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 IRF3 inhibits extracellular matrix expression in keloid fibroblasts.

Keloid is a pathologic fibro-proliferative disorder and is characterized by hyper-proliferation of fibroblasts and excess extracellular matrix (ECM) deposition. Interferon regulatory factor 3 (IRF3) is a member of the interferon-regulatory factor (IRF) family and has been shown to play a critical modulator in the progression of fibrosis. However, the function of IRF3 in dermal fibrosis remains unclear. Thus, in this study, we investigated the effects of IRF3 on keloid-derived fibroblasts (KFs) proliferation and ECM expression, and explored the underlying mechanism. Our results indicated that the expression of IRF3 was highly expressed in human keloid tissues. Down-regulation of IRF3 significantly inhibited KF proliferation and the expression of type I collagen and α-smooth muscle actin (α-SMA), as well as suppressed the expression of TGF-β receptor I and II in TGF-β1-stimulated KFs. Furthermore, down-regulation of IRF3 suppressed the phosphorylation levels of Smad2 and Smad3 in human KFs induced by TGF-β1. Taken together, our data showed that down-regulation of IRF3 inhibited the proliferation and ECM expression in KFs via suppressing the TGF-β1/Smad signaling pathway. Thus, our findings suggest that IRF3 may represent a promising target for treatment of the keloid disease.

Zhang Y ，Zhang L ，Lin XH ，Li ZM ，Zhang QY ... -  《-》

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 ... -  《-》

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

Li T ，Zhao J 《-》

DKK3 regulates cell proliferation, apoptosis and collagen synthesis in keloid fibroblasts via TGF-β1/Smad signaling pathway.

It has been reported that Dickkopf-3 (DKK3) down-regulation was examined in keloid fibroblasts, but the biological functions of DKK3 have not yet been investigated. In this study, we examined the expression of DKK3 in human keloid tissues, further evaluated the biological function of DKK3 and explored its potential molecular mechanism in transforming growth factor-β1 (TGF-β1)-induced keloid fibroblasts. Our results showed that DKK3 mRNA expression in human keloid tissues is down-regulated. DKK3 overexpression inhibited cell proliferation in TGF-β1-induced keloid fibroblasts transfected with pcDNA3.1-DKK3. Furthermore, DKK3 overexpression remarkably upregulated the protein expression levels of Bax and caspase-3, but decreased the protein expression of Bcl-2. In addition, DKK3 overexpression dramatically inhibited the protein and mRNA levels of collagen I (Col-I), collagen III (Col-III) and α-smooth muscle actin (α-SMA). Moreover, the protein expression of TGF-β receptor I (TGF-β RI), TGF-β receptor II (TGF-β RII), the phosphorylation of Smad2 (p-Smad2) and Smad3 (p-Smad3) was dramatically inhibited by pcDNA3.1-DKK3. LY2109761, a TGF-β receptor inhibitor, also suppressed cell proliferation, apoptosis and collagen synthesis in TGF-β1-induced keloid fibroblasts. Taken together, DKK3 overexpression could inhibit cell proliferation, induced cell apoptosis, and suppressed collagen synthesis through TGF-β1/Smad signaling in TGF-β1-induced keloid fibroblasts. Our findings suggest that DKK3 is a novel and promising molecular target for keloid treatment.

Li Y ，Liu H ，Liang Y ，Peng P ，Ma X ，Zhang X ... -  《-》