Epigenetic modulation of lung cancer metastasis by a novel long intergenic RNA

描述(申请人提供)：胸部恶性肿瘤的死亡人数超过前列腺癌、乳腺癌和结直肠癌的总和。最常见的肺癌亚型是肺腺癌(LUAD)，它起源于外周呼吸道，可以迅速扩散到其他重要器官。目前还没有有效的治疗转移性LUAD的方法，这些转移性LUAD在生物学和基因上是多样化的。此外，最近的基因组重新测序工作揭示了数千个新的人类基因座，尽管这些基因座不编码任何蛋白质，但可能对人类医学至关重要。鉴于LUADs的异质性和遗传复杂性，需要一种多学科的方法来了解肺癌转移的分子发病机制，并发现该疾病的新的介质和生物标志物。通过计算和实验方法，我们研究了细胞分化状态、肺癌亚型和临床结果之间的分子关系，以发现细胞谱系限制基因在转移性LUAD中的作用。这些变化包括功能未知的新的长基因间非编码RNA(LincRNAs)转录的变化。特别是，我们发现了一种lincRNA，这里称为Linc-Xim(X连锁转移抑制因子)，是一种潜在的转移抑制因子和表观遗传学异常的生物标志物，尤其是在人类LUAD中。我们推测Linc-Xim通过拮抗多梳抑制物复合体2(PRC2)的活性和/或其对相关基因组靶点的募集来抑制肿瘤转移。因此，抑制Linc-Xim可能通过对惰性LUAD细胞的转录组进行表观遗传重新编程来增强LUAD的转移能力。我们将首先利用我们建立的人LUAD细胞转移扩散和定植的体内模型，表征Linc-Xim在肺LUAD分化、肿瘤生长和远处器官转移中的生物学功能(S)，以检验这一假设。我们将利用遗传学和药理学方法，实现时间上可控的功能获得和丧失，以建立Linc-Xim表达和PRC2活性之间的功能关联。在这些生物学实验的同时，我们将结合分子、生化和原位技术来阐明Linc-Xim隔离或抑制PRC2蛋白亚基并最终调节表观遗传沉默的机制。最后，我们将检验Linc-Xim、PrC2亚单位、PrC2靶基因在人类LUAD生物样本中的表达与临床结局之间的相关性。因此，我们应用的总体目标可能会为组织特异性lincRNAs在癌症进展中的作用提供新的线索，并为有转移风险的肺癌患者提供更有效的表观遗传疗法。

DESCRIPTION (provided by applicant): Thoracic malignancies account for more deaths than prostate, breast and colorectal cancer combined. The most frequent lung cancer subtype is lung adenocarcinoma (LUAD), which is initiated in the peripheral airways and can disseminate rapidly to other vital organs. There are currently no effective therapeutics for metastatic LUAD, which are biologically and genetically diverse. In addition, recent genomic re-sequencing efforts have revealed thousands of new human gene loci that, despite not coding for any proteins, may be critical to human medicine. Given the heterogeneity and genetic complexity of LUADs, a multi-disciplinary approach is needed to understand the molecular pathogenesis of lung cancer metastasis and uncover novel mediators and biomarkers of this disease. Through computational and experimental approaches, we examined the molecular relationship between cell differentiation states, lung cancer subtypes, and clinical outcome, to discover a role for cel lineage- restricted genes in metastatic LUAD. These alterations include changes in the transcription of novel long intergenic non-coding RNAs (lincRNAs) with unknown function. In particular, we identified one lincRNA, referred to here as linc-XIM (X-linked inhibitor of metastasis), as a potential suppressor of metastasis and biomarker of epigenetic abnormalities specifically in human LUADs. We posit that linc-XIM inhibits metastasis by antagonizing the activity of the Polycomb repressor complex 2 (PRC2) and/or its recruitment to relevant genomic targets. Thus, repression of linc-XIM may enhance metastatic competence of LUADs by epigenetically reprogramming the transcriptome of indolent LUAD cells. We will test this hypothesis by first characterizing the biological function(s) of linc-XIM during lung LUAD differentiation, tumor growth and distant organ metastasis, using our established in vivo model of metastatic dissemination and colonization by human LUAD cells. We will employ genetic and pharmacological approaches that enable temporally controlled gain and loss of function, to establish the functional association between linc-XIM expression and PRC2 activity. In parallel to these biological experiments, we will combine molecular, biochemical, and in situ techniques to elucidate the mechanism by which linc-XIM sequesters or inhibits PRC2 protein subunits and ultimately regulates epigenetic silencing. Finally, we will examine the correlation between the expression of linc-XIM, PRC2 subunits, PRC2 target genes, and clinical outcome in human LUAD biospecimens. The overall goal of our application may therefore shed new light into the role of tissue specific lincRNAs in cancer progression, and provide insights into more effective epigenetic therapies for lung cancer patients at risk for metastatic disease.