BACKGROUND - microRNA (miRNA) functions broadly as post-transcriptional regulators of gene expression, and disproportionate miRNAs can result in dysregulation of oncogenes in cancer cells. We have previously shown that gastrin-releasing peptide receptor (GRP-R) signaling regulates tumorigenicity of neuroblastoma cells. Herein, we sought to characterize miRNA profile in GRP-R silenced neuroblastoma cells, and to determine the role of miRNAs on tumorigenicity and metastatic potential.
METHODS - Human neuroblastoma cell lines, BE(2)-C and SK-N-SH, were used for our study. Stably transfected GRP-R silenced cells were assessed for miRNA profiles. Cells were transfected with miR-335, miR-363, or miR-CON, a nontargeting control, and in vitro assays were performed. In vivo functions of miR-335 and miR-363 were also assessed in a spleen-liver metastasis murine model.
RESULTS - GRP-R silencing significantly increased expression of miR-335 and miR-363 in BE(2)-C cells. Overexpression of miR-335 and miR-363 decreased tumorigenicity as measured by clonogenicity, anchorage-independent growth, and metastasis determined by cell invasion assay and liver metastasis in vivo.
CONCLUSION - We report, for the first time, that GRP-R-mediated tumorigenicity and increased metastatic potential in neuroblastoma are regulated, in part, by miR-335 and miR-363. A better understanding of the anti-tumor functions of miRNAs could provide valuable insights to discerning molecular mechanisms responsible for neuroblastoma metastasis.
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