Effect of epidermal growth factor receptor gene silence by miR-7 on inhibiting glioma cell cycle

Objective To study the internal mechanism of inhibition of glioma cell cycle from G1 phase into S phase by miR-7.Methods After transfecting plasmid containing miR-7 into U251 glioma cell line,hybridization in situ and real-time PCR were used to detect the gene integration,and the cell cycle was detected by flow cytometry.The protein expression level of EGFR,CyclinD1,CyclinE,CDK2,CDK4,CDK6,P16,P21 and P27 were detected by Western blot.The corrclation among them was analyzed by software SPSS 13.0.Results The real-time PCR showed that miR-7 gene was successfully integrated into U251 glioma cells,and it was mainly localized in the nucleus and cytoplasm from in situ hybridization results.After miR-7 gene transfection,the cell proliferation rate slowed down,and most of them were inhibited in G1 phase in mitotic cells.As meanwhile,the percentage of S phase cells decreased significantly ( P ＜0.05).The expression level of miR-7 was negatively correlated with EGFR,CyclinD1,CDK4,and CDK6 ( P ＜ 0.01 ),and was negatively correlated with CyclinE and CDK2 (0.01 ＜ P ＜0.05),but was positively correlated with P16 ( P ＜0.01 ).There was no correlation with P21 and P27 ( P＞ 0.05 ).Conclusion Through effective silencing the expression of oncogene EGFR,miR-7 may inhibit the activity of protein complex CyclinD1/CDK4/6,which is an important cell cycle G1 phase regulatory.With the P16 synergies,they inhibit glioma cell cycle from G1 phase into S phase.So miR-7 is expected to become a new drug candidate for glioma treatment. Key words: Glioma; microRNA; Epidermal growth factor receptor