Loss of c-Met accelerates development of liver fibrosis in response to CCl(4) exposure through deregulation of multiple molecular pathways.

HGF/c-Met signaling plays a pivotal role in hepatocyte survival and tissue remodeling during liver regeneration. HGF treatment accelerates resolution of fibrosis in experimental animal models. Here, we utilized Met(fl/fl);Alb-Cre(+/-) conditional knockout mice and a carbon tetrachloride(CCl(4))-induced liver fibrosis model to formally address the role of c-Met signaling in hepatocytes in the context of chronic tissue injury. Histological changes during injury (4weeks) and healing phase (4weeks) were monitored by immunohistochemistry; expression levels of selected key fibrotic molecules were evaluated by western blotting, and time-dependent global transcriptomic changes were examined using a microarray platform. Loss of hepatocyte c-Met signaling altered hepatic microenvironment and aggravated hepatic fibrogenesis. Greater liver damage was associated with decreased hepatocyte proliferation, excessive stellate cell activation and rapid dystrophic calcification of necrotic areas. Global transcriptome analysis revealed a broad impact of c-Met on critical signaling pathways associated with fibrosis. Loss of hepatocyte c-Met caused a strong deregulation of chemotactic and inflammatory signaling (MCP-1, RANTES, Cxcl10) in addition to modulation of genes involved in reorganization of the cytoskeletal network (Actb, Tuba1a, Tuba8), intercellular communications and adhesion (Adam8, Icam1, Itgb2), control of cell proliferation (Ccng2, Csnk2a, Cdc6, cdk10), DNA damage and stress response (Rad9, Rad52, Ercc4, Gsta1 and 2, Jun). Our study demonstrates that deletion of c-Met receptor in hepatocytes results in pronounced changes in hepatic metabolism and microenvironment, and establishes an essential role for c-Met in maintaining the structural integrity and adaptive plasticity of the liver under adverse conditions.

2012 Provisional classification criteria for polymyalgia rheumatica: a European League Against Rheumatism/American College of Rheumatology collaborative initiative.

The objective of this study was to develop European League Against Rheumatism/American College of Rheumatology classification criteria for polymyalgia rheumatica (PMR). Candidate criteria were evaluated in a 6-month prospective cohort study of 125 patients with new-onset PMR and 169 non-PMR comparison subjects with conditions mimicking PMR. A scoring algorithm was developed based on morning stiffness >45 minutes (2 points), hip pain/limited range of motion (1 point), absence of rheumatoid factor and/or anti-citrullinated protein antibody (2 points), and absence of peripheral joint pain (1 point). A score ≥4 had 68% sensitivity and 78% specificity for discriminating all comparison subjects from PMR. The specificity was higher (88%) for discriminating shoulder conditions from PMR and lower (65%) for discriminating RA from PMR. Adding ultrasound, a score ≥5 had increased sensitivity to 66% and specificity to 81%. According to these provisional classification criteria, patients ≥50 years old presenting with bilateral shoulder pain, not better explained by an alternative pathology, can be classified as having PMR in the presence of morning stiffness >45 minutes, elevated C-reactive protein and/or erythrocyte sedimentation rate, and new hip pain. These criteria are not meant for diagnostic purposes.

A novel prognostic subtype of human hepatocellular carcinoma derived from hepatic progenitor cells.

The variability in the prognosis of individuals with hepatocellular carcinoma (HCC) suggests that HCC may comprise several distinct biological phenotypes. These phenotypes may result from activation of different oncogenic pathways during tumorigenesis and/or from a different cell of origin. Here we address whether the transcriptional characteristics of HCC can provide insight into the cellular origin of the tumor. We integrated gene expression data from rat fetal hepatoblasts and adult hepatocytes with HCC from human and mouse models. Individuals with HCC who shared a gene expression pattern with fetal hepatoblasts had a poor prognosis. The gene expression program that distinguished this subtype from other types of HCC included markers of hepatic oval cells, suggesting that HCC of this subtype may arise from hepatic progenitor cells. Analyses of gene networks showed that activation of AP-1 transcription factors in this newly identified HCC subtype might have key roles in tumor development.

2012 provisional classification criteria for polymyalgia rheumatica: a European League Against Rheumatism/American College of Rheumatology collaborative initiative.

The objective of this study was to develop EULAR/ACR classification criteria for polymyalgia rheumatica (PMR). Candidate criteria were evaluated in a 6-month prospective cohort study of 125 patients with new onset PMR and 169 non-PMR comparison subjects with conditions mimicking PMR. A scoring algorithm was developed based on morning stiffness >45 minutes (2 points), hip pain/limited range of motion (1 point), absence of RF and/or ACPA (2 points), and absence of peripheral joint pain (1 point). A score ≥4 had 68% sensitivity and 78% specificity for discriminating all comparison subjects from PMR. The specificity was higher (88%) for discriminating shoulder conditions from PMR and lower (65%) for discriminating RA from PMR. Adding ultrasound, a score ≥5 had increased sensitivity to 66% and specificity to 81%. According to these provisional classification criteria, patients ≥50 years old presenting with bilateral shoulder pain, not better explained by an alternative pathology, can be classified as having PMR in the presence of morning stiffness>45 minutes, elevated CRP and/or ESR and new hip pain. These criteria are not meant for diagnostic purposes.

Met-regulated expression signature defines a subset of human hepatocellular carcinomas with poor prognosis and aggressive phenotype.

Identification of specific gene expression signatures characteristic of oncogenic pathways is an important step toward molecular classification of human malignancies. Aberrant activation of the Met signaling pathway is frequently associated with tumor progression and metastasis. In this study, we defined the Met-dependent gene expression signature using global gene expression profiling of WT and Met-deficient primary mouse hepatocytes. Newly identified transcriptional targets of the Met pathway included genes involved in the regulation of oxidative stress responses as well as cell motility, cytoskeletal organization, and angiogenesis. To assess the importance of a Met-regulated gene expression signature, a comparative functional genomic approach was applied to 242 human hepatocellular carcinomas (HCCs) and 7 metastatic liver lesions. Cluster analysis revealed that a subset of human HCCs and all liver metastases shared the Met-induced expression signature. Furthermore, the presence of the Met signature showed significant correlation with increased vascular invasion rate and microvessel density as well as with decreased mean survival time of HCC patients. We conclude that the genetically defined gene expression signatures in combination with comparative functional genomics constitute an attractive paradigm for defining both the function of oncogenic pathways and the clinically relevant subgroups of human cancers.

Loss of hepatocyte growth factor/c-Met signaling pathway accelerates early stages of N-nitrosodiethylamine induced hepatocarcinogenesis.

Hepatocyte growth factor (HGF) has been reported to have both positive and negative effects on carcinogenesis. Here, we show that the loss of c-Met signaling in hepatocytes enhanced rather than suppressed the early stages of chemical hepatocarcinogenesis. c-Met conditional knockout mice (c-metfl/fl, AlbCre+/-; MetLivKO) treated with N-nitrosodiethylamine developed significantly more and bigger tumors and with a shorter latency compared with control (w/w, AlbCre+/-; Cre-Ctrl) mice. Accelerated tumor development was associated with increased rate of cell proliferation and prolonged activation of epidermal growth factor receptor (EGFR) signaling. MetLivKO livers treated with N-nitrosodiethylamine also displayed elevated lipid peroxidation, decreased ratio of reduced glutathione to oxidized glutathione, and up-regulation of superoxide dismutase 1 and heat shock protein 70, all consistent with increased oxidative stress. Likewise, gene expression profiling done at 3 and 5 months after N-nitrosodiethylamine treatment revealed up-regulation of genes associated with cell proliferation and stress responses in c-Met mutant livers. The negative effects of c-Met deficiency were reversed by chronic p.o. administration of antioxidant N-acetyl-L-cysteine. N-acetyl-L-cysteine blocked the EGFR activation and reduced the N-nitrosodiethylamine-initiated hepatocarcinogenesis to the levels of Cre-Ctrl mice. These results argue that intact HGF/c-Met signaling is essential for maintaining normal redox homeostasis in the liver and has tumor suppressor effect(s) during the early stages of N-nitrosodiethylamine-induced hepatocarcinogenesis.

[Comparative genomic classification of human hepatocellular carcinoma]. / Az emberi májrák komparatív genomikai osztályozása.

Global transcriptome analysis has been successfully applied to characterize various human tumors, including hepatocellular carcinomas. This novel technology can facilitate early diagnosis, as well as prognostic and therapeutic diversification of cancer patients. To enhance access to the genomic information buried in archived pathology samples, we assessed RT-PCR amplification rates in paraffin-embedded tissues preserved in three different fixatives. Reliable amplification could be achieved from all paraffin-embedded specimens, when the amplicon size did not exceed 225 bp. A longer amplicon size resulted in rapid decrease of yield and reproducibility. In addition, formalin provided superior morphology and better reactivity with claudin-4 and -7 immunohistochemistry. Amplification of the initial sample is often required before transcriptome analysis of clinical specimens could be performed. We introduced a random nonamer primed T3 polymerase reaction into the conventional linear RNA amplification protocol. The modified T3T7 method generated a sense strand product ideal for synthesizing indirectly labeled cDNA templates. Microarray analysis of amplified frozen and laser-microdissected Myc and Myc/TGFalpha mouse liver tumors confirmed good reproducibility (r=0.9) of the reaction and conservation of original transcriptional patterns (r=0.78). Finally, we tested the utility of expression profiling for the classification of human HCC samples. By comparing expression data from HGF-treated c-Met conditional knock-out and control primary mouse hepatocytes, we identified 690 HGF/c-Met target genes. Functional analysis of the significant gene set implicated c-Met as key regulator of hepatocyte motility and oxidative homeostasis. Cross comparison of the c-Met-induced transcription signature with human HCC expression profiles revealed a group of tumors (27%) with potentially activated c-Met signaling (MET+). These tumors were characterized by higher vascular invasion rate, increased microvessel density, and shortened survival. A prediction model based on 111 cross-species conserved c-Met signature genes was able to diversify HCC patients into good and bad prognostic groups with 83-95% accuracy. Our results therefore demonstrate that careful experimental design and state-of-the-art laboratory methods could open the way for global expression profiling of archived and limited availability pathologic samples. Comparative functional genomics based analysis of the cancer transcriptome could lead to novel molecular classification systems which are essential for the introduction of individualized cancer therapeutics.

Detection of HER-2/neu gene amplification in breast carcinomas using quantitative real-time PCR - a comparison with immunohistochemical and FISH results.

The aim of our study was to evaluate the value of quantitative real-time-PCR (qPCR) in the determination of HER-2/neu amplification status of human breast carcinomas by comparing qPCR, FISH and immunohistochemistry results from the same samples. A total of 210 breast carcinomas were examined. Ready-to-use CB11 antibody was applied to detect HER-2/neu oncoprotein expression. In 76 out of 210 cases FISH was performed, and 162 cases were investigated with qPCR. Seventy-five tumors were 2+ or 3+ positive with immunohistochemistry, while 135 samples were either completely negative or 1+. In 45 cases results from all three methods were available. Out of these, in twenty negative and sixteen positive cases both FISH and qPCR led to similar results. The mean qPCR amplification ratio in the concordant positive cases was 5.424 while in the qPCR+/FISH- group the mean ratio was 2.765. Out of 121 samples with scores of 0 or 1+ immunohistochemical result, analyzed also with qPCR, 26 showed HER-2/neu gene amplification. In these cases the mean amplification ratio was 2.53. Comparison of FISH and qPCR together with immunohistochemistry shows that qPCR is more sensitive to detect HER-2/neu gene amplification in tumors scored as 2+ with immunohistochemistry, but the diagnostic cut-off ratio should be defined above 2.7 to avoid high number of false positive cases. Amongst the immunohistochemistry score 2+ cases, 10 of 18 showed gene amplification by qPCR while 10 of 26 by FISH. In conclusion, a well calibrated HER-2/neu qPCR assay may serve as useful alternative to FISH in breast cancer patients.

[Polymyalgia rheumatica]. / Polymyalgia rheumatica.

Polymyalgia rheumatica is a disorder that affects people over 50 years of age. The etiology of the disease has not been hitherto clarified exactly. Its incidence among people over 50 is in the range of 0.1-0.5%. The incidence rate peaks in the age group of 60-70 years. It is also found in younger people, but far less frequently. The diagnosis is based primarily on locomotor complains--namely on pronounced pain, morning stiffness of the shoulder girdle, pelvic girdle and neck. Complaints relating to the arms and legs (such as muscular weakness, oedema, tendonitis etc.) are also observed, however, in one third of the cases. The diagnostic criteria are defined empirically. Polymyalgia rheumatica was formerly considered to be a form of elderly onset rheumatoid arthritis. The progressive erosion process is absent in the case of polymyalgia rheumatica unlike in the case of rheumatoid arthritis. Numerous factors are known, which point to a link between polymyalgia rheumatica and giant cell vasculitis, arthritis, but the precise nature of this relationship remains unknown. Both conditions affect the same age group in the general population and they are even found--not infrequently--in the same patient. Polymyalgia rheumatica can be found in 40% of the patients suffering from arthritis while the histological examination detected mild vasculitis in approximately 10% of the patients suffering for "isolated" polymyalgia rheumatica. The response to be given to the acute phase is similar in both disorders. Scandinavian authors consider polymyalgia rheumatica as the appearance of generalised arthritis. Arthroscopic, nuclear magnetic resonance imaging as well as isotopic studies show unequivocally, that in the background of the osteo-muscular symptoms, complaints, inflammation is to be found partly of the joints but primarily that of the periarticular synovial structures. The above mentioned--dominant--proximal symptoms can often mask the distal locomotor disorders (pitting oedema of the hands and feet, tendonitis, tendosynovitis, carpal tunnel syndrome). The disorder may be accompanied by atypical generalised symptoms (loss of appetite, weight loss, fever, fatigue). An excellent indicators of the acute phase reactions are erythrocyte sedimentation rate, C-reactive protein and interleukin-6. These are suitable for monitoring the effectiveness of the therapy, for indicating a relapse/recurrence. It should be noted, that polymyalgia rheumatica may also be present if the erythrocyte sedimentation rate and C-reactive protein values are low. This disorder is also characterised by fast and effective response to corticosteroid, which should be administered for 1-2 years. In some individual cases a different dosage regime may be necessary: steroid administered in low dosage over a longer period of time. Administration of methotrexate and anti-tumor necrotic factor-alpha may also be considered as alternative or adjuvant therapy for lowering the quantity of corticosteroid. Further multicenter, double blind studies should, however, be performed on large number of patients in this regard.

Mosaicplasty: long-term follow-up.

The successful treatment of chondral and osteochondral defects of the weightbearing surfaces is a challenge for orthopaedic surgeons. Autologous osteochondral transplantation is one method that can be used to create a hyaline or hyaline-like repair in the defect area. Ten years of clinical experience with autologous osteochondral mosaicplasty are described. Clinical scores, imaging techniques, arthroscopy, histological examination of biopsy samples, and cartilage stiffness measurements were used to evaluate the clinical outcomes and quality of the transplanted cartilage in a total of 831 patients who underwent mosaicplasty. According to our investigations, good-to-excellent results were achieved in 92% of the patients treated with femoral condylar implantations, in 87% of those treated with tibial resurfacing, in 79% of those treated with patellar and/or trochlear mosaicplasties, and in 94% of those treated with talarprocedures. Long-term donor-site disturbances, which were assessed using the Bandi score, showed that patients had 3% morbidity after mosaicplasty. Sixty-nine of 83 patients who were followed arthroscopically showed congruent gliding surfaces, histological evidence of the survival of the transplanted hyaline cartilage, and fibrocartilage filling of the donor sites. Four deep infections and 36 painful postoperative hemarthroses were experienced as complications arising from the surgical procedures. On the basis of both these promising results and also those of other similar studies, autologous osteochondral mosaicplasty would appears to be an alternative for the treatment of small and medium-sized focal chondral and osteochondral defects of the weightbearing surfaces of the knee and other weightbearing synovial joints.

Oligonucleotide microarray analysis of aminoallyl-labeled cDNA targets from linear RNA amplification.

Single-stranded long oligonucleotide-based (50- to 70-mer) microarrays offer several advantages over conventional cDNA microarrays. These include the easy preparation of the probes, low cost of array production, and low cross-contamination during probe handling. However, the application of oligonucleotide microarrays for the analysis of global gene expression with small amounts of total RNA using the conventional oligo(dT)-T7 promoter-based amplification is hampered by the single-stranded nature (sense strand) of oligonucleotide probes in microarrays. In this report, we describe modified RNA amplification methods generating antisense-labeled cDNA targets and a successful application for oligonucleotide microarray gene expression analysis. In the first round, mRNA was amplified linearly with oligo(dT)24T7-primed reverse transcription and in vitro transcription by T7 RNA polymerase. In the second round, random 9-mer T3 primers and T3 RNA polymerase were used to generate sense-strand amplified RNA (aRNA). Fluorescently labeled cDNA targets were generated from the aRNA and hybridized to the oligonucleotide microarrays. Our data show that the amplification provides highly reproducible results, as evidenced by a significant correlation between the amplified and nonamplified samples. We also demonstrate that amplification of RNA derived from laser-microdissected tumor samples reproduced the gene expression profiles that were obtained from total RNA isolated from the same samples.

Effect of formalin, acetone, and RNAlater fixatives on tissue preservation and different size amplicons by real-time PCR from paraffin-embedded tissue.

RNA recovered from paraffin-embedded tissue has been reported to be a suitable substrate for polymerase chain reaction. During tissue fixation and paraffin embedding, RNA undergoes degradation, but with certain restrictions, it can be used for gene expression studies. At the same time, formalin-fixed, paraffin embedded histopathology archives contain an unestimable collection, which could be analyzed to investigate changes in mRNA expression in pathologic processes. To decide for future tissue conservation of pathology samples, it would be reasonable to satisfy both histologic and molecular biologic needs. The effect of three different fixation methods, RNAlater (SIGMA R 0901, St Louis, MO), acetone, and formalin, were compared by histology, immunohistochemistry, and real-time PCR. To assess tissue structure preservation and antigenicity, hematoxylin-eosin staining and immunohistochemistry were performed; to assess RNA quality, RNA was extracted and the transcription of different amplicon sizes (121, 225, 406 bp for GAPDH; 166, 310, 536 bp for beta globin) were examined on human endometrium samples. The most adequate tissue preservation was found in case of formalin fixation, while there were no significant differences in the three fixatives' yields for various size real-time PCR amplicons. Longer amplicons (above approximately 225 bp) have limited use for gene expression studies, while shorter amplicons could give more reliable results.

Similarities and differences in hepatitis B and C virus induced hepatocarcinogenesis.

Hepatocellular carcinoma (HCC), the major manifestation of primary liver cancer, is one of the most frequent and malignant diseases worldwide. Among other environmental factors, hepatitis viruses, as the hepatitis B (HBV) and hepatitis C (HCV) viruses, are to be listed in the etiology of HCC. Both of these viruses cause a wide spectrum of clinical manifestations, ranging from healthy carrier state to acute and chronic hepatitis, cirrhosis and HCC. HBV and HCV are different viruses in structure: HBV contains a DNA genome which replicates through an RNA intermediate and requires an active viral reverse transcriptase (RT) polymerase enzyme, while HCV is an RNA virus which has no RT activity and replicates on the cellular membrane by RNA replication. In this review we discuss how these two biologically diverse viruses use common pathways to induce hepatocarcinogenesis despite their significant structural and viral cycle differences. A summary is also given of several observable common and different features. Direct integration of HBV viral sequences into the host genome increases the genomic instability, which does not occur in HCV infection. However, viral proteins may directly play a significant role in the induction of carcinogenesis by both viruses.

[Hepatitis viruses and hepatocarcinogenesis]. / Hepatitisvírusok és hepatocarcinogenesis.

INTRODUCTION: Hepatocellular carcinoma (HCC) is one of the most frequent malignancies worldwide. Hepatitis viruses, as the hepatitis virus B (HBV) and hepatitis virus C (HCV), among other environmental factors, are undoubtedly listed in the etiology of HCC. Studies indicate that in the near future viral hepatitis will be of increasing importance in the etiology of HCC. AIM: This review briefly discusses the known carcinogenic effects of HBV and HCV in the light of experimental and human studies. RESULTS: Data show that viral proteins may directly interfere with gene products responsible for cell proliferation and cell growth, therefore this direct effect may influence the basic mechanism of the cell cycle. Many other signal transduction cascades may be affected as well. Direct integration of HBV viral sequences into the host genome increases the genomic instability. The genomic imbalance allows the development and survival of malignant clones bearing defected genomic information. CONCLUSION: HBV and HCV infection induce indirect and direct mechanisms through cellular damage, increased regeneration and cell proliferation, therefore enhancing the development of HCC.

[Hepatitis C virus RNA in the skin eruption from patients with prurigo and chronic hepatitis C]. / Hepatitis C-vírus RNA jelenléte krónikus C-hepatitishez társult prurigóban.

UNLABELLED: Hepatitis C virus RNA in the skin eruption from patients with prurigo and chronic hepatitis C. Since the discovery of hepatitis C virus (HCV) in 1989, many cutaneous disorders have been observed in patients suffering from chronic HCV infection. The relationship between HCV infection and cryoglobulinemia and porphyria cutanea tarda is clearly established, however, the link between HCV and other skin diseases is still controversial. AIM: Two patients with intense pruritus and secondary prurigo in chronic C hepatitis have been presented. METHODS: The chronic hepatitis C of the patients were proved by elevated ALT and AST level, anti HCV (ELISA), HCV-PCR serological examination and liver biopsy. The skin lesions were accompanied by severe itching. According to clinical symptoms the patients suffered from prurigo simplex. RESULTS: HCV RNA in the skin specimen from the biopsy of the skin lesion was detected by RT PCR method, but the non affected skin specimen from the patients was HCV RNA negative. CONCLUSIONS: This report is a case of prurigo simplex with chronic C hepatitis proving a direct relation between the HCV infection and prurigo.

Increased expression of claudin-1 and claudin-7 in liver cirrhosis and hepatocellular carcinoma.

Claudins have been reported to be differentially regulated in malignancies and implicated in the process of carcinogenesis and tumor progression. Claudin-1 has been described as key factor in the entry of hepatitis C virus (HCV) into hepatocytes and as promoter of epithelial-mesenchymal transition in liver cells. The objective of the current study was to characterize claudin expression in hepatocellular carcinoma (HCC) as well as HCC-surrounding and normal liver samples with respect to cirrhosis and HCV infection. Expression of claudin-1, -2, -3, -4, and -7 was measured by morphometric analysis of immunohistochemistry, and Western blotting in 30 HCCs with 30 corresponding non-tumorous tissues and 6 normal livers. Claudin-1 and -7 protein expression was found significantly elevated in cirrhosis when compared with non-cirrhotic liver. HCCs developed in cirrhotic livers showed even higher expression of claudin-1 contrary to decreased claudin-7 expression when compared with cirrhosis. With reference to HCV status, HCCs or surrounding livers of HCV-infected samples did not show significant alterations in claudin expression when compared with HCV-negative specimens. Cirrhotic transformation associates with elevated claudin-1 and -7 expressions in both non-tumorous liver and HCC. The fact that no significant differences in claudin expression were found regarding HCV-positivity in our sample set suggests that HCV infection alone does not induce a major increase in the total amount of its entry co-factor claudin-1. Increased expression of claudin-1 seems to be a consequence of cirrhotic transformation and might contribute to a more effective HCV entry and malignant transformation.

Patient-reported outcomes in polymyalgia rheumatica.

OBJECTIVE: To prospectively evaluate the disease course and the performance of clinical, patient-reported outcome (PRO) and musculoskeletal ultrasound measures in patients with polymyalgia rheumatica (PMR). METHODS: The study population included 85 patients with new-onset PMR who were initially treated with prednisone equivalent dose of 15 mg daily tapered gradually, and followed for 26 weeks. Data collection included physical examination findings, laboratory measures of acute-phase reactants, and PRO measures. Ultrasound evaluation was performed at baseline and Week 26 to assess for features previously reported to be associated with PMR. Response to corticosteroid treatment was defined as 70% improvement in PMR on visual analog scale (VAS). RESULTS: At baseline, 77% had hip pain in addition to shoulder pain and 100% had abnormal C-reactive protein or erythrocyte sedimentation rate. On ultrasound, 84% had shoulder findings and 32% had both shoulder and hip findings. Response to corticosteroid treatment occurred in 73% of patients by Week 4 and was highly correlated with percentage improvement in other VAS measures. Presence of ultrasound findings at baseline predicted response to corticosteroids at 4 weeks. Factor analysis revealed 6 domains that sufficiently represented all the outcome measures: PMR-related pain and physical function, an elevated inflammatory marker, hip pain, global pain, mental function, and morning stiffness. CONCLUSION: PRO measures and inflammatory markers performed well in assessing disease activity in patients with PMR. A minimum set of outcome measures consisting of PRO measures of pain and function and an inflammatory marker should be used in practice and in clinical trials in PMR.

Loss of c-Met disrupts gene expression program required for G2/M progression during liver regeneration in mice.

BACKGROUND: Previous work has established that HGF/c-Met signaling plays a pivotal role in regulating the onset of S phase following partial hepatectomy (PH). In this study, we used Met(fl/fl);Alb-Cre(+/-) conditional knockout mice to determine the effects of c-Met dysfunction in hepatocytes on kinetics of liver regeneration. METHODOLOGY/PRINCIPAL FINDING: The priming events appeared to be intact in Met(fl/fl);Alb-Cre(+/-) livers. Up-regulation of stress response (MAFK, IKBZ, SOCS3) and early growth response (c-Myc, c-Jun, c-Fos, DUSP1 and 6) genes as assessed by RT-qPCR and/or microarray profiling was unchanged. This was consistent with an early induction of MAPK/Erk and STAT3. However, after a successful completion of the first round of DNA replication, c-Met deficient hepatocytes were blocked in early/mid G2 phase as shown by staining with phosphorylated form of histone H3. Furthermore, loss of c-Met in hepatocytes diminished the subsequent G1/S progression and delayed liver recovery after partial hepatectomy. Upstream signaling pathways involved in the blockage of G2/M transition included lack of persistent Erk1/2 activation and inability to up-regulate the levels of Cdk1, Plk1, Aurora A and B, and Mad2 along with a defective histone 3 phosphorylation and lack of chromatin condensation. Continuous supplementation with EGF in vitro increased proliferation of Met(fl/fl);Alb-Cre(+/-) primary hepatocytes and partially restored expression levels of mitotic cell cycle regulators albeit to a lesser degree as compared to control cultures. CONCLUSION/SIGNIFICANCE: In conclusion, our results assign a novel non-redundant function for HGF/c-Met signaling in regulation of G2/M gene expression program via maintaining a persistent Erk1/2 activation throughout liver regeneration.

Central role of c-Myc during malignant conversion in human hepatocarcinogenesis.

Hepatocarcinogenesis is a multistage process in which precursor lesions progress into early hepatocellular carcinomas (eHCC) by sequential accumulation of multiple genetic and epigenetic alterations. To decode the molecular events during early stages of liver carcinogenesis, we performed gene expression profiling on cirrhotic (regenerative) and dysplastic nodules (DN), as well as eHCC. Although considerable heterogeneity was observed at the regenerative and dysplastic stages, overall, 460 differentially expressed genes were detected between DN and eHCC. Functional analysis of the significant gene set identified the MYC oncogene as a plausible driver gene for malignant conversion of the DNs. In addition, gene set enrichment analysis revealed global activation of the MYC up-regulated gene set in eHCC versus dysplasia. Presence of the MYC signature significantly correlated with increased expression of CSN5, as well as with higher overall transcription rate of genes located in the 8q chromosome region. Furthermore, a classifier constructed from MYC target genes could robustly discriminate eHCC from high-grade and low-grade DNs. In conclusion, our study identified unique expression patterns associated with the transition of high-grade DNs into eHCC and showed that activation of the MYC transcription signature is strongly associated with the malignant conversion of preneoplastic liver lesions.

Hepatocyte-specific c-Met deletion disrupts redox homeostasis and sensitizes to Fas-mediated apoptosis.

The hepatocyte growth factor and its receptor c-Met direct a pleiotropic signal transduction pathway that controls cell survival. We previously demonstrated that mice lacking c-Met (Met-KO) in hepatocytes were hypersensitive to Fas-induced liver injury. In this study, we used primary hepatocytes isolated from Met-KO and control (Cre-Ctrl) mice to address more directly the protective effects of c-Met signaling. Loss of c-Met function increased sensitivity to Fas-mediated apoptosis. Hepatocyte growth factor suppressed apoptosis in Cre-Ctrl but not Met-KO hepatocytes concurrently with up-regulation of NF-kappaB and major antiapoptotic proteins Bcl-2 and Bcl-xL. Intriguingly, Met-KO hepatocytes exhibited intrinsic activation of NF-kappaBas well as Bcl-2 and Bcl-xL. Furthermore, unchallenged Met-KO cells displayed oxidative stress as evidenced by overproduction of reactive oxygen species, which was associated with greater NADPH and Rac1 activities, was blocked by the known NADPH oxidase inhibitors, and was paralleled by increased lipid peroxidation and reduced glutathione (GSH) content. N-Acetylcysteine, an antioxidant and GSH precursor, significantly reduced Jo2-induced cell death. Conversely, the GSH-depleting agent buthionine sulfoximine completely abolished the protective effects of N-acetylcysteine in Met-KO hepatocytes. In conclusion, genetic inactivation of c-Met in mouse hepatocytes caused defects in redox regulation, which may account for the increased sensitivity to Fas-induced apoptosis and adaptive up-regulation of NF-kappaB survival signaling. These data provide evidence that intact c-Met signaling is a critical factor in the protection against excessive generation of endogenous reactive oxygen species.