Effects of Polymeric Mucin Expression on Lung Carcinogenesis

肺癌是癌症相关死亡的主要原因，退伍军人的风险高得不成比例。 肺腺癌(LUAD)占肺癌病例的一半，但缺乏有效的治疗方法。 部分原因是对LUAD生物学的不完全理解。LUAD肿瘤起源于呼吸道分泌物 上皮细胞和粘蛋白的表达普遍存在，并与LUAD的侵袭性有关。然而， 粘蛋白影响LUAD发病的机制目前知之甚少。最重要的概念是 这一观点认为LUAD的异常上皮生长是由两种聚合物粘蛋白--MUC5AC和MUC5AC促进的。 MUC5B。尽管MUC5AC和MUC5B在健康人群中是呼吸道防御所必需的，但它们在LUAD中的错误表达 与侵袭性、复发率和死亡率相关，特别是在具有激活的 KRAS--LUAD最常见的致癌驱动因素。我们验证了MUC5AC在氨基甲酸乙酯和 激活Kras基因表达的LUAD小鼠模型。在缺乏Muc5ac的动物中(‘MUC in Human，’MUC‘in 小鼠)，肿瘤数目和大小减少约50%。MUC5B自身的相对促瘤作用 或与Muc5ac的关系尚不清楚。我们试图在这里弥合这一重大差距。我们还试图确定 聚合物粘蛋白介导的肿瘤促进的分子机制。我们和其他人的研究表明 确定了许多刺激LUAD的信号，包括粘液性LUAD亚型。上行信令 途径汇聚在粘蛋白及其生物合成机制上。单个MUC5AC和MUC5B分子 是非常巨大的。它们是多聚体，通过添加糖使它们变得更大 它们的中心糖基化结构域。因此，蛋白质稳态(蛋白质稳态)在 聚合物粘蛋白的生物合成。粘蛋白的翻译、折叠和二聚化发生在内质网中。 (呃)并涉及数百个二硫键的形成。为了处理这些需求，哺乳动物表达了一种 内质网应激感受器肌醇需要酶-1(IRE-1，又称内质网对内质网)的粘液细胞特异性亚型 核信号蛋白，或ERN)。ERN1普遍表达，对内质网应激触发至关重要 凋亡，但称为ERN2的亚型仅限于粘液细胞，在那里它是维持粘蛋白所必需的 尽管存在高水平的内质网压力，但仍有合成。这种适配是通过将ERN2直接绑定到 ERN1和随后对ERN1介导的促凋亡信号的抑制。虽然对主机有利 在健康方面，抑制细胞凋亡可能对LUAD有害。我们假设MUC5AC和 MUC5B通过ER2依赖抑制内质网应激诱导的LUAD上皮细胞生长 细胞凋亡。提出了以下三个具体目标：1)检验MUC5AC/MUC5AC和MUC5AC的假设 MUC5B/MUC5B促进LUAD和粘液性LUAD；2)检验聚合粘蛋白表达假说 在肿瘤细胞中通过ERN2/Ern2依赖的蛋白平衡功能障碍促进LUAD；3)检验假设 多聚粘蛋白表达促进ERN2/Ern2依赖的上皮生长。研究将利用小说 小鼠模型、细胞系和患者样本关注粘蛋白、内质网之间的重要致病联系 压力和LUAD。创新的基因编辑工具将与药物制剂一起使用，如 干预，以及最先进的动物、组织和分子成像技术将被应用。 这些目标的实现有可能对退伍军人及其家人的生活产生重大影响。我们的 团队由粘蛋白和癌细胞生物学方面的专家组成，他们在解决问题方面具有独特的地位 这将提高我们对KRAS诱导的LUAD的理解。研究结果可以确定MUC5AC、MUC5B和 ERN2作为直接限制LUAD增长的目标，并改进这一常见但难以治疗的策略 肺癌的一种形式。

Lung cancer is the leading cause of cancer-related deaths, and risks are disproportionately high in veterans. Lung adenocarcinoma (LUAD) accounts for half of all lung cancer cases, but effective treatments are lacking in part due to an incomplete understanding of LUAD biology. LUAD tumors originate from airway secretory epithelia, and mucin expression is prevalent and associated with LUAD aggressiveness. However, mechanisms by which mucins affect LUAD pathogenesis are poorly understood. The overarching concept of this proposal is that aberrant epithelial growth in LUAD is potentiated by two polymeric mucins--MUC5AC and MUC5B. Though required for airway defense in health, MUC5AC and MUC5B misexpression in LUAD correlates with invasiveness, recurrence, and mortality, especially in patients with activating mutations in KRAS--the most common oncogenic driver of LUAD. We validated MUC5AC causatively in urethane and activated-Kras expression mouse models of LUAD. In animals lacking Muc5ac (‘MUC in humans, ‘Muc’ in mice), tumor number and size decreased by ~50%. The relative tumor-promoting effects of Muc5b on its own or with Muc5ac are not yet known. We seek to close this significance gap here. We also seek to determine molecular mechanisms for polymeric mucin-mediated tumor promotion. Studies by us and by others have identified numerous signals that stimulate LUAD, including mucinous LUAD subtypes. Upstream signaling pathways converge on mucins and their biosynthetic machinery. Individual MUC5AC and MUC5B molecules are extraordinarily large. They multimerize, and they become even more massive through addition of sugars to their central glycosylation domains. Accordingly, protein homeostasis (proteostasis) is tightly regulated during polymeric mucin biosynthesis. Mucin translation, folding, and dimerization occur in the endoplasmic reticulum (ER) and involve formation of hundreds of disulfide bonds. To handle these demands, mammals express a mucous cell specific isoform of the ER stress sensor inositol-requiring enzyme-1 (IRE-1, also called ER-to- nucleus signaling protein, or ERN). ERN1 is ubiquitously expressed and is crucial for ER stress-triggered apoptosis, but an isoform called ERN2 is restricted to mucous cells where it is required for sustaining mucin synthesis despite high levels of ER stress. This adaptation is accomplished by direct binding of ERN2 to ERN1 and subsequent suppression of ERN1-mediated pro-apoptotic signaling. While beneficial for host defense in health, apoptosis suppression could be detrimental in LUAD. We hypothesize that MUC5AC and MUC5B promote epithelial cell growth in LUAD via ERN2-dependent suppression of ER stress-induced apoptosis. The following three Specific Aims are proposed: 1) Test the hypothesis that MUC5AC/Muc5ac and MUC5B/Muc5b promote LUAD and mucinous LUAD; 2) Test the hypothesis that polymeric mucin expression in tumor cells promotes LUAD via ERN2/Ern2 dependent proteostasis dysfunction; 3) Test the hypothesis that polymeric mucin expression promotes ERN2/Ern2-dependent epithelial growth. Studies will utilize novel mouse models, cell lines, and patient samples to focus on significant causative links between mucins, ER stress, and LUAD. Innovative gene-editing tools will be used along with pharmacologic agents as interventions, and state of the art animal, tissue, and molecular imaging techniques will be applied. Completion of these aims has the potential to significantly impact the lives of veterans and their families. Our team comprises experts in mucin and cancer cell biology who are uniquely positioned to address questions that will improve our understanding of KRAS-induced LUAD. Findings could identify MUC5AC, MUC5B, and ERN2 as targets to directly limit LUAD growth and to improve strategies for this common but poorly treatable form of lung cancer.