微型核醣核酸miR-124於神經母細胞瘤之角色

Abstract

神經母細胞瘤係源自於胚胎神經脊細胞的惡性腫瘤，它是不滿一歲以下兒童最常見的腫瘤之一，為一種生物行為十分複雜的腫瘤。目前已知在神經母細胞瘤中若帶有多倍數MYCN其預後極差，但是對於MYCN如何去影響腫瘤的進程其機制尚未明瞭。之前我們的分析發現，MYCN表現量會與AHR表現量呈現高度的負相關，可能代表AHR對於神經母細胞瘤進程有影響，此外經由預測發現miR-124可能會影響AHR的表現量。因此，在本篇實驗中，透過提高和降低miR-124在腫瘤細胞株中的量，我們證實了AHR的表現會受到miR-124的負向調控，而在降低了miR-124的量後MYCN的表現亦隨之下降。在前人的研究當中發現，AHR會影響發育分化過程，也有報告指出，MYCN的高度表現會使細胞走向不分化的命運。而我們在SK-N-SH這株神經母細胞瘤細胞株當中觀察到當miR-124降低，細胞會呈現出相似於分化的外觀，再透過偵測一些會在分化時高度表現的蛋白質表現量，例如growth-associated protein 43 (GAP-43)、calreticulin (CRT)還有neuron-specific enolase (NSE)，證實的確miR-124降低時細胞會走向分化的命運。我們推測很可能是因為在miR-124降低時，AHR表現量升高而MYCN表現量下降導致細胞分化的結果出現。這項研究結果指出miR-124在神經母細胞瘤的進程上也許扮演一個重要的角色，也對未來神經母細胞瘤的治療開啟新的方向。

Neuroblastoma (NB) is an embryonic cancer of the postganglionic sympathetic nervous system, which is the most common tumor in children less than one year of age. Myc myelocytomatosis viral related oncogene, neuroblastoma derived (MYCN) amplification is known to be a marker of poor prognosis in NB patients. Our previous study found that N-myc expression level was inversely correlated with aryl hydrocarbon receptor (AHR). MicroRNAs have recently emerged as important regulators that play a significant role in tumorigenesis. In this study, gain-and loss-of-function analyses of miR-124 showed that miR-124 negatively regulated endogenous AHR protein expression in tumor cells. Anti-miR-124 inhibitor treatment decreased N-myc mRNA expression. MYCN has also been reported to prevent normal induction of neuroblast differentiation. Surprisingly, we observed changes in cellular morphology after inhibiting the endogenous miR-124 in SK-N-SH cell line. We also found that several cell differentiation markers, i.e. growth-associated protein 43 (GAP-43), calreticulin (CRT) and neuron-specific enolase (NSE) were up-regulated after anti-miR-124 treatment. It is possible that miR-124 suppression causes AHR up-regulation and MYCN down-regulation, resulting in cell differentiation. Our data suggest that miR-124 may play an important role in neuroblastoma cell differentiation and serve as a potential target for neuroblastoma therapy.