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Melanoma is an aggressive malignancy with a high mortality rate. Signal transducer and activator of transcription 3 (STAT3), an oncoprotein, is considered as an effective target for treating melanoma. Chrysoeriol is a flavonoid compound, and possesses anti-tumor activity in lung cancer, breast cancer and multiple myeloma; while whether it has anti-melanoma effects is still not known. Chrysoeriol has been shown to restrain STAT3 signaling in an inflammation mouse model.In this study, the anti-melanoma effects of chrysoeriol and the involvement of STAT3 signaling in these effects were investigated.CCK8 assays, 5-ethynyl-2'-deoxyuridine (EdU) staining, Annexin V-FITC/PI staining, Western blot analyses of cleaved caspase-9 and wound healing assays were used to study the anti-melanoma effects of chrysoeriol in cell models. A B16F10 melanoma bearing mouse model was used to evaluate the in vivo anti-melanoma effects of chrysoeriol. Indicators of cell proliferation, cell apoptosis and angiogeneis in melanoma tissues were detected by immunohistochemistry (IHC) staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. Immune cells in melanoma tissues were analyzed by flow cytometry. STAT3-overactivated cell models were used to investigate the involvement of STAT3 signaling in the anti-melanoma effects of chrysoeriol. Molecular dynamics (MD) simulations and surface plasmon resonance (SPR) assays were conducted to determine whether chrysoeriol binds to Src, an upstream kinase of STAT3.The results of cell experiments showed that chrysoeriol dose-dependently inhibited viability, proliferation and migration of, and induced apoptosis in, A375 and B16F10 melanoma cells. Chrysoeriol inhibited the phosphorylation of STAT3, and downregulated the expression of STAT3-target genes involved in melanoma growth and metastasis. Mouse studies showed that chrysoeriol restrained melanoma growth and tumor-related angiogenesis, and altered compositions of immune cells in melanoma microenvironment. Chrysoeriol also inhibited STAT3 signaling in B16F10 allografts. Chrysoeriol's viability-inhibiting effects were attenuated by over-activating STAT3 in A375 cells. Furthermore, chrysoeriol bound to the protein kinase domain of Src, and suppressed Src phosphorylation in melanoma cells and tissues.This study, for the first time, demonstrates that chrysoeriol has anti-melanoma effects, and these effects are partially due to inhibiting STAT3 signaling. Our findings indicate that chrysoeriol has the potential to be developed into an anti-melanoma agent.

Background: Acetaminophen (APAP) overdose results in the production of reactive oxygen species (ROS), induces hepatocyte necrosis, and leads to acute liver failure. Atractylenolide I (AO-I), a phytochemical found in Atractylodes macrocephala Koidz, is known to exhibit antioxidant activity. However, its clinical benefits against drug-induced liver injury remain largely unclear.Purpose: This study aimed at evaluating the protective effects of AO-I against APAP-induced acute liver injury.Methods: C57BL/6 mice were administered 500 mg/kg APAP to induce hepatotoxicity. AO-Ⅰ (60 and 120 mg/kg) was intragastrically administered 2 h before APAP dosing. Liver histopathological changes, oxidative stress and hepatic inflammation markers from each group were observed.Results: We observed that AO-I treatment significantly reversed APAP-induced liver injury, as evidenced by improved plasma alanine transaminase (ALT) level, aspartate aminotransferase (AST) and liver H&E stain. APAP treatment increased liver malondialdehyde (MDA) content and reduced catalase (CAT) and glutathione (GSH) level; however, these effects were alleviated by AO-I intervention. Moreover, AO-I treatment significantly inhibited APAP-induced activation of pro-inflammatory factors, such as IL-1β, IL-6, and TNF-α, at both the mRNA and protein levels. Mechanistic studies revealed that AO-I attenuated APAP-induced activation of TLR4, NF-κB and MAPKs (including JNK and p38).Conclusion: AO-I mediates protective effects against APAP-induced hepatotoxicity via the TLR4/MAPKs/NF-κB pathways. Thus, AO-I is a candidate therapeutic compound for APAP-induced hepatotoxicity.

Doxorubicin-induced cardiotoxicity (DIC) limits the clinical application of the drug in treatment of cancers and imposes a severe health burden on the patients. Therefore, there is an urgent need to develop alternative therapeutic strategies or drugs to minimize DIC. Salidroside is a phenylpropanoid glycoside extracted from Rhodiola rosea with multiple biological effects such as anti-inflammation and antioxidant properties. However, its mechanism of action in DIC is still poorly understood.The present study was aimed to investigate the role of salidroside in DIC and associated mechanism of action for the described effects.Cardiac dysfunction was induced through treatment of mice with doxorubicin in vivo and in vitro. The mechanism of action of salidroside was investigated using western blot assay, qPCR, immunofluorescence, histochemistry, echocardiography, and high-content imaging system.Results of the current study found that treatment of mice with salidroside significantly improved doxorubicin-induced cardiac dysfunction, ferroptosis-like cell damage, and fibrosis in vivo. Further, it was noted that salidroside inhibited ferroptosis in vivo and in vitro by limiting iron accumulation, restoring GPX4-dependent antioxidant capacity, and preventing lipid peroxidation at the cellular or mitochondrial levels. Mechanistically, salidroside inhibited DOX-induced mitochondrial ROS, FeThe present study evidently demonstrated the cardioprotective effects of salidroside against doxorubicin-induced cardiomyopathy. Further, salidroside markedly down-regulated ferroptotic cell death by activating AMPK-dependent signaling pathways including regulating abnormal fatty acid metabolism and maintaining mitochondrial function. Therefore, salidroside is can be exploited to develop a novel medication for clinical DIC and salidroside may represent a novel treatment that improves recovery from DIC by targeting ferroptosis.

Background and Aim: The worldwide prevalence of alcoholic liver disease (ALD) due to escalating alcohol consumption has presented an unprecedented pressure on human health. A few studies have determined long non-coding RNAs (lncRNAs) involved in the pathogenesis of liver diseases. However, the roles of lncRNAs in ALD development is still poorly understood.Methods: An ALD mouse model was established and confirmed. Expression profiles of lncRNAs were obtained by whole transcriptome sequencing. The altered lncRNAs in ALD mice were further verified by qRT-PCR. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to enrich the functions of these lncRNAs. In combination with miRNA and mRNA profiles, we constructed concise endogenous RNA (ceRNA) networks. The function of the most up/downregulated lnRNA was further verified and investigated in both ALD model and AML-12 cells.Results: Totally, five downregulated lncRNAs were obtained and verified in ALD mice. The GO term and KEGG pathway analyses revealed that the identified lncRNAs were associated with alcohol-induced hepatic oxidative damage, cellular inflammation, and lipid metabolism. Combination the differentially modulated miRNAs and mRNAs with ceRNA network analysis, we constructed five ceRNA networks and obtained 30 miRNAs and 25 mRNAs that may participate in ALD. Further, we verified and investigate the function of the most downregulated lnc_1700023H06Rik. Depletion lnc_1700023H06Rik reduced genes encoding for lipid metabolism, especially mRNA Acat2 (ENSMUST00000159697) and Pgrmc2 (ENSMUST00000058578) both in vivo and in vitro. Knocking down lnc_1700023H06Rik induced triglyceride accumulation and lactate dehydrogenase leakage in AML12 cells, consisting with that in alcohol-treated cells.Conclusion: The five remarkably downregulated lncRNAs in ALD mouse model were identified as novel biomarkers, highlighting the key role of lncRNAs in the development of ALD. The effect of lnc_1700023H06Rik plays a pivotal role in lipid deposition and its pathological pathway in ALD needs further investigation.

Background: Salvianolic acid A (Sal A), a natural polyphenolic compound extracted from Radix Salvia miltiorrhiza (Danshen), exhibits exceptional pharmacological activities against cardiovascular diseases. While a few studies have reported anti-obesity properties of Sal A, the underlying mechanisms are largely unknown. Given the prevalence of obesity and promising potential of browning of white adipose tissue to combat obesity, recent research has focused on herbal ingredients that may promote browning and increase energy expenditure.Purpose: The present study was designed to investigate the protective antiobesity mechanisms of Sal A, in part through white adipose browning.Methods: Both high-fat diet (HFD)-induced obese (DIO) male mice model and fully differentiated C3H10T1/2 adipocytes from mouse embryo fibroblasts were employed in this study. Sal A (20 and 40 mg/kg) was administrated to DIO mice by intraperitoneal injection for 13-weeks. Molecular mechanisms mediating effects of Sal A were evaluated.Resluts: Sal A treatment significantly attenuated HFD-induced weight gain and lipid accumulation in epididymal fat pad. Uncoupling protein 1 (UCP-1), a specialized thermogenic protein and marker for white adipocyte browning, was significantly induced by Sal A treatment in both white adipose tissues and cultured adipocytes. Further mechanistic investigations revealed that Sal A robustly reversed HFD-decreased AMP-activated protein kinase (AMPK) phosphorylation and sirtuin 1 (SIRT1) expression in mice. Genetically silencing either AMPK or SIRT1 using siRNA abolished UCP-1 upregulation by Sal A. AMPK silencing significantly blocked Sal A-increased SIRT1 expression, while SIRT1 silencing did not affect Sal A-upregulated phosphorylated-AMPK. These findings indicate that AMPK was involved in Sal A-increased SIRT1.Conclusion: Sal A increases white adipose tissue browning in HFD-fed male mice and in cultured adipocytes. Thus, Sal is a potential natural therapeutic compound for treating and/or preventing obesity.

The occurrence of lipotoxicity during obesity-associated cardiomyopathy is detrimental to health. Salvianolic acid A (SAA), a natural polyphenol extract of Salvia miltiorrhiza Bunge (Danshen in China), is known to be cardioprotective. However, its clinical benefits against obesity-associated cardiomyocyte injuries are unclear. This study aimed at evaluating the protective effects of SAA against lipotoxicity-induced myocardial injury and its underlying mechanisms in high fat diet (HFD)-fed mice and in palmitate-treated cardiomyocyte cells (H9c2). Our analysis of aspartate aminotransferase and creatine kinase isoenzyme-MB (CM-KB) levels revealed that SAA significantly reversed HFD-induced myocardium morphological changes and improved myocardial damage. Salvianolic acid A pretreatment ameliorated palmitic acid-induced myocardial cell death and was accompanied by mitochondrial membrane potential and intracellular reactive oxygen species improvement. Analysis of the underlying mechanisms showed that SAA reversed myocardial TLR4 induction in HFD-fed mice and H9c2 cells. Palmitic acid-induced cell death was significantly reversed by CLI-95, a specific TLR4 inhibitor. TLR4 activation by LPS significantly suppressed SAA-mediated lipotoxicity protection. Additionally, SAA inhibited lipotoxicity-mediated expression of TLR4 target genes, including MyD88 and p-JNK/MAPK in HFD-fed mice and H9c2 cells. However, SAA did not exert any effect on palmitic acid-induced SIRT1 suppression and p-AMPK induction. In conclusion, our data shows that SAA protects against lipotoxicity-induced myocardial damage through a TLR4/MAPKs mediated mechanism.

Background: Salvianolic acid A (Sal A), a natural polyphenol compound extracted from Radix Salvia miltiorrhiza (known as Danshen in China), possesses a variety of potential pharmacological activities. The aim of this study is to determine mechanisms of hepatoprotective effects of Sal A against lipotoxicity both in cultured hepatocytes and in a mouse model of fatty liver disease.Methods: High-fat and high-carbohydrate diet (HFCD)-fed C57BL/6J mice were employed to establish hepatic lipotoxicity in a mouse model. Two doses of Sal A were administered every other day via intraperitoneal injection (20 and 40 mg/kg BW, respectively). After a 10-week intervention, liver injury was detected by immunohistochemical and biochemical analyses. For in vitro studies, we used HepG2, a human hepatoma cell line, and exposed them to palmitic acid to induce lipotoxicity. The protective effects of Sal A on palmitic acid-induced lipotoxicity were examined in Sal A-pretreated HepG2 cells.Results: Sal A treatments attenuated body weight gain, liver injury, and hepatic steatosis in mice exposed to HFCD. Sal A pretreatments ameliorated palmitic acid-induced cell death but did not reverse effects of HFCD- or palmitate-induced activations of JNK, ERK1/2, and PKA. Induction of p38 phosphorylation was significantly reversed by Sal A in HFCD-fed mice but not in palmitate-treated HepG2 cells. However, Sal A rescued hepatic AMP-activated protein kinase (AMPK) suppression and sirtuin 1 (SIRT1) downregulation by both HFCD feeding in mice and exposure to palmitate in HepG2 cells. Sal A dose-dependently up-regulated p-AMPK and SIRT1 protein levels. Importantly, siRNA silencing of either AMPK or SIRT1 gene expression abolished the protective effects of Sal A on lipotoxicity. Moreover, while AMPK silencing blocked Sal A-induced SIRT1, silencing of SIRT1 had no effect on Sal A-triggered AMPK activation, suggesting SIRT1 upregulation by Sal A is mediated by AMPK activation.Conclusion: Our data uncover a novel mechanism for hepatoprotective effects of Sal A against lipotoxicity both in livers from HFCD-fed mice and palmitic acid-treated hepatocytes.

Oxidative stress and TNFα are critically involved in the initiation and progression of non-alcoholic fatty liver disease (NAFLD). In this study, we investigated the effects of dysregulated glutathione homeostasis, a principal feature of oxidative stress, on TNFα-induced hepatotoxicity and its mechanistic implications in NAFLD progression. We showed that mice fed a high-fat diet (HFD) for 12 weeks developed hepatic steatosis and liver injuries, which were associated with not only TNFα overproduction but also hepatic glutathione dysregulation, characterized by GSH reduction and GSSG elevation. Moreover, consuming a HFD increased protein S-glutathionylation (protein-SSG formation) in the liver. Subsequent cell culture studies revealed that GSSG accumulation, as opposed to GSH reduction, sensitized hepatocytes to TNFα killing by reducing the TNFα-triggered NF-κB activity. GSSG prevented TNFα-induced activation of IKK-β, an upstream kinase in the NF-κB signaling pathway, by inducing IKK-β glutathionylation (IKK-β-SSG formation). In animal studies, in comparison to a control diet, HFD consumption resulted in increased hepatic IKK-β-SSG formation, leading to suppressed IKK-β activation and subsequent NF-κB suppression. Furthermore, we found that HFD consumption also led to decreased hepatic expression of glutaredoxin, a key enzyme for de-glutathionylation. Similarly, CdCl2, a chemical inhibitor of glutaredoxin, sensitized hepatocytes to TNFα-mediated cytotoxicity. In conclusion, our data suggest that GSSG is a potent and clinically relevant sensitizer for TNFα-induced hepatotoxicity in NAFLD, which represents a potential therapeutic target for NAFLD., Fatty liver disease: spent antioxidant and liver cell death An imbalance between ROS and antioxidant molecules, induced by a high-fat diet, is a major contributor to non-alcoholic fatty liver disease in a mouse model. Dr. Zhenyuan Song from the University of Illinois at Chicago, USA, and colleagues showed that a 12-week high-fat diet consumption led to increased expression of the pro-inflammatory signaling molecule TNFα in the liver. It also resulted in conversion of the antioxidant molecule glutathione (GSH) into a “spent” form called glutathione disulfide (GSSG), a sign that the liver has dealt with a lot of cellular stress. Experiments in human liver cells showed that intracellualr GSSG accumulation sensitizes hepatocytes to cell death via a molecular cascade triggered by TNFα activity. These findings point to GSSG as a potential drug target for treating non-alcoholic fatty liver disease.

The treatment of sepsis is still challenging and the liver is an important target of sepsis-related injury. Macrophages are important innate immune cells in liver, and modulation of macrophages M1/M2 polarization may be a promising strategy for septic liver injury treatment. Macrophage polarization and inflammation of liver tissue has been shown regulated by pyruvate kinase M2 (PKM2)-mediated aerobic glycolysis and immune inflammatory pathways. Therefore, modulating PKM2-mediated immunometabolic reprogramming presents a novel strategy for inflammation-associated diseases. In this study, cynaroside, a flavonoid compound, promoted macrophage phenotypic transition from pro-inflammatory M1 to anti-inflammatory M2, and mitigated sepsis-associated liver inflammatory damage. We established that cynaroside reduced binding of PKM2 to hypoxia-inducible factor-1α (HIF-1α) by abolishing translocation of PKM2 to the nucleus and promoting PKM2 tetramer formation, as well as suppressing phosphorylation of PKM2 at Y105 in vivo and in vitro. Moreover, cynaroside restored pyruvate kinase activity, inhibited glycolysis-related proteins including PFKFB3, HK2 and HIF-1α, and inhibited glycolysis-related hyperacetylation of HMGB1 in septic liver. Therefore, this study reports a novel function of cynaroside in hepatic macrophage polarization, and cecum ligation and puncture-induced liver injury in septic mice. The findings provide crucial information with regard to therapeutic efficacy of cynaroside in the treatment of sepsis.

Tanshinone IIA, a multi-pharmaceutical compound from traditional Chinese herb, has been reported to have anti-hepatocarcinomic (HCC) properties through cell death induction. Apart from the typical p53-dependent pathway, mechanisms of the anti-carcinogenic role of Tanshinone remain scarce. In an effort to explore the mechanism behind Tanshinone IIA, we detected the upstream of the p53 and the potential novel pathway. Tanshinone IIA dose-dependently initiated HepG2 cell apoptosis and cell cycle arrest at the G1 checkpoint. In the miR30 family, only the transcription of miR30b was downregulated by Tanshinone IIA, which subsequently upregulated both the genomic and protein levels of p53. Further, we screened that PTPN11 and Tp53 are the two critical genomes involved in the pharmacology of Tanshinone IIA. Building upon LASAGNA-search and kinetics binding assay, p53 was found to be a potential transcription factor for PTPN11. Concomitant with the expression of p53, Tanshinone IIA stimulated both PTPN11 and its encoded protein SHP2. Inhibition miR30b attenuated the Tanshinone IIA-induced cytotoxicity, level of p53 and PTPN11 in HepG2 cells. Finally, the apoptotic molecules such as Bax/Bcl2, cleavage caspase 3 and the cell cycle regulation factors including p21, cyclin D1, and CDK6 were changed by Tanshinone IIA. Several cytotoxic endpoints induced by Tanshinone IIA were also checked in Hep3B cells. This study confirmed that Tanshinone IIA may induce hepatoma cell death through the miR30b-p53- PTPN11/SHP2 pathway. With regard to the complicated tumorigenesis of HCC and the multi-targets of Tanshinone IIA, our results propose developing Tanshinone IIA for clinic therapy and the interference of HCC.

Background: Alcoholic liver disease is a type of chronic liver diseases caused by chronic ethanol overconsumption. The pathogenesis of alcoholic liver disease is complex and there is no effective clinical treatment so far. SIRT3 is an NAD+-dependent deacetylase primarily located inside mitochondria, the reports on the effect of chronic alcohol exposure on liver SIRT3 expression are scarce. The study aims to investigate the effect of chronic alcohol consumption on hepatic SIRT3 expression and its role in alcoholic-induced liver injury. Methods: Using Lieber-DeCarli mouse model of alcoholic liver disease, we analyzed the regulation of SIRT3 and the effect of liver-specific knocking-down of SIRT3 on alcohol-induced liver injury. HepG2 and AML12 hepatocytes were employed to detect the biological function of SIRT3 on alcohol-induced hepatic cytotoxicity and its potential mechanism. Results: Chronic alcohol exposure led to hepatic SIRT3 upregulation and liver-specific SIRT3 knockdown alleviated alcoholic feeding-induced liver injury and lipids accumulation, which is associated with improved autophagy induction. Additionally, autophagy induction contributed to the cytoprotective effect of SIRT3 knockdown on ethanol-induced hepatocyte cell death. Conclusion: In summary, our data suggest that hepatic SIRT3 upregulation in response to chronic alcohol exposure and liver-specific SIRT3 knockdown induced autophagy activation further alleviating alcoholic-induced liver injury, which represents a novel mechanism in this process.

Background and Purpose Overactive lipolysis in adipose tissue contributes to the pathogenesis of alcoholic liver disease (ALD); however, the mechanisms involved have not been elucidated. We previously reported that chronic alcohol consumption produces a hypomethylation state in adipose tissue. In this study we investigated the role of hypomethylation in adipose tissue in alcohol-induced lipolysis and whether its correction contributes to the well-established hepatoprotective effect of betaine in ALD.

Lipotoxicity induced by saturated fatty acids (SFAs) plays a pathological role in the development of non-alcoholic fatty liver disease (NAFLD); however, the exact mechanism remains to be clearly elucidated. Palmitate is the most abundant SFA in the circulation and major lipotoxic inducer. Accumulating evidence supports that autophagy induction is protective against palmitate-induced cell death in a variety of cell types, including hepatocytes. Nicotinamide is the amide form of nicotinic acid (vitamin B3, Niacin) and a dietary supplementation as a source of vitamin B3. We previously reported that nicotinamide endowed hepatocytes resistance to palmitate-induced ER stress via up-regulating SIRT1, with cAMP/PKA/CREB pathway activation being a fundamental mechanism. This study was undertaken to investigate the potential anti-lipotoxic effect of nicotinamide and to elucidate underlying mechanism(s). Our data demonstrated that nicotinamide supplementation protected hepatocytes against palmitate-induced cell death. Mechanistic investigations revealed that nicotinamide supplementation activated autophagy in hepatocytes. Importantly, we showed that the anti-lipotoxic property of nicotinamide was abolished by autophagy inhibitors, suggesting that autophagy induction plays a mechanistic role in nicotinamide's anti-lipotoxic effect. Furthermore, we showed that SIRT1 inhibition blunted autophagy induction in response to nicotinamide supplementation and similarly abrogated the anti-lipotoxic effect conferred by nicotinamide supplementation. In conclusion, our data suggest that nicotinamide protects against palmitate-induced hepatotoxicity via SIRT1-dependent autophagy induction and that nicotinamide supplementation may represent a therapeutic choice for NAFLD.

The extract of Penthorum chinense Pursh (PCP), a well-known Miao herb medicine, has been used as a key component for a Chinese patented drug to treat several kinds of liver-related diseases. In this work, 3 pinocembrin derivatives, S1, S2, and S3, were isolated from PCP stems and identified with high-performance liquid chromatography and electrospray ionization mass spectrometer. The molecular masses of S1, S2, and S3 were identical to Pinocembrin-7-O-[4″,6″-hexahydroxydiphenoyl (HHDP)]-β-D-glucose, Pinocembrin-7-O-[3″-O-galloyl-4″,6″-(s)-HHDP)-β-D-glucose, and Thonningianin A, respectively. Their free radical scavenging capability was evaluated with the 2,2-diphenyl-1-picrylhydrazyl assay. The half-maximal effective concentrations of S1, S2, and S3 were 26.75, 9.06, and 5.50 μg/mL, respectively. In vitro AML-12 assays demonstrated that S1 (5-20 μg/mL), S2 (10-40 μg/mL), and S3 (10-40 μg/mL) not only protected cells from H2O2-induced oxidation and alcohol-induced cell damages, but also reduced oleic acid (OA)-induced triglyceride accumulations in a dose-dependent manner. However, the 3 compounds potently exhibited similar cytotoxicity effect at high concentrations. The half-maximal inhibitory concentrations of S1, S2, and S3 to AML-12 cells were 74.19, 85.86, and 80.43 μg/mL. In addition, the 3 compounds also showed antibacterial activity on Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Lactobacillus rhamnosus, and Bacillus subtilis.

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive accumulation of hepatic lipids and oxidative injury of hepatocytes. Rutin is a natural flavonoid with significant roles in combating cellular oxidative stress and regulating lipid metabolism. The current study aims to investigate the molecular mechanisms underlying rutin's hypolipidemic and hepatoprotective effects in nonalcoholic fatty liver disease. Rutin treatment was applied to male C57BL/6 mice maintained on a high-fat diet and HepG2 cells challenged with oleic acid. Hepatic lipid accumulation was evaluated by triglyceride assay and Oil Red O staining. Oxidative hepatic injury was assessed by malondialdehyde assay, superoxide dismutase assay and reactive oxygen species assay. The expression levels of various lipogenic and lipolytic genes were determined by quantitative real-time polymerase chain reactions. In addition, liver autophagy was investigated by enzyme-linked immunosorbent assay. In both fat-challenged murine liver tissues and HepG2 cells, rutin treatment was shown to significantly lower triglyceride content and the abundance of lipid droplets. Rutin was also found to reduce cellular malondialdehyde level and restore superoxide dismutase activity in hepatocytes. Among the various lipid-related genes, rutin treatment was able to restore the expression of peroxisome proliferator-activated receptor alpha (PPAR-α) and its downstream targets, carnitine palmitoyltransferase 1 and 2 (CPT-1 and CPT-2), while suppressing those of sterol regulatory element-binding protein 1c (SREBP-1c), diglyceride acyltransfase 1 and 2 (DGAT-1 and 2), as well as acyl-CoA carboxylase (ACC). In addition, rutin was shown to repress the autophagic function of liver tissues by down-regulating key autophagy biomarkers, including tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β). The experimental data demonstrated that rutin could reduce triglyceride content and mitigate oxidative injuries in fat-enriched hepatocytes. The hypolipidemic properties of rutin could be attributed to its ability to simultaneously facilitate fatty acid metabolism and inhibit lipogenesis.

Long-term alcohol exposure sensitizes hepatocytes to tumor necrosis factor-α (TNF) cytotoxicity. 4-Hydroxynonenal (4-HNE) is one of the most abundant and reactive lipid peroxides. Increased hepatic 4-HNE contents present in both human alcoholics and alcohol-fed animals. In the present study, we investigated the effects of intracellular 4-HNE accumulation on TNF-induced hepatotoxicity and its potential implication in the pathogenesis of alcoholic liver disease. Male C57BL/6 mice were fed an ethanol-containing or a control diet for 5 weeks. Long-term alcohol exposure increased hepatic 4-HNE and TNF levels. Cell culture studies revealed that 4-HNE, at nontoxic concentrations, sensitized hepatocytes to TNF killing, which was associated with suppressed NF-κB transactivity. Further investigation demonstrated that 4-HNE prevented TNF-induced inhibitor of κBα phosphorylation without affecting upstream IκB kinase activity. An immunoprecipitation assay revealed that increased 4-HNE content was associated with increased formation of 4-HNE-inhibitor of κBα adduction in both 4-HNE-treated hepatocytes and in the livers of alcohol-fed mice. Prevention of intracellular 4-HNE accumulation by bezafibrate, a peroxisome proliferator-activated receptor-α agonist, protected hepatocytes from TNF killing via NF-κB activation. Supplementation of N-acetylcysteine, a glutathione precursor, conferred a protective effect on alcohol-induced liver injury in mice, was associated with decreased hepatic 4-HNE formation, and improved hepatic NF-κB activity. In conclusion, increased 4-HNE accumulation represents a potent and clinically relevant sensitizer to TNF-induced hepatotoxicity. These data support the notion that removal of intracellular 4-HNE can serve as a potential therapeutic option for alcoholic liver disease.

Plasma low-density lipoprotein-cholesterol (LDL-C) is mainly taken up and cleared by the hepatocellular LDL receptor (LDL-R). LDL-R gene expression is regulated by the sterol regulatory element binding proteins (SREBPs). Previous studies have shown that curcumin reduces plasma LDL-C and has hypolipidemic and anti-atherosclerotic effects. Herein, we investigated the effect of curcumin on LDL-R expression and its molecular mechanism in HepG2 cells. Curcumin increased LDL-R expression (mRNA and protein) and the resultant uptake of DiI-LDL in a dose- and time-dependent manner. Using a GFP reporter system in a transfected HepG2/SRE-GFP cell line, we found that curcumin activated the sterol regulatory element of the LDL-R promoter. In HepG2/Insig2 cells, curcumin reversed the inhibition of LDL-R expression induced by Insig2 overexpression. These data demonstrate that curcumin increases LDL-R protein expression and uptake activity via the SREBPs pathway. These findings contribute to our further understanding of the cholesterol-lowering and anti-atherosclerotic effects of curcumin.

Alcoholic liver disease (ALD) is a type of chronic liver disease caused by long-term heavy ethanol consumption. Danshen is one of the most commonly used substances in traditional Chinese medicine and has been widely used for the treatment of various diseases, and most frequently, the ALD. The current study aims to determine the potential beneficial effect of Danshen administration on ALD and to clarify the underlying molecular mechanisms. Danshen administration improved liver pathologies of ALD, attenuated alcohol-induced increment of hepatic 4-Hydroxynonenal (4-HNE) formation, and prevented hepatic Peroxisome proliferators activated receptor alpha (PPARα) suppression in response to chronic alcohol consumption. Cell culture studies revealed that both hepatoprotective effect and increased intracellular 4-HNE clearance instigated by Danshen supplementation are PPARα-dependent. In conclusion, Danshen administration can protect against ALD via inducing PPARα activation and subsequent 4-HNE degradation.