MicroRNAs (miRNAs) regulate gene expression by inducing mRNA decay. But miRNAs can be regulated through other RNAs and DNA that bind and sequester them without inducing any mRNA decay; these are known as miRNA sponges. Gilot et al. show that tyrosinase-related protein 1 (TYRP1) mRNA confers a growth advantage to metastatic melanoma cells by functioning as a sponge for miR-16, a tumor-suppressor miRNA. Blocking miR-16 binding to TYRP1 mRNA induced melanoma cell death and reduced the growth of human-derived tumor cells in mice. Thus, understanding the complex interplay and competition between RNAs in gene expression is an important consideration for drug development.
