Metastasis is a common feature in advanced cancers. To elucidate the mechanism underlying metastasis from analysis of primary disease would have substantial clinical benefit. MicroRNAs (miRNAs) have started a revolution in molecular biology, and emerged as key players in carcinogenesis. They have been identified in various tumor types, showing that different sets of miRNAs are usually deregulated in different cancers. Moreover, some miRNAs are aberrantly methylated and silenced, causing tumorigenesis. In the paper evaluated, the authors identified aberrantly methylated and silenced miRNAs that are cancer-specific using miRNA microarray techniques. Functional analyses for the selected genes proved that these miRNAs act on C-MYC, E2F3, CDK6 and TGIF2, resulting in metastasis through aberrant methylation of the miRNAs. These findings may have broad implications for mechanisms underlying metastasis in malignancies, and may be applicable to advance research in the clinical setting.