MicroRNAs in gastrointestinal cancer: a novel biomarker and its clinical application

Gastrointestinal (GI) cancers remain one of the most common malignancies and are the major cause of cancer deaths worldwide. Signifi cant advancements have improved our understanding of the pathogenesis and pathology of GI cancers, but high mortality rates, an unfavorable prognosis, and lack of clinical predictive biomarkers provide an impetus to investigate novel diagnostic/prognostic markers and therapeutic targets for GI cancers. MicroRNAs (miRNAs) are short (19-24 nucleotides), non-coding RNA molecules that regulate gene expression at the post-transcriptional level, thus playing an important role in modulating various biological processes. This includes developmental processes, proliferation, apoptosis, metabolism and differentiation, all involved in initiation and progression of various human cancers. Aberrant miRNA expression profi les have been observed in various cancer types at different stages, suggesting their potential as diagnostic and prognostic biomarkers. Due to their tumorand tissue-specifi c expression profi les, stability, and the availability of robust clinical assays for their detection in serum as well as in formalin-fi xed tissue samples, miRNAs have emerged as attractive candidates for diagnostic and prognostic applications. This review summarizes recent research supporting the utility of miRNAs as novel diagnostic/prognostic tools and therapeutic targets, thus potentially illuminating future treatment strategies for GI cancers.