MiR-155 promotes macroscopic tumor formation yet inhibits tumor dissemination from mammary fat pads to the lung by preventing EMT.

ABSTRACT: A micro-RNA, miR-155, is overexpressed in many types of cancer cells, including breast cancer, and its role(s) in tumor metastasis has been studied on a very limited basis. Tumor metastasis is a multi-step process with the last step in the process being formation of macroscopic tumor in organs distant from the primary tumor site. This step is the least studied. Here, we report that stable expression of miR-155 in 4T1 breast tumor cells reduces significantly the aggressiveness of tumor cell dissemination as a result of preventing epithelial-to-mesenchymal transition (EMT) of tumor cells in vivo. Further, miR-155 directly suppresses the expression of the transcription factor TCF4, which is an important regulator of EMT. However, when tumor cells are injected directly into the bloodstream, mi

SUBMITTER: Xiang X 

PROVIDER: S-EPMC4139014 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature