USF1 prompt melanoma through upregulating TGF-β signaling pathway

OBJECTIVE: The activation of TGF-beta signaling contributes to abnormal EMT process and upstream stimulatory family1 (USF1) was recently found to activate the expression of TGF-beta. 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 alpha-SMA, Vimentin and Fibronectin, while the epithelial marker, E-cad-herin (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-beta 1-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-beta 1 production in melanoma cells.