Targeting USP10 to regulate the DNA damage response in NSCLC

摘要 对抗铂耐药仍然是肺癌治疗中的一项艰巨挑战。激活 细胞DNA损伤反应(DDR)是细胞对顺铂和其他药物敏感性的重要决定因素 化疗药物，通过诱导DNA损伤和检查点来消除肿瘤细胞 激活。我们最近发现组蛋白脱乙酰酶6(HDAC6)可能促进一个关键的DDR的降解 蛋白，检查点蛋白1(Chk1)。G2细胞周期检查点在Chk1-DNA损伤后激活 依赖机制，延长G2期停滞可导致细胞凋亡。我们还发现，一个 去泛素酶(DUB)是一种稳定HDAC6的泛素特异肽酶10(USP10)。我们的小组是 首次发现HDAC6‘S泛素E3连接酶活性，但靶标为HDAC6’S E3连接酶活性 从药理上讲，目前还不可能。因此，我们建议以USP10为靶点来降低蛋白质水平 进而诱导持续高水平的Chk1激活延长的G2检查点停滞 顺铂治疗时，会导致细胞凋亡。因为USP10在癌症中的作用是上下文相关的，我们 搜索TCGA数据库，发现高水平的USP10与较短的总生存期相关 (OS)在来自约1,000名NSCLC患者队列中具有TP53突变的NSCLC子集中，表明USP10 可能是这一亚群中的致癌基因。始终如一地，我们的初步数据表明，USP10的消耗 在TP53中，突变型NSCLC异种移植显著抑制了异种移植瘤的生长，并使其对顺铂敏感。 表明USP10在NSCLC的这一亚组中起致癌作用。来自其他组织以及我们的报告 已有研究表明，HDAC6能稳定NSCLC中的癌基因突变型P53(突变P53)，并使其对顺铂耐药。 根据我们的初步数据和文献，我们假设USP10-HDAC6轴下调 DNA损伤反应蛋白Chk1危及细胞周期检查点，导致顺铂耐药。 因此，以这个轴为靶点将激活检查点，并破坏致癌突变P53的稳定，最终 增加对顺铂的反应性，延长携带TP53突变的非小细胞肺癌患者的总体生存时间。至 检验这一中心假设，我们将首先探索USP10-HDAC6轴赋予 顺铂耐药；然后我们将测试USP10抑制对TP53突变非小细胞肺癌的治疗潜力 评估USP10表达和顺铂疗效之间的相关性，以及两者之间的相关性 突变型非小细胞肺癌标本中USP10‘S底物的表达和顺铂反应。这个 我们提案的结果将确立USP10在非小细胞肺癌突变P53亚群中的致癌作用，并提供 开发临床相关的USP10抑制剂来治疗这一亚型非小细胞肺癌的强有力的理由 患者，从而改善顺铂反应和总体存活率。

ABSTRACT Combating platinum resistance remains a daunting challenge in the treatment of lung cancer. Activation of the cellular DNA damage response (DDR) is an important determinant of cell sensitivity to cisplatin and other chemotherapeutic drugs, which eliminate tumor cells through induction of DNA damage and checkpoint activation. We have recently found that histone deacetylase 6 (HDAC6) may promote degradation of a key DDR protein, checkpoint kinase 1 (Chk1). The G2 cell cycle checkpoint is activated upon DNA damage in a Chk1- dependent mechanism, and prolonged G2 arrest could lead to apoptosis. We have also found that a deubiquitinating enzyme (DUB), ubiquitin-specific peptidase 10 (USP10), could stabilize HDAC6. Our group is the first to discover HDAC6's ubiquitin E3 ligase activity, but targeting HDAC6's E3 ligase activity pharmacologically is not currently possible. Therefore, we propose targeting USP10 to decrease the protein level of HDAC6, which in turn induces persistently high levels of Chk1 to activate a prolonged G2 checkpoint arrest upon cisplatin treatment, leading to apoptosis. Because the role of USP10 in cancer is context-dependent, we searched the TCGA databases and found that a high level of USP10 is associated with shorter overall survival (OS) in a subset of NSCLC with TP53 mutations from a cohort of ~1,000 NSCLC patients, indicating that USP10 may serve as an oncogene in this subset. Consistently, our preliminary data have shown that depletion of USP10 in TP53 mutant NSCLC xenografts drastically inhibits xenografts' growth and sensitizes them to cisplatin, indicating an oncogenic role for USP10 in this subgroup of NSCLC. Reports from other groups as well as ours have shown that HDAC6 stabilizes oncogenic mutant p53 (mutp53) and confers cisplatin resistance in NSCLC. Based on our preliminary data and the literature, we hypothesize that the USP10-HDAC6 axis down-regulates DNA damage response protein Chk1 to compromise the cell cycle checkpoint, leading to cisplatin resistance. Thus, targeting this axis would activate the checkpoint and destabilize oncogenic mutp53, which ultimately increases responsiveness to cisplatin and prolongs overall survival in NSCLC patients with TP53 mutations. To test this central hypothesis, we will first explore the mechanism by which the USP10-HDAC6 axis confers cisplatin resistance; we will then test the therapeutic potential of USP10 inhibition in treating TP53 mutant NSCLC and evaluate a correlation between USP10 expression and cisplatin response, as well as a correlation between expression of USP10's substrates and cisplatin response in a cohort of TP53 mutant NSCLC samples. The outcome of our proposal will establish the oncogenic role of USP10 in the mutp53 subset of NSCLC and provide a strong rationale for the development of clinically relevant USP10 inhibitors to treat this subset of NSCLC patients, thus improving cisplatin responses and overall survival.