Sarcoma Research Group, Discipline of Medicine, University of Adelaide and Hanson Institute Adelaide, South Australia.
Clin Cancer Res. 2011 Feb 1;17(3):494-504. doi: 10.1158/1078-0432.CCR-10-1587. Epub 2010 Nov 23.
Although mutations in the TP53 gene occur in half of all cancers, approximately 90% of Ewing sarcomas retain a functional wild-type p53. The low frequency of TP53 alterations in Ewing sarcoma makes this tumor type an ideal candidate for p53-targeted therapies. In this study, we have examined the molecular and cellular responses of cultured Ewing sarcoma cell lines following exposure to Nutlin-3a, a recently developed MDM2 antagonist.
The ability of Nutlin-3a to impart apoptosis or cell cycle arrest in a p53-dependent manner was determined in a comprehensive panel of Ewing sarcoma cell lines. The capacity of Nutlin-3a to augment the antitumor activity of MDM4 antagonists and cytotoxic agents currently used in the clinical treatment of Ewing sarcoma was also investigated.
Apoptosis was the primary response of wild-type p53 expressing Ewing sarcoma cell lines. The cytotoxicity of Nultin-3a was also synergistic with the chemotherapeutic agents, vincristine, actinomycin D, doxorubicin, and etoposide in a concentration-dependent manner. Significant MDM4 protein overexpression was observed in Ewing sarcoma cell lines of wild-type p53 status, providing a mechanism through which Ewing sarcomas can develop in the absence of TP53 alterations. This study provides the first evidence of synergism between targeted inhibition of MDM2 and MDM4.
Our findings suggest that p53-dependent apoptosis is the primary cellular response of Ewing sarcoma cell lines following exposure to Nutlin-3a. Furthermore, Nutlin-3a can synergize with the current Ewing sarcoma chemotherapy protocols, suggesting p53 activation as a novel systemic therapeutic approach for this disease.
尽管 TP53 基因突变发生在所有癌症的一半中，但大约 90%的尤因肉瘤保留了功能正常的野生型 p53。尤因肉瘤中 TP53 改变的低频率使得这种肿瘤类型成为 p53 靶向治疗的理想候选者。在这项研究中，我们研究了暴露于 Nutlin-3a 后培养的尤因肉瘤细胞系的分子和细胞反应，Nutlin-3a 是一种新开发的 MDM2 拮抗剂。
在全面的尤因肉瘤细胞系面板中，确定 Nutlin-3a 是否能够以 p53 依赖性方式赋予细胞凋亡或细胞周期停滞。还研究了 Nutlin-3a 增强目前用于尤因肉瘤临床治疗的 MDM4 拮抗剂和细胞毒性剂的抗肿瘤活性的能力。
凋亡是表达野生型 p53 的尤因肉瘤细胞系的主要反应。Nutlin-3a 的细胞毒性也与长春新碱、放线菌素 D、阿霉素和依托泊苷等化疗药物呈浓度依赖性协同作用。在野生型 p53 状态的尤因肉瘤细胞系中观察到明显的 MDM4 蛋白过表达，这提供了一种机制，通过该机制，尤因肉瘤可以在没有 TP53 改变的情况下发展。这项研究首次提供了靶向抑制 MDM2 和 MDM4 之间协同作用的证据。
我们的研究结果表明，暴露于 Nutlin-3a 后，p53 依赖性细胞凋亡是尤因肉瘤细胞系的主要细胞反应。此外，Nutlin-3a 可以与当前的尤因肉瘤化疗方案协同作用，提示 p53 激活作为该疾病的一种新的系统治疗方法。
