MicroRNA in colorectal cancer: new perspectives for diagnosis, prognosis and treatment

Colorectal cancer (CRC) is a common condition and represents a lethal disease, following a sequential progression from adenoma to carcinoma. Interfering with such natural history of CRC offers clues to prevention and cure, but current screening methods for CRC are still limited by unsatisfactory sensitivity and specificity. Novel diagnostic, prognostic tools are therefore being actively investigated for CRC. The discovery of microRNAs (miRNAs) has led to active research focusing on their role in cancer and several crucial pathways involving angiogenesis, cancer-stem-cell biology, epithelial-mesenchymal transition, formation of metastasis, and drug resistance. MiRNAs might soon represent novel prognostic and diagnostic tools in patients at high risk of CRC or being diagnosed with CRC. MiRNA might prove useful also as therapeutic tools, since dysregulation of miRNAs in cancer cells results in higher levels of messenger RNA (mRNA) specific to tumor promoter genes or tumor suppressor genes. Thus, novel anticancer therapies might originate from manipulation of oncogenic or tumor suppressor miRNAs in CRC. In this review, the innovative aspects of miRNA are discussed, with respect to biogenesis, their role in CRC, and their potential use as biomarkers. Before miRNAs can become available in the clinical setting, however, a number of large prospective studies are still required.