靶向表皮生长因子受体的小分子RNA干扰抑制人脑胶质瘤Notch1表达的实验研究

The experimental study on the inhibition of Notch1 expression by RNAi EGFR in the human cerebral glioma

目的探讨RNA干扰表皮生长因子受体后Notch1在人脑胶质瘤中的表达变化。方法应用免疫组织化学方法检测不同级别脑胶质瘤组织标本中Notch1的表达水平,并进行相关分析。选择人表皮生长因子受体的两个RNA干扰靶序列构建靶向表皮生长因子受体的RNA干扰表达质粒,进行脂质体介导的TJ905人脑恶性胶质瘤细胞系表达;应用荧光定量逆转录-聚合酶链反应仪观察RNA干扰表皮生长因子受体后TJ905人脑恶性胶质瘤细胞系Notch1的表达变化。结果免疫组织化学检测显示,在不同级别胶质瘤组织标本中Notch1的阳性表达率分别为Ⅳ级93.33%(14/15);Ⅲ级92.31%(12/13);Ⅱ级68.42%(13/19)。Ⅱ级阳性表达程度较Ⅲ、Ⅳ级弱,组间差异有高度统计学意义(H=6.944,P<0.01),提示高级别胶质瘤Notch1阳性表达率高于低级别。RNA干扰表皮生长因子受体后,Notch1在TJ905胶质母细胞瘤细胞系中的表达下降(F=578.728,P<0.01):TJ905组与TJ905+空载组相比,差异无统计学意义(P>0.05);TJ905+空载组与TJ905+516组相比,差异有统计学意义(q=6.359,P<0.05);TJ905+516组与TJ905+2400组比较,差异有统计学意义(q=4.501,P<0.05);TJ905组与TJ905+2400组相比差异亦有统计学意义(q=10.015,P<0.05)。责任基因相对表达量,TJ905组和TJ905+空载组均为2.48×10-5,TJ905+516组为6.64×10-6,TJ905+2400组为2.08×10-7。结论表皮生长因子受体与Notch1关系密切,对二者关系的进一步研究可为胶质瘤的基因治疗提供新的思路。

Objective To study variation of Notchl expression by RNA interference （RNAi） epidermal growth factor receptors （EGFR） in the human cerebral glioma. Methods Immunohistochemical study was used to detect and analyse Notchl expression level in 47 glioma samples of various grades. Two RNAi expression constructs using psiRNA-NeoG 2 vector were transfected into human glioblastoma cell line TJ905 mediated by lipofectamine, and the variation of Notch 1 expression was observed by reverse transcriptase polymerase chain reaction （RT-PCR） after RNAi EGFR. Results Immunohistochemical study displayed that the positive expression rate of Notchl is different in various grade of glioma, grade Ⅳ 93.33% （14/15）, grade Ⅲ 92.31% （12/13）, grade Ⅱ 68.42% （13/19） （H=6.944, P〈0.01, compared with group Ⅲ,Ⅳ）. The variation of expression was statistically significant in different grades of glioma （P〈 0.01）, suggesting that Notchl positive expression rate in high grade glioma was higher than that in low grade. Expression of Notchl in TJ905 cells was downregnlated by RNAi EGFR （F=578.728, P〈 0.01）, there was no significant difference between TJ905 group and TJ905＋no-load group （q=0.801, P〉0.05）. The differences between TJ905＋no-load group and TJ905＋516 group, TJ905＋516 group and TJ905＋2400 group, as well as TJ905 group and TJ905＋2400 group, were statistically significant （P〈 0.05）. The levels of Notch 1 expression in both TJ905 group and TJ905＋no-load group were 2.48× 10^-5. The Notchl expression levels in TJ905＋516 group and TJ905＋2400 group were 6.64×10^-6 and 2.08×10^-7 respectively. Conclusion Notchl is closely related to EGFR. The findings may provide a new approach to the genetherapy of gliomas.