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Br J Cancer. 2011 Jul 12;105(2):296-303. doi: 10.1038/bjc.2011.220. Epub 2011 Jun 7.

Tumour-suppressor microRNAs let-7 and mir-101 target the proto-oncogene MYCN and inhibit cell proliferation in MYCN-amplified neuroblastoma.

Author information

1
Department of Paediatrics, University Hospital of North-Norway, 9038 Tromsø, Norway.

Abstract

BACKGROUND:

MicroRNAs (miRNAs) regulate expression of many cancer-related genes through posttranscriptional repression of their mRNAs. In this study we investigate the proto-oncogene MYCN as a target for miRNA regulation.

METHODS:

A luciferase reporter assay was used to investigate software-predicted miRNA target sites in the 3'-untranslated region (3'UTR) of MYCN. The miRNAs were overexpressed in cell lines by transfection of miRNA mimics or miRNA-expressing plasmids. Mutation of the target sites was used to validate MYCN 3'UTR as a direct target of several miRNAs. To measure miRNA-mediated suppression of endogenous N-myc protein, inhibition of proliferation and inhibition of clonogenic growth, miRNAs were overexpressed in a MYCN-amplified neuroblastoma cell line.

RESULTS:

The results from this study show that MYCN is targeted by several miRNAs. In addition to the previously shown mir-34a/c, we experimentally validate mir-449, mir-19a/b, mir-29a/b/c, mir-101 and let-7e/mir-202 as direct MYCN-targeting miRNAs. These miRNAs were able to suppress endogenous N-myc protein in a MYCN-amplified neuroblastoma cell line. The let-7e and mir-202 were strong negative regulators of MYCN expression. The mir-101 and the let-7 family miRNAs let-7e and mir-202 inhibited proliferation and clonogenic growth when overexpressed in Kelly cells.

CONCLUSION:

The tumour-suppressor miRNAs let-7 and mir-101 target MYCN and inhibit proliferation and clonogenic growth of MYCN-amplified neuroblastoma cells.

PMID:
21654684
PMCID:
PMC3142803
DOI:
10.1038/bjc.2011.220
[Indexed for MEDLINE]
Free PMC Article

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