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Liver fibrosis is a repair response process after chronic liver injury. During this process, activated hepatic stellate cells (HSCs) will migrate to the injury site and secrete extracellular matrix (ECM) to produce fibrous scars. Clearing activated HSCs may be a major strategy for the treatment of liver fibrosis. Curcumol isolated from plants of the genus Curcuma can effectively induce apoptosis of many cancer cells, but whether it can clear activated HSCs remains to be clarified. In the present study, we found that the effect of curcumol in treating liver fibrosis was to clear activated HSCs by inducing necroptosis of HSCs. Receptor-interacting protein kinase 3 (RIP3) silencing could impair necroptosis induced by curcumol. Interestingly, endoplasmic reticulum (ER) stress-induced cellular dysfunction was associated with curcumol-induced cell death. The ER stress inhibitor 4-PBA prevented curcumol-induced ER stress and necroptosis. We proved that ER stress regulated curcumol-induced necroptosis in HSCs via Sirtuin-1(Sirt1)/Notch signaling pathway. Sirt1-mediated deacetylation of the intracellular domain of Notch (NICD) led to degradation of NICD, thereby inhibiting Notch signalling pathway to alleviate liver fibrosis. Specific knockdown of Sirt1 by HSCs in male ICR mice further exacerbated CCl4-induced liver fibrosis. Overall, our study elucidates the anti-fibrotic effect of curcumol and reveals the underlying mechanism between ER stress and necroptosis. [ABSTRACT FROM AUTHOR]

Background: Intracerebral hemorrhage (ICH) induces potently oxidative stress responses and inflammatory processes. Isoliquiritigenin (ILG) is a flavonoid with a chalcone structure and can activate nuclear factor erythroid-2 related factor 2 (Nrf2)-mediated antioxidant system, negatively regulate nuclear factor-κB (NF-κB) and nod-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome pathways, but its role and potential molecular mechanisms in the pathology following ICH remain unclear. The present study aimed to explore the effects of ILG after ICH and underlying mechanisms.Methods: ICH model was induced by collagenase IV (0.2 U in 1 μl sterile normal saline) in male Sprague-Dawley rats weighing 280-320 g. Different doses of ILG (10, 20, or 40 mg/kg) was administrated intraperitoneally at 30 min, 12 h, 24 h, and 48 h after modeling, respectively. Rats were intracerebroventricularly administrated with control scramble small interfering RNA (siRNA) or Nrf2 siRNA at 24 h before ICH induction, and after 24 h, ICH model was established with or without ILG (20 mg/kg) treatment. All rats were dedicated at 24 or 72 h after ICH. Neurological deficits, histological damages, brain water content (BWC), blood-brain barrier (BBB) disruption, and neuronal degeneration were evaluated; quantitative real-time RT-PCR (qRT-PCR), immunohistochemistry/immunofluorescence, western blot, and enzyme-linked immunosorbent assay (ELISA) were carried out; catalase, superoxide dismutase activities and reactive oxygen species (ROS), and glutathione/oxidized glutathione contents were measured.Results: ILG (20 and 40 mg/kg) markedly alleviated neurological deficits, histological damages, BBB disruption, brain edema, and neuronal degeneration, but there was no significant difference between two dosages. ILG (20 mg/kg) significantly suppressed the NF-κB and NLRP3 inflammasome pathways and activated Nrf2-mediated antioxidant system. Gene silencing of Nrf2 aggravated the neurological deficits, brain edema, and neuronal degeneration and increased the protein levels of NF-κB p65, NLRP3 inflammasome components, and IL-1β. ILG delivery significantly attenuated the effects of Nrf2 siRNA interference mentioned above.Conclusions: Intraperitoneal administration of ILG after ICH reduced early brain impairments and neurological deficits, and the mechanisms were involved in the regulation of ROS and/or NF-κB on the activation of NLRP3 inflammasome pathway by the triggering of Nrf2 activity and Nrf2-induced antioxidant system. In addition, our experimental results may make ILG a potential candidate for a novel therapeutical strategy for ICH. [ABSTRACT FROM AUTHOR]

Hepatic steatosis is the most distinctive feature of alcoholic liver disease (ALD). Our previous in vivo study showed that ligustrazine, a major active alkaloid isolated from Ligusticum chuanxiong Hort, attenuated alcohol-induced hepatic steatosis and in vitro study revealed that nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activation might be a prerequisite. This study was aimed to explore the in vivo function of Nrf2 in the protective effect of ligustrazine and illustrate downstream mechanisms. Nrf2 shRNA lentivirus was introduced to establish Nrf2-knockdown mice. Results showed that Nrf2 knockdown aggravated alcoholic liver injury and abolished the protective effect of ligustrazine, evidenced by elevated serum biomarkers and severe liver inflammation. Ligustrazine impressively ameliorated hepatic steatosis through inhibiting hepatic sterol regulatory element-binding protein-1c and inducing peroxisome proliferator-activated receptoralpha, which was abrogated by Nrf2 knockdown. Noteworthily, Nrf2 knockdown apparently reinforced the inductive effect of alcohol on hypoxia-inducible factor 1-alpha (HIF-1α). Ligustrazine weakened the stimulation of alcohol on HIF-1-α expression, which was abrogated by Nrf2 shRNA lentivirus. Consistent results were obtained from in vitro study, implying that Nrf2/HIF-1-α pathway participated in the modulation of ligustrazine. Gain- or loss-of-function analyses further revealed that Nrf2 siRNA and dimethyloxalylglycine, a HIF-1-α agonist, abolished the inhibitory effect of ligustrazine, whereas HIF-1-α siRNA mimicked the role of ligustrazine and even rescued the inhibitory effect of ligustrazine on ethanol-induced lipid accumulation in Nrf2-knockdown hepatocytes. Taken together, we concluded that ligustrazine attenuated alcohol-induced hepatic steatosis via a Nrf2/HIF-1-α pathway-dependent mechanism. [ABSTRACT FROM AUTHOR]

Hepatic stellate cells (HSCs) are liver-specific pericytes that are recruited to vessels and secret pro-angiogenic cytokines, and thus actively involved in pathological vascularization during liver fibrosis. Peroxisome proliferator-activated receptor-γ (PPARγ) is a switch molecule controlling HSC activation. We investigated PPARγ regulation of angiogenic signal transduction and the molecular mechanisms involved in HSCs. Primary rat HSCs and liver sinusoidal endothelial cells (LSECs) were isolated and used in this study. Boyden chamber and tubulogenesis assays, identified that focal adhesion kinase (FAK)-RhoA signaling activated by platelet-derived growth factor (PDGF) was required for HSC motility and the associated vascularization. PDGF also stimulated vascular endothelial growth factor (VEGF) expression and HSC-driven vascularization through signals mediated by extracellular signalregulated kinase (ERK) and mammalian target of rapamycin (mTOR). Gain- and loss-of-function analyses demonstrated that activation of PPARγ interrupted FAK-RhoA, ERK and mTOR cascades and inhibited HSC-based vascularization. Molecular evidence further revealed that PPARγ attenuation of HSC angiogenic properties was dependent on inhibition of PDGF-β receptor expression. We concluded that PPARγ inhibited angiogenic signal transduction through transrepression of PDGF-β receptor leading to reduced HSC motility, reduced VEGF expression, and thereby attenuated HSC-driven angiogenesis. PPARγ could be a molecular target for preventing vascular remolding in hepatic fibrosis. [ABSTRACT FROM AUTHOR]

Age-related macular degeneration (AMD) is a major cause of blindness worldwide. Oxidative stress plays a large role in the pathogenesis of AMD. The present study was to evaluate the effects of Fructus lycii ethanol extract on AMD in mice and to investigate whether combination of lutein and zeaxanthin, two carotenoid pigments in Fructus lycii, could protect human retinal pigment epithelial ARPE-19 cells treated with hydrogen peroxide (H2O2) in vitro. We found that severe sediment beneath retinal pigment epithelium and thickened Bruch membrane occurred in AMD mice. However, Fructus lycii ethanol extract improved the histopathologic changes and decreased the thickness of Bruch membrane. Furthermore, the gene and protein expression of cathepsin B and cystatin C was upregulated in AMD mice but was eliminated by Fructus lycii ethanol extract. Investigations in vitro showed that ARPE-19 cell proliferation was suppressed by H2O2. However, lutein/zeaxanthin not only stimulated cell proliferation but also abrogated the enhanced expression of MMP-2 and TIMP-1 in H2O2-treated ARPE-19 cells.These data collectively suggested that Fructus lycii ethanol extract and its active components lutein/zeaxanthin had protective effects on AMD in vivo and in vitro, providing novel insights into the beneficial role of Fructus lycii for AMD therapy. [ABSTRACT FROM AUTHOR]

Xanthatin, a natural sesquiterpene lactone, has significant antitumor activity against a variety of cancer cells, yet little is known about its anticancer mechanism. In this study, we demonstrated that xanthatin had obvious dose-/time-dependent cytotoxicity against the human non-small-cell lung cancer (NSCLC) cell line A549. Flow cytometry analysis showed xanthatin induced cell cycle arrest at G2/M phase. Xanthatin also had pro-apoptotic effects on A549 cells as evidenced by Hoechst 33258 staining and annexin V-FITC staining. Mechanistic data revealed that xanthatin downregulated Chk1, Chk2, and phosphorylation of CDC2, which contributed to the cell cycle arrest. Xathatin also increased total p53 protein levels, decreased Bcl-2/Bax ratio and expression of the downstream factors procaspase-9 and procaspase-3, which triggered the intrinsic apoptosis pathway. Furthermore, xanthatin blocked phosphorylation of NF-κB (p65) and IκBa, which might also contribute to its pro-apoptotic effects on A549 cells. Xanthatin also inhibited TNFa induced NF-κB (p65) translocation. We conclude that xanthatin displays significant antitumor effects through cell cycle arrest and apoptosis induction in A549 cells. These effects were associated with intrinsic apoptosis pathway and disrupted NF-κB signaling. These results suggested that xanthatin may have therapeutic potential against NSCLC. [ABSTRACT FROM AUTHOR]

Activation of hepatic stellate cells (HSC), the major effectors of hepatic fibrogenesis, is coupled with sequential alterations in gene expression, including an increase in receptors for transforming growth factor-β (TGF-β) and a dramatic reduction in the peroxisome proliferator-activated receptor-γ (PPAR-γ). The relationship between them remains obscure. We previously demonstrated that curcumin induced gene expression of PPAR-γ in activated HSC, leading to reducing cell proliferation, inducing apoptosis and suppressing expression of extracellular matrix genes. The underlying molecular mechanisms are largely unknown. We recently observed that stimulation of PPAR-γ activation suppressed gene expression of TGF-β receptors in activated HSC, leading to the interruption of TGF-β signaling. This observation supported our assumption of an antagonistic relationship between PPAR-γ activation and TGF-β signaling in HSC. In this study, we further hypothesize that TGF-β signaling might negatively regulate gene expression of PPAR-γ in activated HSC. The present report demonstrates that exogenous TGF-β1 inhibits gene expression of PPAR-γ in activated HSC, which is eliminated by the pretreatment with curcumin likely by interrupting TGF-β signaling. Transfection assays further indicate that blocking TGF-β signaling by dominant negative type II TGF-β receptor increases the promoter activity of PPAR-γ gene. Promoter deletion assays, site-directed mutageneses, and gel shift assays localize two Smad binding elements (SBEs) in the PPAR-γ gene promoter, acting as curcumin response elements and negatively regulating the promoter activity in passaged HSC. The Smad3/4 protein complex specifically binds to the SBEs. Overexpression of Smad4 dose dependently eliminates the inhibitory effects of curcumin on the PPAR-γ gene promoter and TGF-β signaling. Taken together, these results demonstrate that the interruption of TGF-β signaling by curcumin induces gene expression of PPAR-γ in activated HSC in vitro. Our studies provide novel insights into the molecular mechanisms of curcumin in the induction of PPAR-γ gene expression and in the inhibition of HSC activation. [ABSTRACT FROM AUTHOR]

Upon liver injury, quiescent hepatic stellate cells (HSCs), the most relevant cell type for hepatic fibrogenesis, become active and over-produce extracellular matrix (ECM). Connective tissue growth factor (CTGF) promotes ECM production. Overexpression of CTGF during hepatic fibrogenesis is induced by transforming growth factor (TGF)-β. We recently demonstrated that curcumin reduced cell growth and inhibited ECM gene expression in activated HSCs. Curcumin induced gene expression of peroxisome proliferator-activated receptor (PPAR)-γ and stimulated its activity in activated HSCs, which was required for curcumin to suppress ECM gene expression, including αI(I)-collagen. The underlying mechanisms remain largely unknown. The aim of this study was to elucidate the mechanisms by which curcumin suppresses αI(I)-collagen gene expression in activated HSCs. We hypothesize that inhibition of αI(I)-collagen gene expression in HSCs by curcumin is mediated by suppressing CTGF gene expression through attenuating oxidative stress and interrupting TGF-β signaling. The present report demonstrated that curcumin significantly reduced the abundance of CTGF in passaged HSCs and suppressed its gene expression. Exogenous CTGF dose dependently abrogated the inhibitory effect of curcumin. Activation of PPAR-γ by curcumin resulted in the interruption of TGF-β signaling by suppressing gene expression of TGF-β receptors, leading to inhibition of CTGF gene expression. The phytochemical showed its potent antioxidant property by significantly increasing the level of total glutathione (GSH) and the ratio of GSH to GSSG in activated HSCs. De novo synthesis of cellular GSH was a prerequisite for curcumin to interrupt TGF-β signaling and inhibited gene expression of CTGF and αI(I)-collagen in activated HSCs. Taken together, our results demonstrate that inhibition of αI(I)-collagen gene expression by curcumin in activated HSCs results from suppression of CTGF gene expression through increasing cellular GSH contents and interruption of TGF-β signaling. These results provide novel insights into the mechanisms underlying inhibition of HSC activation by curcumin. [ABSTRACT FROM AUTHOR]