Bmi-1和N-Myc共同超表达在神经母细胞瘤发生中的作用

目的 研究癌基因Bmi-1和N-Myc在神经母细胞瘤发生中的作用.方法 以神经母细胞瘤细胞系SHEP1细胞为模型,采用逆转录病毒转染法转染目的基因Bmi-1和/或N-Myc,免疫印迹法检测转染效果.软琼脂实验观察获得稳定高表达Bmi-1和/或N-Myc的各组细胞的致瘤性,流式细胞术观察Bmi-1和/或N-Myc转染细胞对凋亡因子(TRAIL和抗Fas抗体)的敏感性.结果 软琼脂实验显示对照组和单纯转染Bmi-1或N-Myc组均未见克隆形成,而Bmi-1和N-Myc共转染组可见克隆形成.流式细胞术发现,经各种凋亡因子作用后,与对照组相比,单纯转染N-Myc组细胞凋亡率显著升高(P＜0.05),而Bmi-1和N-Myc共转染组与单纯转染N-Myc组相比,细胞凋亡率显著降低(P＜0.05).结论 Bmi-1可以通过抑制N-Myc所致的神经母细胞瘤细胞对凋亡因子的敏感性,从而与N-Myc共同参与神经母细胞瘤的发生,是本病发生的关键环节.

Oncogenic cooperation between Bmi-1 and N-Myc in the tumorigenicity of neuroblastoma cells

Objective To define the role of Bmi-1 and N-Myc in neuroblastoma development,and find out a new therapeutic avenue for neuroblastoma.Methods The human Bmi-1 and N.Mycgenes were introduced,individually or sequentially,into SHEPI cells(S-type(substrate adherent)andbenign phenotype neuroblastoma cell line with very low levels of endogenous Bmi-1 and N-Myc)byretroviral infection.The gene expression of infected cells was measured by immunoblotting.Soft agarassays were used to detect tumorigenic activity of the infected cells.Flow cytometry was used to detect the apoptotic rate of cells induced by TRAIL or an agonistic anti-Fas antibody. Results SHEP1 cells infected with either vector control,N-Myc-,or Bmi-1-expressing retroviruses failed to grow in softagar,and the cells infected with both N-Myc- and Bmi-1-expressing retroviruses were able to grow intolarge colonies under the same conditions.The over expression of N-Myc in SHEP1 cells showed amarked increase in their sensitivity to apoptosis induced by a variety of agents.In contrast,the over expressions of N-Myc and Bmi-1 in SHEP1 cells were highly resistant to both of the apoptosis-inducingagents.Conclusions Bmi-1 can cooperate with N-Myc in neuroblastoma development by inhibiting N-Myc induced sensitization of neuroblastoma cells to apoptosis,this is the key pathogenesis of neuroblastoma.