Targeting sfRon-S6K1 signaling and mitotic kinesin Eg5 in ovarian cancer: a novel synergistic treatment strategy

项目总结 卵巢癌仍然是全国所有妇科恶性肿瘤中最致命的。不幸的是，目前的卵巢 在超过85%的患者中，癌症治疗会导致化疗耐药和肿瘤迅速复发。这个 这里概述的项目为治疗干预提供了一个亟需的新机会。我们以前的 发表和正在进行的工作揭示了短形RON(SfRon)，全长RON的截断异构体 (FlRon)受体酪氨酸激酶，可推动卵巢癌的发生和发展。在此之前，我们展示了 SfRon优先通过PI3K途径发出信号，而关键的sfRon效应器S6K1对 促进肿瘤生长的作用。我们的初步发现揭示了sfRon-S6K1信号在诱导 细胞周期的有丝分裂进程。这些数据导致了药物筛选研究表明，sfRon的抑制 或S6K1(分别由BMS777608或AD80产生)使卵巢癌细胞特别容易有丝分裂 激动素EG5抑制剂Ispinesib。我们假设一种协同联合疗法同时 阻断sfRon或S6K1和有丝分裂运动蛋白可能被证明是一种有效的精确治疗晚期 卵巢癌。为了验证这一假设，我们提出了两个具体目标：(1)我们将通过以下方式确定机制 哪个sfRon促进了细胞周期的有丝分裂进程。我们将测试sfRon和/或S6K1是否耗尽 遗传和药物途径的信号影响细胞增殖、细胞周期分布和有丝分裂 关键的有丝分裂调节因子如Aurora B和/或Plk1的进展或正常功能。此外，我们假设 S6K1的缺失有助于卵巢癌细胞有丝分裂的滑移，从而使其对Ispinesib敏感。 为了测试这一点，我们将比较sfRon、S6K1和有丝分裂运动蛋白抑制剂作为单一疗法或在 结合并决定药物诱导的细胞命运，包括有丝分裂停滞、有丝分裂滑移和细胞死亡。 (2)我们将确定协同联合治疗是否阻断sfRon-S6K1信号和有丝分裂运动蛋白导联 使用临床相关的患者来源的异种移植物(PDX)来实现有效和持久的抗肿瘤效果。我们会 使用化疗单纯的PDX并确定sfRon协同通路的抑制是否会导致更多 持续的抗肿瘤反应优于标准化疗。在疾病复发的情况下，我们将使用我们的 化疗耐药的PDX模型，并研究联合治疗是否是一种有效的治疗方案 复发性卵巢肿瘤目前的治疗选择非常有限。这项提议将扩大我们的 了解sfRon和/或S6K1调节细胞周期有丝分裂进程的机制。它 也将为为什么sfRon-S6K1抑制使卵巢癌细胞特别脆弱提供新的见解 到有丝分裂激动素抑制剂。从长远来看，这个项目可能会提供一种新的精确治疗方法，旨在实现 即使对化疗耐药的卵巢肿瘤也有临床意义和持续的抗肿瘤反应。

PROJECT SUMMARY Ovarian cancer remains the deadliest of all gynecologic malignancies nationwide. Unfortunately, current ovarian cancer treatment leads to chemoresistance and a rapid tumor recurrence in more than 85% of patients. The project outlined here represents a much needed new opportunity for therapeutic intervention. Our previous published and ongoing work, has revealed that short-form Ron (sfRon), a truncated isoform of the full-length Ron (flRon) receptor tyrosine kinase, can drive ovarian cancer development and progression. Previously, we showed that sfRon preferentially signals through the PI3K pathway, and that the key sfRon effector S6K1 is crucial for tumor promoting effects. Our preliminary findings revealed a novel function of sfRon-S6K1 signaling in inducing mitotic progression of the cell cycle. These data led to drug screening studies showing that the inhibition of sfRon or S6K1 (by BMS777608 or AD80, respectively) renders ovarian cancer cells particularly vulnerable to mitotic kinesin Eg5 inhibitor Ispinesib. We hypothesize that a synergistic combination therapy simultaneously blocking sfRon or S6K1 and mitotic kinesins could prove an effective precision treatment for advanced ovarian cancer. To test this hypothesis, we propose two specific aims: (1) We will determine the mechanism by which sfRon promotes the mitotic progression of cell cycle. We will test if depletion of sfRon and/or S6K1 signaling by genetic and pharmacological approaches affects cell proliferation, cell cycle distribution, and mitotic progression or proper function of critical mitotic regulators such as Aurora B and/or Plk1. Further, we hypothesize that the depletion of S6K1 contributes to mitotic slippage of ovarian cancer cells sensitizing them to Ispinesib. To test that, we will compare the effects of sfRon, S6K1, and mitotic kinesin inhibitors as monotherapy or in combination and determine the drug-induced cell fate including mitotic arrest, mitotic slippage, and cell death. (2) We will determine if synergistic combination therapy blocking sfRon-S6K1 signaling and mitotic kinesins leads to a potent and sustained antitumor efficacy using clinically relevant patient-derived xenografts (PDXs). We will use chemotherapy naïve PDXs and determine if the inhibition of sfRon synergistic pathways results in a more sustained anti-tumor response than standard chemotherapy. In recurrent disease setting, we will use our chemoresistant PDX models and investigate if the combination therapy is an effective treatment regimen for recurrent ovarian tumors that currently have very limited treatment options. This proposal will expand our understanding of the mechanism by which sfRon and/or S6K1 regulates the mitotic progression of cell cycle. It will also provide new insight into why sfRon-S6K1 inhibition renders ovarian cancer cells particularly vulnerable to mitotic kinesin inhibitors. In the long-term, this project could offer a new precision therapy designed to achieve a clinically meaningful and sustained anti-tumor response to even chemoresistant ovarian tumors.