Departments of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.
Clin Cancer Res. 2012 Dec 15;18(24):6599-608. doi: 10.1158/1078-0432.CCR-12-0838. Epub 2012 Oct 10.
The mutually exclusive pattern of the major driver oncogenes in lung cancer suggests that other mutually exclusive oncogenes exist. We conducted a systematic search for tyrosine kinase fusions by screening all tyrosine kinases for aberrantly high RNA expression levels of the 3' kinase domain (KD) exons relative to more 5' exons.
We studied 69 patients (including five never smokers and 64 current or former smokers) with lung adenocarcinoma negative for all major mutations in KRAS, EGFR, BRAF, MEK1, HER2, and for ALK fusions (termed "pan-negative"). A NanoString-based assay was designed to query the transcripts of 90 tyrosine kinases at two points: 5' to the KD and within the KD or 3' to it. Tumor RNAs were hybridized to the NanoString probes and analyzed for outlier 3' to 5' expression ratios. Presumed novel fusion events were studied by rapid amplification of cDNA ends (RACE) and confirmatory reverse transcriptase PCR (RT-PCR) and FISH.
We identified one case each of aberrant 3' to 5' ratios in ROS1 and RET. RACE isolated a GOPC-ROS1 (FIG-ROS1) fusion in the former and a KIF5B-RET fusion in the latter, both confirmed by RT-PCR. The RET rearrangement was also confirmed by FISH. The KIF5B-RET patient was one of only five never smokers in this cohort.
The KIF5B-RET fusion defines an additional subset of lung cancer with a potentially targetable driver oncogene enriched in never smokers with "pan-negative" lung adenocarcinomas. We also report in lung cancer the GOPC-ROS1 fusion originally discovered and characterized in a glioma cell line.
肺癌中主要驱动致癌基因的互斥模式表明，其他互斥致癌基因也存在。我们通过筛选所有酪氨酸激酶，寻找 3'激酶结构域（KD）外显子相对于更多 5'外显子的异常高 RNA 表达水平，对酪氨酸激酶融合进行了系统搜索。
我们研究了 69 例肺腺癌患者（包括 5 例从不吸烟者和 64 例现吸烟者或前吸烟者），这些患者均为 KRAS、EGFR、BRAF、MEK1、HER2 所有主要突变和 ALK 融合阴性（称为“全阴性”）。设计了一种基于 NanoString 的检测方法，分别在两个位置查询 90 个酪氨酸激酶的转录本：KD 之前和 KD 内或之后。肿瘤 RNA 与 NanoString 探针杂交，并分析异常的 3' 到 5'表达比值。通过快速扩增 cDNA 末端（RACE）和确认性逆转录酶 PCR（RT-PCR）和 FISH 研究推定的新融合事件。
我们在 ROS1 和 RET 中各发现一例异常的 3' 到 5' 比值。RACE 分离出前者的 GOPC-ROS1（FIG-ROS1）融合和后者的 KIF5B-RET 融合，均通过 RT-PCR 证实。RET 重排也通过 FISH 证实。KIF5B-RET 患者是该队列中仅有的 5 例从不吸烟者之一。
KIF5B-RET 融合定义了一个具有潜在可靶向驱动致癌基因的肺癌亚群，在“全阴性”肺腺癌中，从不吸烟者中富含该基因。我们还在肺癌中报告了最初在胶质瘤细胞系中发现和表征的 GOPC-ROS1 融合。
