BACKGROUND: Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) gene showed low expression in glioma cells. LRIG1 gene overexpression significantly enhanced LRIG1 mRNA and protein expression and inhibited its biological behavior. However, very few researchs are reported from the stand-point of inhibition of LRIG1 gene expression. OBJECTIVE: To construct specific RNA interference plasmids for LRIG1, establish stably transfected human glioma GL15 cell line, and observe its effect on expression of target gene LRIG1. METHODS: Designed and synthesized two shRNAs (named LRIG1-shRNA1 and LRIG1-shRNA2) specific for LRIG1 mRNA according to the GenBank, and one scrambled shRNA sequence as negative control, named pGenesil2-negative shRNA. The shRNA was inserted into pGenesil2 vector and sequenced. The recombinant vectors were transformed into E. coli. Picked up the positive clones and extracted the plasmids, which were transfected into GL15 cells by Metafectine. G418 was applied to select the stably transfected cell clones. Western Blotting was performed to examine the LRIG1 protein level.RESULTS AND CONCLUSION: The recombinant plasmids which contain shRNA were analyzed by restriction endonuclease digestion and DNA sequence, and it was proved that the fragment was inserted into the expected sites. Compared with the negative control group, the level of LRIG1 protein expression in pGenesil2-LRIG1-shRNA1(LRIG11) transfected cells and in pGenesil2-LRIG1-shRNA2(LRIG12) transfected cells was decreased by 47.9% (P < 0.01) and 32.8% (P > 0.05). The results confirmed that RNAi expressing vector specific for LRIG1 gene (pGenesil2-LRIG1-shRNA1) was successfully constructed, and the stable cell clones transfected with the shRNA expression vector showed inhibition of the expression of LRIG1 in glioma cell line GL15.

The effects of RNAi-mediated gene silencing of LRIG3 expression on cell cycle and survival of human glioma cell line GLI 5 and the possible mechanisms were explored.The plasmids pGenesil2-LRIG3-shRNA l and pGenesil2-LRIG3-shRNA2 were transfected into GL 15 glioma cells respectively by using Metafectine,and the transfected cells that stably suppressed LRIG3 expression were selected by G418.The control cells were transfected with negative control shRNA.The changes in LRIG3 mRNA and protein levels were measured by RT-PCR and Western blot.The apoptosis rate and cell cycle were analyzed by flow cytometry.As compared with the negative shRNA-transfected GL15 cells,LRIG3 mRNA expression in GLI5 cells transfected with pGenesil2-LRIG3-shRNAl and pGenesil2-LRIG3-shRNA2 was silenced by 52.4%,63.8%,and LRIG3 protein expression was re-duced by 50.9% and 67.4% respectively.The LRIG3-specific siRNA transfected cells had higher proliferation rate than control cells.Cell cycle analysis showed that silencing LRIG3 increased the percentage of G2/M phase cells and the proliferation index significantly (P<0.01).Silencing LRIG3 could inhibit the apoptosis of GLl5 cells (P<0.05).These findings suggest that the siRNA targeting LRIG3 gene shows a dramatic inhibitory effect on RNA transcription and protein expression,then promoting the proliferation of GLI5 cells,arresting GLI5 cells in G2/M phase,and suppressing apoptosis ofGL15 cells.