Let-7a as a Tumor Suppressor Modulates Invasion via Smad2 Signal in Breast Cancer

TGF-β elicits tumor promoting effects through its ability to induce EMT which enhances invasiveness and metastasis, the perturbations of TGF-β/Smad signaling are central to carcinogenesis in most of organs. A shift in Smad2/3 phosphorylation from the carboxy terminus to linker sites is a key event determining biological function of TGF-β. Here, we showed that let-7 was associated with breast cancer development and progression by directly targeted Smad2, suggesting a tumor suppressor role of let-7 and its target Smad2 is critical regulators of TGF-β signaling in breast cancer.