Greatwall in replication stress/DNA damage responses and oral cancer resistance

口腔癌，包括口腔癌和喉癌，是第六大常见癌症 全世界。在美国，每年大约有5万例新的口腔癌病例被诊断出来。首先- 口腔癌的一线治疗通常包括手术和放射治疗，外加化疗以减少 转移的可能性，消除手术后残留的肿瘤细胞，提高放射治疗的疗效 (化疗)，以及确认有远处转移的患者。辐射与口腔癌 化疗药物在很大程度上是通过破坏DNA复制而导致DNA损伤而产生细胞毒性的。 不幸的是，口腔癌的预后，特别是HPV(-)病例，仍然相对较差，需要一个 更好地了解细胞如何应对复制压力和DNA损伤，并相应地发展 更有效的治疗选择和组合，以克服耐药性。在目前的项目中，我们 描述长城(Gwl)激酶在复制应激和DNA损伤反应中的新作用。GWL 在HPV(-)口腔癌中经常上调，与肿瘤进展、肿瘤复发、 病人存活率也很低。GWL促进口腔癌细胞对诱导性药物的恢复和耐药性 复制应激和DNA损伤。GWL耗竭或抑制致敏口腔癌的药物反应 细胞和小鼠肿瘤模型。在这些发现的基础上，我们假设Gwl介导细胞 对复制压力和DNA损伤的反应，因此是口腔癌症治疗的有效靶点。我们 将揭示Gwl在复制应激中的功能和调节的详细机制 DNA损伤反应；我们还将为GWL的发展建立关键的原则证明 癌症治疗中的靶向。在目标1中，我们将描述Gwl是如何通过其 与复制蛋白A(RPA)相互作用，调节磷酸酶介导的对复制应激的反应。 这项研究将为癌症的进展和治疗提供新的线索，因为复制压力是一个标志 抗复制药物通常用于癌症治疗。在《目标2》中，我们将展示一个新的 复制应激和DNA损伤后导致GwL稳定和积累的机制， 潜在地作为启动细胞恢复和赋予肿瘤抗药性的关键事件。GWL的升级是 直接由DNA损伤信号介导，暗示了启动细胞的自我参与的“计时器”机制 痊愈和治疗耐药。最后，在我们机械调查的指导下，我们将在目标3中进行探索 Gwl的治疗靶点，使用干扰Gwl激酶的独特小分子抑制剂 激活或其与RPA的交互。患者来源的口腔肿瘤异种移植和同种异体口腔原位移植 肿瘤模型将被用来综合评估GWL抑制的治疗潜力。一起， 这个项目将使我们更深入地了解细胞对复制压力和DNA的反应。 损害，并表征了一个新的药物靶点，以改善口腔癌症的治疗。

Oral cancer, including cancers of the mouth and the back of the throat, is the sixth most common cancer worldwide. In the United States, approximately 50,000 new oral cancer cases are diagnosed each year. First- line treatments for oral cancer typically include surgery and radiation, with chemotherapy added to decrease the possibility of metastasis, to eliminate residual tumor cells after surgery, to enhance the efficacy of radiation (chemoradiation), and for patients with confirmed distant metastasis. Radiation and oral cancer chemotherapeutics confer cytotoxicity largely by disrupting DNA replication to induce DNA damage. Unfortunately, the prognosis of oral cancer, particularly HPV(-) cases, remains relatively poor, calling for a better understanding of how cells respond to replication stress and DNA damage, and accordingly, developing more effective treatment options and combinations to overcome drug resistance. In the current project, we characterize a new role of Greatwall (Gwl) kinase in the replication stress and DNA damage responses. Gwl was frequently upregulated in HPV(-) oral cancer, in correlation with cancer progression, tumor recurrence, and poor patient survival. Gwl promoted the recovery and resistance of oral cancer cells to drugs that induce replication stress and DNA damage. Gwl depletion or inhibition sensitized the drug responses in oral cancer cells and mouse tumor models. Building on these findings, we hypothesize that Gwl mediates the cellular responses to replication stress and DNA damage, and is therefore a potent target for oral cancer therapy. We will uncover detailed mechanisms underlying the function and regulation of Gwl in the replication stress and DNA damage responses; we will also establish the crucial proof-of-principle for the development of Gwl targeting in cancer treatment. In Aim 1, we will delineate how Gwl is recruited to stalled replication forks via its interaction with replication protein A (RPA) to regulate a phosphatase-mediated response to replication stress. This study will shed new light on cancer progression and treatment, given that replication stress is a hallmark of cancer, and that anti-replication drugs are commonly used in cancer therapy. In Aim 2, we will reveal a new mechanism that leads to Gwl stabilization and accumulation after replication stress and DNA damage, potentially as a key event that initiates cell recovery and confers tumor resistance. Upregulation of Gwl is mediated directly by DNA damage signaling, suggesting a self-engaged “timer” mechanism that initiates cell recovery and treatment resistance. Finally, guided by our mechanistic investigations, we will explore in Aim 3 therapeutic targeting of Gwl, using unique small molecule inhibitors which interfere with either Gwl kinase activation or its interaction with RPA. Both patient-derived oral tumor xenograft and orthotopic syngeneic oral tumor models will be utilized to comprehensively evaluate the therapeutic potential of Gwl inhibition. Together, this project will lead to a deeper understanding of the cellular responses to replication stress and DNA damage, and characterize a new drug target to improve oral cancer therapy.