The role of translation initiation factor eIF5B in lung cancer pathogenesis

翻译起始因子eIF5B在肺癌发病机制中的作用

• 批准号: 10734752
• 负责人: Kathryn Ann O'Donnell
• 金额: $ 47.64万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-06 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10734752
• 关键词: 5' Untranslated Regions; Acceleration; Address; Alleles; Automobile Driving; Bypass; CRISPR screen; Cancer Etiology; Cancer Intervention; Cell physiology; Cells; Cessation of life; Data; EIF-2alpha; Ensure; Epithelial Cells; Gene Expression; Guanosine Triphosphate Phosphohydrolases; Heterozygote; Human; Immune; Immune Evasion; Immunocompetent; Immunocompromised Host; Immunomodulators; Initiator Codon; Internal Ribosome Entry Site; KRASG12D; Knock-out; Knockout Mice; Knowledge; Laboratories; Ligands; LoxP-flanked allele; Lung Adenocarcinoma; Lung Neoplasms; Malignant Neoplasms; Malignant neoplasm of lung; Mediating; Messenger RNA; Modeling; Mus; Nature; Non-Small-Cell Lung Carcinoma; Oncogenes; Oncogenic; Open Reading Frames; Pathogenesis; Pathway interactions; Peptide Initiation Factors; Phosphorylation; Prognosis; Proliferating; Proteins; Repression; Ribosomes; Role; T cell response; T-Lymphocyte; Testing; Transgenic Mice; Translations; Tumor Burden; Tumor Immunity; Tumor Promotion; Untranslated Regions; Up-Regulation; anti-PD-1/PD-L1; anti-PD-L1 antibodies; biological adaptation to stress; bronchial epithelium; c-myc Genes; carcinogenesis; cell growth; eukaryotic initiation factor-5B; experimental study; gain of function; genome-wide; humanized mouse; immune cell infiltrate; immune checkpoint; immune checkpoint blockade; immunoregulation; in vivo; insight; loss of function; lung cancer cell; lung tumorigenesis; mouse model; novel; overexpression; programmed cell death ligand 1; programmed cell death protein 1; programs; receptor; ribosome profiling; translation factor; tumor; tumor growth; tumor progression; tumor-immune system interactions; tumorigenesis

PROJECT SUMMARY Lung cancer cells express high levels of PD-L1, a ligand of the PD-1 receptor on T-cells, allowing tumors to directly suppress T cell activity. Anti-PD-1/PD-L1 antibodies induce potent anti-tumor immunity and have been approved as a first-line therapy for lung cancer. However, only ~20% of all non-small cell lung cancers (NSCLCs) benefit from checkpoint blockade. A further understanding of the mechanisms that regulate the immune checkpoint in lung cancer is therefore needed. To address this, my laboratory used CRISPR-based screening to identify regulators of PD-L1 in lung cancer cells, revealing potent induction of PD-L1 upon activation of the integrated stress response (ISR) pathway. Mechanistically, ISR activation resulted in enhanced PD-L1 translation and suppression of anti-tumor immunity. We further demonstrated that ISR- dependent translation of PD-L1 requires the alternative translation initiation factor eIF5B. The canonical role of this GTPase is to catalyze ribosomal subunit joining, ensuring 80S ribosome assembly and efficient start codon selection. eIF5B overexpression and/or amplification is frequent in human lung cancers and is associated with poor prognosis. Remarkably, eIF5B overexpression is sufficient to induce PD-L1 protein levels even in the absence of ISR activation. These findings uncovered a new mechanism of immune checkpoint activation and suggested that eIF5B may be a novel target for lung cancer intervention. We further demonstrated that enforced expression of eIF5B accelerates proliferation in lung cancer cells, in mouse syngeneic models, and in human bronchial epithelial cells suggesting that it also promotes tumor growth in a cell-autonomous manner. We propose to elucidate the role of eIF5B in lung tumorigenesis by testing the following central hypothesis: EIF5B functions as an oncogene in human lung cancer by inducing PD-L1 translation and by driving a tumor-promoting translational program. Three Specific Aims will be pursued in order to test this hypothesis: In Aim 1, we will dissect the mechanisms through which eIF5B promotes translation of PD-L1 and additional oncogenic mRNAs in lung cancer. In Aim 2, we will functionally evaluate the oncogenic activity of eIF5B using a novel transgenic mouse model with conditional eIF5B overexpression. In Aim 3, we will characterize the effects of eIF5B loss of function on cell autonomous tumor growth versus its effect on T cell responses in the KrasLSL-G12D; Tp53 fl/fl mouse model using a newly generated conditional floxed knockout allele and a heterozygous germline knockout mouse. These aims will take advantage of our expertise, and that of our collaborators, to evaluate eIF5B oncogenic activity, and elucidate the mechanisms through which this translation initiation factor promotes lung tumorigenesis. We anticipate that these studies will provide new insights into mechanisms of translational control in tumor progression and immune evasion.

项目摘要 肺癌细胞表达高水平的PD-L1，PD-L1是T细胞上PD-1受体的配体，使肿瘤得 直接抑制T细胞活性。抗PD-1/PD-L1抗体诱导有效的抗肿瘤免疫，并且已经 被批准为肺癌的一线疗法。但是，只有所有非小细胞肺癌的20％ （NSCLC）受益于检查点封锁。对调节机制的进一步理解 因此，需要在肺癌中进行免疫检查点。为了解决这个问题，我的实验室使用了基于CRISPR的 筛选以鉴定肺癌细胞中PD-L1的调节剂，揭示了PD-L1的有效诱导 综合应力响应（ISR）途径的激活。从机械上讲，ISR激活导致 增强了抗肿瘤免疫力的PD-L1翻译和抑制。我们进一步证明了ISR- PD-L1的依赖翻译需要替代的翻译起始因子EIF5B。规范的角色 该GTPase是催化核糖体亚基连接，以确保80年代的核糖体组装和有效的起始密码子 选择。 EIF5B过表达和/或扩增在人肺癌中经常进行，并且与 预后不良。值得注意的是，即使在 没有ISR激活。这些发现发现了免疫检查点激活的新机制 建议EIF5B可能是肺癌干预的新目标。我们进一步证明了 EIF5B的强制表达加速了肺癌细胞的增殖，小鼠合成模型和在 人支气管上皮细胞表明它也以细胞自主的方式促进肿瘤的生长。 我们建议通过测试以下中心假设来阐明EIF5B在肺肿瘤发生中的作用： EIF5B通过诱导PD-L1翻译和驱动A 促进肿瘤的翻译计划。为了测试这一点，将实现三个具体目标 假设：在AIM 1中，我们将剖析EIF5B促进PD-L1翻译的机制 肺癌中的其他致癌mRNA。在AIM 2中，我们将在功能上评估 EIF5B使用带有条件EIF5B过表达的新型转基因小鼠模型。在AIM 3中，我们将 表征EIF5B功能丧失对细胞自动肿瘤生长的影响与其对T细胞的影响 KRASLSL-G12D中的响应； TP53 FL/FL小鼠模型使用新生成的有条件敲除敲除 等位基因和杂合种系基因敲除老鼠。这些目标将利用我们的专业知识，并 我们的合作者评估EIF5B致癌活动，并阐明了通过 这种翻译起始因子促进了肺肿瘤发生。我们预计这些研究将提供新的 深入了解肿瘤进展和免疫逃避中转化控制机制。