Interplay between host microbiome and immunomodulatory responses in the pathogenesis of Kras mutant lung cancer

项目总结 肺腺癌(LUAD)是终生吸烟者中最常见的癌症，其中 在美国有9000多万人。患有LUAD的吸烟者经常(超过25%)藏匿躯体 激活Kras癌基因的突变。KRAS突变LUAD(KM-LUAD)表现出非常差的临床结果 对治疗的反应较差。尽管迫切需要新的策略来早期治疗这一致命的 疾病，我们仍然不了解促进KM-LUAD发病的有针对性的变化。用一个人类- 由烟草暴露和高体细胞突变组成的相关基因工程小鼠模型 负担包括驱动程序Kras变体，构成LUAD发病机制的完美风暴的功能 在人类中，我们确定了肠道微生物组组成的显著进行性变化，这些变化与 肠道和循环细菌代谢物水平降低，与KM-LUAD的演变密切相关。 在暴露于可燃香烟烟雾(CCS)的小鼠中也观察到了类似的微生物表型。我们 在小鼠肺中进一步发现促肿瘤炎症信号的上调，包括IL-6的激活 /STAT3途径，我们先前已经证明通过免疫促进KM-LUAD的发展 重新编程。此外，我们还注意到Lipocalin 2(Lcn2)，一种释放的宿主防御抗微生物蛋白 在微生物组失衡期间，在正常呼吸道细胞中显著进行性上调 与Kras突变的创业和LUADs的发病有关。这些小鼠的Lcn2基因缺失显著增加 KM-LUAD的发展伴随着肠道微生物群的全球变化和肿瘤前肺的增强 发炎。尽管有这些见解，宿主微生物群和关键免疫反应之间的相互作用 KM-LUAD的发病机制尚不清楚。我们假设宿主微生物群(派生的 来自肠道，可能来自肺)通过以下方式促进烟草相关的KM-LUAD的发展 IL-6/STAT3途径的激活与全身和肺免疫环境的变化。我们会 使用以下三个目标解决我们的假设。在目标1中，使用测序、元基因组学以及 细菌代谢物和免疫简档方法，我们将辨别演变中的微生物组变化 与烟草致癌物和CCS相关的KM-LUAD发展相关的功能连锁以及探针 下游全身和局部(肺内)免疫调节作用，包括对促肿瘤IL-2的影响 6/STAT3途径。在目标2中，我们将确定宿主抗菌和免疫调节信号的作用 Lcn2诱导在KM-LUAD发病机制中的作用在目标3中，我们将研究化学预防和 微生物组干预单独或联合免疫治疗对多发性骨髓瘤的早期治疗作用 路德。在我们的研究结束时，我们将阐明未知的宿主过程中的演变 KM-LUAD，为确定新的目标以指导化学预防和早期检测铺平了道路 并为研究LUAD的发病机制提供了新的模型。

PROJECT SUMMARY Lung adenocarcinoma (LUAD) is the most common cancer diagnosed in lifetime smokers of whom there are more than 90 million in the United States. Smokers with LUAD frequently (more than 25%) harbor somatic activating mutations in the Kras oncogene. Kras-mutant LUAD (KM-LUAD) displays very poor clinical outcome and inferior response to therapy. Despite the urgent need of new strategies for early treatment of this fatal disease, we still do not understand targetable changes that promote onset of KM-LUAD. Using a human- relevant genetically engineered mouse model comprised of tobacco exposure and high somatic mutation burdens including driver Kras variants, features that constitute a perfect storm for LUAD pathogenesis in humans, we identified significant progressive changes in gut microbiome composition that were coexistent with reduced levels of gut and circulating bacterial metabolites and closely associated with evolution of KM-LUAD. Similar microbial phenotypes were observed in mice exposed to combustible cigarette smoke (CCS). We further found in lungs of the mice up-regulation of pro-tumor inflammatory cues including activation of the IL-6 /STAT3 pathway which we have previously shown to promote KM-LUAD development by immune reprogramming. Also, we noted that lipocalin 2 (LCN2), a host defense antimicrobial protein that is released from cells during microbiome imbalance, was markedly progressively up-regulated in normal airway cells prior to onset of Kras-mutant preneoplasias and LUADs. Genetic deletion of Lcn2 in these mice markedly increased KM-LUAD development concomitant with global changes in the gut microbiome and heightened pro-tumor lung inflammation. Despite these insights, the interplay between the host microbiome and key immune responses in the pathogenesis of KM-LUAD are poorly understood. We hypothesize that the host microbiome (derived from the gut and possibly the lung) promotes tobacco-associated KM-LUAD development through activation of the IL-6/STAT3 pathway and changes in systemic and lung immune contexture. We will address our hypothesis using the following three aims. In Aim 1, using sequencing, metagenomics, as well as bacterial metabolite and immune profiling approaches, we will discern evolving microbiome changes that are functionally linked to tobacco carcinogen- and CCS-associated KM-LUAD development as well as probe downstream systemic and local (in lung) immunomodulatory effects including those on the pro-tumor IL- 6/STAT3 pathway. In Aim 2, we will determine the role of host antimicrobial and immunomodulatory cues mediated by LCN2 induction in KM-LUAD pathogenesis. In Aim 3, we will investigate chemopreventive and early therapeutic effects of microbiome intervention, alone or in combination with immunotherapy, against KM- LUAD. At the conclusion of our studies, we will have shed light on uncharted host processes in the evolution of KM-LUAD, paved the way for identification of new targets to guide chemoprevention and early detection of this fatal disease in smokers and contributed novel models for studying LUAD pathogenesis.