Wei J S, Song Y K, Durinck S, Chen Q-R, Cheuk A T C, Tsang P, Zhang Q, Thiele C J, Slack A, Shohet J, Khan J
Oncogenomics Section, Pediatric Oncology Branch, Advanced Technology Center, National Cancer Institute, Gaithersburg, MD 20892, USA.
Oncogene. 2008 Sep 4;27(39):5204-13. doi: 10.1038/onc.2008.154. Epub 2008 May 26.
Loss of 1p36 heterozygosity commonly occurs with MYCN amplification in neuroblastoma tumors, and both are associated with an aggressive phenotype. Database searches identified five microRNAs that map to the commonly deleted region of 1p36 and we hypothesized that the loss of one or more of these microRNAs contributes to the malignant phenotype of MYCN-amplified tumors. By bioinformatic analysis, we identified that three out of the five microRNAs target MYCN and of these miR-34a caused the most significant suppression of cell growth through increased apoptosis and decreased DNA synthesis in neuroblastoma cell lines with MYCN amplification. Quantitative RT-PCR showed that neuroblastoma tumors with 1p36 loss expressed lower level of miR-34a than those with normal copies of 1p36. Furthermore, we demonstrated that MYCN is a direct target of miR-34a. Finally, using a series of mRNA expression profiling experiments, we identified other potential direct targets of miR-34a, and pathway analysis demonstrated that miR-34a suppresses cell-cycle genes and induces several neural-related genes. This study demonstrates one important regulatory role of miR-34a in cell growth and MYCN suppression in neuroblastoma.
在神经母细胞瘤中，1p36杂合性缺失常与MYCN扩增同时出现，且二者均与侵袭性表型相关。数据库检索发现5种微小RNA定位于1p36的常见缺失区域，我们推测这些微小RNA中一种或多种的缺失促成了MYCN扩增肿瘤的恶性表型。通过生物信息学分析，我们确定这5种微小RNA中有3种靶向MYCN，其中miR-34a通过增加凋亡和减少MYCN扩增的神经母细胞瘤细胞系中的DNA合成，对细胞生长产生了最显著的抑制作用。定量逆转录-聚合酶链反应显示，1p36缺失的神经母细胞瘤肿瘤比1p36拷贝数正常的肿瘤表达更低水平的miR-34a。此外，我们证明MYCN是miR-34a的直接靶点。最后，通过一系列mRNA表达谱实验，我们确定了miR-34a的其他潜在直接靶点，通路分析表明miR-34a抑制细胞周期基因并诱导多个神经相关基因。本研究证明了miR-34a在神经母细胞瘤细胞生长和MYCN抑制中的一个重要调节作用。
