MicroRNAs predict and modulate responses to chemotherapy in colorectal cancer

Colorectal cancer (CRC) is the fourth leading cause of cancer-related death globally. Chemotherapy regimens consisting of 5-fluorouracil (5-FU) in combination with either oxaliplatin or irinotecan are the first-line options for treatment of metastatic CRC. However, primary or acquired resistance to these chemotherapeutics is a major clinical challenge. MicroRNAs (miRNAs) are a group of small non-coding RNAs that regulate gene expression post-transcriptionally. miRNAs play important roles in many cancer-related processes, including cell proliferation, apoptosis and invasion, and their dysregulation is implicated in colorectal tumourigenesis. Pertinent to chemotherapy, increasing evidence has revealed that miRNAs can be directly linked to chemosensitivity in CRC. In this review, we summarize current evidence concerning the role of miRNAs in prediction and modulation of cellular responses to 5-FU, oxaliplatin and irinotecan in CRC. We also discuss the possible targets and intracellular pathways involved in these processes.