MicroRNAs: New players in cancer prevention targeting Nrf2, oxidative stress and inflammatory pathways.

miRNAs are endogenous small non-coding RNAs of 20-22 nucleotides that repress gene expression at the post-transcriptional level. There is growing interest in the role of miRNAs in cancer chemoprevention, and several naturally occurring chemopreventive agents have been found to be modulators of miRNA expression both in vitro and in vivo. Moreover, these chemopreventive phytochemicals commonly possess anti-oxidative and/or anti-inflammatory properties, and Nrf2 has been extensively studied as a molecular target in cancer prevention. The crosstalk between miRNAs and the traditional cellular signaling pathways of chemoprevention remain to be fully elucidated. This review summarizes the data regarding the potential interactions between miRNAs and anti-oxidative and anti-inflammatory pathways. Cellular redox homeostasis can affect the biogenesis and processing of miRNAs, which in turn regulate the Nrf2 pathway of detoxifying/anti-oxidative genes. We also discuss the miRNA regulatory mechanisms in relation to inflammation-related cancer signaling pathways.