Augmentation of apoptosis responses in p53-deficient L1210 cells by compounds directed at blocking NFkappaB activation.
Augmentation of apoptosis responses in p53-deficient L1210 cells by compounds directed at blocking NFkappaB activation.
复制标题
通过直接阻断 NFkappaB 激活的化合物增强 p53 缺陷型 L1210 细胞的凋亡反应。
作者：
A. H. Cory;J. G. Cory
对脱氧腺苷有抗性的小鼠白血病L1210细胞株（Y8），即使在基础条件下，也能维持WAF 1/p21 mRNA和蛋白的表达，但p53 mRNA和蛋白表达不足。与亲本野生型（WT）L1210细胞相比，Y8细胞显示出对由多种试剂诱导的细胞凋亡更敏感。Roscovitine是cdk 2和cdk 5的抑制剂，是通过最终涉及caspase-3活性激活的途径引起Y8细胞凋亡增加的药物之一。在这些研究中，研究了来氟米特和parthenoclavine（据报道可改变多种细胞类型中NF κ B活化的药物）作为单药和与roscovitine联合给药在WT和Y8细胞中的细胞周期和凋亡效应。IC 50浓度的来氟米特对WT或Y8细胞的细胞周期分布几乎没有影响，而在更高浓度下，Y8细胞中引起G 0/G1阻滞。在IC 50浓度下，孤雌菊在WT和Y8细胞中引起G 0/G1细胞周期阻滞，但在较高浓度下在Y8细胞中引起G2/M阻滞。来氟米特和roscovitine或parthenoclavine和roscovitine的组合没有以显著的方式改变Y8细胞的细胞周期分布。然而，在来氟米特和罗斯科维汀或小白菊内酯和罗斯科维汀的组合存在下，经历早期细胞凋亡的Y8细胞比例大幅增加，而细胞坏死比例没有相应增加。这些数据表明，针对参与细胞凋亡的不同途径或途径的不同步骤的试剂的组合可以使细胞达到导致协同细胞凋亡的细胞凋亡阈值。
A mouse leukemia L1210 cell line (Y8) selected for resistance to deoxyadenosine was found to be deficient in the expression of p53 mRNA and protein while maintaining the expression of WAF1/p21 mRNA and protein even under basal conditions. The Y8 cells were shown to be more sensitive to apoptosis induced by a variety of agents when compared to the parental wild-type (WT) L1210 cells. Roscovitine, an inhibitor of cdk 2 and cdk5, was one of the agents that caused increased apoptosis in the Y8 cells through a pathway that ultimately involved the activation of caspase-3 activity. In these studies, the effects of leflunomide and parthenolide (drugs reported to alter the activation of NFkappaB in a variety of cell types) were studied for their cell cycle and apoptotic effects in WT and Y8 cells as single agents and in combination with roscovitine. Leflunomide at IC50 concentrations had little effect on the cell cycle distribution of either the WT or Y8 cells while at higher concentrations caused a G0/G1 block in Y8 cells. Parthenolide, at IC50 concentrations, caused a G0/G1 cell cycle block in the WT and Y8 cells but at higher concentrations caused a G2/M block in the Y8 cells. The combinations of leflunomide and roscovitine or parthenolide and roscovitine did not alter, in a significant way the cell cycle distribution of the Y8 cells. However, in the presence of the combinations of leflunomide and roscovitine or parthenolide and roscovitine there were large increases in the fraction of Y8 cells undergoing early apoptosis without a corresponding increase in the necrotic fraction of cells. These data show that combinations of agents directed at different pathways or different steps of pathways involved in apoptosis can cause the cells to reach an apoptotic threshold that results in synergistic apoptosis.