch- 1 mRNA in blank,nonsense controls,siRNA1,2,3 groups were 1.00±0.07,1.04±0.05,0.11 ±0.02,0.12 ±0.01,0.77 ±0.03 by real-time RT- PCR scan analysis,the most effective siRNA was siRNA1.(2) An inhibitory proliferation and growth can be induced in siRNA1 transfected group.(3)Nude mice xenografted with cell suspensions from the nonsense siRNA group developed tumors with a significantly increased volume (from the 18th days) as compared to mice that received the Notch- 1 siRNA1- treated cells.The final tumor volume were less in nude mice injected with Notch- 1 siRNA (748.3 ±154.3 )mm3 compared to nonsense si RNA injection (1739.2 ± 249.7 )mm3,HE stain demonstrate that tumor was multiformity glioblastoma.Conclusion The chemically synthesized siRNA targeted Notch- 1 gene could down -regulate the expression of Notch- 1.In addition,an inhibitory proliferation and growth were induced when compared with the control cells in vitro and in vivo.It was suggested that the suppression of Notch- 1 expression and the inhibition of growth provide a new way to glioma gene therapy. Key words: Glioma; Human Notch-1 gene; Small interference RNA; Nude mice