Luxton Hayley J, Simpson Benjamin S, Mills Ian G, Brindle Nicola R, Ahmed Zeba, Stavrinides Vasilis, Heavey Susan, Stamm Stefan, Whitaker Hayley C
Molecular Therapeutics and Diagnostics Group, University College London, London W1W 7TS, UK.
Uro-Oncology Research Group, Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, UK.
Cancers (Basel). 2019 Aug 23;11(9):1233. doi: 10.3390/cancers11091233.
Oncogenic metadherin is a key contributor to tumourigenesis with metadherin expression and cytoplasmic localisation previously linked to poor survival. A number of reports have shown metadherin localises specifically to nuclear speckles known to be rich in RNA-binding proteins including the splicing proteins YTHDC1, Sam68 and T-STAR, that have been shown to select alternative splice sites in mRNA of tumour-associated proteins including BRCA, MDM2 and VEGF. Here we investigate the interaction and relationship between metadherin and the splice factors YTHDC1, T-STAR and Sam68. Using a yeast two-hybrid assay and immunoprecipitation we show that metadherin interacts with YTHDC1, Sam68 and T-STAR and demonstrate that T-STAR is significantly overexpressed in prostate cancer tissue compared to benign prostate tissue. We also demonstrate that metadherin influences splice site selection in a dose-dependent manner in CD44v5-luc minigene reporter assays. Finally, we demonstrate that prostate cancer patients with higher metadherin expression have greater expression of the CD44v5 exon. CD44v5 expression could be used to discriminate patients with poor outcomes following radical prostatectomy. In this work we show for the first time that metadherin interacts with, and modulates, the function of key components of splicing associated with cancer development and progression.
致癌性黏附素是肿瘤发生的关键促成因素，黏附素的表达和细胞质定位先前与较差的生存率相关。多项报告显示，黏附素特异性定位于富含RNA结合蛋白的核斑点，这些蛋白包括剪接蛋白YTHDC1、Sam68和T-STAR，它们已被证明可在包括BRCA、MDM2和VEGF在内的肿瘤相关蛋白的mRNA中选择可变剪接位点。在此，我们研究黏附素与剪接因子YTHDC1、T-STAR和Sam68之间的相互作用及关系。利用酵母双杂交试验和免疫沉淀，我们发现黏附素与YTHDC1、Sam68和T-STAR相互作用，并证明与良性前列腺组织相比，T-STAR在前列腺癌组织中显著过表达。我们还在CD44v5-luc微型基因报告试验中证明，黏附素以剂量依赖的方式影响剪接位点选择。最后，我们证明黏附素表达较高的前列腺癌患者CD44v5外显子的表达更高。CD44v5表达可用于区分根治性前列腺切除术后预后不良的患者。在这项工作中，我们首次表明黏附素与癌症发生发展相关的关键剪接成分相互作用并调节其功能。
