Micro (mi)RNAs are small, noncoding RNAs that regulate gene expression through binding to the 3´-untranslated region of mRNAs by complementary base pairing and mainly act through cleavage or translational inhibition of mRNAs. Recent studies have shown the roles of miRNAs in development and cancer, revealing the physiological and pathological importance of these tiny molecules. Therefore, as with mRNAs, researchers have focused on the global analyses of miRNAs to seek their potential use as biomarkers for physiological and pathological states of a cell. Methods developed for miRNA profiling are briefly discussed in this review. Recent evidences supporting the use of miRNAs as biomarkers in both differentiation and cancer are presented. The profiling studies may highlight the clinical relevance of miRNAs and will enable the researchers to uncover the enormous potential of these tiny molecules. In the near future, selected miRNA genes based on expression abnormalities will be tested as candidates for miRNA-based cancer gene therapy.
Keywords: biomarker; cancer; cloning; diagnosis; differentiation; miRNAs; microarray; profiling; prognosis; quantitative RT-PCR.