Targeting cellular double-stranded RNA homeostasis in breast cancer

摘要/摘要 免疫不活跃的(感冒)肿瘤是许多癌症有效免疫治疗的主要挑战， 包括乳腺癌。越来越多的证据表明，人类细胞表达各种类型的 内源双链RNA(DsRNAs)与病原体入侵无关，并异常积累 细胞dsRNA可以在细胞内触发有害的先天免疫反应。在癌症中，这些内源性的 免疫原性dsRNAs被认为是一种免疫诱导来源，以提高肿瘤对 免疫疗法。然而，为了将细胞dsRNAs用于癌症的免疫治疗，我们需要了解 正常和恶性肿瘤细胞dsRNA动态平衡的分子机制及寻找特异性 调节免疫原性dsRNA的方法。我们发现抑制DEAD-box RNA解旋酶3X(DDX3X) 导致内源性dsRNAs在乳腺癌细胞胞浆内积聚。DDX3X的损失 增加I型干扰素的产生，STAT1的激活，干扰素刺激基因(ISGs)的表达，以及 MHC-I类分子的表达与乳腺癌细胞的抗原提呈增强有关。DDX3X抑制 抑制肿瘤生长，增加肿瘤组织中CD8T细胞和DC的活性。 同基因乳腺癌小鼠模型。我们假设抑制DDX3X会导致异常积聚 触发I型干扰素反应并诱导先天免疫反应的内源性dsRNAs 肿瘤。拟议的研究将集中在了解DDX3X 调节细胞dsrna的动态平衡，在细胞dsrna和乳房中的免疫信号之间提供联系。 癌症细胞，并建立乳腺癌的新免疫治疗策略。在目标1中，我们将 确定DDX3X调节细胞dsRNAs的分子机制；在目标2，我们将研究 DDX3X-dsRNAs-I型干扰素轴在癌细胞和人类肿瘤中的作用；在目标3中，我们将探讨 抑制DDX3X以增强抗肿瘤免疫，并使肿瘤对免疫治疗敏感。我们的研究将揭示 内源性dsRNAs在癌症中的一种新的调控机制，并可能导致新的治疗靶向 用于新的联合免疫疗法的DDX3X。

Summary/Abstract The immunologically inactive (cold) tumor is a major challenge for effective immunotherapies in many cancers, including breast cancer. Increasing evidence has demonstrated that human cells express various types of endogenous double-stranded RNAs (dsRNAs) regardless of pathogen invasion, and aberrant accumulation of cellular dsRNAs could trigger a detrimental innate immune response in cells. In cancer, these endogenous immunogenic dsRNAs are suggested as a source of immune induction to increase tumor response to immunotherapy. However, to exploit the cellular dsRNAs in immunotherapy for cancer, we need to understand the molecular mechanism for cellular dsRNA homeostasis in normal and malignant cells and find the specific ways to modulate immunogenic dsRNAs. We found that inhibition of DEAD-box RNA helicase 3X (DDX3X) resulted in the cytoplasmic accumulation of endogenous dsRNAs in the breast cancer cells. Loss of DDX3X increased the type I interferon production, STAT1 activation, IFN-stimulated genes (ISGs) expression, and the MHC class I expression with the enhanced antigen presentation on the breast cancer cells. DDX3X inhibition also suppressed the tumor growth and increased the tumor infiltration of active CD8+ T cells and DC in the syngeneic breast cancer mouse model. We hypothesize that inhibiting DDX3X leads to aberrant accumulation of endogenous dsRNAs, which triggers type I IFN responses and induces an innate immune response in the tumor. The proposed studies will be focused on understanding the molecular mechanism by which DDX3X regulates cellular dsRNA homeostasis, providing a link between cellular dsRNAs and immune signals in breast cancer cells, and establishing novel immunotherapeutic strategies for breast cancer. In Aim 1, we will determine the molecular mechanism by which DDX3X regulates cellular dsRNAs; In Aim 2, we will study DDX3X-dsRNAs-Type I IFN axis in cancer cells and human tumor; In Aim 3, we will explore the effect of inhibiting DDX3X to increase anti-tumor immunity and sensitize tumors to immunotherapy. Our study will reveal a novel regulatory mechanism of endogenous dsRNAs in cancer and may lead to novel therapeutics targeting DDX3X for new combinatory immunotherapy.