Targeting defective necroptosis in colorectal cancer

大多数结直肠癌（CRC）患者对治疗性治疗反应不佳。新试剂 迫切需要改进CRC治疗。诱导程序性细胞死亡或凋亡是一个主要的影响 抗癌治疗的方法。最近的研究表明，程序性细胞死亡还包括坏死性凋亡，这是一种受调节的细胞凋亡。 一种由受体相互作用蛋白1（RIP 1）、RIP 3和混合谱系激酶控制的坏死性死亡形式 结构域样蛋白（MLKL）。越来越多的证据表明，坏死性凋亡，类似于细胞凋亡， 作为对抗肿瘤发展的屏障，在抗癌治疗中起重要作用。下调或 RIP 1、RIP 3和MLKL的突变在肿瘤中经常被发现，并有助于肿瘤的治疗。 阻力然而，很少有人尝试靶向癌细胞中的缺陷性坏死性凋亡， 对坏死性凋亡在抗癌治疗中的调节机制和功能作用认识不足。 我们最近的研究发现了一种新的坏死性凋亡途径，它由p53靶点p53 A和BH 3-only Bcl-2介导。 对多种抗癌药物诱导的细胞死亡必不可少的家族蛋白质。这条路可以利用 通过常用的化疗药物如5-氟尿嘧啶（5-FU）杀死CRC细胞的一个子集。然而，这条路 由于RIP 3表达的频繁缺失，通常不能参与CRC细胞，这促使我们寻找 可以在RIP 3缺陷型CRC细胞中恢复坏死性凋亡的药物。我们的初步数据显示，OSW-1，一种天然的 具有有效抗癌活性的化合物，激活p53和p54 A以诱导CRC细胞中的坏死性凋亡。 令人惊讶的是，OSW-1诱导的和PUMA介导的坏死性凋亡不需要RIP 1或RIP 3，这表明 一种新的作用机制。重要的是，OSW-1的体内抗肿瘤活性需要使用 免疫活性肿瘤模型，表明坏死性凋亡触发的抗肿瘤免疫的关键作用。基于 基于这些发现，我们建议使用OSW-1作为化学探针来检验PUMA介导的 并且RIP 3非依赖性坏死性凋亡通过细胞内在和免疫学效应有效对抗CRC，并且 可用于改善CRC治疗。目的1：OSW-1诱导PUMA介导的细胞凋亡的机制 RIP 3缺陷型CRC细胞中的坏死性凋亡;目的2：PUMA介导的和RIP 3非依赖性的坏死性凋亡在 目的3：诱导PUMA介导的和RIP 3非依赖性的坏死性凋亡， 改善CRC治疗。拟议的研究将描绘一种新的坏死性凋亡途径， OSW-1的抗癌活性。这些研究的完成将为发现新的抗癌药物奠定基础。 靶向CRC细胞中的缺陷性坏死性凋亡以增强肿瘤细胞杀伤和抗肿瘤免疫的药剂 这可能最终导致改善CRC和其他癌症的治疗。

Most patients with colorectal cancer (CRC) do not respond well to therapeutic treatment. New agents for improving CRC therapy are urgently needed. Induction of programmed cell death or apoptosis is a major effect of anticancer therapy. Recent studies indicate that programmed cell death also includes necroptosis, a regulated form of necrotic death controlled by Receptor-Interacting Protein 1 (RIP1), RIP3, and Mixed Lineage Kinase Domain-Like protein (MLKL). Accumulating evidence suggests that necroptosis, similar to apoptosis, functions as a barrier against tumor development and plays an important role in anticancer therapy. Downregulation or mutations of RIP1, RIP3, and MLKL have been frequently found in tumors and contribute to therapeutic resistance. However, few attempts have been made to target defective necroptosis in cancer cells due to insufficient understanding of the regulatory mechanism and functional role of necroptosis in anticancer therapy. Our recent studies identified a new necroptosis pathway mediated by PUMA, a p53 target and a BH3-only Bcl-2 family protein that is essential for cell death induced by a variety of anticancer drugs. This pathway can be utilized by common chemotherapeutics such as 5-fluorouracil (5-FU) to kill a subset of CRC cells. However, this pathway often cannot be engaged in CRC cells due to frequent loss of RIP3 expression, which prompted us to search for agents that can restore necroptosis in RIP3-deficient CRC cells. Our preliminary data show that OSW-1, a natural compound with potent anticancer activity, activates p53 and PUMA to induce necroptosis in CRC cells. Surprisingly, OSW-1-induced and PUMA-mediated necroptosis does not require either RIP1 or RIP3, suggesting a novel mechanism of action. Importantly, the in vivo antitumor activity of OSW-1 needs to be characterized using immuno-competent tumor models, suggesting a critical role of necroptosis-triggered antitumor immunity. Based on these findings, we propose to use OSW-1 as a chemical probe to test the hypothesis that PUMA-mediated and RIP3-independent necroptosis is efficacious against CRC via both cell-intrinsic and immunologic effects, and can be exploited to improve CRC therapy. Aim 1: Mechanism by which OSW-1 induces PUMA-mediated necroptosis in RIP3-deficient CRC cells; Aim 2: Role of PUMA-mediated and RIP3-independent necroptosis in tumor suppression by OSW-1; and Aim 3: Induction of PUMA-mediated and RIP3-independent necroptosis for improving CRC therapy. The proposed studies will delineate a novel necroptosis pathway underlying the potent anticancer activity of OSW-1. Completion of these studies will lay a foundation for identifying new anticancer agents that target defective necroptosis in CRC cells to enhance tumor cell killing and antitumor immune response, which may ultimately lead to improved treatment of CRC and other cancers.