O'Brien EM, Selfe JL, Martins AS, Walters ZS, Shipley JM. The long non-coding RNA MYCNOS-01 regulates MYCN protein levels and affects growth of MYCN-amplified rhabdomyosarcoma and neuroblastoma cells.
BMC Cancer 2018;
18:217. [PMID:
29466962 PMCID:
PMC5822637 DOI:
10.1186/s12885-018-4129-8]
[Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 02/13/2018] [Indexed: 12/02/2022] Open
Abstract
Background
MYCN is amplified in small cell lung cancers and several pediatric tumors, including alveolar rhabdomyosarcomas and neuroblastomas. MYCN protein is known to play a key oncogenic role in both alveolar rhabdomyosarcomas and neuroblastomas. MYCN opposite strand (MYCNOS) is a gene located on the antisense strand to MYCN that encodes alternatively spliced transcripts, two of which (MYCNOS-01 and MYCNOS-02) are known to be expressed in neuroblastoma and small cell lung cancer with reciprocal regulation between MYCNOS-02 and MYCN reported for neuroblastomas. We sought to determine a functional role for MYCNOS-01 in alveolar rhabdomyosarcoma and neuroblastoma cells and identify any associated regulatory effects between MYCN and MYCNOS-01.
Methods
MYCNOS-01, MYCNOS-02 and MYCN expression levels were assessed in alveolar rhabdomyosarcoma and neuroblastoma cell lines and tumor samples from patients using Affymetrix microarray data and quantitative RT-PCR. Following MYCNOS-01 or MYCN siRNA knockdown and MYCNOS-01 overexpression, transcript levels were assayed by quantitative RT-PCR and MYCN protein expression assessed by Western blot and immunofluorescence. Additionally, effects on cell growth, apoptosis and cell cycle profiles were determined by a metabolic assay, caspase activity and flow cytometry, respectively.
Results
MYCNOS-01 transcript levels were generally higher in NB and RMS tumor samples and cell lines with MYCN genomic amplification. RNA interference of MYCNOS-01 expression did not alter MYCN transcript levels but decreased MYCN protein levels. Conversely, MYCN reduction increased MYCNOS-01 transcript levels, creating a negative feedback loop on MYCN protein levels. Reduction of MYCNOS-01 or MYCN expression decreased cell growth in MYCN-amplified alveolar rhabdomyosarcoma and neuroblastoma cell lines. This is consistent with MYCNOS-01-mediated regulation of MYCN contributing to the phenotype observed.
Conclusions
An alternative transcript of MYCNOS, MYCNOS-01, post-transcriptionally regulates MYCN levels and affects growth in MYCN-amplified rhabdomyosarcoma and neuroblastoma cells.
Electronic supplementary material
The online version of this article (10.1186/s12885-018-4129-8) contains supplementary material, which is available to authorized users.
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