Targeting cellular double-stranded RNA homeostasis in breast cancer

总结/摘要 免疫失活（冷）肿瘤是许多癌症有效免疫疗法的主要挑战， 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 内源性双链RNA（dsRNA），无论病原体的入侵，和异常积累， 细胞内的双链RNA可能引发细胞内有害的先天免疫反应。在癌症中，这些内源性 免疫原性dsRNA被认为是免疫诱导的来源， 免疫疗法然而，为了在癌症免疫治疗中利用细胞dsRNA，我们需要了解 正常细胞和恶性细胞中细胞dsRNA稳态的分子机制，并找到特异性 调节免疫原性dsRNA的方法。我们发现，抑制DEAD-box RNA解旋酶3X（DDX 3X） 导致内源性dsRNA在乳腺癌细胞中的细胞质积累。DDX 3X丢失 增加I型干扰素的产生、STAT 1的激活、IFN刺激基因（ISGs）的表达， 乳腺癌细胞上MHC I类表达与增强的抗原呈递。DDX 3X抑制 也抑制肿瘤生长，并增加肿瘤中活性CD 8 + T细胞和DC的浸润。 同基因乳腺癌小鼠模型。我们假设抑制DDX 3X导致异常蓄积 内源性双链RNA，其触发I型IFN应答并诱导先天性免疫应答。 肿瘤拟议的研究将集中在了解DDX 3X的分子机制， 调节细胞dsRNA稳态，在乳腺癌中提供细胞dsRNA和免疫信号之间的联系 癌细胞，并建立乳腺癌的新免疫策略。在目标1中，我们 确定DDX 3X调节细胞dsRNA的分子机制;在目标2中，我们将研究 DDX 3X-dsRNA-I型IFN轴在癌细胞和人肿瘤中的作用;在目的3中，我们将探索DDX 3X-dsRNA-I型IFN轴在癌细胞和人肿瘤中的作用。 抑制DDX 3X以增加抗肿瘤免疫并使肿瘤对免疫疗法敏感。我们的研究将揭示 内源性dsRNA在癌症中的一种新的调节机制，并可能导致新的治疗靶向 DDX 3X用于新的联合免疫疗法。

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.