肺腺癌新型驱动基因功能与机制研究

Lung cancer was the leading cause of cancer-related mortality worldwide, leading to over a million deaths each year and lung adenocarcinoma is its most common histologic type. More recently, molecular subtyping is now routinely used in management of patients with lung cancer, largely due to clinical trials that proved superior efficacy of tyrosine kinase inhibitors as compared to standard chemotherapy for patients with EGFR mutations, ALK fusions or ROS1 fusions. However, many patients with lung adenocarcinoma either lack an identifiable oncogenic gene alteration, or harbor mutations in KRAS and are therefore still treated with conventional chemotherapy. We previously defined four novel drivers (HER2, RET, ROS1 and FGFR fusions) in lung adenocarcinomas. Identification of these mutations has led to rational prioritization of effective targeted therapies, providing clinical benefits for patients with lung cancer. We further performed a comprehensive analysis of 13 known oncogenic drivers in a large cohort of lung adenocarcinomas from East Asian population. According to our results, 15.7% of 1358 lung adenocarcinomas harbor no known clinically relevant oncogenic drivers, limiting therapeutic options for these patients. Considering the large number of lung cancer cases, the number of patients who have no target therapy option is enormous. The current study aims to identify and characterize novel driver mutations in order to find new therapies for NSCLC patients. We will pool all lung adenocarcinomas that were analyzed by next generation sequencing techniques by the Cancer Genome Atlas (TCGA) research network and other institutions. Pooling of all lung cancers samples together will increase the statistical power to detect rare potential drivers, thus facilitating the identification of driver genes that are not detected when each tumor is analyzed individually. In our institute, whole exome sequencing will also be utilized to screen novel drivers in 30 lung adenocarcinomas that were negative for all known oncogenic mutations. Following a well-established bioinformatics pipeline, we will generate lists of putative novel somatic mutations by pooling above next generation sequencing data. To characterize the oncogenic potential of candidate driver mutations, we will perform multiple functional and mechanistic assays. Malignant transformation and proliferation assays in vitro and tumor formation ability in vivo using xenografts and/or transgenic mouse models will be utilized. Finally, we will use lung cancer cell lines to identify targeted therapies that may be effective anti-tumor agents against these mutant gene products. We will also explore the signaling pathways affected by mutant gene products.This analysis will result in the comprehensive characterization of the mutational cancer driver genes acting in lung adenocarcinomas and identify the potential therapeutic targets.

肺癌是全球病死率第一位的恶性肿瘤。肺腺癌是目前最常见的病理类型。以驱动基因为基础的肺癌分子分型治疗已成为肺癌治疗的趋势。发现和鉴定新型可靶向治疗的驱动突变是肺癌分子分型治疗研究的关键。我们前期对1358例中国肺腺癌人群基因突变谱研究显示目前仍有15.7％的患者不携带任何已知的驱动突变。这部分"已知驱动突变全阴性"患者目前尚缺乏针对性靶向治疗方法。本研究在前期对我国肺腺癌人群系统性分子分型研究基础上，进一步综合分析以往国际上已发表及本研究中心的大规模测序数据，筛选出可能的驱动突变，分析其致癌功能和机制及可能有效的靶向药物。通过所有已知和新发现驱动突变对5000例中国肺腺癌人群进行分子分型。研究结果将极大完善我国肺腺癌人群分子分型指导提供个体化治疗方案，同时将推动靶向药物的临床试验开展和新药开发。

靶向治疗的出现为肺癌患者的生存带来了极大的获益。在靶向治疗时代，发现和鉴定可靶向治疗的驱动基因突变是关键。我们在前期研究中明确了中国人群肺腺癌的常见致癌基因突变谱。但仍然有大约15%的患者不携带已知的常见驱动突变。因此，当前肺腺癌分子分型研究的关键是发现和鉴定新的驱动基因。围绕这一研究目标，我们开展了一系列研究，在肺腺癌中发现和鉴定了多个新的驱动基因突变。我们的主要研究成果如下。（1）我们在中国人群肺腺癌中发现新型NRG1、EGFR和MET融合基因。其中NRG1融合基因存在于0.36%（6/1681）的肺腺癌患者中，包括4例CD74-NRG1融合基因，1例RBPMS-NRG1融合基因和1例ITGB1-NRG1融合基因。（2）我们通过对98例浸润前肺腺癌和99例浸润性肺腺癌的全外显子测序和RNA测序研究，发现TP53突变与肺腺癌疾病进展相关。（3）我们在704例肺腺癌中定义了NF1突变的临床病理特征，以及对于EGFR靶向治疗的反应。（4）我们发现并通过功能学实验鉴定了位于EGFR胞外域的M277E突变是肺腺癌中的一种新型致癌基因突变，并在细胞和动物模型中发现该突变对EGFR靶向治疗敏感。（5）我们发现超级增强子可能通过RAI14的表达调控肺腺癌的增殖，进而在肺腺癌进展中发挥一定的作用。（6）我们在741例肺腺癌中定义了SETD2突变的临床病理特征，并通过功能学实验阐明其促进肺腺癌转移以及介导靶向药物耐药的分子机制。这一系列的研究成果扩大了我国肺腺癌靶向治疗潜在可获益的人群。