The role of miR-21, an androgen-regulated MicroRNA, in prostate cancer

MicroRNAs (miRNAs) are an established family of small non-protein coding RNAs which broadly regulate gene expression through posttranscriptional mechanisms. Differential miRNA gene expression is common in cancer and other disease states, and there is significant evidence that many miRNAs play a functional role in disease processes. miR-21, a miRNA which imparts cellular growth and survival properties, is commonly overexpressed in malignant and inflamed tissues, including prostate cancer. Its expression is directly induced by the activated androgen receptor (AR), and elevated miR-21 alone is sufficient to impart castration-resistant tumor growth. Therefore, the miR-21 gene is of particular interest in prostate cancer biology. This chapter focuses on the miR-21 gene, its expression and processing, and miR-21 regulated pathways in the prostate and other tissues. The association of miR-21 with clinical prostate cancer is also reviewed.