WISP-1 increases MMP-2 expression and cell motility in human chondrosarcoma cells

Chondrosarcoma is a type of highly malignant tumor with a potent capacity to invade locally and cause distant metastasis. Chondrosarcoma shows a predilection for metastasis to the lungs. WISP-1 is a cysteine-rich protein that belongs to the CCN (Cyr61, CTGF, Nov) family of matricellular proteins. However, the effect of WISP-1 on migration activity in human chondrosarcoma cells is mostly unknown. Here we found that WISP-1 increased the migration and expression of matrix metalloproteinase (MMP)-2 in human chondrosarcoma cells (JJ012 cells). We also found that human chondrosarcoma tissues had significant expression of the WISP-1 which was higher than that in normal cartilage. α5β1 monoclonal antibody and MAPK kinase (MEK) inhibitors (PD98059 and U0126) inhibited the WISP-1-induced increase of the migration and MMP-2 up-regulation of chondrosarcoma cells. WISP-1 stimulation increased the phosphorylation of focal adhesion kinase (FAK), MEK and extracellular signal-regulated kinase (ERK). In addition, NF-κB inhibitors also suppressed the cell migration and MMP-2 expression enhanced by WISP-1. Moreover, WISP-1 increased NF-κB luciferase activity and binding of p65 to the NF-κB element on the MMP-2 promoter. Taken together, our results indicated that WISP-1 enhances the migration of chondrosarcoma cells by increasing MMP-2 expression through the α5β1 integrin receptor, FAK, MEK, ERK, p65 and NF-κB signal transduction pathway.     

Differential effects of echistatin and thrombin on collagen production and prolidase activity in human dermal fibroblasts and their possible implication in beta1-integrin-mediated signaling.

Prolidase [E.C. 3.4.13.9] is a cytosolic imidodipeptidase that plays an important role in collagen biosynthesis. The enzyme contributes to the recovery of proline from protein degradation products (mainly collagen) for collagen resynthesis. Prolidase activity and collagen biosynthesis are supposed to be regulated by beta(1)-integrins, which initiate a signaling pathway in which several kinases and intracellular proteins are involved, including focal adhesion kinase pp125(FAK) (FAK), Src, Shc, growth factor receptor bound protein 2 (Grb-2), son of sevenless protein (SOS), Ras, Raf and mitogen-activated protein kinases (MAPK), extracellular-signal regulated kinase 1 (ERK(1)) and kinase 2 (ERK(2)). We studied the effects of echistatin, a well-known disintegrin and thrombin, a serine protease capable of activation of platelet integrin alpha(2)beta(1) receptor on collagen production, prolidase activity, expression of prolidase, beta(1)-integrin receptor, FAK, SOS-protein and phosphorylated MAP-kinases (ERK(1) and ERK(2)) in confluent human dermal fibroblasts. It has been found that treatment of the cells with 100nM echistatin contributes to inhibition of collagen production, as well as prolidase activity and expression compared to control cells. These phenomena were accompanied by a decrease in the expression of FAK, SOS-protein and phosphorylated MAP-kinases, ERK(1) and ERK(2). An opposite phenomenon was observed in fibroblasts treated with 0.1IU thrombin. In this case, a significant increase in collagen production and prolidase activity, accompanied by a distinct raise in the expression of prolidase, FAK and phosphorylated MAP-kinases and a slight increase in expression of SOS compared to controls were found. The results suggest that regulation of prolidase activity and collagen biosynthesis in human dermal fibroblasts may involve beta(1)-integrin-dependent signaling.     

CCL5 increases lung cancer migration via PI3K, Akt and NF-κB pathways

CCL5 (previously called RANTES) is in the CC-chemokine family and plays a crucial role in the migration and metastasis of human cancer cells. Besides, integrins are the major adhesive molecules in mammalian cells. Here we found CCL5 increased the migration and cell surface expression of αvβ3 integrin in human lung cancer cells (A549 cells). CCL5 stimulation increased phosphorylation of the p85α subunit of phosphatidylinositol 3-kinase (PI3K) and serine 473 of Akt. Also, we found that PI3K inhibitor (Ly294002) or Akt inhibitor suppressed CCL5-induced migration activities and integrin expression of A549 cells. Transfection of cells with p85 or Akt mutant also reduced CCL5-mediated cancer migration. In addition, treatment of A549 cells with CCL5 induced IκB kinase α/β (IKK α/β) phosphorylation, IκB phosphorylation, p65 Ser⁵³⁶ phosphorylation, and κB-luciferase activity. Furthermore, the CCL5-mediated increases in p65 Ser⁵³⁶ phosphorylation were inhibited by Ly294002 and Akt inhibitor. Taken together, our results suggest that CCL5 acts through PI3K/Akt, which in turn activates IKKα/β and NF-κB, resulting in the activation of αvβ3 integrin and contributing to the migration of human lung cancer cells.     

白芍总苷对免疫性肝纤维化大鼠肝组织NF-κB和TGF-β1蛋白表达的影响

目的研究免疫性肝纤维化大鼠肝组织中核转录因子-κB(nuclear factor-κB,NF-κB)和转化生长因子β1(trans-forming growth factor beta1,TGF-β1)的变化以及白芍总苷(TGP)对两者蛋白表达的影响。方法采用猪血清诱导建立大鼠肝纤维化模型,肝组织HE染色和V-G染色观察肝组织损伤及胶原表达变化;免疫组化S-P法观察NF-κB p65和TGF-β1蛋白表达;显微摄像及图像分析检测胶原、NF-κBp65和TGF-β1蛋白的表达量。结果与正常组比较,模型组大鼠肝组织明显破坏,胶原合成增加,NF-κB p65和TGF-β1表达增强(P<0.01);与模型组比较,TGP治疗组肝组织破坏减轻,纤维化程度也明显改善,胶原面积、NF-κB p65和TGF-β1表达均明显减少(P<0.01),三者呈相关性。结论NF-κB介导TGF-β1产生或活化在免疫性肝纤维化过程中可能发挥着重要作用,而TGP抑制纤维化大鼠肝组织NF-κB和TGF-β1的表达可能是TGP的抗肝纤维化主要作用机制之一。     

Genistein modulates NF-κB-associated renal inflammation, fibrosis and podocyte abnormalities in fructose-fed rats

The study determines the effect of genistein on inflammatory status and expression of nuclear factor-kappa B (NF-κB p65), transforming growth factor-β1 (TGF-β1) and receptor for advanced glycation end products (RAGE) in kidney of fructose-fed rats. Adult male Wistar rats were fed a diet containing either starch or fructose as the source of carbohydrate. Fifteen days later, after confirming the development of insulin resistance in fructose-fed rats, the rats in each dietary group were divided into two and treated with either genistein (1 mg/kg/day) in 30% dimethylsulfoxide (DMSO) or 30% DMSO alone for the next 45 days. The expression of NF-κB P(65), TGF-β1 and RAGE, histochemical localization of α-smooth muscle actin (α-SMA), levels of tumour necrosis factor-α (TNF-α) and interleukin-6(IL-6) and ultrastructural analysis were performed at the end of the experimental period. Fructose-fed rats displayed inflammatory changes in kidney. Increased expression of TGF-β1 and RAGE in cytosol and NF-κB p65 in nuclear fraction were observed. α-SMA expression was higher in fructose-fed rat kidney. Proliferation of connective tissue was evident from increased collagen deposition in perivascular and intraglomerular regions. Administration of genistein to fructose-fed rats reduced inflammation, fibrogenesis and NF-κB activation. Genistein also mitigated the structural changes such as basement membrane thickening, reduction in podocyte number and loss of glomerular filtration barrier integrity. These findings suggest that genistein prevents inflammation, fibrosis and early nephropathic changes in fructose-fed insulin resistant rats secondary to the attenuation of NF-κB activation.     

Effects of linalool on inflammation,matrix accumulation and podocyte loss in kidney of streptozotocin-induced diabetic rats

Abstract

Context: This study aimed to evaluate the renoprotective action of linalool (LIN) on streptozotocin (STZ)-induced diabetic rats.

Objective: The pathological changes in diabetic nephropathy (DN) include oxidative stress, renal injury, matrix accumulation and podocyte abnormalities. We investigated the renoprotective actions of LIN, a monoterpene alcohol, present in herbal essential oils in STZ-induced diabetic rats with renal injury.

Materials and methods: STZ-diabetic rats were administered LIN (25?mg/kg) for 45 days, after which the activities of key enzymes of glucose metabolism, collagen content, oxidative damage and expression of glucose transporter-1 (GLUT-1), transforming growth factor-β₁ (TGF-β₁), nuclear factor-κBp65 (NF-κB p65) and nephrin were analyzed.

Results: Diabetic rats displayed altered glucose metabolism, collagen accumulation and increased TGF-β₁ and NF-κB expression in kidney. LIN treatment restored glucose-metabolizing enzymes, collagen content and GLUT-1 expression and also prevented nephrin loss. LIN also rescued kidney from oxidative stress and inflammation by decreasing the expression of TGF-β₁ and NF-κB. Ultrastructural changes such as basement membrane thickening, reduction in podocyte number and loss of filtration barrier integrity in diabetic rats were mitigated by LIN.

Discussion and conclusion: The results of this study suggest that LIN can attenuate nephropathic changes induced in kidney of diabetic rats. These findings highlight the utility of LIN as a potential drug to treat renal damage in diabetic subjects.     

The disintegrin,trimucrin, suppresses LPS-induced activation of phagocytes primarily through blockade of NF-κB and MAPK activation

In addition to antiplatelet activity, disintegrin, a small-mass RGD-containing polypeptide, has been shown to exert anti-inflammatory effects but the mechanism involved remains unclear. In this study, we report that trimucrin, a disintegrin from the venom of Trimeresurus mucrosquamatus, inhibits lipopolysaccharide (LPS)-induced stimulation of THP-1 and RAW 264.7 cells. We also investigate the underlying mechanism. Trimucrin decreased the release of proinflammatory cytokines including tumor necrosis factor α (TNFα), interleukin-6 (IL-6), nitric oxide, and reactive oxygen species (ROS), and inhibited the adhesion and migration of LPS-activated phagocytes. Trimucrin significantly blocked the expression of nuclear factor kappaB (NF-κB)-related downstream inducible enzymes such as inducible nitric oxide synthase (iNOS) and COX-2. In addition, its anti-inflammatory effect was associated with the decreased mitogen-activated protein kinase (MAPK) phosphorylation. Furthermore, trimucrin concentration dependently inhibited LPS-induced phosphorylation of focal adhesion kinase (FAK), PI3K, and Akt. Trimucrin also reversed the DNA-binding activity of NF-κB by suppressing the LPS-induced nuclear translocation of p65 and the cytosolic IκB release. Flow cytometric analyses showed that trimucrin bound to cells in a concentration-dependent manner. The anti-αVβ3 mAb also specifically decreased the binding of fluorescein isothiocyanate (FITC)-conjugated trimucrin. Binding assays demonstrated that integrin αVβ3 was the binding site for trimucrin on THP-1 and RAW 264.7 cells. In conclusion, we showed that trimucrin decreases the inflammatory reaction through the attenuation of iNOS expression and nitric oxide (NO) production by blocking MAP kinase and the NF-κB activation in LPS-stimulated THP-1 and RAW 264.7 cells.     

Stromal cell-derived factor-1 enhances motility and integrin up-regulation through CXCR4, ERK and NF-κB-dependent pathway in human lung cancer cells

The chemokine stromal-derived factor-1α (SDF-1α) and its receptor, CXCR4, play a crucial role in adhesion and migration of human cancer cells. Integrins are the major adhesive molecules in mammalian cells. Here we found that SDF-1α increased the migration and cell surface expression of β1 or β3 integrin in human lung cancer cells (A549 cells). CXCR4-neutralizing antibody, CXCR4 specific inhibitor (AMD3100) or small interfering RNA against CXCR4 inhibited the SDF-1α-induced increase in the migration of lung cancer cells. Stimulation of cells with SDF-1α caused an increase in extracellular signal regulated kinase (ERK) phosphorylation in a time-dependent manner. In addition, treatment of A549 cells with ERK inhibitor (PD98059), NF-κB inhibitor (PDTC) or IκB protease inhibitor (TPCK) inhibited SDF-1α-induced cells migration and integrins expression. Treatment of A549 cells with SDF-1α induced IκB kinase α/β (IKK α/β) phosphorylation, IκBα phosphorylation, IκBα degradation, p65 Ser⁵³⁶ phosphorylation, and κB-luciferase activity. The SDF-1α-mediated increases in IKK α/β phosphorylation, p65 Ser⁵³⁶ phosphorylation, and κB-luciferase activity were inhibited by PD98059 and ERK2 mutant. Taken together, these results suggest that SDF-1α acts through CXCR4 to activate ERK, which in turn activates IKKα/β and NF-κB, resulting in the activations of β1 and β3 integrins and contributing the migration of lung cancer cell.     

Oligo-peptide I-C-F-6 inhibits hepatic stellate cell activation and ameliorates CCl4-induced liver fibrosis by suppressing NF-κB signaling and Wnt/β-catenin signaling

Oligo-peptide I-C-F-6 is a Carapax trionycis extract component that has an effect on hepatic fibrosis, however, its mechanism of action is still unclear. This study investigated whether oligo-peptide I-C-F-6 could inhibit liver fibrosis by suppressing NF-κB and Wnt/β-catenin signaling, which are important in liver fibrosis. HSC-T6 cells were treated with oligo-peptide I-C-F-6, and rats were divided randomly into five groups: control (saline), CCl₄, CCl₄ plus oligo-peptide I-C-F-6 (0.12 and 0.24 mg/kg), and CCl₄ plus colchicine (0.11 mg/kg). Here, we demonstrated that oligo-peptide I-C-F-6 ameliorated liver injury, inflammation, and hepatic fibrogenesis induced by CCl₄. Oligo-peptide I-C-F-6 also inhibited the activation of hepatic stellate cells (HSCs) in vivo and in vitro, as evaluated by the expression of transforming growth factor-β1 (TGF-β1) and α-smooth muscle actin (α-SMA), which is a specific marker of HSC activation. Moreover, oligo-peptide I-C-F-6 significantly reduced the expression and distribution of β-catenin, P-AKT, phospho (P)-GSK-3β, nuclear factor κB (NF-κB) P65, phospho-P65, and IκB kinase α/β (IKK-α/β) levels; additionally, IκB-α level was elevated both in vivo and in vitro. Together, these results indicate that oligo-peptide I-C-F-6 has hepatoprotective and anti-fibrotic effects in animal models of liver fibrosis, the mechanism of which may be related to modulating NF-κB and Wnt/β-catenin signaling.     

Theobromine mitigates IL-1β-induced oxidative stress,inflammatory response,and degradation of type II collagen in human chondrocytes

Osteoarthritis is one of the major causes of disability in elderly adults. Chondrocytes are responsible for the formation and remodeling of articular cartilage in joint tissue. The dysfunction of chondrocytes is a significant factor in the development of osteoarthritis. In the current study, we found that theobromine, a constituent of the cacao plant, possesses a preventive effect against interleukin (IL)-1β-induced chondrocyte dysfunction. Theobromine ameliorates IL-1β-induced production of cellular reactive oxygen species (ROS) and inflammatory mediators including cyclooxygenase-2 (COX-2) and prostaglandin E₂ (PGE₂). The presence of theobromine suppresses IL-1β-induced inducible nitro oxide synthase (iNOS) expression and cellular nitro oxide (NO) production. Theobromine also suppresses IL-1β-induced production of the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1), as well as matrix metalloproteinases (MMP)-3 and MMP-13. Additionally, theobromine mitigates IL-1β-induced type II collagen degradation. Mechanistically, we show that theobromine inhibits IL-1β-induced IκBα activation, nuclear factor-κB (NF-κB) protein p65 accumulation, and transfected NF-κB promoter activity, indicating that theobromine suppresses the NF-κB pathway in chondrocytes. Collectively, our study demonstrates that the natural molecule theobromine has a protective effect to counter cytokine-induced chondrocyte dysfunction, implying its beneficial effect in the prevention of osteoarthritis.     

Pro-inflammatory effects of commercial alpha-lactalbumin on RAW 264.7 macrophages is due to endotoxin contamination

This study investigated the effects of alpha-lactalbumin (α-LA) on cellular signaling molecules associated with inflammatory responses in RAW 264.7 macrophages. The results indicated that commercial α-LA could increase prostaglandin E₂ (PGE₂) and the expression of COX-2 via increased phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK) and jun N-terminal kinase (JNK), and increase nitric oxide (NO) and the expression of iNOS via the activation of ERK1/2 and JNK. Furthermore, commercial α-LA could increase nuclear translocation of p65 nuclear factor-kappa B (p65 NF-κB) through stimulation on inhibitor kappa B-alpha (IκB-α) degradation. Since endotoxin also has these effects, we assayed the content of endotoxin in the commercial α-LA. We found to our surprise that endotoxin was there and that α-LA-induced NO and PGE₂ production could be suppressed by polymyxin B, a specific inhibitor of endotoxin. Thus, the pro-inflammatory effects of commercial α-LA might be caused by endotoxin contamination through activation and expression of iNOS and COX-2 which were upregulated by MAPKs or nuclear translocation of p65 NF-κB in RAW 264.7 cells. It is therefore crucial to assess the possibility of endotoxin contamination within any biological product being studied for immune augmenting activities before a meaning result can be obtained.     

斑蝥素对高转移卵巢癌细胞HO-8910PM中NF-κB(P65)、FAK表达及FAK磷酸化水平的影响

目的研究斑蝥素对HO8910PM细胞内NFκB(P65)、FAK表达及FAK磷酸化水平的影响,探讨其抗肿瘤侵袭转移的作用机制。方法MMT法测定斑蝥素对细胞增殖的影响;Westernblot分析NFκB(P65),FAK表达及FAK磷酸化水平。结果5～20μmol·L-1的斑蝥素作用HO8910PM细胞24h后,NFκB(P65)蛋白表达水平明显下降,并有一定的剂量效应关系;上调FAK表达,使FAK磷酸化水平降低。结论斑蝥素抗肿瘤侵袭转移与NFκB(P65)表达以及FAK磷酸化水平有关。     

The effect of hyaluronic acid on interleukin-1-induced deregulation of collagen metabolism in cultured human skin fibroblasts.

Although hyaluronic acid (HA) has been used in the treatment of osteoarthritis for 30 years, the mechanism of its protective action on collagen metabolism disturbances in tissues during inflammation is not known. The present study was undertaken to evaluate the mechanism of Interleukin-1 (IL-1)-induced deregulation of collagen metabolism in cultured human skin fibroblast and the effect of HA on the process. In normal fibroblasts IL-1 strongly induced inhibition of collagen biosynthesis, while HA counteracted the process. The mechanism of this phenomenon was independent of prolidase activity, an enzyme that plays an important role in collagen biosynthesis at the post-translational level. Instead, IL-1 was found to inhibit the expression of insulin-like growth factor-I receptor (IGF-IR) and MAP kinases-ERK1 and ERK2, while HA was shown to counteract this process. Since insulin-like growth factor-I (IGF-I) is a most potent stimulator of collagen biosynthesis in fibroblasts the mechanism of IL-1-dependent inhibition of collagen biosynthesis may be related to inhibition of IGF-IR expression and signaling. The data suggest that hyaluronic acid protects collagen against IL-1-induced inhibition of biosynthesis of this protein in cultured human skin fibroblasts at the level of IGF-IR signaling.     

15-Deoxy-Δ-prostaglandin J2 induces mitochondrial-dependent apoptosis through inhibition of PKA/NF-κB in renal proximal epithelial cells

We have previously reported the cyclopentenone prostaglandin 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) induces renal proximal epithelial cell death through NF-κB inhibition. However, the upstream and down-stream signaling pathways that NF-κB inhibition mediates 15d-PGJ₂-induced apoptosis remain to be defined. In the present study, we determined whether NF-κB inhibition induces cell death through the mitochondrial apoptotic pathway and whether protein kinase A (PKA) functions upstream of NF-κB inhibition by 15d-PGJ₂. The role of NF-κB inhibition in this apoptotic pathway was evaluated using NF-κB p65 transfected cells. 15d-PGJ₂ induced cell death by a PPARγ-independent mechanism and the cell death was prevented by NF-κB p65 transfection. 15d-PGJ₂ treatment caused disruption of mitochondrial membrane potential, cytochrome c release, and caspase-3 activation, suggesting that 15d-PGJ₂ induces cell death through a mitochondria-dependent apoptotic mechanism. These changes by 15d-PGJ₂ were attenuated by NF-κB p65 transfection. 15d-PGJ₂ treatment resulted in an increase in Bax expression, which were blocked by NF-κB p65 transfection. 15d-PGJ₂ treatment caused PKA inhibition and 15d-PGJ₂-induced cell death was enhanced by the PKA specific inhibitor H89. Inhibition of NF-κB by 15d-PGJ₂ was prevented by addition of forskolin, a PKA activator. Taken together, these results suggest that PKA-dependent NF-κB inhibition stimulates 15d-PGJ₂-mediated mitochondrial apoptotic pathway through alterations in expression of the NF-κB target genes Bax.     

Artemisia fukudo essential oil attenuates LPS-induced inflammation by suppressing NF-κB and MAPK activation in RAW 264.7 macrophages

In the present study, the chemical constituents of Artemisia fukudo essential oil (AFE) were investigated using GC–MS. The major constituents were α-thujone (48.28%), β-thujone (12.69%), camphor (6.95%) and caryophyllene (6.01%). We also examined the effects of AFE on the production of nitric oxide (NO), prostaglandin E₂ (PGE₂), tumour necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. Western blotting and RT-PCR tests indicated that AFE has potent dose-dependent inhibitory effects on pro-inflammatory cytokines and mediators. We investigated the mechanism by which AFE inhibits NO and PGE₂ by examining the level of nuclear factor-κB (NF-κB) activation within the mitogen-activated protein kinase (MAPK) pathway, which is an inflammation-induced signal pathway in RAW 264.7 cells. AFE inhibited LPS-induced ERK, JNK, and p38 phosphorylation. Furthermore, AFE inhibited the LPS-induced phosphorylation and degradation of Iκ-B-α, which is required for the nuclear translocations of the p50 and p65 NF-κB subunits in RAW 264.7 cells. Our results suggest that AFE might exert an anti-inflammatory effect by inhibiting the expression of pro-inflammatory cytokines. Such an effect is mediated by a blocking of NF-κB activation which consequently inhibits the generation of inflammatory mediators in RAW264.7 cells. AFE may be useful for treating inflammatory diseases.     

Sargachromanol G regulates the expression of osteoclastogenic factors in human osteoblast-like MG-63 cells

Bone diseases are characterized by the presence of pro-inflammatory cytokines that regulate bone turnover. The receptor activator of NF-κB ligand (RANKL) is a soluble osteoblast-derived protein that induces bone resorption through osteoclast differentiation and activation. Sargachromanol G (SG) was isolated from the brown algae Sargassum siliquastrum; SG has anti-osteoclastogenic activity, but its mechanism of action and its active components remain largely unknown. In the present study, we investigated the anti-osteoclastogenic effects of SG on the expression of interleukin-1β (IL-1β)-induced osteoclastogenic factors (PGE₂, COX-2, IL-6, OPG, and RANKL) in the human osteoblast cell line MG-63. We also examined the role of the nuclear factor-κB (NF-κB) and the mitogen-activated protein kinase (MAPK) signaling pathways in IL-1β-stimulated MG-63 cells. SG dose-dependently inhibited the production of osteoclastogenic factors in MG-63 cells. SG also inhibited phosphorylation of MAPK (ERK1/2, p38, and JNK) and NF-κB (p65, p50, and IκB-α). These results suggest that the anti-osteoporotic effect of SG may be because of the modulation of osteoclastogenic factors via suppression of MAPK and NF-κB activation.     

Tetrandrine regulates hepatic stellate cell activation via TAK1 and NF-κB signaling

We investigated the anti-fibrotic mechanism of tetrandrine, a bisbenzylisoquinoline alkaloid from the Chinese herb, Stephania tetrandra, on the immortalized HSC-T6 rat hepatic stellate cell line. Tetrandrine (0.39–50 μM) dose- and time-dependently inhibited HSC-T6 cell viability within 24 h and exhibited almost no cytotoxicity at concentrations lower than 6.25 μM in the presence of tumor necrosis factor-α (TNF-α). At a much high concentration (50 μM), tetrandrine caused fatal cytotoxity in both HSCs and hepatocytes. TNF-α time-dependently increased α-smooth muscle actin (α-SMA) expression, while a lower concentration of tetrandrine (6.25 μM) prior to TNF-α treatment reduced the expression of α-SMA and TNFR-1-associated death domain (TRADD). TNF-α treatment induced TGF-β-activated kinase-1 (TAK1) and c-Jun N-terminal kinase (JNK) phosphorylation, which were attenuated by tetrandrine. Furthermore, TNF-α treatment activated nuclear factor-κB (NF-κB) nuclear translocation and IκB-α degradation. Tetrandrine treatment prior to TNF-α reduced nuclear phosphorylated and total NF-κB p65, while the cytosolic IκB-α and NF-κB p65 levels significantly increased. In addition, treatment with only tetrandrine induced the cleavage of caspase-3 and PARP within a range of higher concentrations. Tetrandrine-induced apoptosis was confirmed by the TUNEL assay and flow-cytometric analysis. Treatment with only tetrandrine markedly reduced α-SMA expression, except for at lower concentrations of tetrandrine. A higher concentration of tetrandrine (25 μM) induced a significant increase in JNK and extracellular signal-regulated kinase (ERK) phosphorylation, NF-κB nuclear translocation and IκB-α degradation. In conclusion, the anti-fibrogenic effects of tetrandrine on HSCs involved a dosage-dependent signaling pathway, based on the tetrandrine concentration, by regulating TAK1, JNK and NF-κB. The present data provides strong evidence for the anti-fibrotic dosage-dependent signaling pathway of tetrandrine.