Knockdown of FOXM1 inhibits activation of keloid fibroblasts and extracellular matrix production via inhibition of TGF-β1/Smad pathway.

Keloid is characterized by overactive fibroblasts. Forkhead box M1 (FOXM1) is transcription factor that plays important roles in the progression of fibrosis. However, the role of FOXM1 in keloid has not been elucidated. In the present study, we examined the expression levels of FOXM1 in clinical keloid tissue specimens and primary keloid fibroblasts (KFs). The results showed that FOXM1 levels were significantly increased in both keloid tissues and KFs. To further investigate the biological functions of FOXM1, FOXM1 was knocked down in KFs by transfection with small interfering RNA targeting FOXM1 (si-FOXM1). Knockdown of FOXM1 inhibited transforming growth factor-β1 (TGF-β1)-induced cell proliferation and migration of KFs. Besides, the increased expressions of collagen (coll I), connective tissue growth factor (CTGF), and α-smooth muscle actin (α-SMA) in TGF-β1-induced KFs were suppressed by si-FOXM1 transfection. Furthermore, TGF-β1-induced increase in p-Smad2 and p-Smad3 expressions was attenuated by FOXM1 knockdown. These data indicated that knockdown of FOXM1 inhibited TGF-β1-induced KFs activation and extracellular matrix (ECM) accumulation, which was attributed to the inhibition of TGF-β1/Smad pathway.

Zhang Y ，Cheng C ，Wang S ，Xu M ，Zhang D ，Zeng W ... -  《-》

Silencing NLRC5 inhibits extracellular matrix expression in keloid fibroblasts via inhibition of transforming growth factor-β1/Smad signaling pathway.

Dermal fibrosis is characterized by collagen accumulation and hyperproliferation of fibroblasts. NLRC5, as the largest member of nucleotide-binding domain and leucine-rich repeat (NLRs) family, has recently been implicated in the development of hepatic fibrosis. However, the role of NLRC5 in dermal fibrosis remains unknown. Therefore, herein, we investigated the effects of NLRC5 on keloid fibroblasts (KFs) and transforming growth factor-β1 (TGF-β1)-induced collagen expression and explored the underlying mechanism. We observed that NLRC5 mRNA and protein levels were highly expressed in KFs, silencing NLRC5 greatly suppressed TGF-β1-induced KFs proliferation. Silencing NLRC5 also obviously inhibited the expression of type I collagen, CTGF and α-smooth muscle actin (α-SMA) in human KFs induced by TGF-β1, as well as the expression of TGF-β receptor I and II. Furthermore, silencing NLRC5 suppressed the expression of TGF-β1-induced Smad2 and Smad3 phosphorylation in human KFs. Taken together, our study suggest that silencing NLRC5 reduced ECM expression in KFs through inhibiting the TGF-β1/Smad signaling pathway. Therefore, NLRC5 may represent a promising target for treatment of the keloid disease.

Ma HL ，Zhao XF ，Chen GZ ，Fang RH ，Zhang FR ... -  《-》

Knockdown of elF3a inhibits TGF‑β1‑induced extracellular matrix protein expression in keloid fibroblasts.

Li T ，Zhao J 《-》

Simvastatin inhibits transforming growth factor-β1-induced expression of type I collagen, CTGF, and α-SMA in keloid fibroblasts.

Simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme-A reductase inhibitor, is used to reduce cholesterol levels. Accumulating evidence has revealed the immunomodulatory and anti-inflammatory effects of simvastatin that prevent cardiovascular diseases. In addition, the beneficial effects of statins on fibrosis of various organs have been reported. However, the functional effect of statins on dermal fibrosis of keloids has not yet been explored. The objective of this study was to determine whether simvastatin could affect dermal fibrosis associated with keloids. We examined the effect of simvastatin on transforming growth factor (TGF)-β1-induced production of type I collagen, connective tissue growth factor (CTGF or CCN2), and α-smooth muscle actin (α-SMA). Keloid fibroblasts were cultured and exposed to different concentrations of simvastatin in the presence of TGF-β1, and the effects of simvastatin on TGF-β1-induced collagen and CTGF production in keloid fibroblasts were determined. The type I collagen, CTGF, and α-SMA expression levels and the Smad2 and Smad3 phosphorylation levels were assessed by Western blotting. The effect of simvastatin on cell viability was evaluated by assessing the colorimetric conversion of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide. Simvastatin suppressed TGF-β1-induced type I collagen, CTGF, and α-SMA production in a concentration-dependent manner. The TGF-β1-induced Smad2 and Smad3 phosphorylation levels were abrogated by simvastatin pretreatment. The inhibition of type I collagen, CTGF, and α-SMA expression by simvastatin was reversed by geranylgeranyl pyrophosphate, suggesting that the simvastatin-induced cellular responses were due to inhibition of small GTPase Rho involvement. A RhoA activation assay showed that preincubation with simvastatin significantly blocked TGF-β1-induced RhoA activation. The Rho-associated coiled kinase inhibitor Y27632 abrogated TGF-β1-induced production of type I collagen, CTGF, and α-SMA. However, Y27632 had no significant effect on TGF-β1-induced phosphorylation of Smad2 and Smad3. In conclusion, the present study suggests that simvastatin is an effective inhibitor of TGF-β1-induced type I collagen, CTGF, and α-SMA production in keloid fibroblasts.

Mun JH ，Kim YM ，Kim BS ，Kim JH ，Kim MB ，Ko HC ... -  《-》

Downregulation of CR6-interacting factor 1 suppresses keloid fibroblast growth via the TGF-β/Smad signaling pathway.

Nagar H ，Kim S ，Lee I ，Kim S ，Choi SJ ，Piao S ，Jeon BH ，Oh SH ，Kim CS ... -  《Scientific Reports》