Overexpression of p21waf1 decreases G2-M arrest and apoptosis induced by paclitaxel in human sarcoma cells lacking both p53 and functional rb protein
Overexpression of p21waf1 decreases G2-M arrest and apoptosis induced by paclitaxel in human sarcoma cells lacking both p53 and functional rb protein
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DOI：
10.1124/mol.55.6.1088
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发表时间：
1999-06-01
影响因子：
3.6
通讯作者：
Bertino, JR
中科院分区：
文献类型：
--
作者：
Li, WW;Fan, JG;Bertino, JR
我们研究了p21（waf 1）过表达对紫杉醇细胞毒性的影响，紫杉醇是一种微管稳定剂，在缺乏功能性视网膜母细胞瘤蛋白和p53的人肉瘤细胞（SaOs-2）中使用四环素诱导的表达系统。在正常生长条件下，在SaOs-2细胞中检测不到p21（waf 1）。在四环素停药诱导p21（waf 1）后，我们观察到紫杉醇的凋亡反应降低，IC（50）值比未诱导p21（waf 1）的细胞增加3- 6倍。我们还观察到，当评估对长春新碱（另一种微管破坏剂）的细胞毒性时，IC（50）值增加了5倍，而我们观察到，在对拓扑异构酶II抑制剂依托泊苷（etoposide）进行p21（waf 1）诱导后，IC（50）值显著降低。紫杉醇处理后，与非p21（waf 1）诱导的细胞相比，在p21（waf 1）诱导的细胞中观察到较少的G（2）-M积累（57%对74%）。p21（waf 1）的诱导也抑制了紫杉醇诱导的细胞周期蛋白B1相关激酶活性的增加。在缺乏p53和功能性视网膜母细胞瘤蛋白的SaOs-2细胞中，p21（waf 1）的过表达可能由于抑制S-G（2）检查点而减少紫杉醇诱导的G（2）-M阻滞，导致细胞对紫杉醇的凋亡反应降低。
We examined the effect of overexpression of p21(waf1) on cytotoxicity of paclitaxel, a microtubule stabilizer, using a tetracycline-inducible expression system in human sarcoma cells (SaOs-2) that lack both functional retinoblastoma protein and p53. Under normal growth conditions, p21(waf1) is not detectable in SaOs-2 cells. Upon p21(waf1) induction by tetracycline withdrawal, we observed a reduced apoptotic response to paclitaxel with a 3- to 6-fold increase in IC(50) values compared with that of cells not induced by p21(waf1). We also observed a 5-fold increase in the IC(50) value when cytotoxicity to vincristine, another microtubule-disrupting agent, was assessed, whereas we observed a marked decrease in the IC(50) value after p21(waf1) induction in response to etoposide, a topoisomerase II inhibitor. After treatment with paclitaxel, less accumulation of G(2)-M was observed in p21(waf1)-induced cells compared with non-p21(waf1)-induced cells (57% versus 74%). p21(waf1) induction also inhibited the increased cyclin B1-associated kinase activity induced by paclitaxel. Overexpression of p21(waf1) in SaOs-2 cells lacking both p53 and functional retinoblastoma protein may decrease the G(2)-M arrest induced by paclitaxel due to suppression of the S-G(2) checkpoint, resulting in a decreased apoptotic response of cells to paclitaxel.