Angiogenesis, Metastasis, and the Cellular Microenvironment miRNA-223 Promotes Gastric Cancer Invasion and Metastasis by Targeting Tumor Suppressor EPB41L3

Traditional research modes aim to find cancer-specific single therapeutic target. Recently, emerging evidence suggested that some micro-RNAs (miRNA) can function as oncogenes or tumor suppressors. miRNAs are singlestranded, small noncoding RNA genes that can regulate hundreds of downstream target genes. In this study, we evaluated the miRNA expression patterns in gastric carcinoma and the specific role of miR-223 in gastric cancer metastasis. miRNA expression signature was first analyzed by real-time PCR on 10 paired gastric carcinomas and confirmed in another 20 paired gastric carcinoma tissues. With the 2-fold expression difference as a cutoff level, we identified 22 differential expressed mature miRNAs. Sixteen miRNAs were upregulated in gastric carcinoma, including miR-223, miR-21, miR-23b, miR-222, miR-25, miR-23a, miR-221, miR-107, miR-103, miR-99a, miR-100, miR-125b, miR-92, miR-146a, miR-214 and miR-191, and six miRNAs were downregulated in gastric carcinoma, including let-7a, miR-126, miR-210, miR-181b, miR-197, and miR-30aa-5p. After examining these miRNAs in several human gastric originated cell lines, we found that miR-223 is overexpressed only in metastatic gastric cancer cells and stimulated nonmetastatic gastric cancer cells migration and invasion. Mechanistically, miR-223, induced by the transcription factor Twist, posttranscriptionally downregulates EPB41L3 expression by directly targeting its 30-untranslated regions. Significantly, overexpression of miR-223 in primary gastric carcinomas is associated with poor metastasis-free survival. These findings indicate a new regulatory mode, namely, specific miRNA, which is activated by its upstream transcription factor, could suppress its direct targets and lead to tumor invasion and metastasis. Mol Cancer Res; 9(7); 824–33. 2011 AACR.