cyclin-d1 and Chemical-and-Drug-Induced-Liver-Injury

Hastatoside is an iridoid glycoside extracted from the herb, Verbena officinalis, that exerts various pharmacological effects, including anti-inflammatory, sleep-promoting, and analgesic effects. However, only a few studies have reported the efficacy of hastatoside in liver fibrosis. Liver fibrosis is a pathophysiological process, and its persistence can seriously affect the quality of life and well-being of the patients.. This study aimed to investigate the role of hastatoside on liver fibrosis and its possible underlying mechanisms.. C57BL/6 J mice with carbon tetrachloride (CCl. These findings suggest that hastatoside can bind to GSK-3β and promote its activity, while inhibiting the GSK-3β downstream effector expression of β-catenin, thereby inhibiting the activation and proliferation of HSCs, which further prevents the development of liver fibrosis. These results provide innovative insights into the underlying liver fibrosis. Moreover, hastatoside is a potential anti-fibrosis monomer that can potentially be used for the treatment of liver fibrosis.

Topics: Animals; beta Catenin; Chemical and Drug Induced Liver Injury; Cyclin D1; Disease Models, Animal; Glycogen Synthase Kinase 3 beta; Hepatic Stellate Cells; Humans; Iridoid Glycosides; Liver; Liver Cirrhosis; Mice; Mice, Inbred C57BL; Molecular Docking Simulation; Quality of Life; Signal Transduction

This study aims to evaluate the association between polymorphisms of methotrexate pathway genes and high-dose methotrexate-related hepatotoxicity in Chinese patients with primary central nervous system lymphoma.. Sixty-five patients in 411 treatment courses were enrolled and their toxicities were evaluated. The association between 30 candidate SNPs from 20 methotrexate pathway genes and high-dose methotrexate-related hepatotoxicity was analysed by PLINK and logistic regression.. TYMS 6 bp DI + II (rs151264360; OR, 0.41; 95% CI, 0.25-0.66; P = 0.00029), MTHFD1 1958 GA + AA (rs2236225; OR, 0.55; 95% CI, 0.33-0.91; P = 0.020) and CCND1 870 GA + GG (rs9344; OR, 0.42; 95% CI, 0.24-0.73; P = 0.0024) had less risk of hepatotoxicity compared with their homozygotes (DD, GG and AA, respectively), while ABCC2 intron 29 GA + GG (rs3740065; OR, 3.14; 95% CI, 1.89-5.20; P = 0.00001) was more prevalent in patients with hepatotoxicity than TT.. TYMS 6 bp DI + II, MTHFD1 1958 GA + AA, CCND1 870 GA + GG genotypes were associated with a lower probability of hepatotoxicity in patients with primary central nervous system lymphoma on high-dose methotrexate therapy, and ABCC2 intron 29 GA + GG was correlated with increased risk of hepatotoxicity.

Topics: Adult; Aged; Aminohydrolases; Asian People; Central Nervous System; Chemical and Drug Induced Liver Injury; Cyclin D1; Female; Formate-Tetrahydrofolate Ligase; Genotype; Humans; Introns; Liver; Lymphoma; Male; Methotrexate; Methylenetetrahydrofolate Dehydrogenase (NADP); Middle Aged; Multidrug Resistance-Associated Protein 2; Multienzyme Complexes; Odds Ratio; Polymorphism, Single Nucleotide; Thymidylate Synthase

An important role for β-catenin in regulating p65 (a subunit of NF-κB) during acute liver injury has recently been elucidated through use of conditional β-catenin knockout mice, which show protection from apoptosis through increased activation of p65. Thus, we hypothesized that the p65/β-catenin complex may play a role in regulating processes such as cell proliferation during liver regeneration. We show through in vitro and in vivo studies that the p65/β-catenin complex is regulated through the TNF-α pathway and not through Wnt signaling. However, this complex is unchanged after partial hepatectomy (PH), despite increased p65 and β-catenin nuclear translocation as well as cyclin D1 activation. We demonstrate through both in vitro silencing experiments and chromatin immunoprecipitation after PH that β-catenin, and not p65, regulates cyclin D1 expression. Conversely, using reporter mice we show p65 is activated exclusively in the nonparenchymal (NPC) compartment during liver regeneration. Furthermore, stimulation of macrophages by TNF-α induces activation of NF-κB and subsequent secretion of Wnts essential for β-catenin activation in hepatocytes. Thus, we show that β-catenin and p65 are activated in separate cellular compartments during liver regeneration, with p65 activity in NPCs contributing to the activation of hepatocyte β-catenin, cyclin D1 expression, and subsequent proliferation.

Topics: Active Transport, Cell Nucleus; Animals; beta Catenin; Cell Line, Tumor; Cell Proliferation; Chemical and Drug Induced Liver Injury; Cyclin D1; Gene Expression Regulation; Hepatectomy; Hepatocytes; Humans; Liver; Liver Regeneration; Macrophages; Mice; Mice, Knockout; Mice, Transgenic; Oligonucleotide Array Sequence Analysis; RAW 264.7 Cells; Transcription Factor RelA; Tumor Necrosis Factor-alpha; Wnt Proteins

Overdose of acetaminophen (APAP) is the leading cause of acute liver failure (ALF) in the United States. Timely initiation of compensatory liver regeneration after APAP hepatotoxicity is critical for final recovery, but the mechanisms of liver regeneration after APAP-induced ALF have not been extensively explored yet. Previous studies from our laboratory have demonstrated that activation of β-catenin signaling after APAP overdose is associated with timely liver regeneration. Herein, we investigated the role of glycogen synthase kinase 3 (GSK3) in liver regeneration after APAP hepatotoxicity using a pharmacological inhibition strategy in mice. Treatment with specific GSK3 inhibitor (L803-mts), starting from 4 hours after 600 mg/kg dose of APAP, resulted in early initiation of liver regeneration in a dose-dependent manner, without modifying the peak regenerative response. Acceleration of liver regeneration was not secondary to alteration of APAP-induced hepatotoxicity, which remained unchanged after GSK3 inhibition. Early cell cycle initiation in hepatocytes after GSK3 inhibition was because of rapid induction of cyclin D1 and phosphorylation of retinoblastoma protein. This was associated with increased activation of β-catenin signaling after GSK3 inhibition. Taken together, our study has revealed a novel role of GSK3 in liver regeneration after APAP overdose and identified GSK3 as a potential therapeutic target to improve liver regeneration after APAP-induced ALF.

Topics: Acetaminophen; Animals; beta Catenin; Cell Proliferation; Chemical and Drug Induced Liver Injury; Cyclin D1; Drug Overdose; Glycogen Synthase Kinase 3; Hepatocytes; Liver Regeneration; Mice; Mice, Inbred C57BL; Oligopeptides; Proliferating Cell Nuclear Antigen; Protein Kinase Inhibitors

Babao Dan (BBD), a traditional Chinese medicine, has been widely used as a complementary and alternative medicine to treat chronic liver diseases. In this study, we aimed to observe the protective effect of BBD on rat hepatic fibrosis induced by diethylnitrosamine (DEN) and explore it possible mechanism. BBD was administrated while DEN was given. After eight weeks, values of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) indicated that BBD significantly protected liver from damaging by DEN and had no obvious side effect on normal rat livers. Meanwhile, BBD attenuated hepatic inflammation and fibrosis in DEN-induced rat livers through histopathological examination and hepatic hydroxyproline content. Furthermore, we found that BBD inhibited hepatic stellate cells activation and proliferation without altering the concentration of lipopolysaccharide (LPS) in portal vein. In vitro study, serum from BBD treated rats (BBD-serum) could also significantly suppress LPS-induced HSCs activation through TLR4/NF-κB pathway. In addition, BBD-serum also inhibited the proliferation of HSCs by regulating TLR4/ERK pathway. Our study demonstrated that BBD may provide a new therapy strategy of hepatic injury and hepatic fibrosis.

Topics: Animals; Cell Proliferation; Chemical and Drug Induced Liver Injury; Cyclin D1; Cytokines; Cytoprotection; Diethylnitrosamine; Drugs, Chinese Herbal; Extracellular Signal-Regulated MAP Kinases; Hepatic Stellate Cells; Lipopolysaccharides; Liver; Liver Cirrhosis, Experimental; Male; NF-kappa B; Protective Agents; Rats, Sprague-Dawley; Signal Transduction; Toll-Like Receptor 4

The role(s) of the epidermal growth factor receptor (EGFR) in hepatocytes is unknown. We generated a murine hepatocyte specific-EGFR knockout (KO) model to evaluate how loss of hepatocellular EGFR expression affects processes such as EGF clearance, circulating EGF concentrations, and liver regeneration following 70% resection or CCl4-induced centrilobular injury. We were able to disrupt EGFR expression effectively in hepatocytes and showed that the ability of EGF and heregulin (HRG) to phosphorylate EGFR and ERBB3, respectively, required EGFR. Loss of hepatocellular EGFR impaired clearance of exogenous EGF from the portal circulation but paradoxically resulted in reduced circulating levels of endogenous EGF. This was associated with decreased submandibular salivary gland production of EGF. EGFR disruption did not result in increased expression of other ERBB proteins or Met, except in neonatal mice. Liver regeneration following 70% hepatectomy revealed a mild phenotype, with no change in cyclin D1 expression and slight differences in cyclin A expression compared with controls. Peak 5-bromo-2'-deoxyuridine labeling was shifted from 36 to 48 h. Centrilobular damage and regenerative response induced by carbon tetrachloride (CCl4) were identical in the KO and wild-type mice. In contrast, loss of Met increased CCl4-induced necrosis and delayed regeneration. Although loss of hepatocellular EGFR alone did not have an effect in this model, EGFR-Met double KOs displayed enhanced necrosis and delayed liver regeneration compared with Met KOs alone. This suggests that EGFR and Met may partially compensate for the loss of the other, although other compensatory mechanisms can be envisioned.

Topics: Animals; Carbon Tetrachloride; Chemical and Drug Induced Liver Injury; Cyclin A; Cyclin D1; Epidermal Growth Factor; ErbB Receptors; Hepatocytes; Liver Regeneration; Mice; Neuregulin-1; Proto-Oncogene Proteins c-met; Receptor, ErbB-3

Carbon tetrachloride (CCl4)-induced hepatotoxicity is a common syndrome with simultaneous severe hepatocyte death and acute cholestasis. The purpose of the present study is to investigate the hepatoprotective effect of alisol B 23-acetate (AB23A), a natural triterpenoid from edible botanical Rhizoma alismatis, on acute hepatotoxicity induced by CCl4 in mice, and further to elucidate the involvement of farnesoid X receptor (FXR), signal transducers and activators of transcription 3 (STAT3) in the hepatoprotective effect. H&E staining, BrdU immunohistochemistry and TUNEL assay were used to identify the amelioration of histopathological changes, hepatocyte proliferation and apoptosis. Real-time PCR and western blot assay were used to elucidate the mechanisms underlying AB23A hepatoprotection. The results indicated that AB23A treatment in a dose-dependent manner resulted in protection against hepatotoxicity induced by CCl4via FXR activation. Through FXR activation, AB23A promoted hepatocyte proliferation via an induction in hepatic levels of FoxM1b, Cyclin D1 and Cyclin B1. AB23A also reduced hepatic bile acids through a decrease in hepatic uptake transporter Ntcp, bile acid synthetic enzymes Cyp7a1, Cyp8b1, and an increase in efflux transporter Bsep, Mrp2 expression. In addition, AB23A induced the expression of STAT3 phosphorylation, and STAT3 target genes Bcl-xl and SOCS3, resulting in decreased hepatocyte apoptosis. In conclusion, AB23A produces a protective effect against CCl4-induced hepatotoxicity, due to FXR and STAT3-mediated gene regulation.

Topics: Alanine Transaminase; Alisma; Animals; Apoptosis; Aspartate Aminotransferases; ATP Binding Cassette Transporter, Subfamily B, Member 11; ATP-Binding Cassette Transporters; bcl-X Protein; Bile Acids and Salts; Carbon Tetrachloride; Cell Proliferation; Chemical and Drug Induced Liver Injury; Cholestenones; Cholesterol 7-alpha-Hydroxylase; Cyclin B1; Cyclin D1; Forkhead Transcription Factors; Hepatocytes; Liver; Male; Mice; Mice, Inbred C57BL; Phosphorylation; Rhizome; STAT3 Transcription Factor; Steroid 12-alpha-Hydroxylase; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins; Up-Regulation

Liver cancer is a major health-care concern and its oncogenic mechanisms are still largely unclear. Persistent hepatocyte cell death is a common feature among various chronic liver diseases, the blocking of which presents as logical treatment. Therefore, we aimed at investigating tumor development in mice with hepatocyte-specific Bid depletion--a BH3-only Bcl-2 family member that amplifies apoptotic death signals. Hepatocyte-specific conditional Bid-knockout mice (Bid(Δhep)) were injected with 25 mg/kg diethylnitrosamine (DEN) at 14 days of age, and liver tumorigenesis was investigated 9 months later. Additionally, different models of acute liver injury were used including: acute high-dose DEN challenge, 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet and carbon tetrachloride (CCL4) injection. Bid(Δhep) mice developed significantly fewer tumors, showed smaller maximal and average tumor size and reduced tumor incidence. In the acute DEN model, 48 h post injection we observed a significant reduction in liver injury in Bid(Δhep) animals, assessed via serum transaminases and liver histopathology. Furthermore, TNF-α, IL-1ß, cJUN and IL-6 mRNA expression was reduced. These findings were accompanied by reduced compensatory hepatocyte proliferation in Bid(Δhep) mice when compared with controls by immunohistochemistry for Ki67 and proliferating cell nuclear antigen 48 h after DEN injection. In the acute CCL4 model, Bid(Δhep) mice displayed reductions in liver injury and inflammation when compared with controls. No differences in liver injury and serum bilirubin levels were detected in Bid(Δhep) and Bid(flo/flo) mice fed with DDC, which induces bile duct injury and a ductular reaction. Our study demonstrates that in DEN-induced hepatocellular carcinoma, the inhibition of hepatocyte death pathways through Bid deletion protects animals from tumorigenesis. These results suggest that reducing hepatocyte cell death, liver inflammation and compensatory proliferation has a stronger beneficial effect than the potential side effect of enhancing tumor cell survival.

Topics: Animals; BH3 Interacting Domain Death Agonist Protein; Carbon Tetrachloride; Cell Proliferation; Cells, Cultured; Chemical and Drug Induced Liver Injury; Cyclin D1; Diethylnitrosamine; Disease Models, Animal; Hepatocytes; Hydrogen Peroxide; Inflammation; Interleukin-6; Liver; Liver Neoplasms; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Non-alcoholic Fatty Liver Disease; Pyridines; Tumor Necrosis Factor-alpha

MicroRNAs are small RNA molecules that post-transcriptionally regulate gene expression. MicroRNA-122 is the most abundant and specific liver microRNA. Hepatotoxicity involves a significant alteration of liver gene expression. The aim of this work was to evaluate the microRNA-122 regulatory network in models of hepatotoxicity induced by thioacetamide or carbon tetrachloride. We report that the toxins decreased the expression of microRNA-122, which corresponded with an increase in two target genes: Cyclin G1 and the cationic amino acid transporter CAT-1. We found a decreased expression of its precursor, pri-microRNA-122, and of the transcription factors that specifically bind its promoter: CCAAT/enhancer-binding protein alpha, and members of the hepatocyte nuclear factor family. Therefore, microRNA-122 expression levels are under transcriptional control during hepatotoxicity. We propose that the changes observed are associated with the liver response to cope with the injury caused by the hepatotoxins, likely through a cell proliferation process to repair the damaged tissue.

Topics: Animals; Carbon Tetrachloride; Cationic Amino Acid Transporter 1; CCAAT-Enhancer-Binding Protein-alpha; Chemical and Drug Induced Liver Injury; Cyclin D1; Cyclin G1; Cytochrome P-450 CYP2E1; Disease Models, Animal; Glutamate-Ammonia Ligase; Hepatocyte Nuclear Factor 4; Liver; Male; MicroRNAs; Proliferating Cell Nuclear Antigen; Rats; Rats, Wistar; RNA, Messenger; Thioacetamide; Transcription, Genetic

Acetaminophen (APAP) overdose is the leading cause of drug-induced liver injury. Compensatory liver regeneration is crucial for the final outcome of toxicant-induced injury. However, the molecular mechanisms underlying compensatory liver regeneration in mice after APAP-induced liver injury are not completely understood. This study aimed to investigate the role of dynamic and coordinated regulation of Kelch-like ECH-associated protein 1 (KEAP1)-nuclear factor erythroid 2-related factor 2 (NRF2)- antioxidant response element (ARE) and p53/p21 pathways in APAP injury-responsive liver regeneration. We found that mice exhibited massive hepatic toxicity during the first 12 hours after 400 mg/kg APAP treatment, but responsive liver recovery occurred beyond 24 hours as demonstrated by histopathological and biochemical assessments. The expression and nuclear accumulation of NRF2 was increased after APAP treatment. The expression of. quinone oxidoreductase 1, glutamate-cysteine ligase modifier subunit, and heme oxygenase-1 was inhibited during the first 24 hours and then induced to limit oxidative damage. The content of p53 and its downstream target p21 were significantly increased upon APAP exposure and subsequently decreased to normal levels at 48 hours. Furthermore, levels of cyclin D1, cyclin D-dependent kinase 4, proliferating cell nuclear antigen, and augmenter of liver regeneration at 48 hours were enhanced, suggesting initiation of hepatocyte proliferation and tissue repair. These results demonstrated that dynamic and coordinated regulation of KEAP1-NRF2-ARE and p53/p21 signaling pathways was associated with compensatory liver regeneration after APAP-induced acute liver injury.

Topics: Acetaminophen; Adaptor Proteins, Signal Transducing; Animals; Carboxylic Ester Hydrolases; Cell Proliferation; Chemical and Drug Induced Liver Injury; Cyclin D1; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase Inhibitor p21; Cytoskeletal Proteins; Hepatocytes; Kelch-Like ECH-Associated Protein 1; Liver; Liver Regeneration; Male; Mice; Mice, Inbred C57BL; NF-E2-Related Factor 2; Proliferating Cell Nuclear Antigen; Signal Transduction; Tumor Suppressor Protein p53

Acetaminophen (APAP) overdose induces massive hepatocyte necrosis. Necrotic tissue releases high mobility group B1 (HMGB1), and HMGB1 contributes to liver injury. Even though blockade of HMGB1 does not protect against APAP-induced acute liver injury (ALI) at 9 h time point, the later time points are not studied and the role of HMGB1 in APAP overdose is unknown, it is possible that neutralization of HMGB1 might improve hepatocyte regeneration. This study aims to test whether blockade of HMGB1 improves hepatocyte regeneration after APAP overdose.. Male C57BL/6 mice were treated with a single dose of APAP (350 mg/kg). 2 hrs after APAP administration, the APAP challenged mice were randomized to receive treatment with either anti-HMGB1 antibody (400 μg per dose) or non-immune (sham) IgG every 24 hours for a total of 2 doses.. 24 hrs after APAP injection, anti-HMGB1 therapy instead of sham IgG therapy significantly improved hepatocyte regeneration microscopically; 48 hrs after APAP challenge, the sham IgG treated mice showed 14.6% hepatic necrosis; in contrast, blockade of HMGB1 significantly decreased serum transaminases (ALT and AST), markedly reduced the number of hepatic inflammatory cells infiltration and restored liver structure to nearly normal; this beneficial effect was associated with enhanced hepatic NF-κB DNA binding and increased the expression of cyclin D1, two important factors related to hepatocyte regeneration.. HMGB1 impairs hepatocyte regeneration after APAP overdose; Blockade of HMGB1 enhances liver recovery and may present a novel therapy to treat APAP overdose.

Topics: Acetaminophen; Alanine Transaminase; Animals; Antibodies, Anti-Idiotypic; Aspartate Aminotransferases; Cell Proliferation; Chemical and Drug Induced Liver Injury; Cyclin D1; Dose-Response Relationship, Drug; Hepatocytes; HMGB1 Protein; Immunoglobulin G; Liver Regeneration; Male; Mice; Mice, Inbred C57BL; Models, Animal; NF-kappa B

Acetaminophen (APAP) overdose induces massive hepatocyte necrosis. Liver regeneration is a vital process for survival after a toxic insult. Since hepatocytes are mostly in a quiescent state (G0), the regeneration process requires the priming of hepatocytes by cytokines such as TNF-α and IL-6. Ringer's lactate solution (RLS) has been shown to increase serum TNF-α and IL-6 in patients and experimental animals; in addition, RLS also provides lactate, which can be used as an alternative metabolic fuel to meet the higher energy demand by liver regeneration. Therefore, we tested whether RLS therapy improves liver recovery after APAP overdose.. C57BL/6 male mice were intraperitoneally injected with a single dose of APAP (300 mg/kg dissolved in 1 mL sterile saline). Following 2 hrs of APAP challenge, the mice were given 1 mL RLS or Saline treatment every 12 hours for a total of 72 hours.. 72 hrs after APAP challenge, compared to saline-treated group, RLS treatment significantly lowered serum transaminases (ALT/AST) and improved liver recovery seen in histopathology. This beneficial effect was associated with increased hepatic tissue TNF-α concentration, enhanced hepatic NF-κB DNA binding and increased expression of cell cycle protein cyclin D1, three important factors in liver regeneration.. RLS improves liver recovery from APAP hepatotoxicity.

Topics: Acetaminophen; Alanine Transaminase; Analgesics, Non-Narcotic; Animals; Aspartate Aminotransferases; Chemical and Drug Induced Liver Injury; Cyclin D1; Drug Overdose; Isotonic Solutions; Liver; Male; Mice; Mice, Inbred C57BL; NF-kappa B; Protein Binding; Ringer's Lactate; Tumor Necrosis Factor-alpha

Liver injury initiated by non-lethal doses of CCl(4) and thioacetamide (TA) progresses to hepatic failure and death of type 2 diabetic (DB) rats due to failed advance of liver cells from G(0)/G(1) to S-phase and inhibited tissue repair. Objective of the present study was to investigate cellular signaling mechanisms of failed cell division in DB rats upon hepatotoxicant challenge. In CCl(4)-treated non-diabetic (non-DB) rats, increased IL-6 levels, sustained activation of extracellular regulated kinases 1/2 (ERK1/2) MAPK, and sustained phosphorylation of retinoblastoma protein (p-pRB) via cyclin D1/cyclin-dependent kinase (cdk) 4 and cyclin D1/cdk6 complexes stimulated G(0)/G(1) to S-phase transition of liver cells. In contrast to the non-DB rats, CCl(4) administration led to lower plasma IL-6, decreased ERK1/2 activation, lower cyclin D1, and cdk 4/6 expression resulting in decreased p-pRB and inhibition of liver cell division in the DB rats. Furthermore, higher TGFbeta1 expression and p21 activation may also contribute to decreased p-pRB in DB rats compared to non-DB rats. Similarly, after TA administration to DB rats, down-regulation of cyclin D1 and p-pRB leads to markedly decreased advance of liver cells from G(0)/G(1) to S-phase and tissue repair compared to the non-DB rats. Hepatic ATP levels did not differ between the DB and non-DB rats obviating its role in failed tissue repair in the DB rats. In conclusion, decreased p-pRB may contribute to blocked advance of cells from G(0)/G(1) to S-phase and failed cell division in DB rats exposed to CCl(4) or TA, leading to progression of liver injury and hepatic failure.

Topics: Adenosine Triphosphate; Animals; Carbon Tetrachloride Poisoning; Cell Cycle; Chemical and Drug Induced Liver Injury; Cyclin D1; Cyclin-Dependent Kinases; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Immunoblotting; Interleukin-6; Liver Diseases; Male; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Rats; Rats, Sprague-Dawley; Retinoblastoma Protein; Thioacetamide; Transforming Growth Factor beta1

Eukaryotic cell cycle is regulated by signal transduction pathways mediated by complexes of cyclin dependent kinases (CDKs) and their partner cyclins, or by interaction with CDK inhibitors. Thioacetamide (TA) is a weak hepatocarcinogen causing several types of liver damage in a dose dependent manner and ultimately producing malignant transformation. We investigated alterations of expression of cell cycle regulators in the rat liver, involved in G1 entry and progression during TA administration.. We studied expression patterns of cyclin D1, CDK4, CDK6, p21(CIP1) and p16(INK4a) during daily intraperitoneal injection of low dose TA (50 mg/kg) till 7 day. We used western blot and immunohistochemistry for detection.. Expression of cyclin D1, CDK4, CDK6 and p21(CIP1) increased from 6 hour and peaked at 2, 3 day, then decreased next 2 days, and re-increased at 6 day. Cytoplasmo-nuclear translocation of cyclin D1 and p21(CIP1) was evident within 1 day and prominent at 2 and 7 day. Expression of p16(INK4a) increased immediately after TA treatment and remarkably increased from 3 day and progressed till 7 day, showing cytoplasmic location, suggestive of inactive form. Most of in situ immunoreactions occurred at the centrilobular hepatocytes. Concomitant nuclear translocation of p21(CIP1) and cyclin D1, different with p16(INK4a) suggests that p21(CIP1) might be a transporter for nuclear translocation rather than cell cycle inhibitor.. Daily administration of low dose TA makes cell cycle open and G1 progress, possibly due to cyclin D1, CDK4 and CDK 6, their transporter p21(CIP1), and inactive p16(INK4a), which occur at quiescent hepatocytes, not stem cells.

Topics: Animals; Cell Cycle Proteins; Chemical and Drug Induced Liver Injury; Cyclin D1; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase 6; Cyclin-Dependent Kinase Inhibitor p16; Cyclin-Dependent Kinase Inhibitor p21; G1 Phase; Immunohistochemistry; Liver; Liver Diseases; Male; Rats; Rats, Sprague-Dawley; Thioacetamide

Smad family proteins Smad2 and Smad3 are activated by transforming growth factor beta (TGF-beta)/activin/nodal receptors and mediate transcriptional regulation. Although differential functional roles of Smad2 and Smad3 are apparent in mammalian development, the relative functional roles of Smad2 and Smad3 in postnatal systems remain unclear. We used Cre/loxP-mediated gene targeting for hepatocyte-specific deletion of Smad2 (S2HeKO) in adult mice and generated hepatocyte-selective Smad2/Smad3 double knockouts by intercrossing AlbCre/Smad2(f/f) (S2HeKO) and Smad3-deficient Smad3ex8/ex8 (S3KO) mice. All strains were viable and had normal adult liver. However, necrogenic CCL4-induced hepatocyte proliferation was significantly increased in S2HeKO compared to Ctrl and S3KO livers, and transplanted S2HeKO hepatocytes repopulated recipient liver at dramatically increased rates compared to Ctrl hepatocytes in vivo. Using primary hepatocytes, we found that TGF-beta-induced G1 arrest, apoptosis, and epithelial-to-mesenchymal transition in Ctrl and S2HeKO but not in S3KO hepatocytes. Interestingly, S2HeKO cells spontaneously acquired mesenchymal features characteristic of epithelial-to-mesenchymal transition (EMT). Collectively, these results demonstrate that Smad2 suppresses hepatocyte growth and dedifferentiation independent of TGF-beta signaling. Smad2 is not required for TGF-beta-stimulated apoptosis, EMT, and growth inhibition in hepatocytes.

Topics: Animals; Apoptosis; Carbon Tetrachloride Poisoning; Cell Differentiation; Cell Movement; Cell Proliferation; Cells, Cultured; Chemical and Drug Induced Liver Injury; Cyclin D1; Hepatocytes; Liver; Mesoderm; Mice; Mice, Knockout; Smad2 Protein; Smad3 Protein; Transforming Growth Factor beta

Exposure of pregnant mice to inorganic arsenic induces a spectrum of tumors, including hepatocellular carcinoma (HCC), in their adult offspring similar to that induced by exposing adult mice to estrogenic compounds. To investigate whether arsenic exposure in utero causes altered estrogen signaling, we examined expression of estrogen receptor-alpha (ER-alpha), cyclin D1 (an estrogen-responsive hepatic oncogene), and several cytochrome P450 genes (with sexually dimorphic liver expression patterns) in livers from adult male mice with in utero arsenic-induced HCC.. Quantitative real-time reverse transcription-polymerase chain reaction was used to evaluate gene expression in livers of adult male mice that had (i.e., exposed mice; n = 8) or had not (i.e., control mice; n = 5) been exposed to arsenic in utero. DNA methylation status of portions of the ER-alpha and cyclin D1 gene promoters in liver tissue was measured using methylation-specific polymerase chain reaction. Statistical tests were two-sided.. ER-alpha mRNA levels were 3.1-fold (95% confidence interval [CI] = 2.0-fold to 4.3-fold) higher in livers of exposed mice than in those of control mice, and cyclin D1 levels were 3.0-fold (95% CI = 1.7-fold to 4.3-fold) higher. Exposed mice showed a feminized expression pattern of several cytochrome P450 genes, expressing the female-dominant CYP2A4 (P =.017 versus control) and CYP2B9 (P<.001) genes at 8.7 and 10.5 times, respectively, the level in control mice and expressing the male-dominant CYP7B1 at approximately one-fourth the level in control mice(P =.0012). Exposed mice exhibited reduced (by approximately 90%) methylation of the ER-alpha gene promoter in liver DNA as compared with control mice; the cyclin D1 gene promoter was not methylated in either exposed or control mice.. Altered estrogen signaling may play a role in induction of HCC by arsenic exposure in utero. Specifically, overexpression of ER-alpha, potentially through promoter region hypomethylation, in livers of such mice may be linked to the hepatocarcinogenicity of arsenic.

Topics: Animals; Arsenicals; Aryl Hydrocarbon Hydroxylases; Carcinogens; Chemical and Drug Induced Liver Injury; Cyclin D1; Cytochrome P-450 Enzyme System; Cytochrome P450 Family 2; Cytochrome P450 Family 7; DNA Methylation; Environmental Exposure; Estrogen Receptor alpha; Estrogens; Fetus; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Liver; Liver Diseases; Liver Neoplasms, Experimental; Male; Mice; Receptors, Estrogen; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Steroid Hydroxylases

Profound impairment of liver regeneration in rodents with dysfunctional leptin signaling has been attributed to non-alcohol-induced fatty liver disorders (NAFLD). Our aim was to establish whether defective liver regeneration in ob/ob mice is a direct consequence of leptin-dependent, intracellular signaling mechanisms controlling cell-cycle regulation in hepatocytes.. After exposure to a single hepatotoxic dose of (CCl(4)), the regenerative response to hepatic injury was studied in leptin-deficient ob/ob and control mice. The effects of leptin supplementation (100 microg x kg(-1) x day(-1)) were examined. We assessed entry into and progression through the cell cycle and activation of key signaling intermediates and transcriptional regulators.. CCl(4)-induced liver injury was equally severe in ob/ob and control mice. In leptin-deficient mice, it was associated with exaggerated activation of NF-kappa B and STAT3 during the priming phase, abrogation of tumor necrosis factor (TNF) and interleukin (IL)-6 release at the time of G1/S transition, and failure of hepatocyte induction of cyclin D1 and cell cycle entry. Leptin replacement corrected these defects in ob/ob mice by restoring TNF and IL-6 release and inducing cyclin D1. Hepatocytes entered S phase and progressed, as in wild-type mice, to vigorous mitosis and normal hepatic regenerative response. In ob/ob mice, low doses of TNF before CCl(4) also were associated with restitution of TNF release and proliferative capabilities.. Impaired liver regeneration in ob/ob mice is caused by leptin deficiency. We propose that altered cytokine production in ob/ob mice is part of the mechanisms responsible for impaired proliferation in response to hepatic injury.

Topics: Animals; Carbon Tetrachloride; Cell Division; Chemical and Drug Induced Liver Injury; Cyclin D1; Fatty Liver; Interleukin-6; Leptin; Liver; Liver Regeneration; Mice; Mice, Inbred C57BL; Mice, Obese; Necrosis; Proliferating Cell Nuclear Antigen; Recombinant Proteins; Signal Transduction; Tumor Necrosis Factor-alpha

Intoxication of rats with thioacetamide (TAA) is a model system to investigate mechanisms involved in liver cell death and tissue reconstitution. Our study was undertaken to determine by immunohistochemistry the expression pattern of the cytoprotective chaperone proteins HSC70 and HSP25 and proliferation markers cyclin D1 and PCNA in livers of Wistar rats intraperitoneally injected with TAA at a single dose of 50 mg/kg. For each protein studied we observed distinct dynamic changes in appearance and localization in liver lobules. During 24-36 h after TAA injection the HSC70 cytoplasmic immunoreaction gradually disappeared from hepatocytes localized around central veins and a shift of immunostaining to cell nuclei took place. Then, 36-48 h after TAA injection the HSC70 cytoplasmic immunoreaction reappeared with the highest intensity in hepatocytes surrounding the areas of inflammatory cells. HSP25, undetectable in control hepatocytes began to appear at approximately 36 h after TAA injection and HSP25-immunopositive cells formed a characteristic ring around areas of inflammation. Of the proteins studied, the most rapid reaction to TAA was observed for cyclin D1. As early as 15 min after TAA administration cyclin D1-positive hepatocytes appeared in intermediate and periportal areas of liver lobules and a subsequent shift of staining to centrilobular hepatocytes took place at 36 and 48 h. There was no correlation of cyclin D1 localization either with PCNA-positive cells or mitotic cells. Our observations suggest that in TAA-treated livers HSP25 and HSC70 proteins can play an anti-inflammatory role, and the early and distinct cyclin D1 expression is not related to proliferation of hepatocytes.

Topics: Animals; Blotting, Northern; Blotting, Western; Chemical and Drug Induced Liver Injury; Cyclin D1; Disease Models, Animal; Heat-Shock Proteins; HSC70 Heat-Shock Proteins; HSP27 Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Immunoenzyme Techniques; Injections, Intraperitoneal; Liver; Male; Neoplasm Proteins; Proliferating Cell Nuclear Antigen; Rats; Rats, Wistar; Thioacetamide; Time Factors