Inhibition of Translesion Synthesis as a Novel Strategy for Cancer Chemotherapy

铂和烷化剂是许多形式的人类癌症的标准一线化疗药物。 通常情况下，患者最初对这些药物的反应良好；然而，许多患者可能会产生抵抗力并经历 复发，这需要改变药物治疗方案来对抗复发的癌症。此外，高剂量的 这些抗癌作用所需的药物可能会在整个人体的其他组织中产生毒副作用 机构，限制了一线药物的短期和长期效力。跨病变合成(TLS)是一种 增殖细胞在复制过程中耐受DNA损伤而不修复的重要机制 造成的损害。在癌症治疗的背景下，TLS通过允许复制 铂和烷基DNA加合物，这导致存活的肿瘤细胞增加突变和获得 对第一线特工的抵抗。TLS的阻断使癌症对基因毒性物质敏感并减少 肿瘤中的突变，提示与TLS抑制剂的联合治疗可以提高疗效 治疗一线药物，防止化疗耐药性。因此，TLS的小分子抑制剂正在成为一种 用于癌症化疗一线的新型辅助剂。 介导TLS的多蛋白复合体的组装是由DNA聚合酶Rev1控制的，它 作为中央支架，通过多个蛋白质-蛋白质相互作用(PPI)维持复合体。 TLS的几个基本步骤是通过Rev1的C-末端结构域(Rev1-CT)之间的PPI介导的 和来自多个TLS DNA聚合酶的Rev-1相互作用区(RIR)。之前的研究已经证明 在体外和体内抑制Rev1的表达使癌细胞对遗传毒性化疗药物敏感 并降低肿瘤的获得性耐药性。我们实验室最近的合作研究使我们发现 首次报道的小分子通过直接结合破坏Rev1-CT/RIR PPI来抑制TLS RIR界面上的Rev1-CT。这些化合物增加了顺铂的敏感性，减少了顺铂诱导的 人类癌细胞的诱变作用。我们的结果表明，Rev1-CT/RIR界面是一种可药物的PPI 他们证实，它的破坏增强了一线基因毒剂的抗癌效果。在这个范围内 背景，我们研究的总体目标是应用一种综合的跨学科方法来开发我们的 引导TLS抑制剂作为一类新的抗癌治疗药物。为达致这个目标，我们会进行 具体目标如下：(1)改进的Rev1-CT/RIR小分子抑制剂的合成与表征 PPI，(2)用体外生化和结构方法评价Rev1-CT/RIR抑制剂，(3)探针细胞 Rev1-CT/RIR抑制剂的抗TLS和抗癌活性，以及(4)进行最佳的体内研究 化合物。我们预计，这些研究将发现具有增强的抗TLS活性的小分子，并 改善了类药物的性质，成为有前景的癌症化疗药物。

Platinating and alkylating agents are standard first-line chemotherapy for many forms of human cancer. Typically, patients initially respond well to these agents; however, many can develop resistance and experience relapse, which requires a change in drug regimen to combat the relapsed cancer. In addition, the high doses of these drugs required for their anti-cancer effects can result in toxic side effects in other tissues throughout the body, limiting both the short- and long-term effectiveness of first-line agents. Translesion synthesis (TLS) is an important mechanism through which proliferating cells tolerate DNA damage during replication without repairing the damage. In the context of cancer treatment, TLS promotes survival of tumor cells by allowing replication over platinum and alkyl DNA adducts, which results in increased mutations in surviving tumor cells and acquisition of resistance to the first-line agent. Disruption of TLS sensitizes cancers to genotoxic agents and reduces mutagenesis in tumors, suggesting that combination therapy with an inhibitor of TLS could enhance the efficacy of first-line agents and prevent chemoresistance. As such, small molecule inhibitors of TLS are emerging as a new class of adjuvant agents for first-line cancer chemotherapy. Assembly of the multi-protein complex that mediates TLS is controlled by the DNA polymerase Rev1, which serves as the central scaffold to maintain the complex through multiple protein-protein interactions (PPIs). Several essential steps of TLS are mediated through PPIs between the C-terminal domain of Rev1 (Rev1-CT) and Rev-1 interacting regions (RIR) from multiple TLS DNA polymerases. Previous studies have demonstrated that suppression of Rev1 expression in vitro and in vivo sensitizes cancer cells to genotoxic chemotherapeutics and decreases acquired drug resistance in tumors. Recent collaborative research in our labs has led us to identify the first reported small molecules that inhibit TLS by disrupting the Rev1-CT/RIR PPI through direct binding to Rev1-CT at the RIR interface. These compounds increase cisplatin sensitivity and reduce cisplatin-induced mutagenesis in human cancer cells. Our results demonstrate that the Rev1-CT/RIR interface is a druggable PPI and they validate that its disruption enhances the anti-cancer effects of first-line genotoxic agents. Within this context, the overall goal of our studies is to apply a comprehensive interdisciplinary approach to develop our lead TLS inhibitors as a new class of anti-cancer therapeutics. In pursuit of this goal, we will undertake the following specific aims: (1) synthesize and characterize improved small molecule inhibitors of the Rev1-CT/RIR PPI, (2) evaluate Rev1-CT/RIR inhibitors using in vitro biochemical and structural approaches, (3) probe cellular anti-TLS and anti-cancer activities of the Rev1-CT/RIR inhibitors, and (4) perform in vivo studies on optimal compounds. We anticipate that these studies will identify small molecules with enhanced anti-TLS activity and improved drug-like properties as promising cancer chemotherapeutics.