Lower activity of CCAAT/enhancer-binding protein and expression of cyclin E, but not cyclin D1, activating protein-1 and p21(WAF1), after partial hepatectomy in obstructive jaundice

Role of multiparametric US in the preoperative assessment of hepatic parenchyma in patients with liver tumors

OBJECTIVES

The aim of this study was to evaluate the diagnostic performance of shear wave elastography (SWE), shear wave dispersion (SWD), and attenuation imaging (ATI) in assessment of hepatic parenchyma in patients with liver tumors before resection.

METHODS

Patients with liver tumors were prospectively enrolled in this study. All participants underwent SWE, SWD, and ATI examinations. Fibrosis stage, necroinflammatory activity and hepatic steatosis grade were determined histopathologically. We evaluated the stability of ATI, SWE and SWD examinations. Multivariable linear regression analyses were conducted to determine the determinant factors for SWE, SWD, attenuation coefficient (AC) values. A receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic performance of multiparametric US (ultrasond).

RESULTS

A total of 280 participants were enrolled in this study. TG (triglyceride) and steatosis for AC value were significant determinant factors. PLT (platelet), PT (prothrombin time), GGT (glutamyl transpeptidase), and fibrosis stage for SWE value were significant determinant factors. PLT, fibrosis stage and inflammation activity for SWD value were significant determinant factors. AC value was correlated with hepatic steatosis. Both SWE and SWD values were correlated with fibrosis stage, inflammation activity, respectively. The area under the ROC (AUROC) curve of ATI for predicting hepatic steatosis grade were 0.910(≥ S1), 0.927(≥ S2), 0.962(= S3), respectively. The AUROC curve of SWE for predicting fibrosis stage were 0.923(≥ S1), 0.934(≥ S2), 0.930(≥ S3), 0.895(= S4), respectively. The AUROC curve of SWD for predicting fibrosis stage were 0.858(≥ S1), 0.886(≥ S2), 0.866(≥ S1) (≥ S3), 0.825(= S4). The AUROC curve of SWE for predicting inflammation activity were 0.846(≥ G1), 0.724(≥ G2), 0.787 (≥ G3), respectively. The AUROC curve of SWD for predicting inflammation activity were 0.777(≥ G1), 0.727(≥ G2), 0.803 (≥ G3), respectively.

CONCLUSIONS

For patients with liver tumors, ATI technology showed excellent feasibility and diagnostic performance for detecting and grading hepatic steatosis, SWE was more accurate in detecting fibrosis stage than SWD, SWD was not superior to SWE in detecting inflammation activity.

Clinical Application of Shear Wave Elastography With Shear Wave Dispersion Imaging in the Preoperative Evaluation of Hepatic Parenchyma in Patients With Liver Tumors

OBJECTIVES

This study aimed to compare the diagnostic accuracy of shear wave elastography (SWE) with that of shear wave dispersion (SWD) in evaluation of hepatic parenchyma in patients with liver tumors before resection.

METHODS

A total of 174 patients with liver tumors were prospectively enrolled. SWE and SWD examinations were performed. Fibrosis stage and necroinflammatory activity were determined histopathologically according to the Scheuer standard. We compared the diagnostic accuracy of SWE and SWD.

RESULTS

Both SWE and SWD values of the liver were highly correlated with liver fibrosis stage (P < .05, respectively). Both SWE and SWD values of the liver were moderately correlated with necroinflammatory activity (P < .05, respectively). Both SWE and SWD values of the liver were not correlated with steatosis (P > .05, respectively). Both SWE and SWD values were significantly different among the patients with different stages of liver fibrosis (P < .001, respectively). The area under the receiver operating characteristic (ROC) curve of SWE value was 0.982, 0.977, 0.969, and 0.984 for predicting S ≥ 1, S ≥ 2, S ≥ 3, and S = 4, respectively. The optimal cutoff SWE values were 6.9, 7.9, 8.7, and 10.6 kPa for S ≥ 1, S ≥ 2, S ≥ 3, and S = 4, respectively. The area under the ROC curve of SWD value was 0.967, 0.960, 0.925, and 0.954 for predicting S ≥ 1, S ≥ 2, S ≥ 3, and S = 4, respectively. The optimal cutoff SWD values were 11.2, 12.0, 13.2, and 16.0 m/s/kHz for S ≥ 1, S ≥ 2, S ≥ 3, and S = 4, respectively.

CONCLUSIONS

SWE and SWD could be noninvasive and accurate for predicting the stage of liver fibrosis in patients with liver tumors before surgery. SWE was more accurate than SWD in predicting severe fibrosis (S ≥ 3) and cirrhosis (S = 4).

The platelet-activating receptor C-type lectin receptor-2 plays an essential role in liver regeneration after partial hepatectomy in mice

Essentials Regeneration role of C-type lectin receptor-2 (CLEC-2) after 70% hepatectomy (HPx) was investigated. Wild-type or CLEC-2 deleted from platelets of chimeric mice (flKO) underwent HPx. The liver/body weight ratio was significantly lower in the flKO than in the wild-type. CLEC-2 plays an essential role in liver regeneration after HPx.

SUMMARY

Background and aim The aim of the present study was to investigate the role of C-type lectin receptor (CLEC)-2 in liver regeneration following partial liver resection in mice. Materials and methods Irradiated chimeric mice transplanted with fetal liver cells from wild-type (WT) mice, CLEC-2-deleted (KO) mice or mice with CLEC-2 deleted specifically from platelets (flKO) were generated. Mice underwent 70% partial hepatectomy (PH). Immunohistochemical staining was performed to investigate the expression of the endogenous ligand for CLEC-2, podoplanin. The accumulation of platelets in the liver was also quantified. The hepatic expression of the IL-6/gp130 and STAT3, Akt and ERK1/2 was also examined. Results The liver/body weight ratio and expression of all cell proliferation markers were significantly lower in the flKO group than in the WT group. The expression of phosphorylated (p) Akt and pERK1/2 was similar in the WT and flKO groups. On the other hand, the expression of pSTAT3 and IL-6 was significantly stronger in the WT group than in the flKO group. The expression of podoplanin was detected in the hepatic sinusoids of both groups. However, the extent to which platelets accumulated in hepatic sinusoids was significantly less in the flKO group than in the WT group. Conclusion CLEC-2 was involved in hepatic regeneration after liver resection and CLEC-2-related liver regeneration was attributed to the interaction between platelets and sinusoidal endothelial cells.

Shenhua Tablet inhibits mesangial cell proliferation in rats with chronic anti-Thy-1 nephritis

Background

In China, mesangial proliferative glomerulonephritis (MsPGN) is one of the most common kidney diseases. In this study, we treated a rat model of chronic anti-Thy-1 MsPGN with Shenhua Tablet and evaluated whether the tablet was able to protect the kidney function. Thirty-six Wistar rats were randomly divided into six groups: (1) Sham surgery (Sham); (2) anti-Thy-1 nephritis model (Thy-1); (3) anti-Thy-1 nephritis model + irbesartan-treated (Irb); (4) anti-Thy-1 nephritis model + low-dose of Shenhua Tablet (SHL); (5) anti-Thy-1 nephritis model + medium-dose of Shenhua Tablet (SHM); (6) anti-Thy-1 nephritis model + high-dose of Shenhua Tablet (SHH).

Results

Thirteen weeks after drug treatment, urinary proteins were quantified and renal pathological changes were thoroughly examined at the time point of 24 h. Meanwhile, the expression levels of p-Erk1/2, cyclin D1 and p21 at the renal cortex were also tested. The levels of urinary proteins and total cholesterol in the blood were significantly reduced in rats treated with any drug tested in this study. The level of triglyceride was significantly reduced in all three Shenhua Tablet-treated groups. Renal pathomorphological scores were significantly improved in groups of Irb, SHM and SHH. Mesangial cell proliferation was significantly inhibited in any drug-treated group. p-Erk1/2 and cyclin D1 were downregulated whereas p21 was upregulated in the renal cortex.

Conclusions

Our study indicated that Shenhua Tablet is able to inhibit the abnormal proliferation of mesangial cells and to prevent kidney damage, which is likely associated with downregulation of p-Erk1/2 and reduced activity of its downstream target-cyclin D1.

New paradigms in post-hepatectomy liver failure

INTRODUCTION

Liver failure after hepatectomy remains the most feared postoperative complication. Many risk factors are already known, related to patient's comorbidities, underlying liver disease, received treatments and type of resection. Preoperative assessment of functional liver reserve must be a priority for the surgeon.

METHODS

Physiopathology of post-hepatectomy liver failure is not comparable to fulminant liver failure. Liver regeneration is an early phenomenon whose cellular mechanisms are beginning to be elucidated and allowing most of the time to quickly recover a functional organ. In some cases, microscopic and macroscopic disorganization appears. The hepatocyte hyperproliferation and the asynchronism between hepatocytes and non-hepatocyte cells mitosis probably play a major role in this pathogenesis.

RESULTS

Many peri- or intra-operative techniques try to prevent the occurrence of this potentially lethal complication, but a better understanding of involved mechanisms might help to completely avoid it, or even to extend the possibilities of resection.

CONCLUSION

Future prevention and management may include pharmacological slowing of proliferation, drug or physical modulation of portal flow to reduce shear-stress, stem cells or immortalized hepatocytes injection, and liver bioreactors. Everything must be done to avoid the need for transplantation, which remains today the most efficient treatment of liver failure.

Ursolic acid enhances mouse liver regeneration after partial hepatectomy

CONTEXT

Ursolic acid is a pentacyclic triterpenoid which has hepatoprotective and antihepatotoxic activities.

OBJECTIVE

This study investigated whether ursolic acid is able to stimulate liver regeneration in partially hepatectomized mice.

MATERIALS AND METHODS

Ursolic acid or the vehicle solution was orally administered to the experimental, sham-operated and vehicle-treated group mice for 7 days, positive control animal (mice) was treated with recombinant human hepatocyte growth factor (rhHGF), and then the 70% liver partial hepatectomy was performed. The liver mass recovery rate was estimated by measuring the ratios of mice liver weight to body weight. The liver cells undergoing DNA synthesis were identified by immunohistochemistry analysis using monoclonal anti-BrdU antibodies. The expression levels of cyclin D1, cyclin E and C/EBP proteins (C/EBPα and C/EBPβ) were detected by the Western blotting technique.

RESULTS

Our results showed administration of ursolic acid significantly increased the ratio of the liver to body weight and BrdU labeling index at 36 and 48 h after partial hepatectomy, and the potency of UA is similar to rhHGF treated positive control mice. In addition, ursolic acid treatment significantly increased cyclin D1, cyclin E and C/EBPβ protein expression levels at 36 h after liver PHx compared with the vehicle-treated control mice.

DISCUSSION AND CONCLUSION

All these results suggest that ursolic acid stimulates liver proliferation after partial hepatectomy, and this effect may be associated with the stimulation of C/EBPβ expression.

Impaired activities of cyclic adenosine monophosphate-responsive element binding protein, protein kinase A and calcium-independent phospholipase A2 are involved in deteriorated regeneration of cirrhotic liver after partial hepatectomy in rats

AIMS

  This study is to elucidate whether cyclic adenosine monophosphate (cAMP)-mediated signal is involved in lower regenerative potential of cirrhotic liver.

METHODS

  Hepatic cAMP concentration, activities of protein kinase A (PKA), c-AMP responsive element binding protein (CREB) and Ca(2+) -independent phospholipase A(2) (iPLA2) and regeneration rate were compared between rats with thioacetamide-induced cirrhotic and normal livers after two-third hepatectomy.

RESULTS

  The liver regeneration estimated by the rates of [(3) H]-thymidine incorporation and staining of proliferating cell nuclear antigen was significantly lower in the cirrhotic group. CREB, PKA and iPLA2 activities, assessed by western blots and electromobility shift assay, were significantly impaired after hepatectomy in the cirrhosis group. PKA and iPLA2 silencing by siRNA transfection significantly inhibited CREB activity and cell growth in transformed hepatocytes in vitro.

CONCLUSIONS

  CREB dysfunction, mediated by PKA and iPLA2 suppression, may be involved in the deteriorated liver regeneration in the cirrhotic rats.

Management of large hepatocellular carcinoma in adult patients with Alagille syndrome: a case report and review of literature

BACKGROUND

Alagille syndrome is a multi-system developmental disorder associated with paucity of interlobular bile ducts and cholestasis, rarely associated with hepatocellular carcinoma. Associated syndromic co-morbidities may complicate surgical management. As such, we herein review the modern management of a large hepatocellular carcinoma in an adult patient with Alagille syndrome and review the literature of adult Alagille patients with hepatocellular carcinoma.

CASE PRESENTATION

A 29-year-old woman with a history of Alagille syndrome was referred with biopsy-proven 12 × 8 cm hepatocellular carcinoma replacing her right liver. Biopsy of the contralateral liver demonstrated findings consistent with Alagille syndrome, but no underlying cirrhosis. CT volumetrics demonstrated a future liver remnant of 40%. Extensive hematologic and cardiac work-up was performed pre-operatively, given the syndrome's associated bleeding dyscrasias and cardiac abnormalities. The patient underwent a margin-negative right hepatectomy using the "hanging" technique through a thoracoabdominal approach. The patient developed a transient hyperbilirubinemia but no hepatic insufficiency and did well post-operatively.

CONCLUSION

Since Alagille syndrome affects multiple organ systems, preoperative evaluation of cardiac, hematologic, and hepatic function should be considered. This case illustrates the peri-operative management of an Alagille patient, and highlights several key technical points that contributed to a successful resection.

Predicting liver failure following major hepatectomy

Pre-operative determination of the risk of liver dysfunction has come under criticism with regards to its usefulness in clinical practice. Opinion is split between centres which use such tests uniformly on all patients and those where clinical judgment alone is used. Published data would not suggest any difference in mortality, morbidity or liver failure rates between these groups. This review outlines and presents the evidence for pre-operative quantification of functional liver remnant volume.

Oltipraz promotion of liver regeneration after partial hepatectomy: The role of PI3-kinase-dependent C/EBPbeta and cyclin E regulation

Oltipraz, a representative cancer chemopreventive agent, regenerates cirrhotic liver via CCAAT/enhancer binding protein beta (C/EBPbeta). This study examined the effect of oltipraz on liver regeneration after partial hepatectomy (PH) and explored the role of phosphatidylinositol 3-kinase (PI3K) pathway responsible in liver regeneration. Oltipraz treatment (30 mg/kg/day, for 3 days) promoted liver regeneration in PH rats, but did not increase hepatocyte growth factor production. Subcellular fractionation and electrophoretic mobility shift assays showed that oltipraz treatment increased C/EBPbeta-DNA binding activity in the liver of sham control rats and further enhanced PH-mediated nuclear translocation of C/EBPbeta. The expression of cyclin E and the activity of cyclin E-dependent kinase were both enhanced by oltipraz treatment of PH rats. The signaling pathway that controls C/EBPbeta and cyclin E were studied in H4IIE cells, a rat-derived hepatocyte cell line. Oltipraz potentiated the nuclear accumulation of C/ EBPbeta and C/EBPbeta-DNA binding activity in cells incubated in a medium containing serum. PI3K and its downstream kinase, p70S6 kinase, were both required for C/EBPbeta-dependent induction of cyclin E by oltipraz, as shown by chemical inhibition and plasmid transfection experiments. The results of this study demonstrate that oltipraz treatment enhances liver regeneration after PH, which involves activation of C/EBPbeta and C/EBPbeta-dependent cyclin E expression via the PI3K-p70S6 kinase pathway.

Liver failure after major hepatic resection

INTRODUCTION

The consequence of excessive liver resection is the inexorable development of progressive liver failure characterised by the typical stigmata associated with this condition, including worsening coagulopathy, hyperbilirubinaemia and encephalopathy. The focus of this review will be to investigate factors contributing to hepatocyte loss and impaired regeneration.

METHODS

A literature search was undertaken of Pubmed and related search engines, examining for articles relating to hepatic failure following major hepatectomy.

RESULTS

In spite of improvements in adjuvant chemotherapy and increasing surgical confidence and expertise, the parameters determining how much liver can be resected have remained largely unchanged. A number of preoperative, intraoperative and post-operative factors all contribute to the likelihood of liver failure after surgery.

CONCLUSIONS

Given the magnitude of the surgery, mortality and morbidity rates are extremely good. Careful patient selection and preservation of an obligate volume of remnant liver is essential. Modifiable causes of hepatic failure include avoidance of sepsis, drainage of cholestasis with restoration of enteric bile salts and judicious use of portal triad inflow occlusion intra-operatively. Avoidance of post-operative sepsis is most likely to be achieved by patient selection, meticulous intra-operative technique and post-operative care. Modulation of portal vein pressures post-operatively may further help reduce the risk of liver failure.

Mechanisms of hepatic regeneration following portal vein embolization and partial hepatectomy: a review

BACKGROUND

Portal vein embolization (PVE) improves outcome following major hepatectomy, and basic studies have presented evidence related to the mechanisms responsible for hepatic regeneration. Hemodynamic changes following PVE are similar to, but slightly different from, those of partial hepatectomy (PH) because arterial flow to the embolized lobe is preserved. However, the process of hepatic regeneration is essentially the same after both PVE and PH. A number of mediators are involved in PVE or PH-induced hepatic regeneration. These include inflammatory cytokines, vasoregulators, growth factors, eicosanoids, and various hormones. These mediators activate a complex network of signal transduction that promotes hepatic regeneration. A variety of conditions have been shown to modulate the function of these mediators and inhibit regeneration. These include biliary obstruction, diabetes, chronic ethanol consumption, malnutrition, gender, aging, and infection.

CONCLUSION

Optimizing these factors, where possible, before PVE or PH, is essential to maximize hypertrophy of the liver. A fuller understanding of hepatic physiology and pathophysiology following PVE or PH may lead to greater functional capacity of the remaining liver and extend the indications for hepatectomy in patients who require large liver volume resection.

Mechanism of impaired hepatic regeneration in cholestatic liver

The regenerative capacity of the liver is an important factor following liver surgery. The dramatic change in portal venous flow, due to either portal vein embolization or partial hepatectomy, induces a rapid change in liver volume. In response to these stresses, hepatocytes are primed, through the release of inflammatory cytokines, to increase the expression of immediate early genes and increase the activation of transcriptional factors. The primed hepatocytes then respond to growth factors, including hepatocyte growth factor, epidermal growth factor, and transforming growth factor-alpha. Several pathologic conditions have been shown to inhibit hepatic regeneration. These include diabetes mellitus, malnutrition, aging, infection, chronic ethanol consumption, and biliary obstruction. Impaired hepatic regeneration in the setting of biliary obstruction is an especially serious problem because it can be a major determinant in not considering surgical treatment. The mechanism responsible for impaired hepatic regeneration in patients with biliary obstruction includes decreased portal venous flow, attenuated production of liver proliferation-associated factors, an increased rate of apoptosis, and lack of enterohepatic circulation. Restoring these factors may lead to an improvement in regeneration in a cholestatic liver following portal vein embolization or partial hepatectomy. This review article summarizes the current understanding of the mechanism of hepatic regeneration, with particular emphasis on that in the cholestatic liver.

Cell cycle defects contribute to a block in hormone-induced mammary gland proliferation in CCAAT/enhancer-binding protein (C/EBPbeta)-null mice

In contrast to hormone-dependent breast cancer, steroid hormone-induced proliferation in the normal mammary gland does not occur in the steroid-receptor positive cells but rather in adjacent cells via paracrine signaling involving several local growth factors. To help elucidate the mechanisms involved in the block in proliferation in hormone-receptor positive cells, we have utilized a CCAAT/enhancer binding protein (C/EBPbeta)-null mouse model. Loss of this transcription factor results in increased steroid and prolactin receptor expression concomitant with a 10-fold decrease in proliferation in response to pregnancy hormones. To determine the basis for this decrease, several markers of cell cycle progression were analyzed in wild type and C/EBPbeta-null mammary epithelial cells (MECs). These studies indicated that cell cycle progression in C/EBPbeta-null MECs is blocked at the G1/S transition. C/EBPbeta-null mammary glands display substantially increased levels of the activated form of transforming growth factor beta, a potent inhibitor of epithelial cell proliferation, as well as increased downstream Smad2 expression and signaling. While cyclin D1 levels were equivalent, cyclin E expression was markedly reduced in C/EBPbeta-null as compared with wildtype MECs. In addition, increased p27 stability and retention in the nucleus and decreased levels of the cdc25a phosphatase contributed to a significant loss of cdk2 kinase activity. Collectively, these changes prevent C/EBPbeta-null mammary epithelial cells from responding to hormone-induced proliferative signals.

Liver-enriched transcription factors in liver function and development. Part II: the C/EBPs and D site-binding protein in cell cycle control, carcinogenesis, circadian gene regulation, liver regeneration, apoptosis, and liver-specific gene regulation

In the first part of our review (see Pharmacol Rev 2002;54:129-158), we discussed the basic principles of gene transcription and the complex interactions within the network of hepatocyte nuclear factors, coactivators, ligands, and corepressors in targeted liver-specific gene expression. Now we summarize the role of basic region/leucine zipper protein family members and particularly the albumin D site-binding protein (DBP) and the CAAT/enhancer-binding proteins (C/EBPs) for their importance in liver-specific gene expression and their role in liver function and development. Specifically, regulatory networks and molecular interactions were examined in detail, and the experimental findings summarized in this review point to pivotal roles of DBP and C/EBPs in cell cycle control, carcinogenesis, circadian gene regulation, liver regeneration, apoptosis, and liver-specific gene regulation. These regulatory proteins are therefore of great importance in liver physiology, liver disease, and liver development. Furthermore, interpretation of the vast data generated by novel genomic platform technologies requires a thorough understanding of regulatory networks and particularly the hierarchies that govern transcription and translation of proteins as well as intracellular protein modifications. Thus, this review aims to stimulate discussions on directions of future research and particularly the identification of molecular targets for pharmacological intervention of liver disease.

Blockade of constitutively activated Janus kinase/signal transducer and activator of transcription-3 pathway inhibits growth of human pancreatic cancer

Constitutive activation of signal transducer and activator of transcription (Stat) proteins has been demonstrated in a wide variety of malignancies. In this study, we elucidated the significance of Janus kinase (JAK) and the downstream transcription factor Stat3 signals on malignant potentials of pancreatic cancer. Electrophoretic mobility shift assay and immunohistochemical analysis revealed that Stat3 was constitutively activated in subsets of human pancreatic cancer tissues and cell lines (Panc1, Kp4, AsPC-1, BxPC-3). A JAK-specific inhibitor, tyrphostin AG490, markedly inhibited Stat3 activation and expression of cyclin D1, bcl-xL and vascular endothelial growth factor mRNAs estimated by RT-PCR, as followed by growth arrest (6.3-21.3% vs controls; P<0.001) of pancreatic cancer cells. Inactivation of Stat3 by dominant-negative Stat3 adenovirus partly suppressed the growth of pancreatic cancer cells on day 4 post-inoculation (P<0.05) but not the expression of these mRNAs. These results indicate that activation of the JAK/Stat3 signaling pathway plays an important role in the progression of pancreatic cancer and that blockade of JAK/Stat3 signals may provide a novel therapeutic strategy for pancreatic cancer.

PPARgamma ligand attenuates PDGF-induced mesangial cell proliferation: role of MAP kinase

BACKGROUND

Mesangial proliferation is a key feature in the pathogenesis of a number of renal diseases and can be experimentally induced by the mitogen platelet-derived growth factor (PDGF). Mitogen-activated protein kinase (MAPK) signaling plays a key role in mesangial cell proliferation. In the present study we examined whether peroxisome proliferator-activated receptor gamma (PPARgamma) activators/ligands, thiazolidinediones such as ciglitazone, troglitazone, and rosiglitazone, can inhibit cell proliferation by modulating individual steps in the MAPK pathway.

METHODS

Mouse mesangial cells were made quiescent and proliferation was measured following the application of PDGF. Using ciglitazone as the model compound, the mechanism of the antiproliferative effect of PPARgamma activators on MAPK and specific cell cycle regulatory proteins were examined by Western blot analysis and transfection studies.

RESULTS

Ciglitazone inhibited PDGF-induced mesangial cell proliferation in a dose-dependent manner (1 to 20 micromol/L). The inhibitory effect was blocked by a peroxisome proliferator-activated receptor element (PPRE) decoy oligonucleotide, indicating that the observed effect of ciglitazone was via PPARgamma activation. Ciglitazone (1 to 20 micromol/L) did not affect extracellular signal-regulated protein kinase (ERK) activation but inhibited the activation of serum response element (SRE) by 85 +/- 6% (P < 0.01). This effect was associated with a reduction in c-fos expression (80 +/- 9%, P < 0.01). Ciglitazone (1, 10, and 20 micromol/L) also inhibited cyclin D1 expression by 37 +/- 8%, 79 +/- 15%, and 87 +/- 12%, respectively (P < 0.001 to 0.001), and p21 expression by 45 +/- 6% (P < 0.01), 61 +/- 10% (P < 0.001), and 72 +/- 8% (P < 0.001), respectively. Ciglitazone inhibited PDGF-mediated up-regulation of p27. In addition, the antiproliferative effect of ciglitazone was potentiated by PD98059, a mitogen-activated protein (MAP) kinase kinase (MEK) inhibitor that acts at a step upstream from ERK.

CONCLUSION

These data indicate that PPARgamma activation may inhibit mesangial growth directly by affecting MAPK and cell cycle regulatory proteins. Furthermore, a MAP kinase inhibitor can potentiate the antiproliferative effect.

Inhibited activities in CCAAT/enhancer-binding protein, activating protein-1 and cyclins after hepatectomy in rats with thioacetamide-induced liver cirrhosis

Transcriptional activation of nuclear factor (NF)-kappaB, signal transducers and activators of transcription (STAT) 3, activating protein (AP)-1 and CCAAT/enhancer-binding protein (C/EBP) plays an important role in liver regeneration by modulating cell cycle regulators. The regeneration of cirrhotic liver after hepatectomy is inhibited despite intact expression of growth factors. To elucidate the mechanism involved, regeneration responses in growth factor receptors, transcription factors, and cell cycle regulators after two-thirds hepatectomy were compared between rats with thioacetamide-induced cirrhotic and normal liver. The expression of c-met and epidermal growth factor receptor analyzed by RT-PCR and immunohistochemistry did not differ between the two groups. The activities of C/EBP and AP-1 evaluated by electrophoretic mobility shift assay were significantly inhibited in the cirrhotic group compared with those in the control group, but not those of NF-kappaB and STAT3. The expression of cyclin-D1, -E, and -A assessed by Western blot analysis was significantly decreased in the cirrhotic group compared with the control group. The level in p21(Cip1) or p27(Kip1) did not differ between the two groups. The liver regeneration estimated by the rates of [(3)H]thymidine incorporation into DNA and staining of proliferating cell nuclear antigen was significantly lower in the cirrhotic rats than in the controls. In conclusion, downregulation of cyclin -D1, -E, and -A expression, which may be induced by impaired activities of C/EBP and AP-1, is responsible for the decreased regenerative capacity of cirrhotic liver after partial hepatectomy.