microRNA-101在炎症促进非小细胞肺癌中的作用和机制研究

Chronic inflammation and infection are important risk factors of tumorigenesis. It is evident that tobacco smoke, air pollutant, pulmonary infections, and occupational dust all contribute to the initiation and progression of lung cancer. microRNAs (miRNAs) are a class of ～22 nt small non-coding RNAs that negatively regulate protein genes at posttranscriptional level. The causal roles of miRNAs in cancer have been well documented and miRNA-based anticancer therapies are in development. Moreover, recent studies show that miRNAs function as novel pro-inflammatory regulators, implicating that miRNAs may play important roles in inflammation-associated tumorigenesis. However, how miRNAs link inflammation and lung tumorigenesis is largely unexplored. Our preliminary results showed that pro-inflammatory cytokine IL-1β was dramatically up-regulated in non-small cell lung cancer patients, and that IL-1β increased the proliferation and invasion of non-small cell lung cancer cells. Interestingly, we found that IL-1β repressed a tumor suppressive miRNA, miR-101, in non-small cell lung cancer cells through up-regulation of COX-2, a factor that has been well-known to correlate to both tobacco smoke and tumorigenesis. In this research plan, we will further study the function and mechanism of miR-101 in inflammation-associated lung tumorigenesis. We propose three aims for this project: first, we will define the upstream signal pathways that modulate expression of miR-101 by the approaches of computational prediction, RNAi, overexpression, and reporter assays; second, we will identify the downstream targets of miR-101 by combinations of mutagenesis, immunoblotting, and reporter analyses; third, we will study the function and mechanism of miR-101 as well as its upstream and downstream components in lung tumorigenesis by in vitro and in vivo assays of cell growth, cell migration and metastasis, and metabolism of cancer cells. Data generated from these studies will advance our understanding of the molecular connections between inflammation and lung cancer, and provide useful information for the strategies of effective lung cancer prevention, diagnosis and therapeutics.

肺癌是一种与炎症息息相关的癌症，吸烟、大气污染、肺部感染以及职业粉尘等都是肺癌的诱发因素。miRNA是大小～22 nt非编码小RNA分子，在转录后水平负调控靶基因表达。miRNA在癌症中的调控作用已得到普遍证实，而最近的研究揭示其为一种新型炎性介质因子，提示miRNA可能在炎症相关肿瘤发生中具有重要作用，而目前对炎症、miRNA、肺癌三者间的联系还知之甚少。我们的前期研究发现，在非小细胞肺癌患者中高表达的促炎性细胞因子IL-1β抑制肺癌细胞中抑癌性miR-101的表达，而与吸烟及肿瘤相关的环氧合酶2（COX-2）可能介导该调控作用。在本申请项目中，我们将深入研究IL-1β调控miR-101的分子机制，鉴定miR-101的下游靶基因，调查miR-101的上游炎性调控信号通路和下游靶基因在肺癌发生中的功能机制。研究结果将阐析炎症促进肺癌发生发展的分子机制，为肺癌预防和治疗提供新思路和分子靶。

肺癌是一种与炎症息息相关的癌症，吸烟、大气污染、肺部感染以及职业粉尘等都是肺癌的诱发因素。miRNA是大小~22 nt左右的非编码小RNA分子，在转录后水平负调控靶基因表达。miRNA在癌症中的调控作用已得到普遍证实，而最近的研究揭示其为一种新型炎性介质因子，提示miRNA可能在炎症相关肿瘤发生中具有重要作用，而目前对炎症、miRNA、肺癌三者间的联系还知之甚少。我们的前期研究发现，在非小细胞肺癌患者中高表达的促炎性细胞因子IL-1β抑制肺癌细胞中抑癌性miR-101的表达，而与吸烟及肿瘤相关的环氧合酶2（COX-2）可能介导该调控作用。通过本项目的研究，我们进一步证实，IL-1β通过COX-2/HIF-1α通路负调控mir-101，并且癌基因Lin28B是miR-101的靶基因，miR-101通过负调控Lin28B促进let-7家族miRNAs表达，因此IL-1β通过Lin28B抑制let-7家族miRNAs的表达。进一步，我们发现非甾体类抗炎药阿司匹林和塞来昔布可有效地逆转IL-1β的促癌作用，这一促癌性炎症致肺癌发生的新机制，为阿司匹林等非甾体类抗炎药物的潜在抗癌效应提供了新的证据，完善了其抗癌作用的分子机理。此外，在临床转化上，我们筛选并鉴定了由miR-146a、miR-222和miR-223组成的表达谱，并利用回归方程建立了肺腺癌早期诊断模型，对肺腺癌的早期诊断有很好的应用价值。通过本研究，我们阐明了IL-1β/miR-101/Lin28B调控通路在非小细胞肺癌发生发展中的作用，为炎症和癌症相关性研究领域提供新的实验依据和研究方案，并转化到临床实际应用，建立了肺腺癌早期诊断的miRNA表达谱，有很好的临床转化前景。