Pratilas Christine A, Hanrahan Aphrothiti J, Halilovic Ensar, Persaud Yogindra, Soh Junichi, Chitale Dhananjay, Shigematsu Hisayuki, Yamamoto Hiromasa, Sawai Ayana, Janakiraman Manickam, Taylor Barry S, Pao William, Toyooka Shinichi, Ladanyi Marc, Gazdar Adi, Rosen Neal, Solit David B
Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
Cancer Res. 2008 Nov 15;68(22):9375-83. doi: 10.1158/0008-5472.CAN-08-2223.
Hyperactivated extracellular signal-regulated kinase (ERK) signaling is common in human cancer and is often the result of activating mutations in BRAF, RAS, and upstream receptor tyrosine kinases. To characterize the mitogen-activated protein kinase/ERK kinase (MEK)/ERK dependence of lung cancers harboring BRAF kinase domain mutations, we screened a large panel of human lung cancer cell lines (n = 87) and tumors (n = 916) for BRAF mutations. We found that non-small cell lung cancers (NSCLC) cells with both V600E and non-V600E BRAF mutations were selectively sensitive to MEK inhibition compared with those harboring mutations in epidermal growth factor receptor (EGFR), KRAS, or ALK and ROS kinase fusions. Supporting its classification as a "driver" mutation in the cells in which it is expressed, MEK inhibition in (V600E)BRAF NSCLC cells led to substantial induction of apoptosis, comparable with that seen with EGFR kinase inhibition in EGFR mutant NSCLC models. Despite high basal ERK phosphorylation, EGFR mutant cells were uniformly resistant to MEK inhibition. Conversely, BRAF mutant cell lines were resistant to EGFR inhibition. These data, together with the nonoverlapping pattern of EGFR and BRAF mutations in human lung cancer, suggest that these lesions define distinct clinical entities whose treatment should be guided by prospective real-time genotyping. To facilitate such an effort, we developed a mass spectrometry-based genotyping method for the detection of hotspot mutations in BRAF, KRAS, and EGFR. Using this assay, we confirmed that BRAF mutations can be identified in a minority of NSCLC tumors and that patients whose tumors harbor BRAF mutations have a distinct clinical profile compared with those whose tumors harbor kinase domain mutations in EGFR.
细胞外信号调节激酶（ERK）过度激活在人类癌症中很常见，通常是BRAF、RAS及上游受体酪氨酸激酶激活突变的结果。为了明确携带BRAF激酶结构域突变的肺癌对丝裂原活化蛋白激酶/ERK激酶（MEK）/ERK的依赖性，我们在一大批人类肺癌细胞系（n = 87）和肿瘤（n = 916）中筛查了BRAF突变。我们发现，与那些携带表皮生长因子受体（EGFR）、KRAS或ALK及ROS激酶融合突变的细胞相比，同时具有V600E和非V600E BRAF突变的非小细胞肺癌（NSCLC）细胞对MEK抑制具有选择性敏感性。MEK抑制在（V600E）BRAF NSCLC细胞中可导致大量凋亡诱导，这与EGFR突变NSCLC模型中EGFR激酶抑制所观察到的情况相当，支持了将其归类为在其表达细胞中的“驱动”突变。尽管基础ERK磷酸化水平较高，但EGFR突变细胞对MEK抑制始终具有抗性。相反，BRAF突变细胞系对EGFR抑制具有抗性。这些数据，连同人类肺癌中EGFR和BRAF突变的非重叠模式，表明这些病变定义了不同的临床实体，其治疗应以实时基因分型为指导。为了推动这一工作，我们开发了一种基于质谱的基因分型方法，用于检测BRAF、KRAS和EGFR中的热点突变。使用该检测方法，我们证实可以在少数NSCLC肿瘤中鉴定出BRAF突变，并且与那些肿瘤携带EGFR激酶结构域突变的患者相比，肿瘤携带BRAF突变的患者具有独特的临床特征。
