Clin Cancer Res. 2011 Mar 17. [Epub ahead of print]
Genomic Loss of miR-486 Regulates Tumor Progression and the OLFM4 Anti-apoptotic Factor in Gastric Cancer.
Oh HK, Tan AL, Das K, Ooi CH, Deng NT, Tan IB, Beillard E, Lee J, Ramnarayanan K, Rha SY, Palanisamy N, Voorhoeve PM, Tan P.
Cellular and Molecular Research, National Cancer Centre, Singapore.
Abstract
PURPOSE: MicroRNAs (miRNAs) play pivotal oncogenic and tumor suppressor roles in several human cancers. We sought to discover novel tumor suppressor miRNAs in gastric cancer (GC).
EXPERIMENTAL DESIGN: Using Agilent miRNA microarrays, we compared miRNA expression profiles of 40 primary gastric tumors and 40 gastric normal tissues, identifying miRNAs significantly downregulated in gastric tumors.
RESULTS: Among the top 80 miRNAs differentially expressed between gastric tumors and normals (FDR<0.01), we identified hsa-miR-486 (miR-486) as a significantly downregulated miRNA in primary GCs and GC cell lines. Restoration of miR-486 expression in GC cell lines (YCC3, SCH and AGS) caused suppression of several pro-oncogenic traits, while conversely inhibiting miR-486 expression in YCC6 GC cells enhanced cellular proliferation. Array-CGH analysis of 106 primary GCs revealed genomic loss of the miR-486 locus in ~25-30% of GCs, including two tumors with focal genomic losses specifically deleting miR-486, consistent with miR-486 playing a tumor suppressive role. Bioinformatic analysis identified the secreted anti-apoptotic glycoprotein OLFM4 as a potential miR-486 target. Restoring miR-486 expression in GC cells decreased endogenous OLFM4 transcript and protein levels, and also inhibited expression of luciferase reporters containing a OLFM4 3' untranslated region (UTR) with predicted miR-486 binding sites. Supporting the biological relevance of OLFM4 as a miR-486 target, proliferation in GC cells was also significantly reduced by OLFM4 silencing.
CONCLUSIONS: miR-486 may function as a novel tumor suppressor miRNA in GC. Its anti-oncogenic activity may involve the direct targeting and inhibition of OLFM4.
