Knockdown of fibronectin extra domain B suppresses TGF-β1-mediated cell proliferation and collagen deposition in keloid fibroblasts via AKT/ERK signaling pathway.

Keloids represent a dermal fibrotic disease characterized by excess collagen deposition and invasion of normal skin beyond the wound boundary, similar to malignant tumor features. Fibronectin extra domain B (EDB) is highly expressed in many tumors but has not been studied in keloids. The present study aimed to investigate the expression and the influence of EDB on keloid and elucidate the putative signaling pathway. We examined expression of EDB and the effects of EDB on fibroblast proliferation, apoptosis and the expression of the related proteins and genes. The level of phosphorylation of Smad, ERK, and AKT was estimated to elucidate the signaling pathways. The results showed that EDB in human keloid tissues and fibroblasts was overexpressed. EDB knockdown suppressed the cell proliferation of keloid fibroblasts (KFs) treated by transforming growth factor-β1 (TGF-β1). Also, the phosphorylation of Smad, ERK, and AKT in TGF-β1-induced KFs was inhibited In addition, the low expression of pro-collagen-I (Col-I) and Col-III protein and mRNA level was observed in the siEDB group. EDB knockdown inhibited cell proliferation and suppressed collagen deposition in TGF-1-induced KFs. The underlying mechanism is the activation of TGF-β1/Smad, ERK, and AKT signaling pathways. Together, the results suggested that EDB is a promising therapeutic target for keloid clinical treatment.