Up-regulation of matrix metalloproteinases in a mouse model of chemically induced colitis-associated cancer: the role of microRNAs

Emerging evidence has implicated microRNAs in regulating the production of multiple inflammatory mediators including cytokines and chemokines. We previously elucidated the dynamic activation of key signals that link colitis to colorectal cancer. In this study, we observed a sharp increase in the levels of matrix metalloproteinases (Mmps) that provided a basis for the inflammation-cancer link, and we questioned whether this was a consequence of the dysregulation of Mmp-specific microRNAs, at least partly. We assayed a panel of murine microRNAs that were predicted to target Mmps and found they were downregulated in the inflammation-cancer link. Furthermore, we demonstrated that three murine microRNAs, namely miR-128, -134, and -330, can target the three Mmps Mmp3, Mmp10, and Mmp13, respectively. We also found that the level of the microRNA-processing enzyme Dicer1 was decreased in the inflammation-cancer link. These microRNAs functioned as tumor suppressors in colon cancer cells, attenuating the proliferation, migration, and invasion potential of murine colon cancer cells as well as angiogenesis and the growth of tumors derived from these cells. Our results suggest that microRNAs modulate the production of key inflammatory mediators and that microRNA dysfunction may contribute to the non-resolving inflammation associated with cancer.