Novel splicing variants of recepteur d'origine nantais (RON) tyrosine kinase involving exons 15-19 in lung cancer
Novel splicing variants of recepteur d'origine nantais (RON) tyrosine kinase involving exons 15-19 in lung cancer
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DOI：
10.1016/j.lungcan.2015.12.002
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发表时间：
2016-02-01
期刊：
影响因子：
5.3
通讯作者：
Al-Daghri, Nasser M.
中科院分区：
文献类型：
--
作者：
Krishnaswamy, Soundararajan;Mohammed, Abdul Khader;Al-Daghri, Nasser M.
背景：受体酪氨酸激酶的表达改变驱动了几种癌症的生长和转移。RON是一种单代跨膜受体酪氨酸激酶（RTK），在多种癌症类型中异常表达。然而，RON在癌症中的靶标验证和成功的治疗靶向受到未知数量/类型的同种异构体共存的阻碍，这些同种异构体在结构上相似但在功能上不同。目的：本研究的目的是鉴定RON转录本c端区域的差异剪接，以更好地了解RON在癌症中的信号传导。利用10株SCLC和13株NSCLC细胞株的cDNA，对RON外显子14 ~ 20之间的mRNA转录序列进行PCR扩增和测序。通过测序色谱图与参考RON cDNA序列比对，鉴定出特异性外显子缺失。结果：我们发现了通过跳过外显子15-19、16-19、16-17和16形成的四个独特的RON转录序列变体。除了缺少外显子15-19外，转录本变体在多个细胞系中被发现。一些细胞系含有两到四个这种独特剪接的转录物变体。dbEST（表达序列标签数据库）或其他DNA序列数据库不包含与上述任何外显子缺失对应的RON cDNA序列，表明所有这些转录序列改变都是新的。结论：我们的研究结果表明，肺癌中普遍存在不同类型的RON选择性剪接转录本，这些转录本可能被翻译成缺乏活性激酶结构域的蛋白质。我们的研究结果表明，肿瘤产生几种可能抑制配体依赖性RON信号的显性阴性亚型，因此提出了关于阻断野生型RON信号治疗是否合适的重要问题。此外，转录物变体及其异构体产物的存在可能会干扰目标验证过程中的定量和功能分析。2015爱思唯尔爱尔兰有限公司版权所有。
Background: Altered expressions of receptor tyrosine kinases drive the growth and metastasis of several cancers. RON is a single pass transmembrane receptor tyrosine kinase (RTK) shown to be aberrantly expressed in various cancer types. However, target validation and successful therapeutic targeting of RON in cancers is hampered by the co-existence of unknown number/types of isoforms, which are structurally similar but functionally diverse.Objective: The objective of this study was to identify differential splicing in the C-terminal region of RON transcripts to better understand RON signaling in cancers. mRNA transcript sequence between exons 14 and 20 of RON was PCR amplified and sequenced using cDNA from 10 SCLC and 13 NSCLC cell lines. Specific exon deletions were identified by aligning sequencing chromatograms with reference RON cDNA sequence.Results: We identified the presence of four unique transcript sequence variants of RON formed through skipping of exons 15-19,16-19,16-17 and 16. The transcript variants, except the one lacking exons 15-19, were found in more than one cell line. Several cell lines contained two to four of these uniquely spliced transcript variants. dbEST (Expressed Sequence Tags database) or other DNA sequence databases did not contain RON cDNA sequences corresponding to any of the above exon deletions indicating that all these transcript sequence alterations are novel.Conclusions: Results of our study indicate common occurrence of different types of alternatively spliced transcripts of RON in lung cancer with potential to be translated into proteins lacking active kinase domain. Our findings suggest that tumors produce several dominant negative isoforms which probably inhibit ligand dependent RON signaling, and hence, raise important questions regarding the appropriateness of blocking wild type RON signaling for therapy. Further, presence of transcript variants and their isoform products may interfere with quantitative and functional analysis during target validation. (C) 2015 Elsevier Ireland Ltd. All rights reserved.