Impairment of the DNA repair and growth arrest pathways by p53R2 silencing enhances DNA damage-induced apoptosis in a p53-dependent manner in prostate cancer cells
Impairment of the DNA repair and growth arrest pathways by p53R2 silencing enhances DNA damage-induced apoptosis in a p53-dependent manner in prostate cancer cells
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DOI：
10.1158/1541-7786.mcr-07-2027
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发表时间：
2008-05-01
影响因子：
5.2
通讯作者：
White, Ralph W. deVere
中科院分区：
文献类型：
--
作者：
Devlin, Hong-Lin;Mack, Phillip C.;White, Ralph W. deVere
p53 R2是一种p53诱导的核糖核苷酸还原酶，通过响应DNA损伤提供脱氧核苷酸三磷酸池来促进DNA修复。在这项研究中，我们发现，p53 R2过表达的前列腺肿瘤细胞系相比，永生化的前列腺上皮细胞和DNA损伤后诱导的蛋白质。我们研究了p53 R2沉默对LNCaP细胞（野生型p53）DNA损伤的影响。沉默p53 R2增强了电离辐射和阿霉素治疗的凋亡作用，如通过增加sub-G1含量和减少集落形成所示。这种致敏作用是特异性的DNA损伤剂。彗星试验和γ-H2 AX磷酸化状态显示p53 R2水平降低抑制DNA修复。沉默p53 R2也降低了转录后水平的p21（WAF 1/CIP 1）的水平，表明p53依赖的DNA修复和细胞周期阻滞途径之间的联系。使用稳定表达显性负突变p53的LNCaP亚系，我们发现p53 R2沉默的增敏作用是由p53依赖性凋亡途径介导的。在LNCaP亚系（R273 H、R248 W和G245 S）中，其在诱导p53依赖性细胞凋亡方面具有缺陷，p53 R2沉默不增强DNA损伤诱导的细胞凋亡，而p53 R2沉默在保留诱导p53依赖性细胞凋亡的能力的LNCaP亚系（P151 S）中是有效的。这项研究表明，p53 R2是一个潜在的治疗靶点，可用于增强电离辐射或DNA损伤化疗在前列腺癌患者亚组中的有效性。
p53R2 is a p53-inducible ribonucleotide reductase that contributes to DNA repair by supplying deoxynucleotide triphosphate pools in response to DNA damage. In this study, we found that p53R2 was overexpressed in prostate tumor cell lines compared with immortalized prostatic epithelial cells and that the protein was induced upon DNA damage. We investigated the effects of p53R2 silencing on DNA damage in LNCaP cells (wild-type p53). Silencing p53R2 potentiated the apoptotic effects of ionizing radiation and doxorubicin treatment as shown by increased sub-G, content and decreased colony formation. This sensitizing effect was specific to DNA-damaging agents. Comet assay and gamma-H2AX phosphorylation status showed that the decreased p53R2 levels inhibited DNA repair. Silencing p53R2 also reduced the levels of p21(WAF1/CIP1) at the posttranscriptional level, suggesting links between the p53-dependent DNA repair and cell cycle arrest pathways. Using LNCaP sublines stably expressing dominant-negative mutant p53, we found that the sensitizing effect of p53R2 silencing is mediated by p53-dependent apoptosis pathways. In the LNCaP sublines (R273H, R248W, and G245S) that have defects in inducing p53-dependent apoptosis, p53R2 silencing did not potentiate DNA damage-induced apoptosis, whereas p53R2 silencing was effective in a LNCaP subline (P151S) which retains the ability to induce p53-dependent apoptosis. This study shows that p53R2 is a potential therapeutic target that could be used to enhance the effectiveness of ionizing radiation or DNA-damaging chemotherapy in a subset of patients with prostate cancer.