Coulier F, Kumar R, Ernst M, Klein R, Martin-Zanca D, Barbacid M
BRI-Basic Research Program, National Cancer Institute-Frederick Cancer Research Facility, Maryland 21701.
Mol Cell Biol. 1990 Aug;10(8):4202-10. doi: 10.1128/mcb.10.8.4202-4210.1990.
Malignant activation of the human trk proto-oncogene, a member of the tyrosine protein kinase receptor family, has been implicated in the development of certain human cancers, including colon and thyroid papillary carcinomas. trk oncogenes have also been identified in cultured cells transfected with various DNAs. In this study, we report the characterization of three in vitro-generated trk oncogenes, trk2, trk4, and trk5 (R. Oskam, F. Coulier, M. Ernst, D. Martin-Zanca, and M. Barbacid, Proc. Natl. Acad. Sci. USA 85:2964-2968, 1988), in an effort to understand the spectrum of mutational events that can activate the human trk gene. Nucleotide sequence analysis of cDNA clones of trk2 and trk4 revealed that these oncogenes were generated by a head-to-tail arrangement of two trk tyrosine protein kinase domains connected by a purine-rich region. These oncogenes code for cytoplasmic molecules of 67,000 (p67trk2) and 69,000 (p69trk4) daltons. In contrast, the product of the trk5 oncogene, gp95trk5, is a cell surface glycoprotein of 95,000 daltons. This oncogene was generated by a 153-base-pair in-frame deletion within sequences coding for the extracellular domain of the trk receptor. This activating deletion encompasses a triplet coding for one of the nine cysteine residues that the trk receptor shares with the product of the highly related trkB tyrosine protein kinase gene. Introduction of a single point mutation (TGT----AGT) in this codon resulted in a novel trk oncogene whose product, gp140S345, differs from the nontransforming trk proto-oncogene receptor in a single amino acid residue, Ser-345 instead of Cys-345. These results illustrate that multiple molecular mechanisms, including point mutation, internal deletion, and kinase domain duplication, can result in the malignant activation of the human trk proto-oncogene.
人trk原癌基因是酪氨酸蛋白激酶受体家族的成员，其恶性激活与某些人类癌症的发生有关，包括结肠癌和甲状腺乳头状癌。在转染了各种DNA的培养细胞中也发现了trk癌基因。在本研究中，我们报告了三个体外产生的trk癌基因trk2、trk4和trk5（R. Oskam、F. Coulier、M. Ernst、D. Martin-Zanca和M. Barbacid，《美国国家科学院院刊》85:2964 - 2968，1988）的特征，以了解可激活人trk基因的突变事件谱。trk2和trk4的cDNA克隆的核苷酸序列分析表明，这些癌基因是由两个trk酪氨酸蛋白激酶结构域通过富含嘌呤的区域首尾相连排列产生的。这些癌基因编码67,000道尔顿（p67trk2）和69,000道尔顿（p69trk4）的细胞质分子。相比之下，trk5癌基因的产物gp95trk5是一种95,000道尔顿的细胞表面糖蛋白。该癌基因是由trk受体细胞外结构域编码序列内153个碱基对的框内缺失产生的。这种激活缺失包含一个三联体密码子缺失，该三联体编码trk受体与高度相关的trkB酪氨酸蛋白激酶基因产物共有的九个半胱氨酸残基之一。在这个密码子中引入一个单点突变（TGT----AGT）产生了一个新的trk癌基因，其产物gp140S345与非转化性trk原癌基因受体在单个氨基酸残基上不同，是Ser - 345而非Cys - 345。这些结果表明，多种分子机制，包括点突变、内部缺失和激酶结构域重复，均可导致人trk原癌基因的恶性激活。
