Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
Oncogene. 2012 Mar 1;31(9):1105-16. doi: 10.1038/onc.2011.309. Epub 2011 Jul 18.
The prognosis of patients with uveal melanoma is poor. Because of the limited efficacy of current treatments, new therapeutic strategies need to be developed. Because p53 mutations are uncommon in uveal melanoma, reactivation of p53 may be used to achieve tumor regression. We investigated the use of combination therapies for intraocular melanoma, based on the p53 activators Nutlin-3 and reactivation of p53 and induction of tumor cell apoptosis (RITA) and the topoisomerase I inhibitor Topotecan. Nutlin-3 treatment induced p53-dependent growth inhibition in human uveal melanoma cell lines. The sensitivity to Nutlin-3 of the investigated cell lines did not correlate with basal Hdm2 or Hdmx levels. Nutlin-3 synergized with RITA and Topotecan to induce apoptosis in uveal melanoma cell lines and short-term cultures. Drug synergy correlated with enhanced induction of p53-Ser46 phosphorylation, which was attenuated by ATM inhibition. Nutlin-3 and Topotecan also significantly delayed tumor growth in vivo in a murine B16F10 model for ocular melanoma. Combination treatment appeared to inhibit tumor growth slightly more efficient than either drug alone. Nutlin-3, RITA and Topotecan lead to comparable p53 activation and growth inhibition under normoxia and hypoxia. Treatment with Nutlin-3 or RITA had no effect on HIF-1α induction by hypoxia, whereas the combination of these two drugs did inhibit hypoxia-induced HIF-1α. Also Topotecan, alone or in combination with Nutlin-3, reduced HIF-1α protein levels, suggesting that a certain level of DNA damage response is required for p53-mediated downregulation of HIF-1α. In conclusion, combination treatments based on small-molecule-induced p53 activation may have clinical potential for uveal melanoma.
葡萄膜黑色素瘤患者的预后较差。由于目前治疗方法的疗效有限，需要开发新的治疗策略。由于葡萄膜黑色素瘤中 p53 突变不常见，因此可以重新激活 p53 以实现肿瘤消退。我们研究了基于 p53 激活剂 Nutlin-3 以及重新激活 p53 和诱导肿瘤细胞凋亡（RITA）和拓扑异构酶 I 抑制剂 Topotecan 的组合疗法在眼内黑色素瘤中的应用。Nutlin-3 处理诱导人葡萄膜黑色素瘤细胞系中 p53 依赖性生长抑制。所研究的细胞系对 Nutlin-3 的敏感性与基础 Hdm2 或 Hdmx 水平无关。Nutlin-3 与 RITA 和 Topotecan 协同诱导葡萄膜黑色素瘤细胞系和短期培养物中的细胞凋亡。药物协同作用与增强的 p53-Ser46 磷酸化诱导相关，而 ATM 抑制可减弱该诱导作用。Nutlin-3 和 Topotecan 也在眼部黑色素瘤的小鼠 B16F10 模型中显著延迟体内肿瘤生长。联合治疗似乎比单独使用任何一种药物更能有效抑制肿瘤生长。在常氧和缺氧条件下，Nutlin-3、RITA 和 Topotecan 均导致可比的 p53 激活和生长抑制。缺氧处理对 HIF-1α 的诱导没有影响，但这两种药物的联合使用可抑制缺氧诱导的 HIF-1α。单独使用 Topotecan 或与 Nutlin-3 联合使用均可降低 HIF-1α 蛋白水平，这表明 p53 介导的 HIF-1α 下调需要一定水平的 DNA 损伤反应。总之，基于小分子诱导的 p53 激活的联合治疗可能对葡萄膜黑色素瘤具有临床潜力。
