Stable overexpression of PML alters regulation of cell cycle progression in HeLa cells
Stable overexpression of PML alters regulation of cell cycle progression in HeLa cells
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DOI：
10.1093/carcin/18.11.2063
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发表时间：
1997-11-01
期刊：
影响因子：
4.7
通讯作者：
Chang, KS
中科院分区：
文献类型：
--
作者：
Mu, ZM;Le, XF;Chang, KS
我们以前的研究表明，PML是一种生长抑制因子，可抑制NIH/3 T3细胞和大鼠胚胎成纤维细胞的致癌转化。PML是一种核基质相关的磷蛋白，其表达在细胞周期中受到调节，t（15; 17）在急性早幼粒细胞白血病（APL）中起关键作用，为了进一步研究PML在控制细胞生长中的作用，我们在HeLa细胞系中稳定过表达PML蛋白，PML的过度表达显著降低了HeLa细胞的生长速率，并抑制了软琼脂中的锚定非依赖性生长。结果发现，与亲代HeLa细胞相比，HeLa/PML稳定克隆中G1期细胞比例增加，S期细胞比例减少，G2/M期细胞比例基本相同，HeLa/PML稳定克隆中G1期细胞比例延长，倍增时间明显延长，PML对HeLa细胞的凋亡无影响，提示PML通过延长细胞周期而抑制细胞生长。为了进一步了解PML对HeLa细胞的作用机制，分析了HeLa/PML和亲代HeLa细胞中细胞周期相关蛋白的表达，我们发现在PML稳定克隆中Rb磷酸化水平显著降低，cyclin E、Cdk 2和p27蛋白的表达也显著降低，这些研究表明PML通过介导通常控制细胞周期进程的几个关键蛋白的表达来影响细胞周期进程，这些结果进一步扩展了我们目前对PML在人类细胞中的功能及其在细胞周期调控中的重要作用的理解。
Our previous studies demonstrated that PML is a growth suppressor that suppresses oncogenic transformation of NIH/3T3 cells and rat embryo fibroblasts. PML is a nuclear matrix-associated phosphoprotein whose expression is regulated during the cell cycle, Disruption of PML function by t(15;17) in acute promyelocytic leukemia (APL) plays a critical role in leukemogenesis, To further study the role of PML in the control of cell growth, we have stably overexpressed PML protein in the HeLa cell line, This overexpression of PML significantly reduced the growth rate of HeLa cells and suppressed anchorage-independent growth in soft agar. We consequently investigated several parameters correlated with cell growth and cell cycle progression, We found that, in comparison with the parental HeLa cells, HeLa/PML stable clones showed proportionally more cells in G1 phase, fewer cells in S phase and about the same number in G2/M phase, The HeLa/PML clones showed a significantly longer doubling time as a result of a lengthening of the G1 phase, No effect on apoptosis was found in HeLa cells overexpressing PML, This observation indicates that PML suppresses cell growth by increasing cell cycle duration as a result of G1 elongation, To further understand the mechanism of the effect of PML on HeLa cells, expression of cell cycle-related proteins in HeLa/PML and parental HeLa cells was analyzed, We found that Rb phosphorylation was significantly reduced in PML stable clones, Expression of cyclin E, Cdk2 and p27 proteins was also significantly reduced, These studies indicate that PML affects cell cycle progression by mediating expression of several key proteins that normally control cell cycle progression, These results further extend our current understanding of PML function in human cells and its important role in cell cycle regulation.