Mechanism of postoperative liver failure after excessive hepatectomy investigated using a cDNA microarray

The multifaceted role of macrophages during acute liver injury

The liver is situated at the interface of the gut and circulation where it acts as a filter for blood-borne and gut-derived microbes and biological molecules, promoting tolerance of non-invasive antigens while driving immune responses against pathogenic ones. Liver resident immune cells such as Kupffer cells (KCs), a subset of macrophages, maintain homeostasis under physiological conditions. However, upon liver injury, these cells and others recruited from circulation participate in the response to injury and the repair of tissue damage. Such response is thus spatially and temporally regulated and implicates interconnected cells of immune and non-immune nature. This review will describe the hepatic immune environment during acute liver injury and the subsequent wound healing process. In its early stages, the wound healing immune response involves a necroinflammatory process characterized by partial depletion of resident KCs and lymphocytes and a significant infiltration of myeloid cells including monocyte-derived macrophages (MoMFs) complemented by a wave of pro-inflammatory mediators. The subsequent repair stage includes restoring KCs, initiating angiogenesis, renewing extracellular matrix and enhancing proliferation/activation of resident parenchymal and mesenchymal cells. This review will focus on the multifaceted role of hepatic macrophages, including KCs and MoMFs, and their spatial distribution and roles during acute liver injury.

Remifentanil upregulates hepatic IL-18 binding protein (IL-18BP) expression through transcriptional control

Interleukin (IL)-18 plays an important role in liver ischemia/reperfusion (I/R) injury. We have previously demonstrated that remifentanil protects against liver I/R injury by upregulating the hepatic expression of IL-18-binding protein (IL-18BP), a natural IL-18 inhibitor. The current study was performed to further clarify the effects of remifentanil on IL-18BP expression in the liver as well as investigate the underlying mechanisms. In Sprague-Dawley (SD) rats, we demonstrated that remifentanil significantly increased the expression of IL-18BP in normal rat liver tissue over a 24-h time period with maximal expression at 24 h after treatment. The upregulation of remifentanil on IL-18BP expression displayed similar trends in in vitro cellular studies, including mouse primary hepatocytes, normal human hepatocyte LO2, and mouse hepatoma cells Hep1-6. In LO2 cells, preexposure of the cells to remifentanil significantly inhibited IL-18-activated p65 NF-κB phosphorylation, and the inhibition was absent when the cells were transfected with IL-18BP siRNA, indicating the functional effects of IL-18BP induced by remifentanil. Pretreatment with actinomycin D abolished remifentanil-induced upregulation of IL-18BP mRNA, suggesting that the induction occurred at the transcriptional level. This was further supported by the luciferase reporter assay, which demonstrated that remifentanil treatment significantly increased transcription of the IL-18BP promoter. Both western blot analysis and ChIP assays showed that STAT1 and C/EBP β were activated by remifentanil. Furthermore, remifentanil failed to upregulate IL-18BP expression after silencing STAT1 or C/EBP β gene expression. These findings demonstrate that remifentanil could upregulate hepatic IL-18BP expression through transcriptional activation of the IL-18BP promoter, and STAT1 and C/EBP β are two key transcriptional factors involved in this process.

Visualization of Hepatocellular Regeneration in Mice After Partial Hepatectomy

BACKGROUND

Although hepatocellular regeneration is the cornerstone of liver homeostasis, current techniques for assessing such regeneration are limited. A method for visualizing the regeneration process would provide a means for advanced studies. Therefore, we examined the possibility of using fluorescence ubiquination-based cell cycle indicator (Fucci) mice for direct visualization of hepatocellular regeneration.

MATERIALS AND METHODS

We performed a two-thirds partial hepatectomy in conventional and Fucci mice. Fucci animals have orange Cdt1 expressed in the G₁ phase and green Geminin expressed in S/G₂/M phases. Regenerating livers were procured daily for 7 d. Immunohistochemical staining was performed for proliferative Ki67 and mitotic pHH3 serine 10 (pHH3) markers on formalin-fixed, paraffin-embedded tissue sections from conventional mice. The orange Cdt1 and green Geminin fluorescence indicative of the G₁ and S/G₂/M phases, respectively, were assessed in liver tissues, in vivo and ex vivo, with two-photon laser scanning microscopy.

RESULTS

Immunostaining with Ki67 and pHH3 revealed a typical profile of hepatocellular regeneration after hepatectomy in conventional mice, although immunostaining required more than a week to process. In contrast, hepatocellular regeneration could be visualized with two-photon microscopy within a few hours in regenerating livers of the Fucci mice. Only orange G₁ hepatocytes were seen in the baseline liver specimens; however, multiple bright green and yellow hepatocytes were seen 48 h after hepatectomy, indicating active hepatocytes in the S/G₂/M phases of the cell cycle.

CONCLUSIONS

Hepatocellular regeneration is readily visualized in regenerating livers of Fucci mice. The Fucci model is an exciting tool for advanced studies of hepatocellular and liver regeneration.

Remifentanil Ameliorates Liver Ischemia-Reperfusion Injury Through Inhibition of Interleukin-18 Signaling

BACKGROUND

Hepatic injury induced by ischemia-reperfusion (I/R) after transplantation or lobectomy is a major clinical problem. The potential benefit of remifentanil in these hepatic surgeries remains unknown. The current study investigated whether remifentanil protects the liver against I/R injury in a rat model and whether the underlying mechanism involves the modulation of interleukin (IL)-18 signaling.

METHODS

Male Sprague-Dawley rats were subjected to 45 minutes of partial hepatic ischemia followed by 6 hours of reperfusion. Then, they received an intravenous saline or remifentanil (0.4, 2, or 10 μg/kg per minute) infusion from 30 minutes before ischemia until the end of ischemia with or without previous administration of naloxone, a nonselective opioid receptor antagonist. Serum aminotransferase, hepatic morphology, and hepatic neutrophil infiltration were analyzed. The expression of hepatic IL-18; IL-18-binding protein (BP); and key cytokines downstream of IL-18 signaling were measured.

RESULTS

Remifentanil significantly decreased serum aminotransferase levels and profoundly attenuated the liver histologic damages. Liver I/R injury increased the expression of both hepatic IL-18 and IL-18BP. Although remifentanil pretreatment significantly decreased I/R-induced IL-18 expression, it further upregulated IL-18BP levels in liver tissues. The I/R-induced increases of hepatic interferon-γ, tumor necrosis factor-α and IL-1β expression, and neutrophil infiltration were also significantly reduced by remifentanil. Naloxone inhibited the remifentanil-induced downregulation of IL-18, but not the elevation of IL-18BP, and significantly attenuated its protective effects on liver I/R injury.

CONCLUSIONS

Remifentanil protects the liver against I/R injury. Modulating the hepatic IL-18/IL-18BP balance and inhibiting IL-18 signaling mediate, at least in part, the hepatoprotective effects of remifentanil.

mTOR-Dependent Suppression of Remnant Liver Regeneration in Liver Failure After Massive Liver Resection in Rats

BACKGROUND AND AIMS

Massive hepatectomy often leads to fatal liver failure because of a small remnant liver volume. The aim of this study was to investigate the potential mechanisms leading to liver failure.

METHODS

Sprague-Dawley rats had performed a sham operation, 85 % partial hepatectomy (PH) or 90 % PH, and all had free access to water with or without supplemented glucose. Liver function and survival were evaluated. Liver parenchymal injury was assessed by evaluating hepatic pathology, blood biochemistry, and apoptotic and necrotic alterations. The regeneration response was assessed by the weight gain of the remnant liver, hepatocyte proliferation markers, and regeneration-related molecules.

RESULTS

The 90 % hepatectomy resulted in a significantly lower survival rate and impaired liver function; however, no significant more serious liver parenchymal injuries were detected. TNF-α, HGF, myc and IL-6 were either similarly expressed or overexpressed; however, the increase in remnant liver weight, mitotic index, and the presence of Ki-67 and PCNA were significantly lower in the 90 %-hepatectomized rats. mTOR, p70S6K and 4EBP1 were not activated in the remnant liver after a 90 % hepatectomy as obviously as those after an 85 % hepatectomy, which was concomitant with the higher expression of phospho-AMPK and a lower intrahepatic ATP level. Glucose treatment significantly improved the survival rate of 90 %-hepatectomized rats.

CONCLUSIONS

Suppression of remnant liver regeneration was observed in the 90 % PH and contributed to fatal liver failure. This suppressed liver regenerative capacity was related to the inhibited activation of mTOR signaling.

Gene profile in the spleen under massive partial hepatectomy using complementary DNA microarray and pathway analysis

BACKGROUND AND AIM

In general, the spleen is one of the abdominal organs connected by the portal system, and a splenectomy improves hepatic functions in the settings of partial hepatectomy (Hx) for portal hypertensive cases or living donor liver transplantation with excessive portal vein flow. Those precise mechanisms remain still unclear; therefore, we investigated the DNA expression profile in the spleen after 90% Hx in rats using complementary DNA microarray and pathway analysis.

METHODS

Messenger RNAs (mRNAs) were prepared from three rat spleens at each time point (0, 3, and 6 h after 90% Hx). Using the gene chip, mRNA was hybridized to Affymetrix GeneChip Rat Genome 230 2.0 Array (Affymetrix®) and pathway analysis was done with Ingenuity Pathway Analysis (IPA®).

RESULTS

We determined the 3-h or 6-h/0-h ratio to assess the influence of Hx, and cut-off values were set at more than 2.0-fold or less than 1/2 (0.5)-fold. Chemokine activity-related genes including Cxcl1 (GRO1) and Cxcl2 (MIP-2) related pathway were upregulated in the spleen. Also, immediate early response genes including early growth response-1 (EGR1), FBJ murine osteosarcoma (FOS) and activating transcription factor 3 (ATF3) related pathway were upregulated in the spleen.

CONCLUSIONS

We concluded that in the spleen the expression of numerous inflammatory-related genes would occur after 90% Hx. The spleen could take a harmful role and provide a negative impact during post Hx phase due to the induction of chemokine and transcription factors including GRO1 and EGR1.

Effects of splenectomy on hepatic gene expression profiles after massive hepatectomy in rats

BACKGROUND AND AIM

Possible spleno-hepatic relationships affected by hepatectomy still remained unclear. We have previously reported that splenectomy may ameliorate liver injuries and promote appropriate liver regeneration after massive hepatectomy. Therefore, we investigated the effects of splenectomy on the DNA expression profile in the liver after massive hepatectomy in rats.

METHODS

Rats were divided into the following two groups: 90% hepatectomy (Hx group) and 90% hepatectomy with splenectomy (Hx + Sp group). Rats were sacrificed 3 and 6 h after surgery, and mRNA from liver tissue was isolated and hybridized to Affymetrix GeneChip Rat Genome 230 2.0 Array (Affymetrix, Santa Clara, CA, USA) and a pathway analysis was done with Ingenuity Pathway Analysis (Ingenuity Systems, Mountain View, CA, USA).

RESULTS

We determined the Hx + Sp/Hx ratio to assess the influence of splenectomy, and cut-off values were set at more than 2.0-fold or less than 1/2 (0.5)-fold. Immediate early response gene including early growth response-1 and FBJ murine osteosarcoma-related pathways were markedly downregulated by splenectomy. In contrast, heme oxygenase-1 gene-related pathway was upregulated by splenectomy.

CONCLUSIONS

Splenectomy provided the protective effects for liver failure and promoted liver regeneration, possibly owing to the downregulation of immediate early response genes and upregulation of the heat shock protein, heme oxygenase-1.

Hypothermia predicts hepatic failure after extensive hepatectomy in mice

AIM

To investigate the effect of hypothermia on the function of the liver remnant (LR) after extended hepatectomy.

METHODS

We performed a 75% partial hepatectomy (PH) in male C57BL/6J mice. Body temperature was measured with a rectal probe. The study mice were prospectively grouped as hypothermic (HT) or normothermic (NT) if their body temperature was < 34 °C vs ≥ 34 °C, respectively. Blood and liver samples were obtained at 24 and 48 h after 75% PH. Various factors during and after 75% PH were compared at each time point and the most important factor for a good outcome after 75% PH was determined.

RESULTS

At 24 and 48 h after 75% PH, LR weight was decreased in HT mice compared with that in NT mice and the assay results in the HT mice were consistent with liver failure. NT mice had normal liver regeneration. Each intra- and post-operative factor which showed statistical significance in univariate analysis was evaluated by multivariate analysis. The most important factor for a good outcome after 75% PH was body temperature at both 24 and 48 h after surgery.

CONCLUSION

Hypothermia after an extensive hepatectomy predicts impending liver failure and may be a useful clinical marker for early detection of liver failure after extended hepatectomy.

Co-administration of prostaglandin E1 with somatostatin attenuates acute liver damage after massive hepatectomy in rats via inhibition of inflammatory responses, apoptosis and endoplasmic reticulum stress

Acute liver damage is considered to be the major cause of mortality after massive hepatectomy. Prostaglandin E1 (PGE1) and somatostatin (SST) have been shown to protect against hepatic injury of rats after partial hepatectomy. However, the precise mechanisms remain largely unknown. In this study, we examined the effects of PGE1, SST and the combination of these two drugs on acute liver damage of rats after 90% hepatectomy. We found that animal survival was improved when pretreated with PGE1 and SST. Portal venous pressure (PVP), serum alanine aminotransferase (ALT) and aspartate aminotransaminase (AST), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were all reduced after administration of PGE1 and SST. In addition, apoptosis was inhibited via upregulation of Bcl-2 and downregulation of Bax and caspase-3 in drug treatment groups. Furthermore, pretreatment with PGE1 and SST alleviated endoplasmic reticulum (ER) stress by induction of heat shock protein 70 (HSP70) and glucose-regulated protein 78 (GRP78), but suppression of transcription factor C/EBP homologous protein (CHOP). Our data suggest that administration of PGE1 and SST, particularly in combination, may prevent acute liver damage of rats after massive hepatectomy by inhibiting inflammatory responses, apoptosis and ER stress.

The effects of Crataegus aronia var. dentata Browicz extract on biochemical indices and apoptosis in partially hepatectomized liver in rats

Crataegus species have been widely used in herbal medicine, especially for the hearth diseases. In the present study, the effect of Crataegus aronia var. dentata Browicz extract on partially hepatectomized rats was investigated with biochemical and TUNEL apoptosis assays. The extracts of the plant at the concentrations of 0.5 and 1 ml/100 g body weight/day were administered orally to the two experimental groups including partially hepatectomized rats for 42 days. At the end of the experimental period, animals were sacrificed, blood was collected for the assessment of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyltransferase (GGT), and the liver tissue was used for TUNEL assay. In biochemical assay, it was found a significant decrease in the levels of serum ALT and AST in the experimental groups. On the other hand, the plant extract did not cause any significant changes in the level of GGT in these groups. In apoptosis assay, TUNEL positive hepatocytes could not be detected in both experimental groups. The present findings can suggest that Crataegus aronia var. dentata Browicz extract can decrease the levels of serum ALT and AST and play a role in apoptosis of hepatocytes in the liver of partially hepatectomized rats. However, further studies are required to confirm the effects of the plant extract on hepatoprotection and apoptosis in the regenerating liver after partial hepatectomy in animal models.

Olprinone attenuates excessive shear stress through up-regulation of endothelial nitric oxide synthase in a rat excessive hepatectomy model

After extended hepatectomy, excessive shear stress in the remnant liver causes postoperative liver failure. Olprinone (OLP), a selective phosphodiesterase inhibitor, has been reported to improve microcirculation and attenuate inflammation. The aim of this study was to investigate the effects of OLP on shear stress in rats with an excessive hepatectomy (EHx) model. In this study, EHx comprised 90% hepatectomy with ligation of the left and right Glisson's sheaths in Lewis rats. OLP or saline was intraperitoneally administered with an osmotic pump 48 hours before EHx. To evaluate the shear stress, we measured the portal vein (PV) pressure. We also assessed sinusoidal endothelial cell injury by immunohistochemistry and electron microscopy. Furthermore, we assessed apoptosis in the liver with the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method. Treatment with OLP up-regulated hepatic endothelial nitric oxide synthase (eNOS) expression. The increase in the PV pressure due to Glisson's sheath ligation was attenuated in OLP-treated rats during a 30-minute period after ligation. Treatment with OLP preserved sinusoidal endothelial cells and reduced apoptosis in the remnant liver. The probability of survival in the OLP-treated rats was significantly better than that in the controls (33.3% versus 13.3%). Furthermore, the postoperative eNOS activity in the OLP-treated rats was higher than that in the controls. The administration of Nω-nitro-l-arginine methyl ester to OLP-treated rats eliminated the effects of OLP on PV pressure and survival after EHx. Therefore, we concluded that OLP attenuates excessive shear stress through the up-regulation of eNOS and improves the survival rate after EHx.

Analysis of gene expression profiles in fatal hepatic failure after hepatectomy in mice

BACKGROUND

We developed 90%-hepatectomized mice that were the fatal model, and analyzed the gene expression profiles using a complementary DNA (cDNA) microarray to clarify the mechanisms of hepatic failure after excessive hepatectomy.

MATERIALS AND METHODS

Ribonucleic acid (RNA)s from the remnant hepatic tissue of 70%- and 90%-hepatectomized mice were labeled with fluorescent dyes, and hybridized to the Riken set of 39,168 full-length enriched mouse cDNA arrays. The gene expression profiles in 90%- and 70%-hepatectomized mice were analyzed by scanning date for fluorescent dye signals.

RESULTS

The down-regulated genes in 90%-hepatectomized mice were genes activating extracellular matrix (ECM) remodeling (matrix metalloproteinases, laminins, and integrins), genes related to cytokines (tumor necrosis factor α converting enzyme, and Janus kinase 3) that were related to the priming, genes related to growth factor (heparin-binding epidermal growth factor-like growth factor and others), and genes promoting cell cycle progression (cyclin D1, D2, and E2) that were related to the progression of hepatocytes. The up-regulated genes were genes inhibiting ECM remodeling [plasminogen activator inhibitors (PAIs)].

CONCLUSIONS

Hepatic failure after hepatectomy was characterized by the inhibition of hepatic cell cycle priming and progression both induced by ECM remodeling in liver regeneration. Particularly, the overexpression of PAIs was thought to play the major role in the first step of inhibition of ECM remodeling.

Artificial cell microencapsulated stem cells in regenerative medicine, tissue engineering and cell therapy

Adult stem cells, especially isolated from bone marrow, have been extensively investigated in recent years. Studies focus on their multiple plasticity oftransdifferentiating into various cell lineages and on their potential in cellular therapy in regenerative medicine. In many cases, there is the need for tissue engineering manipulation. Among the different approaches of stem cells tissue engineering, microencapsulation can immobilize stem cells to provide a favorable microenvironment for stem cells survival and functioning. Furthermore, microencapsulated stem cells are immunoisolated after transplantation. We show that one intraperitoneal injection of microencapsulated bone marrow stem cells can prolong the survival of liver failure rat models with 90% of the liver removed surgically. In addition to transdifferentiation, bone marrow stem cells can act as feeder cells. For example, when coencapsulated with hepatocytes, stem cells can increase the viability and function of the hepatocytes in vitro and in vivo.

Improved survival of fulminant liver failure by transplantation of microencapsulated cryopreserved porcine hepatocytes in mice

The aim of this study was to establish hepatocyte isolation in pigs, and to evaluate function of isolated hepatocytes after encapsulation, cryopreservation, and transplantation (Tx) in a mouse model of fulminant liver failure (FLF). After isolation, porcine hepatocytes were microencapsulated with alginate-poly-L-Lysine-alginate membranes and cryopreserved. In vitro, albumin production of free and encapsulated hepatocytes were measured by enzyme linked-immunoadsorbent assay. In vivo, encapsulated hepatocytes were transplanted into different groups of mice with FLF and the following experimental groups were performed: group 1, Tx of empty capsules; group 2, Tx of free primary porcine hepatocytes; group 3, Tx of fresh encapsulated porcine hepatocytes; group 4, Tx of cryopreserved encapsulated porcine hepatocytes. In vitro, fresh or cryopreserved encapsulated porcine hepatocytes showed a continuous decreasing metabolic function over 1 week (albumin and urea synthesis, drug catabolism). In vivo, groups 1 and 2 showed similar survival (18% and 25%, respectively, p > 0.05). In groups 3 and 4, Tx of fresh or cryopreserved encapsulated porcine hepatocytes significantly increased survival rate to 75% and 68%, respectively (p < 0.05). Primary porcine hepatocytes maintained metabolic functions after encapsulation and cryopreservation. In mice with FLF, Tx of encapsulated xenogeneic hepatocytes significantly improved survival. These results indicate that porcine hepatocytes can successfully be isolated, encapsulated, stored using cryopreservation, and transplanted into xenogeneic recipients with liver failure and sustain liver metabolic functions.

Impaired liver regeneration with humoral and genetic disturbances in urinary trypsin inhibitor-deficient mice

BACKGROUND/AIMS

Urinary trypsin inhibitor (UTI) is an innate anti-inflammatory regulator. It can block the release of inflammatory factors, prevent the cascade reaction of cytokines and inhibit excessive activation of leukocytes. Liver regeneration (LR) is a dynamic molecular phenomenon without inflammation. Many cytokines, including tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), have been implicated in regulating LR. However, the role of UTI in LR is totally unknown. The aim of this study was to elucidate the role of UTI in LR using genetically UTI-deficient mice.

METHODS

We performed 68% hepatectomy, comparing UTI (-/-) and UTI (+/+) mice. Recovery of liver weight was recorded and we calculated labelling indices after 5-bromo-2'-deoxyuridine (BrdU) immunohistochemistry. A DNA microarray was used to examine gene expression followed by real-time polymerase chain reaction. Serum IL-6, IL-10, monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1beta (MIP-1beta) were measured.

RESULTS

LR in UTI (-/-) mice was delayed at 36 h after hepatectomy, at which time the DNA profile was different. One hundred and fourteen genes were upregulated and 100 genes were downregulated in UTI (-/-) mice at 36 h after hepatectomy among the 21, 977 mRNAs examined. Furthermore, serum IL-6, IL-10, MCP-1 and MIP-1beta levels at 36 h after hepatectomy in the UTI (-/-) mice were significantly higher than in the UTI (+/+) mice.

CONCLUSION

UTI appears to important cytokine and chemokine regulation in normal liver regeneration.

An overview of animal models for investigating the pathogenesis and therapeutic strategies in acute hepatic failure

Acute hepatic failure (AHF) is a severe liver injury accompanied by hepatic encephalopathy which causes multiorgan failure with an extremely high mortality rate, even if intensive care is provided. Management of severe AHF continues to be one of the most challenging problems in clinical medicine. Liver transplantation has been shown to be the most effective therapy, but the procedure is limited by shortage of donor organs. Although a number of clinical trials testing different liver assist devices are under way, these systems alone have no significant effect on patient survival and are only regarded as a useful approach to bridge patients with AHF to liver transplantation. As a result, reproducible experimental animal models resembling the clinical conditions are still needed. The three main approaches used to create an animal model for AHF are: surgical procedures, toxic liver injury and infective procedures. Most common models are based on surgical techniques (total/partial hepatectomy, complete/transient devascularization) or the use of hepatotoxic drugs (acetaminophen, galactosamine, thioacetamide, and others), and very few satisfactory viral models are available. We have recently developed a viral model of AHF by means of the inoculation of rabbits with the virus of rabbit hemorrhagic disease. This model displays biochemical and histological characteristics, and clinical features that resemble those in human AHF. In the present article an overview is given of the most widely used animal models of AHF, and their main advantages and disadvantages are reviewed.

Prostaglandin E1 prevents liver failure after excessive hepatectomy in the rat by up-regulating Cyclin C, Cyclin D1, and Bclxl

Prostaglandin E1 (PGE1) has wide-ranging effects on cytoprotection and may play a role in preventing liver failure following excessive hepatectomy. We examined the effect of PGE1 on hepatocyte apoptosis and liver regeneration after 95% hepatectomy in a rat model. PGE1 or vehicle was intravenously administered 30 minutes before and during hepatectomy. The extent of hepatocyte injury was evaluated by serum alanine aminotransferase and aspartate aminotransferase levels. To evaluate hepatocyte apoptosis and liver regeneration, terminal deoxynucleotidyl transferase dUTP nick end labeling staining and Ki67 labeling were performed. The expression levels of Bcl-xL, Bcl-2, Bax, Cyclin C, Cyclin D1, Cyclin E, p21, transforming growth factor-beta, plasminogen activator inhibitor-1, and glyceraldehyde-2-phosphate dehydrogenase mRNA were also examined by reverse transcription-polymerase chain reaction. Survival was improved in the PGE1 group (26.6%), whereas all rats in the vehicle group died within 60 hours. PGE1 significantly suppressed the release of alanine aminotransferase and aspartate aminotransferase at 12 hours postoperatively. Pretreatment with PGE1 significantly increased the Ki67-positive cell count and decreased the terminal deoxynucleotidyl transferase dUTP nick end labeling positive cell count after hepatectomy, and also significantly increased the expression levels of Bcl-xL, Cyclin C, and Cyclin D1. Our results suggest that pretreatment with PGE1 may increase survival following hepatectomy by salvaging the remaining liver tissue, which it does by inhibiting apoptosis and stimulating hepatocyte proliferation.

Beneficial effects of splenectomy on massive hepatectomy model in rats

AIM

Possible spleno-hepatic relationships during hepatectomy remain unclear. The purpose of this study was to investigate the impact of splenectomy during massive hepatectomy in rats.

METHODS

Rats were divided into the following two groups: 90% hepatectomy (Hx group), hepatectomy with splenectomy (Hx+Sp group). The following parameters were evaluated; survival rate, biochemical parameters, quantitative RT-PCR for hemeoxygenase-1 (HO-1) and tumor necrosing factor alpha (TNFalpha), immunohistochemical staining for HO-1, proliferating cell nuclear antigen labeling index and liver weights.

RESULTS

The survival rate after massive hepatectomy significantly improved in Hx+Sp group as well as serum biochemical parameters, compared with Hx group (P < 0.05). HO-1 positive hepatocytes and its mRNA expression significantly increased and TNFalpha mRNA expression significantly decreased in Hx+Sp group compared with Hx group (P < 0.05). Moreover, liver regeneration was significantly accelerated at 48 and 72 h after hepatectomy in Hx+Sp group.

CONCLUSIONS

Splenectomy had beneficial effects on massive hepatectomy by ameliorating liver injuries and promoting preferable liver regeneration.

Unique early gene expression patterns in human adult-to-adult living donor liver grafts compared to deceased donor grafts

Because of inherent differences between deceased donor (DD) and living donor (LD) liver grafts, we hypothesize that the molecular signatures will be unique, correlating with specific biologic pathways and clinical patterns. Microarray profiles of 63 biopsies in 13 DD and 8 LD liver grafts done at serial time points (procurement, backbench and postreperfusion)were compared between groups using class comparisons, network and biological function analyses. Specific genes were validated by quantitative PCR and immunopathology. Clinical findings were also compared. Following reperfusion, 579 genes in DD grafts and 1324 genes in LDs were differentially expressed (p < 0.005). Many upregulated LD genes were related to regeneration, biosynthesis and cell cycle, and a large number of downregulated genes were linked to hepatic metabolism and energy pathways correlating with posttransplant clinical laboratory findings. There was significant upregulation of inflammatory/immune genes in both DD and LD, each with a distinct pattern. Gene expression patterns of select genes associated with inflammation and regeneration in LD and DD grafts correlated with protein expression. Unique patterns of early gene expression are seen in LD and DD liver grafts, correlating with protein expression and clinical results, demonstrating distinct inflammatory profiles and significant downregulation of metabolic pathways in LD grafts.

Role of nitric oxide synthesized by nitric oxide synthase 2 in liver regeneration

BACKGROUND/AIMS

Nitric oxide synthase 2 (NOS2) is expressed during liver regeneration after a partial hepatectomy (PHx); NOS2 subsequently synthesizes nitric oxide (NO). However, the role of NOS2-synthesized NO in post-PHx liver regeneration remains unclear. We investigated the role of NOS2-synthesized NO in liver regeneration.

METHODS

NOS2 knockout (NOS2-KO) mice and control mice were subjected to PHx. Liver mass recovery and serum alanine aminotransferase (ALT) levels were then evaluated. The expressions of Ki-67 and single-strand DNA were also evaluated in remnant liver specimens. Differences in the gene expression profiles of the two groups of remnant liver specimens were analysed using a microarray and were validated using a reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

In NOS2-KO mice, liver regeneration was delayed and apoptosis and serum ALT levels were higher than the levels in the control mice. A microarray study and RT-PCR revealed that heat shock protein 70 family (HSP70 family), haeme oxygenase 1 (Hmox1), neuropilin 1 (Nrp1) and epidermal growth factor receptor (EGFR) were downregulated in NOS2-KO mice.

CONCLUSIONS

NOS2-synthesized NO may improve hepatocyte viability through the induction of the HSP70 family and Hmox1 and may sensitize the remnant liver to growth factors through the induction of Nrp1 and EGFR post-PHx.

Liver failure after partial hepatic resection: definition, pathophysiology, risk factors and treatment

Liver failure is a dreaded and often fatal complication that sometimes follows a partial hepatic resection. This article reviews the definition, incidence, pathogenesis, risk factors, risk assessment, prevention, clinical features and treatment of post-resectional liver failure (PLF). A systematic, computerized search was performed using key words related to 'partial hepatic resection' and 'liver failure' to review most relevant literature about PLF published in the last 20 years. The reported incidence of PLF ranges between 0.7 and 9.1%. An inadequate quantity or quality of residual liver mass are key events in its pathogenesis. Major risk factors are the presence of comorbid conditions, pre-existent liver disease and small remnant liver volume (RLV). It is essential to identify these risk factors during the pre-operative assessment that includes evaluation of liver volume, anatomy and function. Preventive measures should be applied whenever possible as curative treatment options for PLF are limited. These preventive measures intend to increase RLV and protect remnant liver function. Management principles focus on support of end-organ and liver function. Further research is needed to elucidate the exact pathogenesis of PLF and to develop and validate adequate treatment options.

Role of bile in intestinal motility after massive liver resection in conscious rats

AIM

To investigate the effect of 90% partial hepatectomy (90% PHx) and the involvement of bile on ileal motility in conscious rats.

METHODS

Two strain gauge force transducers were chronically implanted in the ileum of each of 20 rats. The rats were divided into four groups, three of which underwent 90% PHx. The experiments were performed with the rats in a conscious, fasted state. After ileal motility was recorded, bile or saline was perfused into the duodenum of each rat in two of the 90% PHx groups. The effects of the perfusion on ileal motility were observed and recorded using the motility index (MI), defined as the area under the contraction cues after surgery and expressed as the ratio to the MI in the preoperational motility. The time of the first passage of stool after surgery was recorded.

RESULTS

A typical migrating motor complex (MMC) pattern was observed in normal fasted rats. Increased MMC cycle lengths and a decreased MI at 1 day and 3 days after 90% PHx were observed. The MMC after 90% PHx was characterized by an increased duration of Phase 2-like activity. The MMC cycle length, the MI, and the time of the first passage of stool after 90% PHx were improved by perfusion of bile into the duodenum through the biliary cannula but were not influenced by perfusion of saline into the duodenum through the biliary cannula.

CONCLUSION

The MMC cycle length and the MI were inhibited after 90% PHx, with the involvement of decreased bile flow into the gastrointestinal tract by liver resection.

Beneficial effects of hyperbaric oxygen pretreatment on massive hepatectomy model in rats

BACKGROUND

The purpose of this study was to investigate the impact of hyperbaric oxygen (HBO) pretreatment in massive hepatectomy model, a surrogate model of small-for-size graft, using rats.

METHODS

(Experiment I) Rats were divided into the following four groups: HBO (-), HBO-1D (day), HBO-3D, and HBO-5D. Samples were taken after the completion of HBO pretreatment, and the following parameters were evaluated: reverse transcription polymerase chain reaction and immunohistochemical staining for HSP 70 and HO-1; biochemical parameters; and liver weight to body weight ratio (Lw/Bw ratio). (Experiment II) Rats were divided into four groups as follows; 70% hepatectomy (Hx), 70% Hx-HBO, 90% Hx, and 90% Hx-HBO group. Samples were taken 12, 24, 48, and 72 hr after hepatectomy and the following parameters were investigated: biochemical analysis; Lw/Bw ratio; PCNA labeling index; and survival.

RESULTS

(Experiment I) The expression of HSP70 mRNA was significantly increased in the HBO-3D group compared with the HBO (-) group (P<0.05). HSP70- and HO-1-positive hepatocytes were significantly increased in the HBO-3D group compared with the HBO (-) group (P<0.05). (Experiment II) Transaminases were significantly decreased in both 70% and 90% Hx-HBO groups compared with Hx alone group (P<0.05). The Lw/Bw ratio and PCNA labeling index of the 90% Hx-HBO group were significantly increased compared with the 90% Hx group, 24, 48 and 72 hr after hepatectomy (P<0.05). The survival rate in the 90% Hx-HBO group was significantly higher than that in the 90% Hx group (P=0.01).

CONCLUSIONS

HBO pretreatment had beneficial effects in a massive hepatectomy model in rats via the induction of HSP70 and HO-1.

Gene expression during liver regeneration after partial hepatectomy in mice lacking type 1 tumor necrosis factor receptor

BACKGROUND

To investigate the function of tumor necrosis factor-alpha (TNF-alpha) during hepatocyte proliferation, we studied liver regeneration following partial hepatectomy in mice lacking type 1 TNF receptor (TNFR-1).

MATERIALS AND METHODS

TNFR-1 knockout (KO) and wild-type mice were subjected to partial (two-thirds) hepatectomy. Liver regeneration was evaluated by assessing liver weights and Ki67 immunohistochemistry. Riken complementary DNA microarray analysis was performed for liver samples from mice undergoing partial hepatectomy to better compare different mouse partial hepatectomy models (TNFR-1 KO mice, KO group; and wild-type mice, W group).

RESULTS

Liver weight was regained after 14 days in the KO group, and after 7 days in the W group. Genes including lipopolysaccharide, toll-like receptor 4 precursor, mitogen-activated protein kinase kinase kinase 4, mitogen-activated protein kinase kinase kinase kinase 4, and mitogen-activated protein kinase 8-interacting protein were up-regulated in the KO group. As for the cell-cycle-regulated genes, the levels of cyclin D1, nuclear factor-kappa B light chain, and TNF receptor super family membrane 1a were down-regulated in the KO group. Microarray analysis showed decreased activities of the hexokinase- and phospho-fructokinase-related glycolytic pathways in the KO group.

CONCLUSIONS

These results contribute to the better understanding of the mechanisms of liver regeneration after partial hepatectomy in TNFR-1 KO mice.

Improvement of the survival rate after rat massive hepatectomy due to the reduction of apoptosis by caspase inhibitor

BACKGROUND AND AIM

Acute liver failure after massive hepatectomy is caused by both necrosis and apoptosis in the remnant liver. We investigate the protective effect of the caspase inhibitor on apoptosis after massive hepatectomy in rats.

METHODS

Benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (ZVAD-fmk) is a general inhibitor of the caspase. Male Wister rats weighing 200-300 g were divided into three groups: 90Hx group undergoing 90% hepatectomy, 95Hx group undergoing 95% hepatectomy, 95Hx + ZVAD group undergoing 95% hepatectomy and administration of ZVAD-fmk. The 7-day survival rate was studied, and the rats were sacrificed at the 1, 2, 3, 5, and 7th day after hepatectomy. The remnant liver tissues were stained with hematoxylin-eosin, and with proliferating cell nuclear antigen (PCNA) for evaluation of liver regeneration, and with TdT-mediated dUTP-biotin nick end labeling (TUNEL) and in situ oligo ligation method (ISOL) for evaluation of apoptosis.

RESULTS

The 7-day survival rates were 100%, 0%, and 30%, in the 90Hx, 95Hx, and 95Hx + ZVAD groups, respectively. There was no significant difference in PCNA labeling index (LI) between the 95Hx and 95Hx + ZVAD groups. TUNEL and ISOL LI of 95Hx + ZVAD group were significantly lower than those of 95Hx group. Fatal liver failure after massive hepatectomy was characterized by more apoptosis and less mitosis of hepatocytes. ZVAD-fmk could significantly attenuate apoptosis of hepatocytes in the remnant liver and improve the survival rate after 95% hepatectomy in rats.

CONCLUSION

Caspase inhibitors such as ZVAD-fmk may provide a new adjuvant therapy to treat liver failure after massive hepatectomy.

Adult rat hepatic bipotent progenitor cells remain dormant even after extensive hepatectomy

S It remains unknown whether the normal adult liver contains bipotent stem/progenitor cells, and if it does, then what are the circumstances under which they proliferate. The aim of this study was to clarify whether the normal adult liver contains hepatic stem/progenitor cells, and if it does, will they be activated by extensive hepatectomy? Adult rat liver cells were isolated and cultured at a low-density, and the colony-forming assay was performed to evaluate the cell proliferative capacity. Immunocytochemistry and reverse transcription-polymerase chain reaction were used to investigate the multilineage differentiation capability. The rate of colony formation by cells from the normal liver and those from the regenerating liver after partial hepatectomy (PH) were compared to determine whether progenitor cell proliferation might be activated by PH. Only a few epithelial colonies (0.043+/-0.009% of nonparenchymal cells) continued to proliferate for more than 1 month. Reverse transcription-polymerase chain reaction and immnocytochemistry showed that these progenitor colonies expressed both hepatocyte and cholangiocyte markers. The proportion of progenitor cells that formed bipotential colonies did not differ significantly between the cells obtained from the normal and PH livers. Adult normal liver contains bipotent hepatic progenitor cells, but they are scarcely activated even after extensive hepatectomy.

PAI-1 plays an important role in liver failure after excessive hepatectomy in the rat

BACKGROUND/AIMS

Well-organized turnover of the extracellular matrix is important in liver regeneration, which is regulated by the plasminogen activating system. The aim of this study was to investigate the role of plasminogen activator inhibitor-1 (PAI-1) after excessive hepatectomy and to ascertain whether angiotensin-converting enzyme (ACE) inhibitors, which are PAI-1 inhibitors as well, successfully improve the survival rate of rats that have undergone 95% partial hepatectomy (PHx).

METHODS

Using liver tissues sampled after 90% or 95% PHx, the expression of PAI-1 mRNA was evaluated using reverse transcription polymerase chain reaction. Hepatic PAI-1 protein and urokinase-type plasminogen activator (uPA) levels were determined by enzyme-linked immunosorbent assay. Survival study and cytodynamic analysis by 5-bromo-2'-deoxyuridine staining were performed to evaluate the effects of ACE inhibition.

RESULTS

The levels of PAI-1 mRNA and hepatic PAI-1 protein in the 95% PHx group peaked and were then maintained. By contrast, the uPA level fell relative to the 90% PHx group. Additionally, the hepatic PAI-1 protein level decreased and the survival rate improved in the 95% PHx rats that had undergone ACE inhibition.

CONCLUSIONS

Our experimental results suggest that PAI-1 plays a role in the occurrence of liver failure after excessive hepatectomy via accelerated maturation of pro-uPA and fibrinolytic factors. These are potential molecular therapeutic targets for liver failure after excessive hepatectomy.

Prostaglandin E1 improves survival rate after 95% hepatectomy in rats

BACKGROUND/AIM

Prostaglandin E1 (PGE1) has a wide-ranging effect on cytoprotection. Overproduction of heat shock protein 70 (HSP70) in the liver protects hepatocytes under various pathologic conditions. In this study, we examined the effect of a nontoxic HSP-inducer, PGE1, on acute liver failure after 95% hepatectomy in rats.

METHODS

PGE1 or vehicle was intravenously administered to rats 30 min before and during hepatectomy.

RESULTS

Nine of 30 rats pretreated with PGE1 survived, whereas all 20 rats pretreated with vehicle died within 96 h after operation. During the 24-h postoperative period, PGE1 significantly suppressed the release of alanine aminotransferase and elevation of hyaluronic acid. Histological examination showed that the vacuolized hepatocytes and round hepatocytes with pyknotic nuclei are frequently seen in rats pretreated with vehicle, whereas active regeneration is seen in rats pretreated with PGE1. During the first 24 h after surgery, HSP70 induction was absent in the residual livers of vehicle-treated rats. In contrast, PGE1 stimulated the HSP accumulation within 24 h, and viable hepatocytes contained abundant HSP70 in their nuclei.

CONCLUSION

Our results suggest that PGE1 may prevent acute liver failure after massive hepatectomy, at least in part, by enhancing HSP70 production in the residual liver.

Akt-mediated liver growth promotes induction of cyclin E through a novel translational mechanism and a p21-mediated cell cycle arrest

The control of hepatocyte growth is relevant to the processes of liver regeneration, development, metabolic homeostasis, and cancer. A key component of growth control is the protein kinase Akt, which acts downstream of mitogens and nutrients to affect protein translation and cell cycle progression. In this study, we found that transient transfection of activated Akt triggered a 3-4-fold increase in liver size within days but only minimal hepatocyte proliferation. Akt-induced liver growth was associated with marked up-regulation of cyclin E but not cyclin D1. Analysis of liver polyribosomes demonstrated that the post-transcriptional induction of cyclin E was associated with increased translational efficiency of this mRNA, suggesting that cell growth promotes expression of this protein through a translational mechanism that is distinct from the cyclin D-E2F pathway. Treatment of Akt-transfected mice with rapamycin only partially inhibited liver growth and did not prevent the induction of cyclin E protein, indicating that target of rapamycin activity is not necessary for this response. In the enlarged livers, cyclin E-Cdk2 complexes were present in high abundance but were inactive due to increased binding of p21 to these complexes. Akt transfection of p21(-/-) mice promoted liver growth, activation of Cdk2, and enhanced hepatocyte proliferation. In conclusion, growth promotes cyclin E expression through a novel translational mechanism in the liver, suggesting a new link between cell growth and the cell cycle machinery. Furthermore, p21 suppresses proliferation in the overgrown livers and may play a role in preventing cell cycle progression in response to organ size homeostatic mechanisms.

Type-2 dominant cytokine gene expression following hepatic surgery

BACKGROUND/PURPOSE

Hemorrhage and ischemic liver injuries associated with hepatic resection are thought to play a role in postoperative complications, possibly through altered cytokine production. The current study was performed to investigate the effects of hepatectomy on cytokine gene expression.

METHODS

We collected blood preoperatively, at completion of operation, and on postoperative days 1 and 5 from ten patients undergoing hepatic resection. The peripheral blood mononuclear cells were evaluated with real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) for gene expression of interleukin-10 (IL-10), proinflammatory cytokines (interferon-gamma [IFNgamma], IL-15, tumor necrosis factor alpha [TNFalpha], and chemokines regulated on activation, normal T expressed and secreted [RANTES], macrophage inflammatory protein 1 alpha [MIP-1alpha], [MIP-1beta]). Wilcoxon Rank and paired t-tests were used for statistical analysis.

RESULTS

Immediately following hepatectomy there was a significant (31.4 +/- 60.5-fold; P < 0.05) increase in IL-10 gene expression that was sustained until the first postoperative day. In contrast, there was a significant downregulation (38 +/- 71 eight fold lower than preoperative; P < 0.05) of IFNgamma gene expression on day 1. By postoperative day 5, the changes in gene transcript levels of both IL-10 and IFNgamma had returned to the preoperative baselines. This contrasting change in IL-10 and IFNgamma gene expression in response to hepatic resection was statistically significant (P = 0.02).

CONCLUSIONS

Hepatectomy elicits an imbalance towards the immunosuppressive type-2 cytokine profile in the early postoperative period. Measurement of cytokine gene transcripts following hepatic resection may have predictive value for clinical outcome, and deserves further study.

Marginal hepatectomy in the rat: from anatomy to surgery

OBJECTIVE

Based on the 3-dimensional visualization of vascular supply and drainage, a vessel-oriented resection technique was optimized. The new surgical technique was used to determine the maximal reduction in liver mass enabling a 50% 1-week survival rate.

BACKGROUND DATA

Determination of the minimal liver mass is necessary in clinical as well as in experimental liver surgery. In rats, survival seems to depend on the surgical technique applied. Extended hepatectomy with removal of 90% of the liver mass was long regarded as a lethal model. Introduction of a vessel-oriented approach enabled long-term survival in this model.

METHODS

The lobar and vascular anatomy of rat livers was visualized by plastination of the whole organ, respectively, by corrosion casts of the portal vein, hepatic artery and liver veins. The three-dimensional models were used to extract the underlying anatomic structure. In 90% partial hepatectomy, the liver parenchyma was clamped close to the base of the respective liver lobes (left lateral, median and right, liver lobe). Piercing sutures were placed through the liver parenchyma, so that the stem of portal vein and the accompanying hepatic artery but also the hepatic vein were included.

RESULTS

A 1-week survival rate of 100% was achieved after 90% hepatectomy. Extending the procedure to 95% resection by additional removal of the upper caudate lobe led to a 1-week survival rate of 66%; 97% partial hepatectomy, accomplished by additional resection of the lower caudate lobe only leaving the paracaval parts of the liver behind, resulted in 100% lethality within 4 days.

CONCLUSIONS

Using a anatomically based, vessel-oriented, parenchyma-preserving surgical technique in 95% liver resections led to long-term survival. This represents the maximal reduction of liver mass compatible with survival.

A good model of hepatic failure after excessive hepatectomy in mice

AIMS

This study was intended to establish in mice: 1) a safety limit for the extent of hepatectomy and 2) the extent of hepatectomy invariably causing fatal hepatic failure, to facilitate gene expression analysis.

MATERIALS AND METHODS

In 70%-hepatectomy, the left lateral and median lobes were removed, and in 90%-hepatectomy, all lobes except the caudate were resected. One-week survival rates, serum concentrations of aspartate aminotransferase, alanine aminotransferase and total bilirubin were measured. Histological examinations were performed using hematoxylin and eosin staining, and immunohistochemical tests were done with antibody against Ki-67 antigen.

RESULTS

All of the 70%-hepatectomized mice were alive at 1 week, but the 90%-hepatectomized mice all died within 24 h after hepatectomy. Serum aminotransferase and total bilirubin levels were significantly higher in the 90%-hepatectomized mice than in the 70%-hepatectomized mice. Liver histology revealed more prominent vacuolar degeneration in the former. Ki67-positive hepatocytes appeared and proliferated immediately after 70%-hepatectomy, but few were observed in the 70%-hepatectomized mice.

CONCLUSION

We established 90%-hepatectomy as the safety limit for murine hepatectomy and as a model for liver regeneration, and 90%-hepatectomy as a "fatal hepatic failure level."

Effectiveness of combining plasma exchange and continuous hemodiafiltration in patients with postoperative liver failure

Nine patients with postoperative liver failure were treated with plasma exchange (PE) or PE and continuous hemodiafiltration (CHDF), and various biochemical parameters were determined before and after treatment. Although citrate levels increased significantly after treatment compared with pretreatment levels in both the PE group and the PE + CHDF group (P < 0.0001 and P < 0.0001, respectively), the percentage of the increase in citrate levels was significantly higher in the PE group than in the PE + CHDF group (P = 0.0051). Total bilirubin (T-Bil) levels were significantly lower after treatment in both the PE and PE + CHDF groups (P < 0.0001 and P = 0.0001, respectively). There were no significant differences in T-Bil levels between the two groups (P = 0.5181). There were no significant differences in interleukin (IL)-6 levels before and after treatment in both the PE and PE + CHDF groups (P = 0.1281 and P = 0.2273, respectively). IL-18 levels were significantly lower after treatment in both the PE and PE + CHDF groups (P < 0.0001 and P = 0.0002, respectively), but there were no significant differences in the removal rate of IL-18 in both the PE and PE + CHDF groups (P = 0.8749). These results indicate that combining PE and CHDF in a series-parallel circuit is an effective modality for suppressing the elevation of blood citrate levels. This finding may have important implications for the development of an effective treatment for patients with postoperative liver failure.

Concise prediction models of anticancer efficacy of 8 drugs using expression data from 12 selected genes

We developed concise, accurate prediction models of the in vitro activity for 8 anticancer drugs (5-FU, CDDP, MMC, DOX, CPT-11, SN-38, TXL and TXT), along with individual clinical responses to 5-FU using expression data of 12 genes. We first performed cDNA microarray analysis and MTT assay of 19 human cancer cell lines to sort out genes which were correlative in expression levels with cytotoxicities of the 8 drugs; we selected 13 genes with proven functional significance to drug sensitivity from a huge number of potent prediction marker genes. The correlation significance of each was confirmed using expression data quantified by real-time RT-PCR, and finally 12 genes (ABCB1, ABCG2, CYP2C8, CYP3A4, DPYD, GSTP1, MGMT, NQO1, POR, TOP2A, TUBB and TYMS) were selected as more reliable predictors of drug response. Using multiple regression analysis, we fixed 8 prediction formulae which embraced the variable expressions of the 12 genes and arranged them in order, to predict the efficacy of the drugs by referring to the value of Akaike's information criterion for each sample. These formulae appeared to accurately predict the in vitro efficacy of the drugs. For the first clinical application model, we fixed prediction formulae for individual clinical response to 5-FU in the same way using 41 clinical samples obtained from 30 gastric cancer patients and found to be of predictive value in terms of survival, time to treatment failure and tumor growth. None of the 12 selected genes alone could predict such clinical responses.

Gene expression profile analysis of regenerating liver after portal vein ligation in rats by a cDNA microarray system

AIMS

We assessed changes in gene expression of hypertrophied liver after portal vein ligation (PL) in a test group of rats compared to a control group, which had the same size liver but no PL.

METHODS

The portal veins of the left and median lobes in the test group were ligated in an initial operation. Four days after the PL, the liver volume of the posterior caudate lobe (5%) increased two-fold and comprised 10% of the liver. A 90% hepatectomy was then performed, leaving only the hypertrophied posterior caudate lobe, and leaving the normal anterior and posterior caudate lobes (10%) in the control (sham) group. A comparison of the expression profiles between two groups was performed using cDNA microarrays and the hepatic ATP level was measured.

RESULTS

The survival rate for the PL group was significantly higher than for the sham group at 4 days after the hepatectomy (56.3% and 26.7%, P < 0.05). Gene expression of cyclin D1, proliferating cell nuclear antigen, cyclin A and B was upregulated, and the cyclin-dependent kinase inhibitor was downregulated. Increases were observed in: (i) pyruvate dehydrogenase, the tricarboxylic acid cycle cycle regulator, (ii) acyl-CoA dehydrogenase, the oxidation regulator, and (iii) cytochrome oxidases, the oxidative phosphorylation regulator. Hepatic ATP concentration after hepatectomy was better maintained in the PL group than in the sham group (0.48 +/- 0.01 micromol/ml vs. 0.33 +/- 0.01 micromol/ml, P < 0.05).

CONCLUSION

The regenerating liver increased tolerance for extended hepatectomy compared to normal liver. It is believed that this is because the induced rapid regeneration of the remaining liver after hepatectomy increases ATP metabolism.

Low hepatic glutathione S-transferase and increased hepatic DNA adduction contribute to increased tumorigenicity of aflatoxin B1 in newborn and partially hepatectomized mice

Low levels of hepatic glutathione S-transferase and increased formation of aflatoxin B1 (AFB1)-DNA adducts correlate with hepatocyte proliferation and increased hepatocarcinogenesis in both newborn mice and partially hepatectomized adult mice, as compared to normal, adult C57BL/6J mice. Newborn mice, which are highly susceptible to the hepatocarcinogenic effects of AFB1, have active proliferation of hepatocytes until 3 weeks of age, when hepatocyte proliferation abruptly ceases. At about this time, the mice become highly resistant to AFB1. In adult mice, AFB1 carcinogenicity is increased after stimulation of liver proliferation by partial hepatectomy. To become carcinogenic, AFB1 is activated in the liver by the P450 enzyme system to electrophilic intermediates, some of which form DNA adducts believed to be responsible for mutations leading to cancer. The most carcinogenic intermediate, AFB(1)-8,9-epoxide, is detoxified by glutathione S-transferase-mediated conjugation to glutathione. Glutathione levels, glutathione S-transferase levels, and AFB1-DNA adduct formation were measured at 4, 10, 30, 120, 245 and 365 days of age in C57BL/6J mice. There was a 5-fold increase in hepatic glutathione S-transferase levels and 13-fold decrease in hepatic AFB1-DNA adduct formation over these ages. Induction of hepatocyte proliferation following partial hepatectomy of 120-day-old mice lowered hepatic glutathione S-transferase levels and increased the extent of hepatic AFB1-DNA formation to levels similar to those measured in 4-day-old mice. These results indicate that increased susceptibility to AFB1 hepatocarcinogenesis in newborn mice, and in adult mice following partial hepatectomy, is due to decreased GST and increased adduct formation in proliferating liver.

Current progress in the prediction of chemosensitivity for breast cancer

Advances in chemotherapy have improved the prognosis of patients with breast cancer significantly. Individualization is important for optimization of chemotherapy. The prediction of tumor sensitivity to anticancer agents has been intensively investigated for that purpose. There have been 2 approaches to predict the efficacy of drugs against individual tumors, drug-sensitivity tests and molecular marker genes. Although some of these tests are already available clinically, the prediction of chemosensitivity remains a goal to be achieved. Several studies with microarrays revealed that comprehensive analyses of genes may provide useful information for determining the chemosensitivity of cancer. We have started to use a cDNA microarray to study the chemosensitivity of breast cancer. Taken together with recent data, studies for drug sensitivity should provide insights into the mechanisms of drug sensitivity and the optimal design of more effective treatment strategies in breast cancer.

Changes of hepatocyte cell cycle after partial hepatectomy in cirrhotic rat liver

AIM

To investigate the effects of cyclins and oncogene proteins on liver regeneration after partial hepatectomy in cirrhotic rats.

METHODS

By employing immunohistochemistry and in situ hybridization, we observed the changes of liver cyclin A, D and oncogene proteins in the model of rat liver cirrhosis(CCL₄) after partial hepatectomy.

RESULTS

The expressions and distributions of hepatocyte cyclin A and D were similar, which were mainly in the cytoplasm and nuclei of the cells. Around the central veins, the expressions were high and early at about 6 h postoperation. During liver regeneration, the expressions of cyclin A and D mRNA were marked and locally distributed. Cyclin B and Rb proteins were distributed in the cytoplasm and nuclei of the cells. Cyclin B and Rb proteins had stronger expressions in the liver at 6-24 h after operation. P27 expressions occured at 24 h after operation, and were most marked at 1 wk after operation. RB protein also showed stronger expressions.

CONCLUSION

Liver regeneration is dependent on a muti-pathway mechanism.