Abstract
MicroRNAs (miRNA) play pivotal oncogenic and tumor-suppressor roles in several human cancers. We sought to discover novel tumor-suppressor miRNAs in gastric cancer (GC). 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. Among the top 80 miRNAs differentially expressed between gastric tumors and normals (false discovery rate < 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, whereas 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 approximately 25% to 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 antiapoptotic 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 an OLFM4 3' untranslated region 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. miR-486 may function as a novel tumor-suppressor miRNA in GC. Its antioncogenic activity may involve the direct targeting and inhibition of OLFM4.
Highlights
Gastric cancer (GC) is the second leading cause of global cancer mortality with a high incidence in many Asian countries [1]
Among the top 80 miRNAs differentially expressed between gastric tumors and normals, we identified hsa-miR-486 as a significantly downregulated miRNA in primary GCs and GC cell lines
Supporting the biological relevance of OLFM4 as a miR-486 target, proliferation in GC cells was significantly reduced by OLFM4 silencing
Summary
Gastric cancer (GC) is the second leading cause of global cancer mortality with a high incidence in many Asian countries [1]. Most GC patients are diagnosed with advanced stage disease and show extremely poor prognosis [2]. The 5-year survival rate for patients with stage II disease. Authors' Affiliations: 1Cellular and Molecular Research and 2Division of Medical Oncology, National Cancer Centre of Singapore; 3Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School; 4Genome Institute of Singapore; 5Cancer Science Institute of Singapore, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; and 6Department of Internal Medicine, Yonsei Cancer Center, Yonsei University College of Medicine, Seodaemun-Ku, Seoul, Korea. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). Palanisamy: Michigan Center for Translational Pathology and Departments of Pathology, Ann Arbor, MI 48109.
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