UCN-01-mediated G1 arrest in normal but not tumor breast cells is pRb-dependent and p53-independent
UCN-01-mediated G1 arrest in normal but not tumor breast cells is pRb-dependent and p53-independent
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DOI：
10.1038/sj.onc.1202948
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发表时间：
1999-10-07
期刊：
影响因子：
8
通讯作者：
Keyomarsi, K
中科院分区：
文献类型：
--
作者：
Chen, XM;Lowe, M;Keyomarsi, K
在这项研究中，我们研究了UCN-01对几种正常和肿瘤来源的人乳腺上皮细胞的生长抑制作用。我们发现，虽然正常乳腺上皮细胞对UCN-01非常敏感，IC50为10 nM，但在较低的UCN-01浓度(即0-80 nM)下，肿瘤细胞对任何可测量的IC几乎没有抑制作用。UCN-01处理的正常细胞滞留在G1期，大多数关键的细胞周期调节因子的表达减少，导致CDK2活性的抑制，这是由于p27与CDK2结合的增加，另一方面，肿瘤细胞的任何细胞周期分布或细胞周期调节因子的表达没有变化。对E6和E7来源的正常细胞株的检测表明，在UCN-01介导的G1期停滞中，pRb而不是P53功能是必不可少的。最后，用高剂量的UCN-01(即300 nM)处理正常细胞和肿瘤细胞，揭示了一个功能正常的G1检查点在调节生长停滞中的必要作用。正常细胞有一个功能正常的G1检查点，即使在很高浓度的UCN-01下也总是停滞在G1期，而肿瘤细胞则有一个缺陷的G1检查点，只有在高浓度UCN-01的作用下才会停滞在S期，因此UCN-01对细胞周期的影响与UCN-01的结构类似物星状孢子素截然不同，后者将正常细胞同时滞留在G1和G2期，而肿瘤细胞仅停滞在细胞周期的G2期。我们的结果表明，与肿瘤细胞相比，正常细胞对UCN-01的不同敏感性取决于一个功能上的pRB和一个受调控的G1检查点。
In this study we investigated the growth inhibitory effects of UCN-01 in several normal and tumor-derived human breast epithelial cells. We found that while normal mammary epithelial cells were very sensitive to UCN-01 with an IC50 of 10 nM, tumor cells displayed little to no inhibition of growth with any measurable IC,, at low UCN-01 concentrations (i.e. 0-80 nM). The UCN-01 treated normal cells arrested in G1 phase and displayed decreased expression of most key cell cycle regulators examined, resulting in inhibition of CDK2 activity due to increased binding of p27 to CDK2, Tumor cells on the other hand displayed no change in any cell cycle distribution or expression of cell cycle regulators. Examination of E6- and E7-derived strains of normal cells revealed that pRb and not p53 function is essential for UCN-01-mediated G1 arrest. Lastly, treatment of normal and tumor cells with high doses of UCN-01 (i.e. 300 nM) revealed a necessary role for a functional G1 checkpoint in mediating growth arrest. Normal cells, which have a functional G1 checkpoint, always arrest in G1 even at very high concentrations of UCN-01, Tumor cells on the other hand have a defective G1 checkpoint and only arrest in S phase with high concentrations of UCN-01, The effect of UCN-01 on the cell cycle is thus quite different from staurosporine, a structural analogue of UCN-01, which arrests normal cells in both G1 and G2, while tumor cells arrest only in the G2 phase of the cell cycle. Our results show the different sensitivity to UCN-01 of normal compared to tumor cells is dependent on a functional pRb and a regulated G1 checkpoint.