Functional interplay between MYCN, NCYM, and OCT4 promotes aggressiveness of human neuroblastomas.
Functional interplay between MYCN, NCYM, and OCT4 promotes aggressiveness of human neuroblastomas.
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DOI：
10.1111/cas.12677
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发表时间：
2015-07
期刊：
影响因子：
5.7
通讯作者：
Nakagawara A
中科院分区：
文献类型：
--
作者：
Kaneko Y;Suenaga Y;Islam SM;Matsumoto D;Nakamura Y;Ohira M;Yokoi S;Nakagawara A
神经母细胞瘤是一种起源于胚胎神经嵴细胞的儿童实体瘤。在预后不良的神经母细胞瘤中，MYCN基因位点经常扩增，其基因产物促进神经母细胞瘤的进展。然而，MYCN扩增导致神经母细胞瘤干细胞样状态的分子机制仍然不清楚。在本研究中，我们发现MYCN及其顺式反义基因NCYM与OCT4形成一个正反馈回路，OCT4是维持神经干细胞多能状态的核心调控基因。我们之前报道过，在原发性人类神经母细胞瘤中，NCYM与MYCN基因共同扩增，并且该基因产物通过稳定MYCN促进神经母细胞瘤的侵袭性。在36例MYCN扩增的原发性人类神经母细胞瘤中，OCT4 mRNA表达与不良预后相关，并且与NCYM的表达相关。OCT4蛋白在人类神经母细胞瘤细胞中诱导NCYM和MYCN，而NCYM稳定MYCN以诱导OCT4以及干细胞相关基因，包括NANOG、SOX2和LIN28。与MYCN形成鲜明对比的是，强制表达c - MYC不会增强人类神经母细胞瘤细胞中OCT4的表达。全反式维甲酸治疗降低了MYCN、NCYM和OCT4的表达，同时伴随着募集到MYCN内含子1区域的OCT4数量减少。敲低NCYM或OCT4抑制了神经母细胞瘤细胞球的形成，并促进了MYCN扩增的人类神经母细胞瘤细胞的不对称细胞分裂。这些结果表明，MYCN、NCYM和OCT4之间的功能相互作用促进了MYCN扩增的人类神经母细胞瘤的侵袭性。
Neuroblastoma is a pediatric solid tumor that originates from embryonic neural crest cells. The MYCN gene locus is frequently amplified in unfavorable neuroblastomas, and the gene product promotes the progression of neuroblastomas. However, the molecular mechanisms by which MYCN amplification contributes to stem cell-like states of neuroblastoma remain elusive. In this study, we show that MYCN and its cis-antisense gene, NCYM, form a positive feedback loop with OCT4, a core regulatory gene maintaining a multipotent state of neural stem cells. We previously reported that NCYM is co-amplified with the MYCN gene in primary human neuroblastomas and that the gene product promotes aggressiveness of neuroblastoma by stabilization of MYCN. In 36 MYCN-amplified primary human neuroblastomas, OCT4 mRNA expression was associated with unfavorable prognosis and was correlated with that of NCYM. The OCT4 protein induced both NCYM and MYCN in human neuroblastoma cells, whereas NCYM stabilized MYCN to induce OCT4 and stem cell-related genes, including NANOG, SOX2, and LIN28. In sharp contrast to MYCN, enforced expression of c-MYC did not enhance OCT4 expression in human neuroblastoma cells. All-trans retinoic acid treatment reduced MYCN, NCYM, and OCT4 expression, accompanied by the decreased amount of OCT4 recruited onto the intron 1 region of MYCN. Knockdown of NCYM or OCT4 inhibited formation of spheres of neuroblastoma cells and promoted asymmetric cell division in MYCN-amplified human neuroblastoma cells. These results suggest that the functional interplay between MYCN, NCYM, and OCT4 contributes to aggressiveness of MYCN-amplified human neuroblastomas.