Oxytocin stimulates expression of a noncoding RNA tumor marker in a human neuroblastoma cell line.

AIMS

A noncoding RNA, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), is upregulated in several malignant tumors. Its expression in neuroblastoma, however, is not known, and the regulatory mechanisms of MALAT1 gene expression have not been elucidated. The aim of this study is to clarify how MALAT1 gene expression is altered by extracellular signals in the SK-N-SH neuroblastoma cell line and to define its proximal promoter in order to study the mechanism of MALAT1 gene expression.

METHODS

Transcript amounts were analyzed by real-time semiquantitative polymerase chain reaction (qPCR). Genes coregulated with MALAT1 were identified by DNA microarray analysis. The structure of the MALAT1 transcript was delineated using a tiling microarray, and the 5'-end was determined using the rapid amplification of cDNA ends (RACE) method. We investigated binding of the cyclic AMP-responsive element binding (CREB) transcription factor to the MALAT1 promoter by using chromatin immunoprecipitation (ChIP) followed by tiling array analysis, and the results were confirmed using ChIP-qPCR.

KEY FINDINGS

The posterior pituitary hormone oxytocin increased the levels of MALAT1 and immediate early gene transcripts as early as 15 min after stimulation. Although the expression of immediate early genes returned to basal levels after 3h, MALAT1 transcript levels peaked 6-24h after stimulation. We identified a shorter transcriptional initiation site and found that CREB binds to the defined proximal promoter of the MALAT1 gene.

SIGNIFICANCE

The expression of the tumor marker MALAT1 ncRNA is sensitive to cell surface receptor activation by oxytocin in a neuroblastoma cell line.