USF1 prompt melanoma through upregulating TGF-β signaling pathway.

Objective: The activation of TGF-β signaling contributes to abnormal EMT process and upstream stimulatory family1 (USF1) was recently found to activate the expression of TGF-β. However, the specific role of USF1 in melanoma has never been explored.
Materials and Methods: The expression of USF1 was analyzed using real-time PCR and Western blot. The changes of cell morphology were observed under a microscope. Cell migration was determined using in vitro scratch test. A specific siRNA was applied to knockdown of USF1.
Results: The mRNA and protein levels of USF1 were significantly enhanced in melanoma cell lines, 1205-Lu, DO4, WM3211, and WM278, compared with normal human melanocytes PIG1. Overexpression of USF1 induced demonstrated an elongated and spindle-shaped morphology in the 1205-Lu cells. Meanwhile, USF1 induced the expression of α-SMA, Vimentin and Fibronectin, while the epithelial marker, E-cadherin (E-cad), was significantly decreased. Furthermore, in vitro scratch test demonstrated that overexpression of USF1 markedly enhanced 1205-Lu cell migration capacity at 24 h and 48 h. More importantly, knockdown of USF1 could partially reverse TGF-β1-treatment-induced changes of EMT markers as well as cell morphological changes.
Conclusions: We first demonstrate that overexpression of USF1 prompts the EMT process through the accumulation of TGF-β1 production in melanoma cells.