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PubMed1966

Influence of ethanol on the metabolism of perfused normal, fatty and cirrhotic rat livers.

1. The influence of ethanol on the metabolism of perfused livers from normal rats and rats in various stages of development of dietary cirrhosis was studied. A choline-deficient, low-protein and high-fat diet was used. Results were obtained on oxygen consumption and carbon dioxide production, on glucose release and uptake by the liver and on changes in the concentrations of lactate and pyruvate and of beta-hydroxybutyrate and acetoacetate in the perfusion medium. 2. Oxygen consumption and carbon dioxide production were lower in fatty and cirrhotic livers than in normal livers. Ethanol had no effect on the oxygen consumption of any of the various livers. After addition of ethanol to the perfusion medium carbon dioxide production ceased almost completely in normal livers. Only a slight decrease in the carbon dioxide production occurred in fatty and cirrhotic livers. 3. With every type of liver glucose was released from the liver into the perfusion medium during the initial control period. This release continued after the addition of ethanol to the perfusion medium in experiments with normal and fatty livers, whereas with cirrhotic livers a marked uptake of glucose from the medium was found. A simultaneous release of the glycolytic end products lactate and pyruvate into the medium occurred. 4. The production of ketone bodies was equal in normal and early fatty livers (6 weeks on the fat diet). It was smaller in late fatty livers (3-4 months on the fatty diet) and in cirrhotic livers. 5. The lactate/pyruvate concentration ratio in the perfusion medium increased from 11 to 67 with normal livers, from 12 to 16 with early fatty livers, from 13 to 26 with late fatty livers and from 21 to 55 with cirrhotic livers when the livers were perfused with a medium containing ethanol. The beta-hydroxybutyrate/acetoacetate concentration ratio increased from 1.2 to 8.4 in normal livers, from 2.0 to 2.8 in early fatty livers, from 1.2 to 2.4 in late fatty livers and from 2.1 to 4.0 in cirrhotic livers when ethanol was added to the medium. 6. The effects of ethanol on liver metabolism during the development of dietary cirrhosis are discussed and related to human fatty liver and cirrhosis during chronic ethanol consumption.

Animals↗
PubMed2003

Expression of hepatoma-derived growth factor in hepatocarcinogenesis.

BACKGROUND AND AIM: The present study investigated the expression of hepatoma-derived growth factor (HDGF) in human hepatocellular carcinoma (HCC) and in the liver during hepatocarcinogenesis in two rodent models. METHODS: Expression of HDGF was analyzed using northern blotting and immunohistochemistry in the human and rodent models. RESULTS: Hepatoma-derived growth factor was more highly expressed in HCC than in the adjacent liver in humans with hepatitis, as shown by northern blotting. Using immunohistochemistry with the specific anti-HDGF antibody, HDGF was more strongly and frequently expressed in the nucleus and cytoplasm of HCC cells than in the adjacent normal hepatocytes. Hepatoma-derived growth factor was also more strongly expressed in the tumors than in the adjacent fatty liver of fatty liver Shionogi (FLS) mice, than in the cirrhotic liver of choline-deficient amino acid feeding rats, as shown by northern blotting and immunohistochemistry. In the liver of FLS mice, HDGF expression increased gradually from the age of 24 weeks through to 52 weeks after birth, showing that HDGF expression was already increased at an early stage before tumor development. In the non-tumorous liver with fatty change, the foci expressing HDGF appeared at 24 weeks of age, which were the activated macrophage clusters with enhanced DNA synthesis and fat droplets. It is suggested that HDGF was secreted or released from these foci and stimulated hepatocyte proliferation in a paracrine manner in FLS mice, and stimulated the proliferation of hepatic tumor cells in an autocrine manner. CONCLUSIONS: The present findings suggest that HDGF plays an important role in the development or progression of HCC in humans and rodents.

Animals↗
PubMed2002

Animal models of steatohepatitis.

Animal models of hepatic steatosis and steatohepatitis have improved our understanding of the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Three models, genetically obese ob/ob mice, lipoatrophic mice and normal rats fed choline-deficient, methionine-restricted diets, have been particularly informative. All support the multiple 'hit' hypothesis for NAFLD pathogenesis that suggests that fatty livers are unusually vulnerable to oxidants and develop steatohepatitis when secondary insults generate sufficient oxidants to cause liver cell death and inflammation. Steatohepatitis, in turn, increases sensitivity to other insults that induce hepatic fibrosis, promoting the evolution of cirrhosis. Early during NAFLD pathogenesis, inhibitor kappa kinase beta (IKKbeta), an enzyme that induces tumour necrosis factor alpha (TNFalpha) and other proinflammatory cytokines, is activated and this causes insulin resistance. Inhibition of IKKbeta or TNFalpha improves insulin sensitivity, steatosis and steatohepatitis in animals, suggesting novel strategies to prevent and treat early NAFLD in humans.

Animals↗
PubMed1996

Decreased interleukin-2 production in murine acute pancreatitis: potential for immunomodulation.

BACKGROUND & AIMS: The role of the cytokine interleukin 2 (IL-2) has long been recognized as central to normal immunologic function and defense against infection after burns and trauma, but little effort has been directed towards its role in acute pancreatitis (AP), which also has a high mortality related to sepsis. This study investigated the potential role of IL-2 in mice with diet-induced AP. METHODS: AP was induced in mice by 10 days of feeding a choline-deficient, ethionine-supplemented diet. T-helper (CD4) cells were estimated, and T-cell mitogen-stimulated splenocyte proliferation and IL-2 production in vitro were measured on days 3, 7, and 10. RESULTS: Significant reduction in IL-2 production was found on day 3 (32%; P < 0.05) and day 10 (48%; P < 0.005). Administration of intraperitoneal lipopolysaccharide on day 10 was associated with reduced IL-2 production (P < 0.025) 4 hours later and 90% mortality in animals with AP. In vivo therapy with recombinant IL-2 improved in vitro IL-2 secretion (P < 0.05) and reduced lipopolysaccharide-induced mortality (P = 0.036). CONCLUSIONS: Murine diet-induced AP is associated with impaired immune function and increased susceptibility to sepsis and may be a valuable tool in the investigation of immunomodulation in AP.

Acute Disease↗
PubMed2005

Human homologue of maid is a useful marker protein in hepatocarcinogenesis.

BACKGROUND & AIMS: Human homologue of maid (HHM) is a helix-loop-helix (HLH) transcriptional regulatory protein that is involved in the hepatic stem cell development and differentiation. We analyzed the potential involvement of HHM in hepatocarcinogenesis. METHODS: We analyzed HHM expression in the choline-deficient L-amino acid defined (CDAA) diet model of rat hepatocarcinogenesis and in human adenomatous hyperplasia (AH) and hepatocellular carcinoma (HCC) biopsy samples. We assessed the effects of HHM on cell proliferation. We screened proteins that bind to HHM protein using a yeast 2-hybrid screen. RESULTS: High HHM expression was seen in foci and HCC induced in the rat CDAA diet model. HHM protein was expressed in 23 of 32 AH samples (72%), 19 of 28 well-differentiated HCC samples (68%), and 9 of 18 poorly-moderately differentiated HCC samples (50%). Over-expressed HHM enhanced the S phase. HHM interference RNA significantly inhibited cell proliferation. A yeast 2-hybrid screen identified Jun activation domain-binding protein 1 (Jab1) as a binding partner for HHM. We confirmed HHM and Jab1 binding by immunoprecipitation and immunofluorescent histochemistry. The expression of Jab1 was found in human AH and HCC samples. We found an association between levels of expression of HHM and those of Jab1 in AH and HCC tissues examined (P = .027 by chi2 test). CONCLUSIONS: High-level HHM expression was found from the very early stages of hepatocarcinogenesis, suggesting that HHM may be a useful marker protein to detect.

Adenoma↗
PubMed2001

Heterogeneity and plasticity of hepatocyte lineage cells.

It is hypothesized that the liver has 3 levels of cells in the hepatic lineage that respond to injury or carcinogenesis: 1) the mature hepatocyte, which responds to partial hepatectomy (PH), to centrolobular injury, such as that induced by carbon tetrachloride (CCl(4)), and to dimethylnitrosamine (DEN) hepatocarcinogenesis; 2) the ductular "bipolar" progenitor cell, which responds to centrolobular injury when the proliferation of hepatocytes is inhibited, and to N-2-acetylaminofluorene (AAF) hepatocarcinogenesis; and 3) the putative periductular stem cell, which responds to periportal injury, such as induced by allyl alcohol and to choline-deficiency models of hepatocarcinogenesis. Hepatocytes are numerous, respond rapidly by 1 or 2 cell cycles, but can only produce other hepatocytes. The ductular progenitor cells are less numerous, may proliferate for longer times than hepatocytes, and are generally considered "bipolar," i.e., can give rise to biliary cells or hepatocytes. Periductular stem cells are rare in the liver, have a very long proliferation potential, and may be multipotent, but their full potential has yet to be defined. Extrahepatic (bone marrow) origin of the periductular stem cells is supported by recent data showing that hepatocytes may express genetic markers of donor hematopoietic cells after bone marrow transplantation. Thus, experimental models of liver injury and of hepatocarcinogenesis may call forth a cellular response at different levels in the hepatic lineage (heterogeneity), and these cells have different potential to form cells of other types (plasticity).

Animals↗
PubMed2001

Mitochondrial oxidative injury and energy metabolism alteration in rat fatty liver: effect of the nutritional status.

Hepatic steatosis is associated with mitochondrial oxidative alterations. This study aimed to characterize in a choline-deficient model of rat fatty liver whether this oxidative imbalance is related to an impairment of the capacity of ATP synthesis both under fed conditions and after starvation, which may sensitize mitochondria to oxidative injury. Mitochondria were isolated from normal and fatty livers of fed or 18-hour fasted rats. Oxidative injury was evaluated by measuring the mitochondrial content of thiobarbituric reactive substances, protein carbonyls, glutathione, and protein sulfhydryls. The mitochondrial F(0)F(1)-ATP synthase content, tissue ATP concentration, and liver histology were also determined. Compared with normal liver, under fed conditions, fatty livers showed a greater mitochondrial content of oxidized lipids and proteins together with a low concentration of sulfhydryls and glutathione. The mitochondrial catalytic beta-F(1) subunit of the F(0)F(1)-ATP synthase was about 35% lower in fatty livers. Hepatic ATP was also significantly reduced in fatty liver. Starvation exacerbated mitochondrial oxidative injury in both groups but to a greater extent in fatty livers. In the steatotic group, fasting induced a significant decrease of the ATP levels, which was accompanied by a 70% fall of the catalytic beta-F(1) subunit. These data indicate that the mitochondrial oxidative alterations in fatty livers are associated with an important reduction of the F(0)F(1)-ATP synthase. These changes, which are greatly exacerbated after starvation, may account for the reduced synthesis of the hepatic ATP observed in the presence of fatty infiltration.

ATP Synthetase Complexes↗
PubMed2000

Substance P is a determinant of lethality in diet-induced hemorrhagic pancreatitis in mice.

BACKGROUND: The neuropeptide substance P (SP) induces plasma extravasation and neutrophil infiltration by activating the neurokinin 1-receptor (NK1-R). SP-induced neurogenic inflammation is terminated by the cell surface enzyme neutral endopeptidase (NEP), which degrades SP. We determined whether genetic deletion of the NK1-R reduces mortality and, conversely, whether genetic deletion of NEP increases mortality in a lethal model of hemorrhagic pancreatitis. METHODS: Necrotizing pancreatitis was induced by feeding mice a diet deficient in choline and supplemented with ethionine. We determined the length of survival, the severity of pancreatitis (by measuring the neutrophil enzyme myeloperoxidase [MPO] and by histologic evaluation), and the severity of pancreatitis-associated lung injury (lung MPO and histology) in NK1-R (+/+)/(-/-) and NEP (+/+)/(-/-) mice. RESULTS: Genetic deletion of the NK1-R significantly improved survival (100% vs 8% at 120 hours, P <.001) and reduced pancreatic MPO and acinar cell necrosis. Conversely, genetic deletion of NEP significantly worsened survival (0% vs 90% at 120 hours, P <.001) and exacerbated pancreatic MPO and pancreatitis-associated lung injury. CONCLUSIONS: Substance P is an important determinant of lethality in this model of necrotizing pancreatitis. Defects in NEP expression could lead to uncontrolled inflammation.

Acute Disease↗
PubMed2006

Metabolic profiling reveals a contribution of gut microbiota to fatty liver phenotype in insulin-resistant mice.

Here, we study the intricate relationship between gut microbiota and host cometabolic phenotypes associated with dietary-induced impaired glucose homeostasis and nonalcoholic fatty liver disease (NAFLD) in a mouse strain (129S6) known to be susceptible to these disease traits, using plasma and urine metabotyping, achieved by (1)H NMR spectroscopy. Multivariate statistical modeling of the spectra shows that the genetic predisposition of the 129S6 mouse to impaired glucose homeostasis and NAFLD is associated with disruptions of choline metabolism, i.e., low circulating levels of plasma phosphatidylcholine and high urinary excretion of methylamines (dimethylamine, trimethylamine, and trimethylamine-N-oxide), coprocessed by symbiotic gut microbiota and mammalian enzyme systems. Conversion of choline into methylamines by microbiota in strain 129S6 on a high-fat diet reduces the bioavailability of choline and mimics the effect of choline-deficient diets, causing NAFLD. These data also indicate that gut microbiota may play an active role in the development of insulin resistance.

Animals↗
PubMed2001

Methionine adenosyltransferase 1A knockout mice are predisposed to liver injury and exhibit increased expression of genes involved in proliferation.

Liver-specific and nonliver-specific methionine adenosyltransferases (MATs) are products of two genes, MAT1A and MAT2A, respectively, that catalyze the formation of S-adenosylmethionine (AdoMet), the principal biological methyl donor. Mature liver expresses MAT1A, whereas MAT2A is expressed in extrahepatic tissues and is induced during liver growth and dedifferentiation. To examine the influence of MAT1A on hepatic growth, we studied the effects of a targeted disruption of the murine MAT1A gene. MAT1A mRNA and protein levels were absent in homozygous knockout mice. At 3 months, plasma methionine level increased 776% in knockouts. Hepatic AdoMet and glutathione levels were reduced by 74 and 40%, respectively, whereas S-adenosylhomocysteine, methylthioadenosine, and global DNA methylation were unchanged. The body weight of 3-month-old knockout mice was unchanged from wild-type littermates, but the liver weight was increased 40%. The Affymetrix genechip system and Northern and Western blot analyses were used to analyze differential expression of genes. The expression of many acute phase-response and inflammatory markers, including orosomucoid, amyloid, metallothionein, Fas antigen, and growth-related genes, including early growth response 1 and proliferating cell nuclear antigen, is increased in the knockout animal. At 3 months, knockout mice are more susceptible to choline-deficient diet-induced fatty liver. At 8 months, knockout mice developed spontaneous macrovesicular steatosis and predominantly periportal mononuclear cell infiltration. Thus, absence of MAT1A resulted in a liver that is more susceptible to injury, expresses markers of an acute phase response, and displays increased proliferation.

Animals↗
PubMed2005

Isoniazid and rifampicin treatment on phospholipids and their subfractions in liver tissue of rabbits.

Although combined treatment of isoniazid (INH) and rifampicin (RIF) has been documented to induce hepatotoxicity and hepatocellular damage, their effect on liver tissue phospholipids is still unknown. Because phospholipids constitute an integral part of hepatocellular membrane, studies were conducted to evaluate the effect of individual and combined treatment of INH and RIF on liver tissue phospholipids in rabbits. Simultaneous administration (i.p.) of INH and RIF (group IV; n = 6), each at a dose of 25 mg/kg for 11 days, caused a significant elevation of phospholipids in plasma from day 5 till day 11. This treatment also caused a significant fall in total inorganic phosphorous, phosphatidylcholine (PC), and cardiolipin (CL) with concomitant increase in phosphatidylethanolamine (PE) and phosphatitylserine (PS) subfractions of phospholipids in the liver tissue of rabbits. Though INH-alone treatment (group II; n = 5) produced a significant fall in total inorganic phosphorous content in the liver tissue, the phospholipid subfractions remain unaltered. RIF-alone treatment (group III; n = 5) did not produce any alteration in phospholipids and their subfractions in liver tissue and plasma of rabbits, and they were comparable to saline-treated control (group I; n = 5). It is likely that simultaneous treatment of INH and RIF could cause choline deficiency, resulting in lowering of phospholipids in the hepatocellular membrane and obstruction of lipoprotein synthesis, culminating in liver injury.

Animals↗
PubMed2000

Impaired preneoplastic changes and liver tumor formation in tumor necrosis factor receptor type 1 knockout mice.

Hepatic stem cells (oval cells) proliferate within the liver after exposure to a variety of hepatic carcinogens and can generate both hepatocytes and bile duct cells. Oval cell proliferation is commonly seen in the preneoplastic stages of liver carcinogenesis, often accompanied by an inflammatory response. Tumor necrosis factor (TNF), an inflammatory cytokine, is also important in liver regeneration and hepatocellular growth. The experiments reported here explore the relationship among the TNF inflammatory pathway, liver stem cell activation, and tumorigenesis. We demonstrate that TNF is upregulated during oval cell proliferation induced by a choline-deficient, ethionine-supplemented diet and that it is expressed by oval cells. In TNF receptor type 1 knockout mice, oval cell proliferation is substantially impaired and tumorigenesis is reduced. Oval cell proliferation is impaired to a lesser extent in interleukin 6 knockout mice and is unchanged in TNF receptor type 2 knockout mice. These findings demonstrate that TNF signaling participates in the proliferation of oval cells during the preneoplastic phase of liver carcinogenesis and that loss of signaling through the TNF receptor type 1 reduces the incidence of tumor formation. The TNF inflammatory pathway may be a target for therapeutic intervention during the early stages of liver carcinogenesis.

Animals↗
PubMed1951

The in vitro preparation and histochemical properties of substances resembling ceroid.

Substances possessing the same histochemical properties as the ceroid in cirrhotic livers of rats fed choline-deficient diets have been prepared from various unsaturated fats, fatty acids and their esters by autoxidation but could not be obtained from hydrocarbons or saturated fats or fatty acids. The formation of ceroid-like substances occurred first on surfaces or at interfaces in the reaction mixtures. It was inhibited by antioxidants and was accelerated by the addition of tissues, blood cells, erythrocytic stroma, or hemoglobin, by emulsification, by increasing the surface exposed to the air, and by increasing the temperature. Histochemical studies provided much evidence that the following properties of ceroid might be attributed to the products of the autoxidation of unsaturated lipids: insolubility in organic solvents, sudanophilia, yellowing by concentrated nitric acid, positive periodic acid-Schiff's reaction, basophilia, acid fastness, positive hernofuscin reaction, and reduction of diammine silver carbonate and alkaline potassium permanganate. The normal reactivity of cells or tissues embedded in ceroid was effectively masked by the pigment, apparently, initially at least, by preventing the reagents' gaining access to them. It is suggested that the iron sometimes demonstrated in ceroid may be that of blood cells or tissue fragments incompletely masked by the ceroid. It is concluded that whenever conditions are such that unsaturated fats accumulate in tissues to such an extent that a relative lack of biological anti-oxidants results, autoxidation of the fats and their conversion to ceroid pigment are favored, and that ceroid and the lipofuscin pigment of vitamin E deficiency may be fundamentally similar.

Animals↗
PubMed1999

Pharmacologic properties of phenyl N-tert-butylnitrone.

Phenyl N-tert-butylnitrone (PBN) is the parent of a family of nitrones used as spin-trapping agents to trap free radicals. PBN's pharmacological effects in animal models are extensive, ranging from protection against death after endotoxin shock, protection from ischemia-reperfusion injury, to increasing the life span of mice. Recent additions to the list include protection from bacterial meningitis, thalidomide-induced teratogenicity, drug-induced diabetogenesis, and choline-deficient hepatocarcinogenesis. Because PBN reacts with oxygen radicals to produce less reactive species, it has been suggested that this is the basis of its pharmacological effects. However, there has been no hard evidence for this notation. Nevertheless, many investigators have used the presence of PBN's pharmacologic effect as evidence for free radical involvement in their models. Mechanistic studies on the PBN's antisepsis action revealed that PBN inhibits expression of various pro-inflammatory genes, suggesting that the protective action involves more than a straightforward free radical-scavenging mechanism. Previous and recent developments in the investigations on the pharmacologic properties of PBN are described in this review.

Aging↗
PubMed1997

Severity and mortality of experimental pancreatitis are dependent on interleukin-1 converting enzyme (ICE).

Interleukin-1 beta (IL-1 beta) is produced in large amounts during acute pancreatitis and is believed to play a role in disease progression. Because secretion of IL-1 beta is dependent on intracellular processing of pro-IL-1 beta by IL-1 converting enzyme (ICE), we aimed to determine the efficacy of a novel ICE inactivator (VE-13045) in inhibiting secretion of active IL-1 beta in vivo and if the loss of ICE activity would affect the severity and mortality of experimental pancreatitis. Severe hemorrhagic pancreatitis was induced in adult rats by infusion of bile acid into the pancreatic duct. Animals were randomized to receive VE-13045 or vehicle before induction of pancreatitis. To confirm our findings and to ensure that the results were not model dependent, a second series of experiments was conducted using mice possessing a homozygous knockout of the ICE gene in which lethal pancreatitis was induced by feeding a choline-deficient, ethionine-supplemented diet. The severity of pancreatitis was assessed for both experiments by standard surrogate markers, blind histologic grading, and serum IL-1 beta and tumor necrosis factor-alpha (TNF-alpha) levels. Pancreatic IL-1 beta mRNA induction was assessed by differential RT-PCR. Acute pancreatitis was associated with a 120-fold increase in IL-1 beta mRNA, which was not affected by ICE inhibition or gene deletion. Cytokine processing and secretion were affected, as evidenced by decreased serum levels of IL-1 beta and TNF-alpha (p < 0.001) in all animals with an inactive ICE enzyme. This lack of cytokine production increased survival from 32% to 78% following bile salt pancreatitis (p < 0.01) and from 24% to 80% following diet-induced pancreatitis (p < 0.005). Both ICE-defective groups demonstrated decreased pancreatic necrosis, edema, inflammation, wet weight (all p < 0.05), and amylase and lipase (p < 0.01). In vivo blockade or genetic deletion of ICE inhibits pancreatitis-induced secretion of proinflammatory cytokines without altering IL-1 mRNA production and is associated with decreased pancreatitis severity and dramatic survival benefits.

Animals↗
PubMed1989

Expression of N-acetylglucosaminyltransferase III in hepatic nodules generated by different models of rat liver carcinogenesis.

Our earlier studies revealed that N-acetylglucosaminyltransferase III (GnTase III), which catalyzes the insertion of a bisecting N-acetylglucosamine (bi-Gn) in the complex-type N-linked glycans of cellular glycoproteins, is present in hepatic nodules promoted by the orotic acid model. Neither the bi-Gn residues nor the activity of GnTase III is detectable in normal livers and in the surrounding non-nodular liver of the rat. The present study was designed to find out whether an expression of activity of GnTase III is a phenotypic property characteristic of hepatic nodules or simply unique to nodules produced by the orotic acid model. Fischer male 344 rats were initiated with two different carcinogens namely 1,2-dimethyl-hydrazine or diethylnitrosamine and promoted by other models such as the resistant hepatocyte model and the choline deficient diet model, in addition to the orotic acid model. The hepatic nodules generated by these three different models and hepatocellular carcinomas exhibited significant levels of activity of GnTase III while non-nodular surrounding liver, regenerating liver after 2/3 partial hepatectomy or livers of age and sex matched control rats, had no detectable activity. The detection of the activity of GnTase III in nodules and in cancer is in agreement with the presence of bi-Gn residues reported in gamma-glutamyltranspeptidase of cancer tissues of rats. These results are consistent with the conclusion that the expression of GnTase III is activated during hepatocarcinogenesis and is not related to any particular initiator or promoter.

Animals↗
PubMed1993

Cyclosporine stimulates hepatocyte proliferation and accelerates development of hepatocellular carcinomas in rats.

A recent study from our laboratory demonstrated that cyclosporine (CsA), a prototype immunosuppressant, enhanced the growth of carcinogen-induced enzyme altered foci in rat liver, suggesting that CsA may stimulate development of hepatocellular carcinomas. In the present study, we examined (i) whether CsA accelerates development of hepatocellular carcinomas in experimental animals, (ii) whether CsA stimulates the proliferation of resting hepatocyte in vivo and (iii) whether CsA modulates the production of growth factors implicated in liver cell growth, hepatocyte growth factor (HGF), transforming growth factor alpha (TGF alpha) and transforming growth factor beta 1 (TGF beta 1). Foci of hepatocytes, positive for glutathione S-transferase placental form were induced in male F344 rats by a single dose of diethylnitrosamine followed by 7 weeks promotion by a choline-deficient diet. The animals were then divided in two groups, and subsequent development of hepatocellular carcinomas was compared in rats fed a basal diet or a basal diet containing 0.015% CsA. Development of hepatocellular carcinoma was accelerated in the rats maintained on a CsA diet. Feeding a CsA diet as the sole treatment, for 2, 4 and 10 weeks induced significant increases in liver weight, and resulted also in an enhanced incorporation by hepatocytes of 5-bromo-2-deoxy-uridine. Serum levels of glutamate-oxaloacetate transferase, glutamate-pyruvate transferase and lactic dehydrogenase were not altered by feeding a CsA diet. Northern Blot analyses of the expression of HGF, TGF alpha and TGF beta 1 mRNAs in the liver showed similar patterns of expression between rats fed a basal diet and a CsA diet. The levels of HGF mRNA were not altered in the lungs and kidneys of rats fed a CsA diet. These results indicate that CsA stimulates rat liver cell proliferation in vivo without inducing liver cell necrosis, and that this effect may contribute to accelerated development of hepatocellular carcinomas in rats fed a CsA diet. As previously observed with BR 931, a hypolipidemic peroxisome proliferator, stimulation of liver cell growth by CsA did not entail changes in the production of HGF, TGF alpha or TGF beta 1.

Alanine Transaminase↗
PubMed2002

Generation and characterization of p53 null transformed hepatic progenitor cells: oval cells give rise to hepatocellular carcinoma.

Oval cells are bipotential liver stem cells able to differentiate into hepatocytes and bile duct epithelia. In normal adult liver oval cells are quiescent, existing in low numbers around the periportal region, and proliferate following severe, prolonged liver trauma. There is evidence implicating oval cells in the development of hepatocellular carcinoma, and hence the availability of an immortalized oval cell line would be invaluable for the study of liver cell lineage differentiation and carcinogenesis. A novel approach in the generation of cell lines is the use of the p53 knockout mouse. Absence of p53 allows a cell to cycle past the normal Hayflick limit, rendering it immortalized, although subsequent genetic alterations are thought necessary for transformation. p53 knockout mice were fed a choline-deficient, ethionine-supplemented diet, previously shown to increase oval cell numbers in wild-type mice. The oval cells were isolated by centrifugal elutriation and maintained in culture. Colonies of hepatic cells were isolated and characterized with respect to phenotype, growth characteristics and tumorigenicity. Analysis of gene expression by Northern blotting and immunocytochemistry suggests they are oval-like cells by virtue of albumin and transferrin expression, as well as the oval cell markers alpha fetoprotein, M(2)-pyruvate kinase and A6. Injection into athymic nude mice shows the cell lines are capable of forming tumors which phenotypically resemble hepatocellular carcinoma. Thus, the use of p53 null hepatic cells successfully generated immortalized and tumorigenic hepatic stem cell lines. The results presented support the idea that deleting p53 allows immortalization and contributes to the transformation of the oval-like cell lines. Further, the tumorigenic status of the cell lines is direct evidence for the participation of oval cells in the formation of hepatocellular carcinoma.

Animals↗