Dietary Methionine Restriction-Based Cancer Chemotherapy in Rodents.

The elevated methionine (MET) requirement for the growth of tumors, first observed by Sugimura in 1959, termed MET dependence, is a potentially highly effective therapeutic target. Proof of this principle is that when MET restriction (MR) was initially established in co-cultures of cancer and normal cells, MET dependence could be exploited to selectively kill cancer cells without killing co-cultured normal cells. MET-dependent cells become reversibly blocked in the late S/G2 phase of the cell cycle under MR enabling selective and effective S-phase chemotherapy against these blocked cancer cells. Subsequent MET repletion with an anti-mitotic drug was totally effective at selectively eliminating the MET-dependent cancer cells enabling the normal MET-dependent cells to take over the culture. We have also observed that the MET analog ethionine (ETH) is synergistic with MR in arresting the growth of the Yoshida sarcoma both in vitro and eliminating metastasis when transplanted to nude mice. MR increased the efficacy of cisplatinum (CDDP) against the MX-1 human breast carcinoma cell line when grown in nude mice. MR increased 5-fluorouracil (5-FU) efficacy on a human gastric cancer xenograft, SC-1-NU, in nude mice. MET-restricted total parenteral nutrition (MR TPN) was effective in Yoshida sarcoma-bearing rats. MR TPN with doxorubicin (DOX) and vincristine (VCR) resulted in significant tumor suppression and prolonged survival of Yoshida-sarcoma-bearing rats. These results were the basis of subsequent studies that used methioninase to effect MR for effective cancer therapy.

Loss of trefoil factor 1 inhibits biliary regeneration but accelerates the hepatic differentiation of progenitor cells in mice.

Although the regeneration of the adult liver depends on hepatic progenitor cells (HPCs), many uncertainties regarding hepatic regeneration in the injured liver remain. Trefoil factor family 1 (TFF1), a secretory protein predominantly expressed in the gastrointestinal tract, is responsible for mucosal restitution. Here, we investigated the role of TFF1 in liver regeneration using a mouse model of hepatic injury (choline-deficient ethionine-supplemented diet and carbon tetrachloride administration) and genetically engineered mice (TFF1 knockout (TFF1-/-)). Immunohistochemistry analysis of human liver samples revealed TFF1 expression in the hepatocytes close to ductular reaction and the regenerating biliary epithelium in injured liver. The number of cytokeratin 19 (CK19)-positive bile ducts was significantly decreased in the TFF1-/- mice after liver injury. Notch pathway in the TFF1-/- mice was also downregulated. HPCs in the control mice differentiated into biliary cells (CK19+/SRY HMG box 9 (SOX9)+) more frequently. In contrast, HPCs in the TFF1-/- mice more frequently differentiated into a hepatic lineage (alpha fetoprotein+/SOX9+) after acute liver damage. Hepatocyte proliferation was upregulated, and the liver weight was increased in TFF1-/- mice in response to chronic liver damage. Thus, TFF1 is responsible for liver regeneration after liver injury by promoting HPC differentiation into a biliary lineage and inhibiting HPC differentiation into a hepatic lineage.

The Murine Choline-Deficient, Ethionine-Supplemented (CDE) Diet Model of Chronic Liver Injury.

Chronic liver diseases, such as viral hepatitis, alcoholic liver disease, or non-alcoholic fatty liver disease, are characterized by continual inflammation, progressive destruction and regeneration of the hepatic parenchyma, liver progenitor cell proliferation, and fibrosis. The end-stage of every chronic liver disease is cirrhosis, a major risk factor for the development of hepatocellular carcinoma. To study processes regulating disease initiation, establishment, and progression, several animal models are used in laboratories. Here we describe a six-week time course of the choline-deficient and ethionine-supplemented (CDE) mouse model, which involves feeding six-week old male C57BL/6J mice with choline-deficient chow and 0.15% DL-ethionine-supplemented drinking water. Monitoring of animal health and a typical body weight loss curve are explained. The protocol demonstrates the gross examination of a CDE-treated liver and blood collection by cardiac puncture for subsequent serum analyses. Next, the liver perfusion technique and collection of different hepatic lobes for standard evaluations are shown, including liver histology assessments by hematoxylin and eosin or Sirius Red stainings, immunofluorescent detection of hepatic cell populations as well as transcriptome profiling of the liver microenvironment. This mouse model is suitable for studying inflammatory, fibrogenic, and liver progenitor cell dynamics induced through chronic liver disease and can be used to test potential therapeutic agents that may modulate these processes.

Effects of Berberine on Acute Necrotizing Pancreatitis and Associated Lung Injury.

OBJECTIVES: We set out to examine whether berberine (BBR) might affect the severity of pancreatitis and pancreatitis-associated lung injury in choline-deficient ethionine-supplemented (CDE) diet-induced severe acute pancreatitis. METHODS: Severe acute pancreatitis was induced by feeding a CDE diet for 3 days. Berberine was administered intraperitoneally during CDE diet. Mice were killed on days 1, 2, and 3 after the onset of CDE diet. The severity of pancreatitis was assessed by evaluating changes to the pancreas and lung and survival rate. Blood, pancreas, and lung were harvested for further examination. Furthermore, the regulating mechanisms of BBR were evaluated on the pancreas. RESULTS: Administration of BBR significantly inhibited histological damage to the pancreas and lung and decreased serum level of amylase and lipase, myeloperoxidase activity, cytokine production, and the mortality rate. Furthermore, administration of BBR inhibited activation of nuclear factor kappa B, c-Jun N-terminal kinases, and p38 in the pancreas during CDE diet. CONCLUSIONS: These findings suggest that BBR attenuates the severity of pancreatitis by inhibiting activation of nuclear factor kappa B, c-Jun N-terminal kinase, and p38 and that BBR could be used as a beneficial agent to regulate AP.

S-Adenosyl-L-Methionine augmentation in patients with stage II treatment-resistant major depressive disorder: an open label, fixed dose, single-blind study.

We investigated the efficacy of S-Adenosyl-L-Methionine (SAMe) augmentation in patients with treatment-resistant depressive disorder (TRD). Thirty-three outpatients with major depressive episode who failed to respond to at least 8 weeks of treatment with two adequate and stable doses of antidepressants were treated openly with fixed dose of SAMe (800 mg) for 8 weeks, added to existing medication. The primary outcome measure was the change from baseline in total score on Hamilton Rating Scale for Depression (HAM-D). The Clinical Global Impression of Improvement (CGI-I) was rated at the endpoint. Patients with a reduction of 50% or more on HAM-D total score and a CGI-I score of 1 or 2 at endpoint were considered responders; remission was defined as a HAM-D score ≤7. Secondary outcome measures included the Snaith-Hamilton Pleasure Scale (SHAPS) and the Sheehan Disability Scale (SDS). At 8 weeks, a significant decrease in HAM-D score was observed with response achieved by 60% of the patients and remission by 36%. Also a statistically significant reduction in SHAPS and SDS was observed. Our findings indicate that SAMe augmentation may be effective and well tolerated in stage II TRD. However, limitations of the present study must be considered and further placebo-controlled trials are needed.

Inhibin B response to testicular toxicants hexachlorophene, ethane dimethane sulfonate, di-(n-butyl)-phthalate, nitrofurazone, DL-ethionine, 17-alpha ethinylestradiol, 2,5-hexanedione, or carbendazim following short-term dosing in male rats.

BACKGROUND: Inhibin B is a heterodimer glycoprotein that downregulates follicle-stimulating hormone and is produced predominantly by Sertoli cells. The potential correlation between changes in plasma Inhibin B and Sertoli cell toxicity was evaluated in male rats administered testicular toxicants in eight studies. Inhibin B fluctuations over 24 hr were also measured. METHODS: Adult rats were administered one of eight testicular toxicants for 1 to 29 days. The toxicants were DL-ethionine, dibutyl phthalate, nitrofurazone, 2,5-hexanedione, 17-alpha ethinylestradiol, ethane dimethane sulfonate, hexachlorophene, and carbendazim. In a separate study plasma was collected throughout a 24-hr period via an automatic blood sampler. RESULTS: Histomorphologic testicular findings included seminiferous tubule degeneration, round and elongate spermatid degeneration/necrosis, seminiferous tubule vacuolation, aspermatogenesis, and interstitial cell degeneration. There was a varying response of plasma Inhibin B levels to seminiferous tubule toxicity, with three studies showing high correlation, three studies with a response only at a certain time or dose, and two studies with no Inhibin B changes. In a receiver operating characteristics exclusion model analysis, where treated samples without histopathology were excluded, Inhibin B showed a sensitivity of 70% at 90% specificity in studies targeting seminiferous tubule toxicity. CONCLUSION: Decreases in Inhibin B correlated with Sertoli cell toxicity in the majority of studies evaluated, demonstrating the value of Inhibin B as a potential biomarker of testicular toxicity. There was no correlation between decreases in Inhibin B and interstitial cell degeneration. In addition, a pattern of Inhibin B secretion could not be identified over 24 hr.

Role of bone marrow cells in the development of pancreatic fibrosis in a rat model of pancreatitis induced by a choline-deficient/ethionine-supplemented diet.

Bone marrow cell (BMC)-derived myofibroblast-like cells have been reported in various organs, including the pancreas. However, the contribution of these cells to pancreatic fibrosis has not been fully discussed. The present study examined the possible involvement of pancreatic stellate cells (PSCs) originating from BMCs in the development of pancreatic fibrosis in a clinically relevant rat model of acute pancreatitis induced by a choline-deficient/ethionine-supplemented (CDE) diet. BMCs from female transgenic mice ubiquitously expressing green fluorescent protein (GFP) were transplanted into lethally irradiated male rats. Once chimerism was established, acute pancreatitis was induced by a CDE diet. Chronological changes in the number of PSCs originating from the donor BMCs were examined using double immunofluorescence for GFP and markers for PSCs, such as desmin and alpha smooth muscle actin (αSMA), 1, 3 and 8 weeks after the initiation of CDE feeding. We also used immunohistochemical staining to evaluate whether the PSCs from the BMCs produce growth factors, such as platelet-derived growth factor (PDGF) and transforming growth factor (TGF) ß1. The percentage of BMC-derived activated PSCs increased significantly, peaking after 1 week of CDE treatment (accounting for 23.3±0.9% of the total population of activated PSCs) and then decreasing. These cells produced both PDGF and TGFß1 during the early stage of pancreatic fibrosis. Our results suggest that PSCs originating from BMCs contribute mainly to the early stage of pancreatic injury, at least in part, by producing growth factors in a rat CDE diet-induced pancreatitis model.

Macrophage-derived Wnt opposes Notch signaling to specify hepatic progenitor cell fate in chronic liver disease.

During chronic injury a population of bipotent hepatic progenitor cells (HPCs) become activated to regenerate both cholangiocytes and hepatocytes. Here we show in human diseased liver and mouse models of the ductular reaction that Notch and Wnt signaling direct specification of HPCs via their interactions with activated myofibroblasts or macrophages. In particular, we found that during biliary regeneration, expression of Jagged 1 (a Notch ligand) by myofibroblasts promoted Notch signaling in HPCs and thus their biliary specification to cholangiocytes. Alternatively, during hepatocyte regeneration, macrophage engulfment of hepatocyte debris induced Wnt3a expression. This resulted in canonical Wnt signaling in nearby HPCs, thus maintaining expression of Numb (a cell fate determinant) within these cells and the promotion of their specification to hepatocytes. By these two pathways adult parenchymal regeneration during chronic liver injury is promoted.

Proliferation, differentiation and apoptosis of choline deficient ethionine supplemented diet-rat oval cells under the influence of 2-methoxyestradiol.

Since numerous studies indicate that 2-methoxyestradiol (2-ME) as a metabolite of 17beta estradiol (17ß-E(2)) may exert antitumor activity by unclear mechanism, we undertake the study to elucidate the effect of 2-ME on oval cells (OC) activated by a carcinogenic choline deficient ethionine supplemented diet (CDE diet). Isolated OC were treated with different concentrations of 2-ME for 24, 48 and 72 hours. In these periods of time phenotypic studies, apoptosis detection and proliferative activity of cells were performed. A marked inhibition of OC proliferation was observed at the presence of 1.0 µM of 2-ME, with the lowest value obtained after 48 h. However, at the end of the cells' incubation, maximally reduced proliferative response of OC was attributed to 2.0 µM of 2-ME. Simultaneously with the time of incubation the amount of Thy-1-positive cells decreased slightly from 50.5±1.4% to 31.5±3.6%. Contrary to 1.0 and 2.0 µM of 2-ME, its lowest value (0.5 µM) reduced Thy-1 positive cells after 48 hours. The same 2-ME concentration resulted in the elevation of the cell number expressing CK-19. In turn, the marked increase of albumine-positive cells was observed under 1.0 µM of 2-ME and reaching 21.5±6.2 % and 23.9±5.7% after 48 and 72 hours, respectively. Although the presence of 1.0 µM of 2-ME dramatically intensified apoptosis within 24 h of cell culture, the percentage of apoptotic cells remained unchanged under 2.0 µM of 2-ME. When subjected to the carcinogenic effect of CDE, 2-ME exerts anti-proliferative, proapoptotic, and differentiation effects in OC.

Fatty liver is associated with impaired activity of PPARγ-coactivator 1α (PGC1α) and mitochondrial biogenesis in mice.

Accumulating evidence indicates that mitochondria have a key role in non-alcoholic fatty liver disease (NAFLD). C57BL/6J mice were fed a choline-deficient, ethionine-supplemented (CDE) diet. Histological studies demonstrated accumulation of fat vacuoles in up to 90% of hepatocytes in mice fed the CDE diet for 14 days. In addition, a decrease in mitochondrial levels, together with an increase in superoxide radicals' levels were observed, indicating elevation of oxidative stress in hepatocytes. ATP levels were decreased in livers from CDE-fed mice after overnight fasting. This was accompanied by a compensative and significant increase in peroxisome-proliferator-activated receptor-γ coactivator 1α (PGC1α) mRNA levels in comparison to control livers. However, there was a reduction in PGC1α protein levels in CDE-treated mice. Moreover, the expression of mitochondrial biogenesis genes nuclear respiratory factor 1 (NRF-1), mitochondrial transcription factor A (TFAM), mitochondrial transcription factor B1 (TFB1M) and mitochondrial transcription factor B2 (TFB2M), which are all regulated by PGC1α activity, remained unchanged in fasted CDE-treated mice. These results indicate impaired activity of PGC1α. The impaired activity was further confirmed by chromatin immunoprecipitation analysis, which demonstrated decreased interaction of PGC1α with promoters containing NRF-1 and NRF-2 response elements in mice fed the CDE diet. A decrease in PGC1α ability to activate the expression of the gluconeogenic gene phosphoenol-pyruvate carboxykinase was also observed. This study demonstrates, for the first time, that attenuated mitochondrial biogenesis in steatotic livers is associated with impaired biological activity of PGC1α.

Remodelling of extracellular matrix is a requirement for the hepatic progenitor cell response.

BACKGROUND AND METHODS: In advanced liver damage, hepatic regeneration can occur through proliferation of a resident hepatic progenitor cell (HPC) population. HPCs are located within a designated niche in close association with myofibroblasts and bone marrow (BM) derived macrophages. Extra-cellular matrix (ECM) laminin invariably surrounds HPCs, but the functional requirement of this matrix-cell association is untested in vivo. Using the collagen Iα1((r/r)) mouse (r/r), which produces mutated collagen I resistant to matrix metalloproteinase degradation and has an exaggerated fibrotic response to liver injury, we test the relationship between collagen degradation, laminin deposition, and the HPC response. RESULTS: Chronic fibrotic carbon tetrachloride (CCl4) injury can induce a florid HPC response associated with dense laminin deposition. In the recovery phase after chronic CCl4 injury, r/r mice have a markedly attenuated HPC response compared to wild-types, together with persistence of collagen I and failure to deposit ECM laminin. Similar results were found in r/r mice given the choline-deficient ethionine supplemented diet, another model of the HPC response. In cross-over sex-mismatched BM transplantation (BMT) experiments between r/r mice and wild-types, the blunted HPC response of r/r mice was not rescued by wild-type BMT and likewise not conferred on to wild-type recipients by r/r BMT, demonstrating that the attenuated HPC response in r/r mice is a property intrinsic to the liver. CONCLUSION: Failure of ECM remodelling after chronic fibrotic liver injury hinders the ability of the liver to activate HPCs. Laminin-progenitor cell interactions within the HPC niche are a critical for HPC mediated regeneration.

Age dependence of oval cell responses and bile duct carcinomas in male fischer 344 rats fed a cyclic choline-deficient, ethionine-supplemented diet.

UNLABELLED: The age dependence of the oval cell response and bile duct carcinomas of male F344 rats exposed to a cyclic choline deficiency-ethionine (CDE) diet (2 weeks on, 1 week off) supports the concept of loss of potential of liver stem cells to form cancers with aging. Livers of rats exposed at 3 weeks of age demonstrated a robust and widespread oval cell proliferation followed by cholangiofibrosis and bile duct metaplasia with extensive mucinous cysts throughout all lobes, and induction of cholangiocarcinomas (CCAs) in seven of eight rats. Livers of rats exposed beginning at 8 weeks of age had much less oval cell response and cholangiofibrosis with only 1 of 15 rats developing a CCA. Livers in old (10-12 months when started) rats remained virtually unaffected, with minimal oval cell proliferation, only occasional and small foci of ductular dysplasia, and none of 16 rats developed CCAs. In contrast to most published studies using uninterrupted choline deficiency plus a carcinogen, hepatocellular carcinoma (HCC) was not observed under the conditions of this study. CONCLUSION: With aging, male F344 rats exposed to cyclic CDE diet display a diminished oval cell response and fewer CCAs. The absence of HCC is possibly due to the fact that during cyclic CDE, the week off may allow putative liver stem cells to avoid death or differentiation and survive to give rise to CCAs, whereas with continuous CDE exposure, the stem cells are forced to differentiate and develop into HCCs with relatively few CCAs.

Chronic pancreatitis in mice by treatment with choline-deficient ethionine-supplemented diet.

Although chronic pancreatitis is a risk factor for pancreatic ductal adenocarcinoma (PDA), the relationship between chronic pancreatitis and PDA remains obscure. A critical obstacle to understanding the role of chronic pancreatitis is the lack of animal models. To develop one such model, mice were fed long-term with a choline deficient ethionine-supplemented (CDE) diet. Histological evaluation revealed that chronic pancreatitis, characterized by acinar atrophy, fibrosis and well-developed tubular complexes (TCs), was observed after 24 weeks of CDE diet treatment. Furthermore, expression of epidermal growth factor receptor (EGFR) and its ligands; serine protease inhibitor Kazal type 3 (Spink3) and transforming growth factor alpha (TGF alpha) and activation of K-Ras (GTP-Ras formation), which are frequently observed in human PDA, were indeed observed in parallel with TCs formation. Neoplastic lesions were not found after 54 weeks of treatment, suggesting that a continuation of CDE diet or another insult is required for the development of PDA.

Effects of acute ethionine injection on plasma ghrelin and obestatin levels in trained male rats.

Ghrelin and obestatin are orexigenic and anorexigenic peptides, respectively, that are secreted from the stomach mucosa into the circulation. These peptides have opposing actions on food intake, weight gain, and adiposity. It is thought that ghrelin is sensitive to a negative energy environment and also plays a considerable role in short- and long-term energy balance and glucose homeostasis. It has been suggested that the levels of ghrelin and obestatin are upregulated by fasting, hypoglycemic status, and a physical-exercise-induced energy deficit. Ethionine (ETH), the ethyl analogue of methionine, has been shown to increase food intake, decrease adenosine triphosphate (ATP) and glycogen levels, and inhibit protein synthesis in the liver. The purpose of this study was to examine the effect of a single dose of ETH (0.7 mg/g of body weight) injection on resting plasma total ghrelin and obestatin concentrations in male trained rats. Thirty-two adult Wistar male rats weighing 180 to 200 g were randomly assigned to control (n = 16) and training (n =16) groups. The training group was exercised for 10 weeks (25 m/min, 0% grade, 60 minutes, and 5 d/wk). Seventy-two hours after the last exercise session, rats were injected with either saline (NaCl) or ETH and then killed. Ethionine compared with a NaCl injection resulted in significant (P < .013) reductions in resting hepatic ATP and glycogen levels, and in a significant (P < .001) increase in concentrations of plasma total ghrelin but not obestatin. The results indicate that ETH-induced liver ATP and glycogen deficiency could exert a powerful regulatory influence on plasma total ghrelin, but this is not the case for obestatin. Findings demonstrate the short-term energy-regulating capacity of ghrelin.

Time-resolved biomarker discovery in 1H-NMR data using generalized fuzzy Hough transform alignment and parallel factor analysis.

This work addresses the subject of time-series analysis of comprehensive (1)H-NMR data of biological origin. One of the problems with toxicological and efficacy studies is the confounding of correlation between the administered drug, its metabolites and the systemic changes in molecular dynamics, i.e., the flux of drug-related molecules correlates with the molecules of system regulation. This correlation poses a problem for biomarker mining since this confounding must be untangled in order to separate true biomarker molecules from dose-related molecules. One way of achieving this goal is to perform pharmacokinetic analysis. The difference in pharmacokinetic time profiles of different molecules can aid in the elucidation of the origin of the dynamics, this can even be achieved regardless of whether the identity of the molecule is known or not. This mode of analysis is the basis for metabonomic studies of toxicology and efficacy. One major problem concerning the analysis of (1)H-NMR data generated from metabonomic studies is that of the peak positional variation and of peak overlap. These phenomena induce variance in the data, obscuring the true information content and are hence unwanted but hard to avoid. Here, we show that by using the generalized fuzzy Hough transform spectral alignment, variable selection, and parallel factor analysis, we can solve both the alignment and the confounding problem stated above. Using the outlined method, several different temporal concentration profiles can be resolved and the majority of the studied molecules and their respective fluxes can be attributed to these resolved kinetic profiles. The resolved time profiles hereby simplifies finding true biomarkers and bio-patterns for early detection of biological conditions as well as providing more detailed information about the studied biological system. The presented method represents a significant step forward in time-series analysis of biological (1)H-NMR data as it provides almost full automation of the whole data analysis process and is able to analyze over 800 unique features per sample. The method is demonstrated using a (1)H-NMR rat urine dataset from a toxicology study and is compared with a classical approach: COW alignment followed by bucketing.

Impaired liver glucose production in a murine model of steatosis and endotoxemia: protection by inducible nitric oxide synthase.

This study hypothesized that upregulation of inducible nitric oxide synthase (iNOS) would preserve the metabolic status of the liver under conditions of steatosis and acute inflammation. Wild-type C57BL/6J and C57BL/6 iNOS-knockout (-/-) mice were fed a choline-deficient ethionine-supplemented diet (CDE). Mice were also injected with 5 mg/kg lipopolysaccharide (LPS) to induce endotoxemia. Consumption of the CDE diet led to steatosis of the liver and decreased expression of the gluconeogenic genes compared with controls. LPS treatment exacerbated these effects because of inhibition of PGC-1alpha expression, which resulted in hypoglycemia. In steatotic livers, LPS-induced iNOS expression was enhanced. Comparison between wild-type and iNOS-knockout mice under these conditions demonstrated a protective role of iNOS against fatal hypoglycemia. Nitric oxide (NO) signaling effects were confirmed by treatment of hepatocytes in culture with an NO donor, which resulted in increased expression of PGC-1alpha and gluconeogenic genes. In conclusion, iNOS was found to act as a protective protein and provides a possible mechanism by which the liver preserves glucose homeostasis under stress.

Expression of extracellular matrix genes in cultured hepatic oval cells: an origin of hepatic stellate cells through transforming growth factor beta?

BACKGROUND: Hepatic oval cells, progenitor cells in the liver, can differentiate into hepatocytes and bile duct cells both in vitro and in vivo. Although hepatic stellate cells are another important cell component in the liver, less attention has been focused on the relationship between hepatic oval cells and hepatic stellate cells. METHODS: Hepatic oval cells were isolated from rats fed a choline-deficient diet supplemented with 0.1% ethionine for 6 weeks and characterized by electron microscopy, flow cytometry, reverse transcription polymerase chain reaction, Western blot and bi-direction differentiation. After treatment with transforming growth factor-beta1 (TGF-beta1), changes in cell viability, morphology, extracellular matrix (ECM) expression and immune phenotype were analysed in these cultured and adherent hepatic oval cells. RESULTS: The primary cultured hepatic oval cells were positive for the oval cell-specific markers OV-6, BD-1/BD-2 and M2PK as well as the hepatocyte markers albumin and alpha-foetoprotein. These hepatic oval cells differentiated bipotentially into hepatocytes or bile duct-like cells under appropriate conditions. It is noteworthy that these bipotential hepatic oval cells expressed ECM genes stably, including collagens, matrix metalloproteinases and tissue inhibitor of mellatoproteinase. Furthermore, except for growth inhibition and morphological changes in the hepatic oval cells after exposure to TGF-beta1, there was an increased expression of ECM genes, the onset expression of snail and loss expression of E-cadherin. During this process, TGF-beta1 treatment induced an upregulation of marker genes for hepatic stellate cells in hepatic oval cells, such as desmin and GFAP. CONCLUSION: Except for the expression of ECM, the cultured hepatic oval cells could induce an increased expression of hepatic stellate cell markers by TGF-beta1 through an epithelial-mesenchymal transition process, which might indicate the contribution of hepatic oval cells to liver fibrosis.

C-kit inhibition by imatinib mesylate attenuates progenitor cell expansion and inhibits liver tumor formation in mice.

BACKGROUND & AIMS: Numerous studies have linked the proliferation of liver progenitor cells (LPCs) during chronic liver disease to the risk for development of hepatocellular carcinoma. Thus, selective inhibition of LPC growth during preneoplastic injury may prevent or delay the onset of liver cancer. Rats carrying a germ-line mutation in c-kit have an impaired LPC response to liver injury. Therefore, we hypothesized that the c-kit inhibitor imatinib mesylate (IM) would suppress LPC growth and, therefore, may exert antitumorigenic effects in the liver. METHODS: Expression of IM target proteins was examined in chronically injured rodent and human livers. The effect of IM was examined in vitro using LPC lines and in vivo in mice fed a choline-deficient, ethionine-supplemented (CDE) diet. Livers were examined following short-term (up to 1 month) or long-term (up to 14 months) feeding of CDE diet and drug treatments. RESULTS: C-kit was significantly up-regulated in chronic injury and expressed by LPCs. IM was antiproliferative to LPC lines, and knockdown of c-kit reduced this response. IM treatment inhibited the LPCs response and early fibrogenesis induced by a short-term CDE diet. On the longer term, IM treatment reduced the extent of fibrosis and significantly inhibited tumor formation. CONCLUSIONS: Tyrosine kinase inhibitors, such as IM, may be suited for the prevention of hepatocellular carcinoma in the setting of chronic liver injury via antiproliferative effects on c-kit-expressing LPCs.

Bone marrow cells play only a very minor role in chronic liver regeneration induced by a choline-deficient, ethionine-supplemented diet.

Liver progenitor (oval) cells have enormous potential in the treatment of patients with liver disease using a cell therapy approach, but their use is limited by their scarcity and the number of donor livers from which they can be derived. Bone marrow may be a suitable source. Previously the derivation of oval cells from bone marrow was examined in rodents using hepatotoxins and partial hepatectomy to create liver damage. These protocols induce oval cell proliferation; however, they do not produce the disease conditions that occur in humans. In this study we have used the choline-deficient, ethionine-supplemented (CDE) diet (which causes fatty liver) and viral hepatitis as models of chronic injury to evaluate the contribution of bone marrow cells to oval cells under conditions that closely mimic human liver disease pathophysiology. Following transplantation of lacZ-transgenic bone marrow cells into congenic mice, liver injury was induced and the movement of bone marrow cells to the liver monitored. Bone marrow-derived oval cells were observed in response to the CDE diet and viral injury but represented a minor fraction (0-1.6%) of the oval cell compartment, regardless of injury severity. In all situations only rare, individual bone marrow-derived oval cells were observed. We hypothesized that the bone marrow cells may replenish oval cells that are expended by protracted liver injury and regeneration; however, experiments involving a subsequent episode of chronic liver injury failed to induce proliferation of the bone marrow-derived oval cells that appeared as a result of the first episode. Bone marrow-derived hepatocytes were also observed in all injury models and controls at a frequency unrelated to that of oval cells. We conclude that during viral-and steatosis-induced liver disease the contribution of bone marrow cells to hepatocytes, either via oval cells or by independent mechanisms, is minimal and that the majority of oval cells responding to this injury are sourced from the liver.

Isolation, culture and immortalisation of hepatic oval cells from adult mice fed a choline-deficient, ethionine-supplemented diet.

Oval cells have great potential for use in cell therapy to treat liver disease, however this cannot be achieved until the factors which govern their proliferation and differentiation are better understood. We describe a method to establish primary cultures of murine oval cells, and the derivation of two novel lines from these. Primary cultures from the livers of wildtype or TAT-GRE lacZ transgenic mice subjected to a choline-deficient, ethionine-supplemented diet comprised up to 80% oval cells at day 7 based on A6 or CK19 staining. Cell lines were clonally derived, which underwent spontaneous immortalisation following prolonged maintenance in culture. Immunostaining and RT-PCR demonstrated they express hepatocytic and biliary markers and they were therefore termed "bipotential murine oval liver" (BMOL) cells. Under proliferating culture conditions, BMOL or BMOL-TAT cells abundantly expressed oval cell and biliary markers, whereas mature hepatocytic markers were upregulated when the growth conditions were changed to facilitate differentiation. Hepatic differentiation of BMOL-TAT cells could be traced by measuring the expression of their lacZ transgene, which is driven by a promoter element from tyrosine aminotransferase (TAT), a marker of adult hepatocytes. Interestingly, haematopoietic markers were upregulated in superconfluent cultures, indicating a possible multipotentiality. None of the cell lines grew in semi-solid agar, nor did they form tumours in nude mice, suggesting they are non-tumourigenic. These novel murine oval cell lines, together with a reliable method for isolation and culture of primary oval cells, will provide a useful tool for investigating the contribution of oval cells to liver regeneration.