MYC—EZH2相互作用及其在3型髓母细胞瘤化疗耐药中的作用

MYC-EZH2 interactions and its role of chemoresistance in type 3 medulloblastoma

目的研究MYC-EZH2在3型髓母细胞瘤中的相互作用关系及其对化疗耐药的作用。方法通过建立原代的3型髓母细胞瘤细胞系，通过慢病毒转染的方法分别干扰MYC和EZH2基因的表达，检测干扰后MYC与EZH2之间的相互关系，并在耐药性评价模型中检测其对3型髓母细胞瘤化疗抵抗的作用。结果成功建立3型原代髓母细胞瘤细胞系，免疫荧光检测示NPR3阳性，该细胞系中MYC及EZH2同时高表达，其△Ct分别为7.9和2.5。MYC干扰慢病毒LV-pds19-shMYC浸染细胞的情况下，MYC、EZH2表达量均下降，其中MYC的相对表达量平均下降至0.27（0.30、0.25、0.25），EZH2相对表达量平均下降至0.70（0.68、0.74、0.68），干扰前后比较，差异均有统计学意义（P＝0和0.001 6）。用EZH2干扰慢病毒LV-pds19-shEZH2浸染细胞的情况下，MYC、EZH2表达量均下降，其中MYC的相对表达量下降至0.56（0.58、0.48、0.62），EZH2相对表达量下降至0.29（0.31、0.28、0.28），干扰前后比较，差异均有统计学意义（P＝0.004 1和0），说明MYC-EZH2之间存在正向相互调控。分别用MYC干扰慢病毒、EZH2干扰慢病毒干扰顺铂处理后的3型髓母细胞瘤细胞，于不同时间点用CCK-8试剂在波长为450 nm时检测各种处理后细胞的OD值，发现与未用MYC干扰慢病毒及EZH2干扰慢病毒干扰的顺铂处理后细胞相比，MYC干扰慢病毒、EZH2干扰慢病毒干扰后的顺铂处理后的3型髓母细胞瘤细胞OD值均下降，即细胞的增殖明显下降。结论3型髓母细胞瘤中MYC、EZH2间存在正向的相互调控，通过干预MYC-EZH2相互作用这一过程，可降低3型髓母细胞瘤对化疗药物的耐药性，这一发现为3型髓母细胞瘤的化学治疗提供了针对MYC、EZH2的治疗靶点。

ObjectiveTo explore the MYC-EZH2 interactions and its role of chemoresistance in type 3 medulloblastoma.MethodsType 3 medulloblastoma cell line was established by primary culture. The gene expressions of EZH2 and MYC were analyzed after transfecting shMYC and shEZH2 with lentiviral vectors. Using cell proliferation analysis, in the presence of low-dose cisplatin after siRNA transfection, an interruption of MYC-EZH2 interaction significantly reduced the chemoresistance in type 3 medulloblastoma.ResultsType 3 medulloblastoma cell line was established successfully and NPR3 was positive by immunofluorescent test. The expression of EZH2 decreased （P=0 and 0.001 6） after transfecting LV-pds19-shMYC and the expression of MYC decreased （P=0.004 1 and 0） after transfecting LV-pds19-shEZH2. It hinted at a positive regulation of MYC-EZH2. By interrupting MYC-EZH2 loop, it could significantly improve the resistance of chemotherapeutic agents.ConclusionsA positive interaction exists between MYC and EZH2. And an intervention of this process can successfully reduce the chemoresistance in type 3 medulloblastoma cell line and offer potential treatment.