Background/Objectives: The BRG1 loss-of-function (LOF) mutation is found in ~10% of non-small cell lung cancer (NSCLC) cases, but its role in lung tumorigenesis is unclear and so it is investigated in this study. Methods: BRG1-knockout (KO) lines were generated from various non-malignant, pre-malignant, and malignant human lung epithelium-derived cell lines using CRISPR. The effects of BRG1-KO on cell growth, the transcriptome, the methylome, and epigenetic therapy were compared with those of wild-type (BRG1-WT) isogenic controls using standard in vitro and in vivo assays. Results: The BRG1 protein was expressed in all non-/pre-malignant lung epithelial cells but lost in 47% (14/30) of NSCLC cell lines. BRG1-KO and cigarette smoke (CS) exposure individually transformed human bronchial epithelial cell lines (HBECs), as evidenced by anchorage-independent growth. BRG1-KO and CS produced additive to synergistic effects on sensitivity to transformation that differed across HBECs. RNA-seq analysis revealed that BRG1-KO significantly changed the expression of over 8500 genes on average, impacting lung development, function, damage repair, and cancer pathways, including axonal guidance, pulmonary wound healing, and epithelial-to-mesenchymal transition (EMT). BRG1-KO also led to the hypermethylation of >47,000 promoter CpGs within ~9500 genes on average in different HBECs, including silencing of epithelial genes involved in EMT and tumor suppressor genes. BRG1-KO also moderately increased the in vitro and in vivo sensitivity of NSCLC cells to some epigenetic drugs. Conclusions: BRG1-LOF is frequent in NSCLC; can drive the transformation of lung epithelial cells such that they acquire properties of pre-malignant cells, indicating a potential role in lung cancer initiation; and sensitizes lung tumors to epigenetic therapy.
背景/目的：BRG1功能缺失突变在约10%的非小细胞肺癌病例中被发现，但其在肺肿瘤发生中的作用尚不明确，本研究对此进行探讨。方法：利用CRISPR技术从多种非恶性、癌前及恶性人肺上皮来源细胞系中构建BRG1敲除细胞系。通过标准体外及体内实验，将BRG1敲除对细胞生长、转录组、甲基化组及表观遗传治疗的影响与野生型同基因对照组进行比较。结果：BRG1蛋白在所有非恶性/癌前肺上皮细胞中均有表达，但在47%（14/30）的非小细胞肺癌细胞系中缺失。BRG1敲除与香烟烟雾暴露均可独立诱导人支气管上皮细胞系发生转化，表现为锚定非依赖性生长。二者对转化敏感性的影响在不同支气管上皮细胞系中呈现叠加至协同效应。RNA-seq分析显示，BRG1敲除平均显著改变超过8500个基因的表达，影响肺发育、功能、损伤修复及癌症相关通路，包括轴突导向、肺损伤修复及上皮-间质转化等过程。在不同支气管上皮细胞系中，BRG1敲除还导致约9500个基因内超过47000个启动子CpG位点发生高甲基化，包括参与上皮-间质转化的上皮基因及抑癌基因的沉默。此外，BRG1敲除可适度增强非小细胞肺癌细胞在体外及体内对部分表观遗传药物的敏感性。结论：BRG1功能缺失在非小细胞肺癌中较为常见；可驱动肺上皮细胞转化并获得癌前细胞特性，提示其在肺癌起始阶段可能发挥作用；并能增强肺肿瘤对表观遗传治疗的敏感性。
肿瘤(癌症)患者之家