Taylor B Frazier, McNeely Samuel C, Miller Heather L, Lehmann Geniece M, McCabe Michael J, States J Christopher
Department of Pharmacology and Toxicology, University of Louisville, 570 South Preston Street, Suite 221, Louisville, KY 40202, USA.
J Pharmacol Exp Ther. 2006 Jul;318(1):142-51. doi: 10.1124/jpet.106.103077. Epub 2006 Apr 13.
Arsenic trioxide, an acute promyelocytic leukemia chemotherapeutic, may be an efficacious treatment for other cancers. Understanding the mechanism as well as genetic and molecular characteristics associated with sensitivity to arsenite-induced cell death is key to providing effective chemotherapeutic usage of arsenite. Arsenite sensitivity correlates with deficient p53 pathways in multiple cell lines. The role of p53 in preventing arsenite-induced mitotic arrest-associated apoptosis (MAAA), a form of mitotic catastrophe, was examined in TR9-7 cells, a model cell line with p53 exogenously regulated in a tetracycline-off expression system. Arsenite activated G1 and G2 cell cycle checkpoints independently of p53, but mitotic catastrophe occurred preferentially in p53- cells. Cyclin B/CDC2(CDK1) stabilization and caspase-3 activation persisted in arsenite-treated p53- cells consistent with MAAA/mitotic catastrophe. N-Benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone, a pan-caspase inhibitor, completely abolished arsenite-induced MAAA/mitotic catastrophe and greatly increased the mitotic index. WEE1 and p21CIP1/WAF1 inhibit cyclin B/CDC2 by CDC2 tyrosine-15 phosphorylation and direct binding, respectively. CDC2-Y15-P was transiently elevated in arsenite-treated p53+ cells but persisted in p53- cells. Arsenite induced p53-S15-P and p21CIP1/WAF1 only in p53+ cells. P21CIP1/WAF1-siRNA-treated p53+ cells were similar to p53- cells in mitotic index and cell cycle protein levels. p53-inducible proteins GADD45alpha and 14-3-3sigma are capable of inhibiting cyclin B/CDC2 but did not play a p53-dependent role in mitotic escape in TR9-7 cells. The data indicate that p53 mediates cyclin B/CDC2 inactivation and mitotic release directly via p21CIP1/WAF1 induction.
三氧化二砷是一种用于治疗急性早幼粒细胞白血病的化疗药物，可能对其他癌症也有疗效。了解与亚砷酸盐诱导的细胞死亡敏感性相关的机制以及遗传和分子特征，是有效使用亚砷酸盐进行化疗的关键。在多个细胞系中，亚砷酸盐敏感性与p53通路缺陷相关。在TR9-7细胞中研究了p53在预防亚砷酸盐诱导的有丝分裂停滞相关凋亡（MAAA，一种有丝分裂灾难形式）中的作用，TR9-7细胞是一种在四环素关闭表达系统中外源调节p53的模型细胞系。亚砷酸盐独立于p53激活G1和G2细胞周期检查点，但有丝分裂灾难优先发生在p53缺失的细胞中。在亚砷酸盐处理的p53缺失细胞中，细胞周期蛋白B/细胞周期蛋白依赖性激酶2（CDK1）的稳定和半胱天冬酶-3的激活持续存在，这与MAAA/有丝分裂灾难一致。泛半胱天冬酶抑制剂N-苄氧羰基-Val-Ala-Asp-氟甲基酮完全消除了亚砷酸盐诱导的MAAA/有丝分裂灾难，并大大增加了有丝分裂指数。WEE1和p21CIP1/WAF1分别通过细胞周期蛋白依赖性激酶2酪氨酸-15磷酸化和直接结合来抑制细胞周期蛋白B/细胞周期蛋白依赖性激酶2。在亚砷酸盐处理的p53阳性细胞中，细胞周期蛋白依赖性激酶2-Y15-P短暂升高，但在p53缺失细胞中持续存在。亚砷酸盐仅在p53阳性细胞中诱导p53-S15-P和p21CIP1/WAF1。用p21CIP1/WAF1小干扰RNA处理的p53阳性细胞在有丝分裂指数和细胞周期蛋白水平上与p53缺失细胞相似。p53诱导蛋白GADD45α和14-3-3σ能够抑制细胞周期蛋白B/细胞周期蛋白依赖性激酶2，但在TR9-7细胞的有丝分裂逃逸中不发挥p53依赖性作用。数据表明，p53通过诱导p21CIP1/WAF1直接介导细胞周期蛋白B/细胞周期蛋白依赖性激酶2的失活和有丝分裂释放。
