Role of the DREAM complex in the lung tumor suppression

摘要 肺癌是美国和世界范围内癌症死亡的主要原因。最常见的肺类型 癌症是非小细胞肺癌(NSCLC，84%)和小细胞肺癌(SCLC，13%)。非小细胞肺癌 包括两种主要的组织学亚型，腺癌(AC)和鳞癌(SCC)。全 肺癌的亚型被认为是由暴露于基因毒性环境中的呼吸道上皮细胞受损引起的， 最常见的包括烟草烟雾和氡辐射。这些受损的细胞经常获得早期驱动因素 KRAS基因的突变也可能存在于晚期肺癌中。然而，即使在这种情况下 长期大量接触(如重度吸烟者)，并不是所有受损的细胞都会导致癌症，而且 阻止早期癌前病变进展为癌症的机制仍不完全清楚。 使用基因工程小鼠模型(GEMM)的研究强调了细胞周期停滞和 由视网膜母细胞瘤(RB)家族蛋白和P53介导的衰老在肺肿瘤发生中的保护作用。 然而，需要进一步的研究才能从分子上更好地了解肺癌发生的障碍。 水平，并开发代表肺癌发病机制早期阶段的准确模型。 在此之前，我们描述了一种称为DREAM的转录抑制复合体，它在G0/G1中组装 当Rb样蛋白p130招募E2F4、DP1和LIN9、LIN37、LIN52等5种蛋白质的稳定核心时， LIN54和RBBP4。梦想与启动子结合，并介导对&gt；800细胞周期基因的抑制。 包括DNA损伤反应和修复所需的大多数基因。丝氨酸-28残基的磷酸化 DYRK1A激酶的LIN52是DREAM组装所必需的。Dream-DYRK1A通路可能与 癌症，因为抑制DYRK1A或S28A-LIN52突变导致绕过致癌的RAS- 在永生化的人和小鼠细胞系中诱导衰老。KRAS基因突变15%-30% NSCLC病例中，其在肺癌中的驱动作用得到了令人鼓舞的NSCLC临床数据的有力支持 使用KRASG12C靶向疗法。然而，梦境破灭的病理生理学意义 在肺癌中的作用尚不清楚，缺乏DREAM的细胞的衰老旁路机制也不是很好 明白了。在这里，我们测试了我们的假设，即梦境复合体通过以下方式有助于肿瘤预防 在肺癌发病的早期阶段抑制受损细胞的DNA修复。 此前，由于缺乏合适的小鼠，不能直接研究DREAM在肺癌中的作用 模特们。为了解决这一知识差距，我们产生了一只S28A突变的无梦纯合子小鼠 在Lin52基因中，采用CRISPR-Cas9基因编辑。我们将使用我们的新型Lin52S28A小鼠模型来研究 DYRK1A-DREAM通路在基因毒性肺癌发病早期的作用 压力或KrasG12C突变。

ABSTRACT Lung cancer is the major cause of cancer deaths in the U.S. and worldwide. The most common types of lung cancer are non-small cell lung carcinoma (NSCLC, 84%) and small cell lung carcinoma (SCLC, 13%). NSCLC includes two major histological subtypes, adenocarcinoma (AC), and squamous cell carcinoma (SCC). All subtypes of lung cancer are thought to arise from airway epithelial cells damaged by genotoxic exposure, which most commonly include tobacco smoke and radon radiation. These damaged cells frequently acquire early driver mutations in the KRAS gene that could be also present in advanced lung cancers. However, even in the cases with significant and chronic exposure (such as in heavy smokers), not all damaged cells give rise to cancer, and the mechanisms that prevent the progression of early premalignant lesions to cancer are still not fully understood. Studies using genetically engineered mouse models (GEMMs) highlighted the roles of cell cycle arrest and senescence, mediated by retinoblastoma (Rb) family proteins and p53, in protection from lung tumorigenesis. However, further research is required to better understand the barriers to lung carcinogenesis at the molecular level, and to develop accurate models representing early stages of lung cancer pathogenesis. Previously, we characterized a transcriptional repressor complex called DREAM that assembles in G0/G1 when Rb-like protein p130 recruits E2F4, DP1, and a stable core of five proteins including LIN9, LIN37, LIN52, LIN54, and RBBP4. The DREAM binds to promoters and mediates the repression of >800 cell cycle genes, including most genes required for DNA damage response and repair. Phosphorylation of serine-28 residue in LIN52 by DYRK1A kinase is required for the DREAM assembly. DREAM-DYRK1A pathway could be relevant to cancer because either inhibition of DYRK1A, or S28A-LIN52 mutation result in bypass of the oncogenic Ras- induced senescence in the immortalized human and mouse cell lines. The KRAS gene is mutated in 15% - 30% of NSCLC cases, and its driver role in lung cancer is strongly supported by encouraging NSCLC clinical data using KRASG12C-targeted therapeutics. However, the pathophysiological significance of the DREAM disruption in lung cancer is not known, and the mechanisms of senescence bypass in the cells lacking DREAM are not well understood. Here, we test our hypothesis that DREAM complex contributes to tumor prevention by suppressing DNA repair in the damaged cells during early stages of lung cancer pathogenesis. Previously, the role of DREAM in lung cancer could not be directly investigated due to a lack of suitable mouse models. To address this knowledge gap, we generated a DREAM-less mouse homozygous for S28A mutation in the Lin52 gene, using CRISPR-Cas9 gene editing. We will use our novel Lin52S28A mouse model to investigate the role of the DYRK1A-DREAM pathway during the early steps of lung cancer pathogenesis driven by genotoxic stress or KrasG12C mutation.