Herrero-Martín D, Osuna D, Ordóñez J L, Sevillano V, Martins A S, Mackintosh C, Campos M, Madoz-Gúrpide J, Otero-Motta A P, Caballero G, Amaral A T, Wai D H, Braun Y, Eisenacher M, Schaefer K-L, Poremba C, de Alava E
Molecular Pathology Program, Centro de Investigación del Cáncer-IBMCC (USAL-CSIC), Campus Unamuno s/n, Salamanca, Spain.
Br J Cancer. 2009 Jul 7;101(1):80-90. doi: 10.1038/sj.bjc.6605104. Epub 2009 Jun 2.
Ewing sarcoma is a paradigm of solid tumour -bearing chromosomal translocations resulting in fusion proteins that act as deregulated transcription factors. Ewing sarcoma translocations fuse the EWS gene with an ETS transcription factor, mainly FLI1. Most of the EWS-FLI1 target genes still remain unknown and many have been identified in heterologous model systems.
We have developed a stable RNA interference model knocking down EWS-FLI1 in the Ewing sarcoma cell line TC71. Gene expression analyses were performed to study the effect of RNA interference on the genetic signature of EWS-FLI1 and to identify genes that could contribute to tumourigenesis.
EWS-FLI1 inhibition induced apoptosis, reduced cell migratory and tumourigenic capacities, and caused reduction in tumour growth. IGF-1 was downregulated and the IGF-1/IGF-1R signalling pathway was impaired. PBK/TOPK (T-LAK cell-originated protein kinase) expression was decreased because of EWS-FLI1 inhibition. We showed that TOPK is a new target gene of EWS-FLI1. TOPK inhibition prompted a decrease in the proliferation rate and a dramatic change in the cell's ability to grow in coalescence.
This is the first report of TOPK activity in Ewing sarcoma and suggests a significant role of this MAPKK-like protein kinase in the Ewing sarcoma biology.
尤因肉瘤是实体瘤中存在染色体易位的典型例子，这种易位会产生融合蛋白，这些融合蛋白作为失调的转录因子发挥作用。尤因肉瘤易位会将EWS基因与ETS转录因子（主要是FLI1）融合。大多数EWS-FLI1靶基因仍不为人知，许多已在异源模型系统中得到鉴定。
我们构建了一个稳定的RNA干扰模型，在尤因肉瘤细胞系TC71中敲低EWS-FLI1。进行基因表达分析以研究RNA干扰对EWS-FLI1基因特征的影响，并鉴定可能有助于肿瘤发生的基因。
EWS-FLI1抑制诱导细胞凋亡，降低细胞迁移和致瘤能力，并导致肿瘤生长减缓。IGF-1下调，IGF-1/IGF-1R信号通路受损。由于EWS-FLI1抑制，PBK/TOPK（T-LAK细胞起源的蛋白激酶）表达降低。我们证明TOPK是EWS-FLI1的一个新靶基因。TOPK抑制促使增殖率降低以及细胞聚集体生长能力发生显著变化。
这是关于TOPK在尤因肉瘤中活性的首次报道，并表明这种类MAPKK蛋白激酶在尤因肉瘤生物学中具有重要作用。
