Department of Paediatrics, University Hospital of North-Norway, 9038 Tromsø, Norway.
Differentiation. 2011 Jan;81(1):25-34. doi: 10.1016/j.diff.2010.09.184. Epub 2010 Oct 25.
Neuroblastoma is a malignant childhood tumour arising from precursor cells of the sympathetic nervous system. Genomic amplification of the MYCN oncogene is associated with dismal prognosis. For this group of high-risk tumours, the induction of tumour cell differentiation is part of current treatment protocols. MicroRNAs (miRNAs) are small non-coding RNA molecules that effectively reduce the translation of target mRNAs. MiRNAs play an important role in cell proliferation, apoptosis, differentiation and cancer. In this study, we investigated the role of N-myc on miRNA expression in MYCN-amplified neuroblastoma. We performed a miRNA profiling study on SK-N-BE (2) cells, and determined differentially expressed miRNAs during differentiation initiated by MYCN knockdown, using anti-MYCN short-hairpin RNA (shRNA) technology.
Microarray analyses revealed 23 miRNAs differentially expressed during the MYCN knockdown-mediated neuronal differentiation of MNA neuroblastoma cells. The expression changes were bidirectional, with 11 and 12 miRNAs being up- and down-regulated, respectively. Among the down-regulated miRNAs, we found several members of the mir-17 family of miRNAs. Mir-21, an established oncomir in a variety of cancer types, became strongly up-regulated upon MYCN knockdown and the subsequent differentiation. Neither overexpression of mir-21 in the high-MYCN neuroblastoma cells, nor repression of increased mir-21 levels during MYCN knockdown-mediated differentiation had any significant effects on cell differentiation or proliferation.
We describe a subset of miRNAs that were altered during the N-myc deprived differentiation of MYCN-amplified neuroblastoma cells. In this context, N-myc acts as both an activator and suppressor of miRNA expression. Mir-21 was up-regulated during cell differentiation, but inhibition of mir-21 did not prevent this process. We were unable to establish a role for this miRNA during differentiation and proliferation of the two neuroblastoma cell lines used in this study.
神经母细胞瘤是一种起源于交感神经系统前体细胞的恶性儿童肿瘤。MYCN 癌基因的基因组扩增与预后不良相关。对于这组高危肿瘤，诱导肿瘤细胞分化是当前治疗方案的一部分。microRNAs（miRNAs）是小的非编码 RNA 分子，可有效降低靶 mRNA 的翻译。miRNAs 在细胞增殖、凋亡、分化和癌症中发挥重要作用。在这项研究中，我们研究了 N-myc 在 MYCN 扩增神经母细胞瘤中对 miRNA 表达的作用。我们对 SK-N-BE（2）细胞进行了 miRNA 谱分析，并使用抗 MYCN 短发夹 RNA（shRNA）技术确定了在 MYCN 敲低诱导的神经分化过程中差异表达的 miRNAs。
微阵列分析显示，在 MNA 神经母细胞瘤细胞的 MYCN 敲低介导的神经元分化过程中，有 23 个 miRNAs 差异表达。表达变化是双向的，分别有 11 个和 12 个 miRNAs 上调和下调。在下调的 miRNAs 中，我们发现了几个 mir-17 家族的 miRNA。mir-21 是多种癌症类型中的一种公认的致癌 miRNA，在 MYCN 敲低和随后的分化过程中强烈上调。在高 MYCN 神经母细胞瘤细胞中过表达 mir-21 或在 MYCN 敲低介导的分化过程中抑制 mir-21 水平的增加都没有对细胞分化或增殖产生任何显著影响。
我们描述了一组在 MYCN 扩增神经母细胞瘤细胞缺乏 N-myc 分化过程中改变的 miRNAs。在这种情况下，N-myc 既是 miRNA 表达的激活剂又是抑制剂。mir-21 在细胞分化过程中上调，但抑制 mir-21 并不能阻止这一过程。我们无法确定该 miRNA 在这两种神经母细胞瘤细胞系的分化和增殖过程中的作用。
