miR-21 promotes collagen production in keloid via Smad7

Abstract Objective To explore the biological function of miR-21 in the formation of keloid. Methods Normal skin and keloid tissue samples underwent histopathologic study and qPCR analysis. The expression of miR-21 and mRNA expression of Smad7, Col1A1, Col3A1 in fibroblasts derived from keloid tissue and normal skin tissue samples were detected by qPCR. Normal and keloid fibroblasts were transfected with miR-21 mimics or inhibitor respectively, and expression of Smad7, Col1A1 and Col3A1 were examined. After the normal fibroblasts were transfected with Smad7 siRNA, expression of Col1A1 and Col3A1 were detected by Western blot and qPCR analysis. Results Collagen was obviously thick and disorganized in keloid tissue. The expression of miR-21, Col1A1 and Col3A1 in keloid tissue and keloid-derived fibroblasts were higher than that of normal counterparts, while the expression of Smad7 in keloid tissue and keloid-derived fibroblasts was lower. miR-21 mimics attenuated expression of Smad7, and enhanced the expression of Col1A1, Col3A1. Furthermore, the Smad7 siRNA increased expression of Col1A1and Col3A1. Conclusions miR-21 promoted collagen production in keloid by negatively regulating the expression of the Smad7.