ABSTRACT

The role of the inflammation-silencing ribonuclease, MCPIP1 (monocyte chemoattractant protein-induced protein 1), in neoplasia continuous to emerge. The ribonuclease can cleave not only inflammation-related transcripts but also some microRNAs (miRNAs) and viral RNAs. The suppressive effect of the protein has been hitherto suggested in breast cancer, clear cell renal cell carcinoma, osteosarcoma, and neuroblastoma. Our previous results have demonstrated a reduced levels of several oncogenes, as well as inhibited growth of neuroblastoma cells upon MCPIP1 overexpression. Here, we investigate the mechanisms underlying the suppression of MYCN proto-oncogene, bHLH transcription factor (MYCN)-amplified neuroblastoma cells overexpressing the MCPIP1 protein. We showed that the levels of several transcripts involved in cell cycle progression decreased in BE(2)-C and KELLY cells overexpressing MCPIP1 in a ribonucleolytic activity-dependent manner. However, RNA immunoprecipitation indicated that only AURKA mRNA (encoding for Aurora A kinase) interacts with the ribonuclease. Furthermore, the application of a luciferase assay suggested MCPIP1-dependent destabilization of the transcript. Further analyses demonstrated that the entire conserved region of AURKA seems to be indispensable for the interaction with the MCPIP1 protein. Additionally, we examined the effect of the ribonuclease overexpression on the miRNA expression profile in MYCN-amplified neuroblastoma cells. However, no significant alterations were observed. Our data indicate a key role of the binding and cleavage of the AURKA transcript in an MCPIP1-dependent suppressive effect on neuroblastoma cells.

摘要

炎症沉默核糖核酸酶 MCPIP1（单核细胞趋化蛋白诱导蛋白 1）在瘤形成中的作用不断出现。核糖核酸酶不仅可以切割与炎症相关的转录物，还可以切割一些微 RNA (miRNA) 和病毒 RNA。迄今为止，已经在乳腺癌、透明细胞肾细胞癌、骨肉瘤和神经母细胞瘤中提出了该蛋白质的抑制作用。我们之前的结果表明，MCPIP1 过表达后几种致癌基因的水平降低，并且神经母细胞瘤细胞的生长受到抑制。在这里，我们研究了抑制 MYCN 原癌基因 bHLH 转录因子（MYCN)-扩增的神经母细胞瘤细胞过度表达 MCPIP1 蛋白。我们表明，在 BE(2)-C 和 KELLY 细胞中，参与细胞周期进程的几种转录物的水平以一种依赖于核糖核酸活性的方式过表达 MCPIP1。然而，RNA 免疫沉淀表明只有AURKA mRNA（编码 Aurora A 激酶）与核糖核酸酶相互作用。此外，荧光素酶测定的应用表明转录物的 MCPIP1 依赖性不稳定。进一步的分析表明，AURKA的整个保守区域似乎对于与 MCPIP1 蛋白的相互作用是必不可少的。此外，我们检查了核糖核酸酶过表达对MYCN 中miRNA 表达谱的影响-扩增的神经母细胞瘤细胞。然而，没有观察到显着的改变。我们的数据表明AURKA转录物的结合和裂解在对神经母细胞瘤细胞的 MCPIP1 依赖性抑制作用中起关键作用。