Toll-like Receptor 4 on Macrophage Promotes the Development of Steatohepatitis-related Hepatocellular Carcinoma in Mice.

The role of Toll-like receptor (TLR) signaling has attracted much attention in the development of hepatic inflammation and hepatocellular carcinoma (HCC). We herein sought to determine the role of TLRs and responsible cells in steatohepatitis-related HCC. We used hepatocyte-specific Pten-deficient (Pten(Δ) (hep)) mice, which exhibit steatohepatitis followed by liver tumor formation, including HCC. We then generated Pten(Δ) (hep)/Tlr4(-/-) and Pten(Δ) (hep)/Tlr2(-/-) double-mutant mice and investigated the role of macrophages using reconstitution of bone marrow (BM)-derived cells, chemical depletion of macrophages, and isolated macrophages. Tlr4 but not Tlr2 deficiency in the Pten(Δ) (hep) mice suppressed tumor growth as well as hepatic inflammation. Gut sterilization by an antibiotic mixture reduced the portal LPS levels as well as tumor growth in the Pten(Δ) (hep) mice. Tumor growth was also decreased by reconstitution of BM-derived cells to Tlr4(-/-) BM cells. In addition, chemical depletion of macrophages significantly reduced tumor size and numbers. Macrophages expressing Ly6C were increased in number, which was associated with inflammation and tumor progression in the Pten(Δ) (hep) mice. Hepatic macrophages isolated from the Pten(Δ) (hep) mice abundantly expressed the Ly6C gene and produced much more IL-6 and TNFα in response to LPS. These proinflammatory cytokines induced the proliferation of HCC cells as well as oval cells, putative cancer progenitor cells. Indeed, putative cancer progenitor cells emerged before the development of macroscopic liver tumors and then increased in number under sustained inflammation. TLR4 on macrophages contributes to the development of steatohepatitis-related HCC in mice.

The PtdIns(3,4)P(2) phosphatase INPP4A is a suppressor of excitotoxic neuronal death.

Phosphorylated derivatives of phosphatidylinositol, collectively referred to as phosphoinositides, occur in the cytoplasmic leaflet of cellular membranes and regulate activities such as vesicle transport, cytoskeletal reorganization and signal transduction. Recent studies have indicated an important role for phosphoinositide metabolism in the aetiology of diseases such as cancer, diabetes, myopathy and inflammation. Although the biological functions of the phosphatases that regulate phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) have been well characterized, little is known about the functions of the phosphatases regulating the closely related molecule phosphatidylinositol-3,4-bisphosphate (PtdIns(3,4)P(2)). Here we show that inositol polyphosphate phosphatase 4A (INPP4A), a PtdIns(3,4)P(2) phosphatase, is a suppressor of glutamate excitotoxicity in the central nervous system. Targeted disruption of the Inpp4a gene in mice leads to neurodegeneration in the striatum, the input nucleus of the basal ganglia that has a central role in motor and cognitive behaviours. Notably, Inpp4a(-/-) mice show severe involuntary movement disorders. In vitro, Inpp4a gene silencing via short hairpin RNA renders cultured primary striatal neurons vulnerable to cell death mediated by N-methyl-d-aspartate-type glutamate receptors (NMDARs). Mechanistically, INPP4A is found at the postsynaptic density and regulates synaptic NMDAR localization and NMDAR-mediated excitatory postsynaptic current. Thus, INPP4A protects neurons from excitotoxic cell death and thereby maintains the functional integrity of the brain. Our study demonstrates that PtdIns(3,4)P(2), PtdIns(3,4,5)P(3) and the phosphatases acting on them can have distinct regulatory roles, and provides insight into the unique aspects and physiological significance of PtdIns(3,4)P(2) metabolism. INPP4A represents, to our knowledge, the first signalling protein with a function in neurons to suppress excitotoxic cell death. The discovery of a direct link between PtdIns(3,4)P(2) metabolism and the regulation of neurodegeneration and involuntary movements may aid the development of new approaches for the treatment of neurodegenerative disorders.

Critical roles of type III phosphatidylinositol phosphate kinase in murine embryonic visceral endoderm and adult intestine.

The metabolism of membrane phosphoinositides is critical for a variety of cellular processes. Phosphatidylinositol-3,5-bisphosphate [PtdIns(3,5)P(2)] controls multiple steps of the intracellular membrane trafficking system in both yeast and mammalian cells. However, other than in neuronal tissues, little is known about the physiological functions of PtdIns(3,5)P(2) in mammals. Here, we provide genetic evidence that type III phosphatidylinositol phosphate kinase (PIPKIII), which produces PtdIns(3,5)P(2), is essential for the functions of polarized epithelial cells. PIPKIII-null mouse embryos die by embryonic day 8.5 because of a failure of the visceral endoderm to supply the epiblast with maternal nutrients. Similarly, although intestine-specific PIPKIII-deficient mice are born, they fail to thrive and eventually die of malnutrition. At the mechanistic level, we show that PIPKIII regulates the trafficking of proteins to a cell's apical membrane domain. Importantly, mice with intestine-specific deletion of PIPKIII exhibit diarrhea and bloody stool, and their gut epithelial layers show inflammation and fibrosis, making our mutants an improved model for inflammatory bowel diseases. In summary, our data demonstrate that PIPKIII is required for the structural and functional integrity of two different types of polarized epithelial cells and suggest that PtdIns(3,5)P(2) metabolism is an unexpected and critical link between membrane trafficking in intestinal epithelial cells and the pathogenesis of inflammatory bowel disease.

Control of cell polarity and motility by the PtdIns(3,4,5)P3 phosphatase SHIP1.

Proper neutrophil migration into inflammatory sites ensures host defense without tissue damage. Phosphoinositide 3-kinase (PI(3)K) and its lipid product phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) regulate cell migration, but the role of PtdIns(3,4,5)P(3)-degrading enzymes in this process is poorly understood. Here, we show that Src homology 2 (SH2) domain-containing inositol-5-phosphatase 1 (SHIP1), a PtdIns(3,4,5)P(3) phosphatase, is a key regulator of neutrophil migration. Genetic inactivation of SHIP1 led to severe defects in neutrophil polarization and motility. In contrast, loss of the PtdIns(3,4,5)P(3) phosphatase PTEN had no impact on neutrophil chemotaxis. To study PtdIns(3,4,5)P(3) metabolism in living primary cells, we generated a novel transgenic mouse (AktPH-GFP Tg) expressing a bioprobe for PtdIns(3,4,5)P(3.) Time-lapse footage showed rapid, localized binding of AktPH-GFP to the leading edge membrane of chemotaxing ship1(+/+)AktPH-GFP Tg neutrophils, but only diffuse localization in ship1(-/-)AktPH-GFP Tg neutrophils. By directing where PtdIns(3,4,5)P(3) accumulates, SHIP1 governs the formation of the leading edge and polarization required for chemotaxis.

Nod1 acts as an intracellular receptor to stimulate chemokine production and neutrophil recruitment in vivo.

Nod1 is a member of family of intracellular proteins that mediate host recognition of bacterial peptidoglycan. To characterize immune responses mediated by Nod1, synthetic ligand compounds possessing enhanced ability to stimulate Nod1 were developed to study the function of Nod1. Stimulation of epithelial cells with Nod1 stimulatory molecules induced chemokines and other proinflammatory molecules that are important for innate immune responses and recruitment of acute inflammatory cells. Administration of Nod1 ligands into mice induced chemokines and recruitment of acute inflammatory cells, an activity that was abolished in Nod1-null mice. Microarray analysis revealed that Nod1 stimulation induces a restricted number of genes in intestinal epithelial cells compared with that induced by tumor necrosis factor (TNF) alpha. Nod1 stimulation did not induce TNFalpha, interleukin 12, and interferon gamma, suggesting that the primary role of Nod1 is to induce the recruitment of immune cells. These results indicate that Nod1 functions as a pathogen recognition molecule to induce expression of molecules involved in the early stages of the innate immune response.

Interferon regulatory factor-2 regulates exocytosis mechanisms mediated by SNAREs in pancreatic acinar cells.

BACKGROUND & AIMS: Pancreatic acinar cells are used to study regulated exocytosis. We investigated the role of interferon regulatory factor-2 (IRF2) in exocytosis in pancreatic acinar cells. METHODS: Pancreas tissues from Irf2⁺/⁺, Irf2⁺/⁻), and Irf2⁻/⁻ mice were examined by microscopy, immunohistochemical, and immunoblot analyses; amylase secretion was quantified. We also compared salivary glands and pancreatic islets of Irf2⁻/⁻ mice with those of Irf2⁺/⁻ mice. To examine the effects of increased signaling by type I interferons, we studied pancreatic acini from Irf2⁻/⁻Ifnar1⁻/⁻ mice. The effect of IRF2 on amylase secretion was studied using an acinar cell line and a retroviral system. We studied expression of IRF2 in wild-type mice with cerulein-induced pancreatitis and changes in pancreatic tissue of Irf2⁻/⁻ mice, compared with those of Irf2⁺/⁻ mice. RESULTS: Irf2⁻/⁻ pancreas was white and opaque; numerous and wide-spread zymogen granules were observed throughout the cytoplasm, along with lack of fusion between zymogen granules and the apical membrane, lack of secretagogue-stimulated amylase secretion, and low serum levels of amylase and elastase-1, indicating altered regulation of exocytosis. The expression pattern of soluble N-ethylmaleimide-sensitive factor attachment protein receptors changed significantly, specifically in pancreatic acini, and was not rescued by disruption of type I interferon signaling. Down-regulation of IRF2 decreased amylase secretion in an acinar cell line. In mice with pancreatitis, levels of IRF2 were reduced. Irf2⁻/⁻ acini were partially resistant to induction of pancreatitis. CONCLUSIONS: IRF2 regulates exocytosis in pancreatic acinar cells; defects in this process might be involved in the early phases of acute pancreatitis.

Nucleotide oligomerization binding domain-like receptor signaling enhances dendritic cell-mediated cross-priming in vivo.

Nucleotide oligomerization binding domain (Nod)-like receptors are critical cytosolic sensors for the recognition of bacterial peptidoglycan. However, their role in the induction of dendritic cell (DC)-mediated cross-priming remains unclear. In this study, we demonstrate that injecting ligands for Nod1 and Nod2 along with Ag into wild-type mice significantly enhanced the cross-priming of Ag-specific CD8+ T cells by CD8alpha+ DCs, as assessed from the expansion of IFN-gamma+ CD8+ T cells, CTL activity against Ag-pulsed targets, and the rejection of transplanted tumors expressing the cognate Ag. The enhancement of CD8alpha+ DC-mediated cross-priming was likely due to the upregulation of Ag cross-presentation and of costimulatory molecules. Our findings collectively indicate that Nod1/2 signaling is critical for the optimal induction of DC cross-priming in vivo, which may offer an alternative therapeutic pathway in cancer and hosts refractory to TLR signals or paralyzed by viral evasion strategy.

Molecular cloning reveals nearly half of patients with Crohn's disease have an antibody to peroxiredoxin 6-like protein.

BACKGROUND AND AIM: Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) of unknown etiology. We aimed to identify the etiological agent of CD using a molecular cloning strategy that was particularly focused on identifying agents causing immune abnormalities and infectious agents. METHODS: We constructed a cDNA library derived from the inflamed intestinal tissue of a CD patient, and screened 1.5 million clones in this library with the serum from another typical CD patient. The expressed cDNA clones that positively reacted with the serum were then expressed as fusion proteins with glutathione S-transferase, and western blotting was performed using the sera of 22 CD, 13 ulcerative colitis (UC), and 16 non-IBD patients. RESULTS: We identified nine positive clones that did not contain any viral or bacterial genomic DNA. Of these, we selected one clone (clone 50) with which the typical CD patient's serum most strongly reacted. Clone 50 is highly homologous to the antioxidant protein peroxiredoxin 6. In western blotting, the sera of 47.6% CD patients (small intestine type 80%, large and small intestine type 43%, large intestine type 0%) showed strong reactivity to clone 50, none of the UC patients were reactive to clone 50, and 18.8% of non-IBD patients were very weakly reactive to it. We also found that the expression of peroxiredoxin 6 was significantly increased in inflamed intestinal epithelia of CD. CONCLUSION: The present study first showed that some CD patients have an antibody against peroxiredoxin 6-like protein, which may be involved in the pathogenesis of CD.

Epimorphin protects hepatocytes from oxidative stress by inhibiting mitochondrial injury.

BACKGROUND AND AIMS: Many investigations have demonstrated that cell injuries caused by generation of reactive oxygen species (ROS) is a common mechanism of various hepatic disorders. Recently, we have demonstrated that epimorphin, originally cloned as a mesenchymal protein, protects cultured intestinal epithelial cells from ROS. We therefore examine whether epimorphin protects primary cultured hepatocytes from ROS-induced cell injury. METHODS: We explored the cell viability and the intracellular ROS levels of purified murine hepatocytes after exposure to 0.5 mM H(2)O(2) with or without pretreatment of epimorphin. Then, we observed mitochondrial permeability transition (MPT) and depolarization using confocal microscopy to make clear the mechanism that epimorphin inhibited cell injuries after exposure to H(2)O(2). In addition, to clarify the signaling pathways related to cell survival, we carried out Western blotting analysis with phosphorylated stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) polyclonal antibody to evaluate the inhibition of JNK by epimorphin. Finally, we evaluated the cell viability in hepatocytes administered JNK inhibitor. RESULTS: Epimorphin protected primary cultured hepatocytes from H(2)O(2)-induced cell injuries independent of intracellular ROS levels. Epimorphin also inhibited onset of MPT, depolarization of the mitochondrial membrane potential, and eventually cell killing. The cell protective function of epimorphin after exposure to H(2)O(2) was not dependent on Akt signaling but on JNK signaling. CONCLUSION: Epimorphin can protect hepatocytes from MPT-dependent cell injury induced by ROS. Since hepatic disorders could be caused by MPT-dependent cell injuries with excessive ROS, epimorphin might open a new therapeutic avenue for hepatic disorders.

Pten controls lung morphogenesis, bronchioalveolar stem cells, and onset of lung adenocarcinomas in mice.

PTEN is a tumor suppressor gene mutated in many human cancers. We generated a bronchioalveolar epithelium-specific null mutation of Pten in mice [SP-C-rtTA/(tetO)(7)-Cre/Pten(flox/flox) (SOPten(flox/flox)) mice] that was under the control of doxycycline. Ninety percent of SOPten(flox/flox) mice that received doxycycline in utero [SOPten(flox/flox)(E10-16) mice] died of hypoxia soon after birth. Surviving SOPten(flox/flox)(E10-16) mice and mice that received doxycycline postnatally [SOPten(flox/flox)(P21-27) mice] developed spontaneous lung adenocarcinomas. Urethane treatment accelerated number and size of lung tumors developing in SOPten(flox/flox) mice of both ages. Histological and biochemical examinations of the lungs of SOPten(flox/flox)(E10-16) mice revealed hyperplasia of bronchioalveolar epithelial cells and myofibroblast precursors, enlarged alveolar epithelial cells, and impaired production of surfactant proteins. Numbers of bronchioalveolar stem cells (BASCs), putative initiators of lung adenocarcinomas, were increased. Lungs of SOPten(flox/flox)(E10-16) mice showed increased expression of Spry2, which inhibits the maturation of alveolar epithelial cells. Levels of Akt, c-Myc, Bcl-2, and Shh were also elevated in SOPten(flox/flox)(E10-16) and SOPten(flox/flox)(P21-27) lungs. Furthermore, K-ras was frequently mutated in adenocarcinomas observed in SOPten(flox/flox)(P21-27) lungs. These results indicate that Pten is essential for both normal lung morphogenesis and the prevention of lung carcinogenesis, possibly because this tumor suppressor is required for BASC homeostasis.

Eicosapentaenoic acid ameliorates steatohepatitis and hepatocellular carcinoma in hepatocyte-specific Pten-deficient mice.

BACKGROUND/AIMS: Eicosapentaenoic acid (EPA) has been known as a reagent for improving lipid metabolism and inflammation. Hepatocyte-specific Pten-deficient mice exhibit hepatic lesions analogous to non-alcoholic steatohepatitis (NASH). Therefore, we administered EPA to Pten-deficient mice to investigate the mechanisms of NASH. METHODS: Pten-deficient mice were assigned to a control group fed with a standard chow or an EPA group fed with a 5% EPA-supplemented standard chow. At 40 weeks, livers from each group were processed to measure triglyceride content, gene expression analysis, Western blotting analysis, and histological examination. Level of serum reactive oxygen species (ROS) was also determined. Forty- and 76-week-old mice were used in tumor burden experiments. RESULTS: EPA-ameliorated hepatic steatosis in Pten-deficient mice was based on decreased expression of AMPKalpha1-mediated SREBP-1c and increased PPARalpha expression. The EPA group exhibited less severe chronic hepatic inflammation compared to the control group, resulting from decreased ROS formation and a dramatically low ratio of arachidonic acid to EPA. Moreover, EPA inhibited development of hepatocellular carcinoma (HCC) in Pten-deficient mice based on an inhibition of MAPK activity and a low ratio of oleic to stealic acid, and a reduction in ROS formation. CONCLUSIONS: EPA ameliorated steatohepatitis and development of HCC in Pten-deficient mice.

Phosphatase and tensin homolog (PTEN) regulates hepatic lipogenesis, microsomal triglyceride transfer protein, and the secretion of apolipoprotein B-containing lipoproteins.

Hepatic apolipoprotein B (apoB) lipoprotein production is metabolically regulated via the phosphoinositide 3-kinase cascade; however, the role of the key negative regulator of this pathway, the tumor suppressor phosphatase with tensin homology (PTEN), is unknown. Here, we demonstrate that hepatic protein levels of apoB100 and microsomal triglyceride transfer protein (MTP) are significantly down-regulated (73% and 36%, respectively) in the liver of PTEN liver-specific knockout (KO) mice, and this is accompanied by increased triglyceride (TG) accumulation and lipogenic gene expression, and reduced hepatic apoB secretion in freshly isolated hepatocytes. MTP protein mass and lipid transfer activity were also significantly reduced in liver of PTEN KO mice. Overexpression of the dominant negative mutant PTEN C/S124 (adenovirus expressing PTEN C/S mutant [AdPTENC/S]) possessing constitutive phospoinositide 3-kinase activity in HepG2 cells led to significant reductions in both secreted apoB100 and cellular MTP mass (76% and 34%, respectively), and increased messenger RNA (mRNA) levels of sterol regulatory element binding protein 1c (SREBP-1c), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). Reduced apoB100 secretion induced by AdPTENC/S was associated with increased degradation of newly-synthesized cellular apoB100, in a lactacystin-sensitive manner, suggesting enhanced proteasomal degradation. AdPTENC/S also reduced apoB-lipoprotein production in McA-RH7777 and primary hamster hepatocytes. Our findings suggest a link between PTEN expression and hepatic production of apoB-containing lipoproteins. We postulate that perturbations in PTEN not only may influence hepatic insulin signaling and hepatic lipogenesis, but also may alter hepatic apoB-lipoprotein production and the MTP stability. On loss of PTEN activity, increased lipid substrate availability in the face of reduced hepatic lipoprotein production capacity can rapidly lead to hepatosteatosis and fatty liver.

Sex difference in the liver of hepatocyte-specific Pten-deficient mice: A model of nonalcoholic steatohepatitis.

AIM: Nonalcoholic fatty liver disease (NAFLD) is considered to be a public health problem worldwide. NAFLD is more prevalent in men than in women. Tamoxifen, a potent estrogen receptor antagonist, causes nonalcoholic steatohepatitis (NASH), a severe form of NAFLD. Thus, there may be a sex difference that is dependent on estrogens in NAFLD and NASH. Hepatocyte-specific Pten-deficient mice exhibit hepatic lesions analogous to NASH and are considered to be a clinical model of NASH. We aimed to shed light on any sex differences in the hepatic lesions of Pten-deficient mice and the underlying mechanisms. METHODS: At 40 weeks, livers from male and female Pten-deficient mice were processed for measuring lipid content, genes expression analysis, and histological examination. Level of serum reactive oxygen species (ROS) was also determined. Seventy-six-week-old mice were used in tumor burden experiments. RESULTS: Hepatic steatosis, inflammation, and even carcinogenesis in Pten-deficient mice were attenuated in females compared to males. Attenuated fatty liver in females was ascribed to inactivation of sterol regulatory element binding protein-1c. Hepatic inflammation in females was suppressed via decreased ROS with increased antioxidant gene expression and decreased proinflammatory cytokine production. Anti-cancer effect in female mice was, at least in part, due to the significantly lower ratio of oleic to stearic acid in the liver. CONCLUSIONS: Hepatic lesions in Pten-deficient mice were attenuated in females compared to males, as were human NAFLD and NASH. Some of the underlying mechanisms in sex difference appeared to be due to the change of gene expression, dependent on estrogens.

Hepatocyte-specific Pten deficiency results in steatohepatitis and hepatocellular carcinomas.

PTEN is a tumor suppressor gene mutated in many human cancers, and its expression is reduced or absent in almost half of hepatoma patients. We used the Cre-loxP system to generate a hepatocyte-specific null mutation of Pten in mice (AlbCrePten(flox/flox) mice). AlbCrePten(flox/flox) mice showed massive hepatomegaly and steatohepatitis with triglyceride accumulation, a phenotype similar to human nonalcoholic steatohepatitis. Adipocyte-specific genes were induced in mutant hepatocytes, implying adipogenic-like transformation of these cells. Genes involved in lipogenesis and beta-oxidation were also induced, possibly as a result of elevated levels of the transactivating factors PPARgamma and SREBP1c. Importantly, the loss of Pten function in the liver led to tumorigenesis, with 47% of AlbCrePten(flox/flox) livers developing liver cell adenomas by 44 weeks of age. By 74-78 weeks of age, 100% of AlbCrePten(flox/flox) livers showed adenomas and 66% had hepatocellular carcinomas. AlbCrePten(flox/flox) mice also showed insulin hypersensitivity. In vitro, AlbCrePten(flox/flox) hepatocytes were hyperproliferative and showed increased hyperoxidation with abnormal activation of protein kinase B and MAPK. Pten is thus an important regulator of lipogenesis, glucose metabolism, hepatocyte homeostasis, and tumorigenesis in the liver.

Sucralfate prevents the delay of wound repair in intestinal epithelial cells by hydrogen peroxide through NF-kappaB pathway.

BACKGROUND: Recent studies have shown that sucralfate (SF) has therapeutic effects on colonic inflammation in ulcerative colitis. The aim of this study was to clarify the function of SF for wound repair in intestinal epithelial cells (IEC). METHODS: (1) Activation of signal proteins [ERK1/2 mitogen-activated protein kinase (MAPK), IkappaB-alpha] in IEC-6 cells after stimulation with 10(-4) M potassium sucrose octasulfate (SOS), which is the functional element of SF, was assessed by Western blot. (2) Induction of transforming growth factor (TGF)-beta1, TGF-alpha, EGF, and cyclooxygenase-2 (COX-2) mRNA after stimulation of IEC-6 cells with SOS was assessed by reverse transcriptase-polymerase chain reaction. (3) IEC-6 cells were wounded and cultured for 24 h with various concentrations of SOS in the absence or presence of 20 microM H(2)O(2). Epithelial migration or proliferation was assessed by counting migrating cells or bromodeoxyuridine (BrdU)-positive cells across the wound border. RESULTS: (1) SOS activated IkappaB-alpha, but it did not activate ERK1/2 MAPK. (2) SOS enhanced the expression of COX-2 mRNA, but it did not change the mRNA expression of other growth factors. (3) SOS did not enhance wound repair in IEC-6 cells, but it decreased the number of dead cells (maximum, 74%) (P < 0.01) in a dose-dependent manner and prevented the diminishment of epithelial migration (maximum, 61%) (P < 0.01) and proliferation (maximum, 37%) (P < 0.05) induced by H(2)O(2). These functions of SOS were suppressed by the NF-kappaB and COX-2 inhibitors. CONCLUSIONS: SOS prevented the delay of wound repair in IEC-6 cells induced by H(2)O(2), probably through induction of COX-2 and an anti-apoptotic mechanism. These effects of SOS might be given through the activation of the NF-kappaB pathway.

Hepatic gene expression in hepatocyte-specific Pten deficient mice showing steatohepatitis without ethanol challenge.

Hepatocyte-specific Pten deficient (Pten KO) mice possess almost the same hepatic lesions histologically as human NASH and are thought to represent some limited NASH patients. We analyzed a comprehensive gene expression of hepatocytes derived from 10- to 35-week-old Pten KO mice using the DNA microarray technology to find out the candidate genes related to development and aggravation of human NASH. Spp1, Vnn1, Itga6, Abcd2, Auh, Acox1, Pdk4, Cpt1a, Lcn2, Igfbp2, Gstm6, Socs3, Tgm2, and Aldh9a1 were regarded as the candidate genes related to inflammation. The candidate genes of fibrosis were Spp1, Ctgf, and Cyp2c39 and moreover Cidec and Spp1 were regarded as the candidate genes of carcinogenesis. To confirm that these genes contribute to the etiology of some human NASH, further investigations using human liver samples are needed.

[Hepatocyte-specific Pten deficient mice].

Histological findings of hepatocyte-specific Pten deficient(Pten KO) mice livers were consistent with the criteria of human nonalcoholic steatohepatitis(NASH). Therefore, Pten KO mice are a powerful animal model of NASH. In Pten KO mice livers, steatosis develops based on the increased expression of genes that promote fatty acids synthesis. The increased expression of beta, oxidation-related genes accumulates oxidative stress in Pten KO mice livers resulting in hepatitis based on lipid hyperoxidation of hepatocytes membranes. Onset and exacerbation of hepatitis are also related to endotoxins derived from intestinal bacteria. Oxidative DNA damage, hyperproliferation of hepatocytes induced by the activation of Akt and ERK, and the increasement of malignant potential based on the change of fatty acids composition in the livers contribute to the development of hepatocellular carcinoma in Pten KO mice. Since it is considered that the mechanism to induce hepatic lesions in some NASH patients is the same as that in Pten KO mice, the investigation using Pten KO mice gives us clues to clarify the pathogenesis or develop effective therapy of NASH.

Ecabet sodium prevents the delay of wound repair in intestinal epithelial cells induced by hydrogen peroxide.

BACKGROUND: Recent studies showed that ecabet sodium (ES), a gastro-protective agent, also had a therapeutic effect on inflammation in ulcerative colitis. The aim of this study was to clarify the function of ES in wound repair in intestinal epithelial cells (IECs). METHODS: The activation of signal proteins (ERK1/2 mitogen-activated protein kinase MAPK, and IkappaB-alpha) in IEC-6 cells after stimulation with 2.5 mg/ml of ES was assessed by Western blot. The induction of transforming growth factor (TGF)-beta1, TGF-alpha, and cyclooxygenase-2 (COX-2) mRNAs after the stimulation of IEC-6 cells with ES was assessed by reverse transcription ploymerase chain reaction (RT-PCR). IEC-6 cells were wounded and cultured for 24 h with various concentrations of ES in the absence or presence of 20 microM H2O2. Epithelial migration or proliferation was assessed by counting migrated or bromodeoxyuridine (BrdU)-positive cells observed across the wound border. We also assessed apoptotic epithelial cells after the culture. RESULTS: ES clearly activated ERK1/2 MAPK and slightly activated IkappaB-alpha. ES also enhanced the expression of TGF-alpha and COX-2 mRNAs. This enhancement was suppressed by a MAPK/Erk kinase (MEK) inhibitor. ES did not enhance epithelial migration in the absence of H2O2. In contrast, ES significantly decreased the number of apoptotic cells and prevented the reduction of epithelial migration (51.1%; P < 0.01) and proliferation (56%; P < 0.01) induced by H2O2. The function of ES was suppressed by a cyclooxygenase-2 (COX-2) inhibitor and by the MEK inhibitor, and partly suppressed by a nuclear factor (NF)-kappaB inhibitor. CONCLUSIONS: ES prevents the delay of wound repair in IEC-6 cells induced by H2O2, probably through the activation of ERK1/2 MAPK and the induction of COX-2.

Hepatocyte-specific Pten-deficient mice as a novel model for nonalcoholic steatohepatitis and hepatocellular carcinoma.

Phosphatase and tensin homolog (PTEN) is a multifunctional phosphatase whose substrate is phosphatidylinositol-3,4,5-triphosphate (PIP3), and it is also a ubiquitously expressed tumor suppressor gene that down-regulates phosphatidylinositol-3-kinases (PI3Ks). Although there are a few reports about PTEN related to hepatocellular carcinoma, the role of PTEN in the liver remains unclear. Therefore, to clarify the role of PTEN in the liver, we generated and analyzed hepatocyte-specific Pten-deficient mice (Pten-deficient mice). The liver of 40-week-old Pten-deficient mice revealed macrovesicular steatosis, ballooning hepatocytes, lobular inflammatory cell infiltration, and perisinusoidal fibrosis that are characteristic of human nonalcoholic steatohepatitis (NASH). By 80 weeks of age, 100% of Pten-deficient livers showed adenomas and 66% had hepatocellular carcinomas. Thus, PTEN is important for the prevention of adipogenic and tumorigenic transformation, and Pten-deficient mice are a novel model for NASH and hepatocellular carcinoma. Our results suggest that the controlled blocking of molecules acting downstream of PI3K might provide significant therapeutic benefit to patients predisposed to NASH and hepatocellular carcinoma.

[Tumor suppressor gene PTEN and non-alcoholic steatohepatitis (NASH)].

Although hepatic steatosis had been considered to be a benign condition that does not deteriorate to either liver cirrhosis or hepatocellular carcinoma (HCC). Non-alcoholic steatohepatitis (NASH) is notable disease that has similar pathological features to alcoholic liver injury and progresses to liver cirrhosis and HCC. But the molecular mechanism for the onset of NASH, and for the transformation from steatosis to carcinogenesis are still unclear. Hepatocyte-specific PTEN deficient mice, we generated, have similar histological features to the patients of human NASH. These hepatocytes showed enhanced lipid accumulation, inflammatory change, and hyperoxidation. Moreover, they developed into HCC. Thus, impairment of PI3K/PTEN signaling may possibly be involved in a part of NASH/HCC cases in human.