MicroRNAs in gastric cancer: from bench to bedside

Gastric carcinogenesis results from complex interactions between host and environmental and bacterial factors, and this leads to genetic and epigenetic deregulation of oncogenic and tumor-suppressive genes. MicroRNAs (miRNAs) are a class of small noncoding RNAs which regulate almost 30% of human genes post transcriptionally and they are crucial in the initiation and progression of various diseases; especially malignancies. Accumulated evidence documents changes in gene sequences and epigenetic modifications. These then lead to abnormal miRNA expression in gastric cancer (GC) and also to deregulated miRNAs which act as oncogenes or tumor suppressors by regulating related target genes and contributing to malignant phenotypes. This altered miRNA expression in body fluids could well provide a novel biomarker for GC patient diagnosis and prognosis. MiRNAs present a promising target for GC treatment, and more tempting, for eradication of gastric cancer stem cells. This latter sub-group of tumor cells is thought to initiate and maintain GC development. Herein, we review the aberrant expression of miRNA expression and the underlying mechanisms and consequential effects of miRNA de-regulation. This identifies the responsible gastric cancer target genes, and highlights potential clinical applications.