MicroRNA as a molecular target for gastrointestinal cancers

MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally suppress the expression of many target genes, thereby contributing to the modulation of diverse cellular fates in tumor biology. Recent accumulating evidences have demonstrated that aberrant expression of miRNAs is highly associated with tumor initiation, progression and metastasis in various types of cancers including gastrointestinal (GI) cancers. Exploration of precise miRNA-based gene regulatory networks in the pathogenesis of GI cancers will provide important information for the development of novel anticancer strategies aimed at normalizing the critical miRNAs that are deregulated in GI cancers. Recent reports using clinical samples have shown the potential of upregulation of oncogenic miR-21 and of downregulation of the tumor-suppressive miR-34 family as novel molecular biomarkers for the diagnostic and prognostic prediction of GI cancers. In this review, we have focused on the functional roles of these two cancer-related miRNAs, miR-21 and miR-34, that are commonly deregulated during the development and progression of GI cancers. Moreover, the therapeutic potential of miRNA-targeting anticancer therapy is discussed for clinical application as novel anticancer therapy for GI cancers.