Abstract
Purpose:MYCN is one of the most well-characterized genetic markers of neuroblastoma. However, the mechanisms as to how MYCN mediate neuroblastoma tumorigenesis are not fully clear. Increasing evidence has confirmed that the dysregulation of miRNAs is involved in MYCN-mediated neuroblastoma tumorigenesis, supporting their potential as therapeutic targets for neuroblastoma. Although miR-221 has been reported as one of the upregulated miRNAs, the interplay between miR-221 and MYCN-mediated neuroblastoma progression remains largely elusive.Experimental Design: The expression of miR-221 in the formalin-fixed, paraffin-embedded tissues from 31 confirmed patients with neuroblastoma was detected by locked nucleic acid-in situ hybridization and qRT-PCR. The correlation between miR-221 expression and clinical features in patients with neuroblastoma was assessed. The mechanisms as to how miR-221 regulate MYCN in neuroblastoma were addressed. The effect of miR-221 on cellular proliferation in neuroblastoma was determined both in vitro and in vivoResults: miR-221 was significantly upregulated in neuroblastoma tumor cells and tissues that overexpress MYCN, and high expression of miR-221 was positively associated with poor survival in patients with neuroblastoma. Nemo-like kinase (NLK) as a direct target of miR-221 in neuroblastoma was verified. In addition, overexpression of miR-221 decreased LEF1 phosphorylation but increased the expression of MYCN via targeting of NLK and further regulated cell cycle, particularly in S-phase, promoting the growth of neuroblastoma cells.Conclusions: This study provides a novel insight for miR-221 in the control of neuroblastoma cell proliferation and tumorigenesis, suggesting potentials of miR-221 as a prognosis marker and therapeutic target for patients with MYCN overexpressing neuroblastoma. Clin Cancer Res; 23(11); 2905-18. ©2016 AACR.
Highlights
Neuroblastoma is the most common childhood solid tumor, accounting for more than 7% of childhood malignancies and approximately 15% of all pediatric cancer deaths [1,2,3]
Results: miR-221 was significantly upregulated in neuroblastoma tumor cells and tissues that overexpress MYCN, and high expression of miR-221 was positively associated with poor survival in patients with neuroblastoma
This study provides a novel insight for miR-221 in the control of neuroblastoma cell proliferation and tumorigenesis, suggesting potentials of miR-221 as a prognosis marker and therapeutic target for patients with MYCN overexpressing neuroblastoma
Summary
Neuroblastoma is the most common childhood solid tumor, accounting for more than 7% of childhood malignancies and approximately 15% of all pediatric cancer deaths [1,2,3]. MYCN encodes the transcriptional regulator MYCN, which is expressed in the migrating neural crest [7]. MYCN has been shown to modulate the transcription of genes involved in cellular proliferation [9], cell cycle [10], DNA damage [11], and apoptosis [12, 13] in neuroblastoma. Hedgehog, and other growth factors have been identified to be involved in inducing MYCN expression in the neural crest [4] and might contribute to neuroblastoma initiation and progression. A direct link between MYCN and neuroblastoma is well-established, the regulatory mechanisms mediated by MYCN in neuroblastoma are not fully understood
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