RNA silencing of checkpoint regulators sensitizes p53-defective prostate cancer cells to chemotherapy while sparing normal cells
RNA silencing of checkpoint regulators sensitizes p53-defective prostate cancer cells to chemotherapy while sparing normal cells
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DOI：
10.1158/0008-5472.can-04-2502
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发表时间：
2005-04-01
期刊：
影响因子：
11.2
通讯作者：
Ferbeyre, G
中科院分区：
文献类型：
--
作者：
Mukhopadhyay, UK;Senderowicz, AM;Ferbeyre, G
P53在前列腺癌患者中经常发生突变，尤其是在晚期患者中。因此，选择性清除p53突变细胞可能会对前列腺癌的治疗产生影响。由于p53在细胞周期检查点中起着重要作用，因此预计检查点通路的调节应该使p53缺陷细胞对化疗敏感，同时保留正常细胞。为了验证这一想法，我们通过RNA干扰在前列腺癌细胞系和正常人类二倍体成纤维细胞IMR90中敲除了失调毛细血管扩张突变（ATM）基因。在p53缺陷的PC3前列腺癌细胞中，ATM敲低加速了其细胞周期转变，增加了E2F活性和增殖细胞核抗原表达，并破坏了通常由DNA损伤诱导的细胞周期检查点。因此，PC3细胞对dna损伤药物阿霉素的杀伤作用敏感。将ATM敲除与Chk1抑制剂UCN-01结合，进一步增加了这些细胞对阿霉素的敏感性。相反，同样的策略没有使IMR90或LNCaP前列腺癌细胞增敏，这两种细胞都有正常的p53。然而，当p53和ATM功能均被抑制时，IMR90和LNCaP细胞对阿霉素或阿霉素加UCN-01更加敏感。此外，G(2)检查点调节因子ATR和Chk1的敲低也使PC3细胞对阿霉素敏感，并增加E2F靶基因PCNA的表达。总之，我们的数据支持通过结合DNA损伤和检查点抑制剂选择性消除p53突变细胞的概念，并提出了这种治疗如何选择性杀死肿瘤细胞的新的机制见解。
p53 is frequently mutated in patients with prostate cancer, especially in those with advanced disease. Therefore, the selective elimination of p53 mutant cells will likely have an impact in the treatment of prostate cancer. Because p53 has important roles in cell cycle checkpoints, it has been anticipated that modulation of checkpoint pathways should sensitize p53-defective cells to chemotherapy while sparing normal cells. To test this idea, we knocked down ataxia telangiectasia mutated (ATM) gene by RNA interference in prostate cancer cell lines and in normal human diploid fibroblasts IMR90. ATM knockdown in p53-defective PC3 prostate cancer cells accelerated their cell cycle transition, increased both E2F activity and proliferating cell nuclear antigen expression, and compromised cell cycle checkpoints, which are normally induced by DNA damage. Consequently, PC3 cells were sensitized to the killing effects of the DNA-damaging drug doxorubicin. Combining ATM knockdown with the Chk1 inhibitor UCN-01 further increased doxorubicin sensitivity in these cells. In contrast, the same strategy did not sensitize either IMR90 or LNCaP prostate cancer cells, both of which have normal p53. However, IMR90 and LNCaP cells became more sensitive to doxorubicin or doxorubicin plus UCN-01 when both p53 and ATM functions were suppressed. In addition, knockdown of the G(2) checkpoint regulators ATR and Chk1 also sensitized PC3 cells to doxorubicin and increased the expression of the E2F target gene PCNA. Together, our data support the concept of selective elimination of p53 mutant cells by combining DNA damage with checkpoint inhibitors and suggest a novel mechanistic insight into how such treatment may selectively kill tumor cells.