Sixteen carbazole alkaloids from
Clausena vestita D. D. Tao were extracted, and their anti-tumor activities were evaluated. Among the extracts,
Clauszoline-I exhibited an obvious growth inhibitory ...activity against several cancer cell lines through its ability to induce cell cycle arrest in the S and G2/M phases. A dramatic morphologic change with decreased F-actin staining and RhoA activity was found in
Clauszoline-I treated HepG2 cells, in which the phosphorylation of PKCδ (Ser643) was inhibited. Our results indicated that induction cell cycle arrest by
Clauszoline-I might be achieved by decreasing the RhoA activity via the inhibition of PKCδ phosphorylation.
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Clauszoline-I is a carbazole alkaloid from
Clausena vestita D. D. Tao. ► It induced cell cycle arrest and Chk1 redistribution from nucleus into cytoplasm. ► It caused morphological changes via repression of RhoA activation. ► It inhibited PKCδ (Ser643) phosphorylation.
Malignant gliomas represent one of the most aggressive types of cancers and their recurrence is closely linked to acquired therapeutic resistance. A combination of chemotherapy is considered a ...promising therapeutic model in overcoming therapeutic resistance and enhancing treatment efficacy. Herein, we show by colony formation, Hochest 33342 and TUNEL staining, as well as by flow cytometric analysis, that LY294002, a specific phosphatidylinositide-3-kinase (PI3K) inhibitor, enhanced significantly the sensitization of a traditional cytotoxic chemotherapeutic agent, tamoxifen-induced apoptosis in C6 glioma cells. Activation of PI3K signaling pathway by IGF-1 protected U251 cells from apoptosis induced by combination treatment of LY294002 and tamoxifen. Interference of PI3K signaling pathway by PI3K subunit P85 siRNA enhanced the sensitization of U251 glioma cells to tamoxifen -induced apoptosis. By Western blotting, we found that combination treatment showed lower levels of phosphorylated Akt(Ser473) and GSK-3β(Ser9) than a single treatment of LY294002. Further, we showed a significant decrease of nuclear β-catenin by combination treatment. In response to the inhibition of β-catenin signaling, mRNA and protein levels of Survivin and the other three antiapoptotic genes Bcl-2, Bcl-xL, and Mcl-1 were significantly decreased by combination treatment. Our results indicated that the synergistic cytotoxic effect of LY294002 and tamoxifen is achieved by the inhibition of GSK-3β/β-catenin signaling pathway.
Chronic excessive alcohol use is a well-recognized risk factor for pancreatic dysfunction and pancreatitis development. Evidence from in vivo and in vitro studies indicates that the detrimental ...effects of alcohol on the pancreas are from the direct toxic effects of metabolites and byproducts of ethanol metabolism such as reactive oxygen species. Pancreatic dysfunction and pancreatitis development are now increasingly thought to be multifactorial conditions, where alcohol, genetics, lifestyle, and infectious agents may determine the initiation and course of the disease. In this review, we first highlight the role of nonoxidative ethanol metabolism in the generation and accumulation of fatty acid ethyl esters (FAEEs) that cause multi-organellar dysfunction in the pancreas which ultimately leads to pancreatitis development. Further, we discuss how alcohol-mediated altered autophagy leads to the development of pancreatitis. We also provide insights into how alcohol interactions with other co-morbidities such as smoking or viral infections may negatively affect exocrine and endocrine pancreatic function. Finally, we present potential strategies to ameliorate organellar dysfunction which could attenuate pancreatic dysfunction and pancreatitis severity.
Sirt1 and nuclear factor-E2 related factor 2 (Nrf2)-anti-oxidant response element (ARE) anti-oxidative pathway play important regulatory roles in the pathological progression of diabetic nephropathy ...(DN) induced by advanced glycation-end products (AGEs). Polydatin (PD), a glucoside of resveratrol, has been shown to possess strong anti-oxidative bioactivity. Our previous study demonstrated that PD markedly resists the progression of diabetic renal fibrosis and thus, inhibits the development of DN. Whereas, whether PD could resist DN through regulating Sirt1 and consequently promoting Nrf2-ARE pathway needs further investigation. Here, we found that concomitant with decreasing RAGE (the specific receptor for AGEs) expression, PD significantly reversed the downregulation of Sirt1 in terms of protein expression and deacetylase activity and attenuated FN and TGF- beta 1 expression in GMCs exposed to AGEs. Under AGEs-treatment condition, PD could decrease Keap1 expression and promote the nuclear content, ARE-binding ability, and transcriptional activity of Nrf2. In addition, PD increased the protein levels of heme oxygenase 1 (HO-1) and superoxide dismutase 1 (SOD1), two target genes of Nrf2. The activation of Nrf2-ARE pathway by PD eventually led to the quenching of ROS overproduction sharply boosted by AGEs. Depletion of Sirt1 blocked Nrf2-ARE pathway activation and reversed FN and TGF- beta 1 downregulation induced by PD in GMCs challenged with AGEs. Along with reducing HO-1 and SOD1 expression, silencing of Nrf2 increased FN and TGF- beta 1 levels. PD treatment elevated Sirt1 and Nrf2 levels in the kidney tissues of diabetic rats, then improved the anti-oxidative capacity and renal dysfunction of diabetic models, and finally reversed the upregulation of FN and TGF- beta 1. Taken together, the resistance of PD on upregulated FN and TGF- beta 1 induced by AGEs via oxidative stress in GMCs is closely associated with its activation of Sirt1-Nrf2-ARE pathway. Abbreviations * AGEs, advanced glycation-end products * ARE, anti-oxidant response element * BSA, bovine serum albumin * DN, diabetic nephropathy * ECM, extracellular matrix * EMSA, electrophoretic mobility shift assay * FN, fibronectin * GMCs, glomerular mesangial cells * HG, high glucose * HO-1, heme oxygenase 1 * Keap1, kelch like ECH-associated protein 1 * SOD, superoxide dismutase * MDA, malondialdehyde * NAD super(+), nicotinamide adenosine dinucleotide super(+) * Nrf2, nuclear factor E2-related factor 2 * OSS, oxidative stress * PD, polydatin * RAGE, the specific receptor for AGEs * ROS, reactive oxygen species * STZ, streptozocin * TGF- beta 1, transforming growth factor- beta 1
•PD increased Sirt1 levels, promoted Nrf2-ARE pathway activation, and reduced ROS levels in AGEs-treated GMCs.•PD resisted AGEs-induced upregulation of FN and TGF-β1 by activating Sirt1-Nrf2-ARE ...pathway.•PD ameliorated DN in a STZ-induced diabetic rat model.
Sirt1 and nuclear factor-E2 related factor 2 (Nrf2)-anti-oxidant response element (ARE) anti-oxidative pathway play important regulatory roles in the pathological progression of diabetic nephropathy (DN) induced by advanced glycation-end products (AGEs). Polydatin (PD), a glucoside of resveratrol, has been shown to possess strong anti-oxidative bioactivity. Our previous study demonstrated that PD markedly resists the progression of diabetic renal fibrosis and thus, inhibits the development of DN. Whereas, whether PD could resist DN through regulating Sirt1 and consequently promoting Nrf2-ARE pathway needs further investigation. Here, we found that concomitant with decreasing RAGE (the specific receptor for AGEs) expression, PD significantly reversed the downregulation of Sirt1 in terms of protein expression and deacetylase activity and attenuated FN and TGF-β1 expression in GMCs exposed to AGEs. Under AGEs-treatment condition, PD could decrease Keap1 expression and promote the nuclear content, ARE-binding ability, and transcriptional activity of Nrf2. In addition, PD increased the protein levels of heme oxygenase 1 (HO-1) and superoxide dismutase 1 (SOD1), two target genes of Nrf2. The activation of Nrf2-ARE pathway by PD eventually led to the quenching of ROS overproduction sharply boosted by AGEs. Depletion of Sirt1 blocked Nrf2-ARE pathway activation and reversed FN and TGF-β1 downregulation induced by PD in GMCs challenged with AGEs. Along with reducing HO-1 and SOD1 expression, silencing of Nrf2 increased FN and TGF-β1 levels. PD treatment elevated Sirt1 and Nrf2 levels in the kidney tissues of diabetic rats, then improved the anti-oxidative capacity and renal dysfunction of diabetic models, and finally reversed the upregulation of FN and TGF-β1. Taken together, the resistance of PD on upregulated FN and TGF-β1 induced by AGEs via oxidative stress in GMCs is closely associated with its activation of Sirt1-Nrf2-ARE pathway.
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Alcoholic liver disease (ALD) is one of the major causes of chronic liver disease worldwide. We previously demonstrated that chronic plus acute alcohol binge (“Gao‐binge”) impaired ...hepatic transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, resulted in insufficient autophagy that contributes to Gao‐binge alcohol‐induced liver injury in mice. Trehalose, a disaccharide, has been shown to activate TFEB and protects against diet‐induced non‐alcoholic fatty liver disease in mice. The aim of the present study was to investigate whether trehalose would reverse impaired TFEB and insufficient autophagy induced by Gao‐binge alcohol and in turn protect against Gao‐binge alcohol‐induced liver injury. We found that trehalose increased TFEB nuclear translocation, elevated levels of LC3‐II and lysosomal proteins in cultured AML12 cells and in mouse livers, confirming the activation of TFEB by trehalose. Surprisingly, trehalose failed to activate TFEB in Gao‐binge alcohol‐treated mouse livers. As a result, trehalose failed to protect against Gao‐binge alcohol‐induced liver injury and steatosis. However, Gao‐binge alcohol increased infiltration of hepatic neutrophils and levels of inflammatory cytokine gene expression, which were attenuated by trehalose, suggesting trehalose inhibits alcohol‐induced inflammation independent of TFEB activation. In conclusion, our results indicate that trehalose fails to improve the impaired TFEB and liver injury but ameliorates hepatic inflammation induced by Gao‐binge alcohol.
Support or Funding Information
NIH R01 AA020518, R01 DK102142, U01 AA024733 AND P30GM118247 (W.X.D).
Impaired macroautophagy/autophagy has been implicated in experimental and human pancreatitis. However, the transcriptional control governing the autophagy-lysosomal process in pancreatitis is largely ...unknown. We investigated the role and mechanisms of TFEB (transcription factor EB), a master regulator of lysosomal biogenesis, in the pathogenesis of experimental pancreatitis. We analyzed autophagic flux, TFEB nuclear translocation, lysosomal biogenesis, inflammation and fibrosis in GFP-LC3 transgenic mice, acinar cell-specific tfeb knockout (KO) and tfeb and tfe3 double-knockout (DKO) mice as well as human pancreatitis samples. We found that cerulein activated MTOR (mechanistic target of rapamycin kinase) and increased the levels of phosphorylated TFEB as well as pancreatic proteasome activities that led to rapid TFEB degradation. As a result, cerulein decreased the number of lysosomes resulting in insufficient autophagy in mouse pancreas. Pharmacological inhibition of MTOR or proteasome partially rescued cerulein-induced TFEB degradation and pancreatic damage. Furthermore, genetic deletion of tfeb specifically in mouse pancreatic acinar cells increased pancreatic edema, necrotic cell death, infiltration of inflammatory cells and fibrosis in pancreas after cerulein treatment. tfeb and tfe3 DKO mice also developed spontaneous pancreatitis with increased pancreatic trypsin activities, edema and infiltration of inflammatory cells. Finally, decreased TFEB nuclear staining was associated with human pancreatitis. In conclusion, our results indicate a critical role of impaired TFEB-mediated lysosomal biogenesis in promoting the pathogenesis of pancreatitis.
Abbreviations: AC: acinar cell; AMY: amylase; ATP6V1A: ATPase, H+ transporting, lysosomal V1 subunit A; ATP6V1B2: ATPase, H+ transporting, lysosomal V1 subunit B2; ATP6V1D: ATPase, H+ transporting, lysosomal V1 subunit D; ATP6V1H: ATPase, H+ transporting, lysosomal V1 subunit H; AV: autophagic vacuole; CDE: choline-deficient, ethionine-supplemented; CLEAR: coordinated lysosomal expression and regulation; CQ: chloroquine; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; EM: electron microscopy; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GFP: green fluorescent protein; H & E: hematoxylin and eosin; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MAPK1/ERK2: mitogen-activated protein kinase 1; MTORC1: mechanistic target of rapamycin kinase complex 1; ND: normal donor; NEU: neutrophil; PPARGC1A/PGC1α: peroxisome proliferator-activated receptor, gamma, coactivator 1 alpha; RIPA: radio-immunoprecipitation; RPS6: ribosomal protein S6; SQSTM1/p62: sequestosome 1; TFEB: transcription factor EB; TM: tamoxifen; WT: wild-type; ZG: zymogen granule
Diabetic nephropathy (DN) is the leading cause of end-stage renal failure and is characterized by excessive deposition of extracellular matrix (ECM) proteins such as fibronectin (FN), in the ...glomerular mesangium and tubulointerstitium. Betulinic acid (BA), a pentacyclic triterpene derived from the bark of the white birch tree, has been demonstrated to have many pharmacological activities. However, the effect of BA on DN has not been fully elucidated. To explore the possible anti-inflammatory effects of BA and their underlying mechanisms, we used streptozotocin-induced diabetic rat kidneys and high glucose-treated glomerular mesangial cells. Our study showed BA could inhibit the degradation of IκBα and the activity of NF-κB in diabetic rat kidneys and high glucose-induced mesangial cells, resulting in reduction of FN expression. In addition, BA suppressed the DNA binding activity and transcriptional activity of NF-κB in high glucose-induced glomerular mesangial cells (GMCs). Furthermore, BA enhanced the interaction between IκBα and β-arrestin2 in mesangial cells. Taken together, our data suggest BA inhibits NF-κB activation through stabilizing NF-κB inhibitory protein IκBα, thereby preventing diabetic renal fibrosis.
•Betulinic acid ameliorated diabetic nephropathy in the streptozocin-induced diabetic rats.•Betulinic acid suppressed the expression of fibronectin in both diabetic rat kidneys and high glucose-treated GMCs.•Betulinic acid blocked high glucose-induced NF-κB activity.
Tsc1 (Tuberous Sclerosis 1) and Tsc2 are tumor suppressor genes and negative regulators of mTORC1, and the mutation of Tsc1 or Tsc2 is associated with various cancers including hepatocellular ...carcinoma (HCC). mTORC1 activation promotes anabolic protein synthesis and inhibits catabolic autophagy process. Either hepatic persistent activation of mTORC1 due to the loss of Tsc1 or impaired hepatic autophagy due to the loss of Atg5 leads to spontaneous liver tumorigenesis in mice. However, how autophagy impacts mTORC1‐mediated liver metabolic changes and tumorigenesis is less clear. Here we show that deletion of Atg5 in liver‐specific Tsc1 knockout (L‐Tsc1 KO) mice inhibited liver tumorigenesis but increased mortality of L‐Tsc1 KO mice. Histological and unbiased RNA‐seq as well as metabolomic analysis revealed that lack of hepatic autophagy dramatically induced the remodeling of liver cell population and hepatic metabolic reprogramming in L‐Tsc1 KO mice. RNA‐seq analysis revealed increased cholangiocyte, hepatic stellate cell and macrophage but decreased hepatocyte gene signatures in liver‐specific Tsc1 and Atg5 double knockout (DKO) mice. Histologically, Atg5 and Tsc1 DKO mice had increased hepatomegaly, ductular reactions, increased number of macrophage/Kupffer cells and infiltrated neutrophils as well as massive fibrosis, and the DKO mice died at the age of approximately 8‐months‐old with no detectable liver tumors. Metabolomic analysis revealed marked increased hepatic glutathione and glutathione metabolites but decreased hepatic levels of glucose and lipid with accumulation of TCA cycle intermediate metabolites and fatty acid oxidation intermediates in Atg5 and Tsc1 DKO mice. Deletion of hepatic p62 partially but deletion of Nrf2 almost completely rescued the liver cell type remodeling and metabolic reprogramming and the mortality of Atg5 and Tsc1 DKO mice. Deletion of p62 promoted whereas deletion of Nrf2 suppressed the liver tumorigenesis of Atg5 and Tsc1 DKO mice. These results reveal a critical role of Nrf2 in regulating liver cell type remodeling and metabolic reprogramming in mice lack of hepatic autophagy with mTORC1 activation. Our data may provide a mechanistic basis for a precision medicine to target Nrf2 pathway for treating as subset of HCC, especially in HCV‐ or alcohol‐associated liver cancers that may have defective autophagy and mTOR activation.
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