Loss of p53 function at late stages of tumorigenesis confers ARF-dependent vulnerability to p53 reactivation therapy
Loss of p53 function at late stages of tumorigenesis confers ARF-dependent vulnerability to p53 reactivation therapy
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DOI：
10.1073/pnas.1910255116
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发表时间：
2019-10-29
影响因子：
11.1
通讯作者：
Stiewe, Thorsten
中科院分区：
文献类型：
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作者：
Klimovich, Boris;Mutlu, Samet;Stiewe, Thorsten
癌症的发展是由激活的癌基因和肿瘤抑制因子的丢失驱动的。虽然癌基因抑制剂已进入常规临床实践，但肿瘤抑制剂再激活治疗仍有待建立。对于最常失活的肿瘤抑制因子p53，遗传小鼠模型已经证明了p53再激活后p53-null肿瘤的消退。虽然这在由p53缺失作为起始病变驱动的肿瘤模型中显示，但许多人类肿瘤最初在野生型p53存在下发展，在p53途径中获得畸变以绕过p53介导的肿瘤抑制，并且仅在转移进展或治疗期间的后期阶段才抑制p53本身。为了探索p53再激活在这种情况下的功效，我们使用可逆可转换的p53（p53ER（TAM））小鼠等位基因在活性p53存在的情况下产生E mu-Myc驱动的淋巴瘤，并且在完全淋巴瘤建立后，关闭p53以模拟晚期p53失活。尽管这些淋巴瘤是在活性p53存在的情况下进化的，但后来的缺失和随后的p53再活化令人惊讶地激活了p53靶基因，引发了大规模的细胞凋亡、肿瘤消退和大多数动物的长期治愈。从机制上讲，再激活反应依赖于Cdkn2a/p19Arf，这是通常沉默的p53野生型淋巴瘤，但成为后期p53失活后重新表达。同样，当CDKN2A/p14 ARF功能恢复或用Mdm 2抑制剂模拟时，具有CRISPR工程化可转换p53 ER（TAM）等位基因的人p53野生型肿瘤细胞对p53再活化有反应。总之，这些实验提供了概念的遗传学证据，即肿瘤可以以ARF依赖性方式对p53再激活作出反应，即使在肿瘤演变的后期发生了p53失活。
Cancer development is driven by activated oncogenes and loss of tumor suppressors. While oncogene inhibitors have entered routine clinical practice, tumor suppressor reactivation therapy remains to be established. For the most frequently inactivated tumor suppressor p53, genetic mouse models have demonstrated regression of p53-null tumors upon p53 reactivation. While this was shown in tumor models driven by p53 loss as the initiating lesion, many human tumors initially develop in the presence of wild-type p53, acquire aberrations in the p53 pathway to bypass p53-mediated tumor suppression, and inactivate p53 itself only at later stages during metastatic progression or therapy. To explore the efficacy of p53 reactivation in this scenario, we used a reversibly switchable p53 (p53ER(TAM)) mouse allele to generate E mu-Myc-driven lymphomas in the presence of active p53 and, after full lymphoma establishment, switched off p53 to model late-stage p53 inactivation. Although these lymphomas had evolved in the presence of active p53, later loss and subsequent p53 reactivation surprisingly activated p53 target genes triggering massive apoptosis, tumor regression, and long-term cure of the majority of animals. Mechanistically, the reactivation response was dependent on Cdkn2a/p19Arf, which is commonly silenced in p53 wild-type lymphomas, but became reexpressed upon late-stage p53 inactivation. Likewise, human p53 wild-type tumor cells with CRISPR-engineered switchable p53ER(TAM) alleles responded to p53 reactivation when CDKN2A/p14ARF function was restored or mimicked with Mdm2 inhibitors. Together, these experiments provide genetic proof of concept that tumors can respond, in an ARF-dependent manner, to p53 reactivation even if p53 inactivation has occurred late during tumor evolution.