KIT Mutation Incidence and Pattern of Melanoma in Central Europe.

Data on the KIT mutation rate in melanoma in the central European region is missing. Accordingly, in a cohort of 79 BRAF/NRAS double wild type cutaneous melanoma and 17 mucosal melanoma KIT mutation was assessed by Sanger sequencing of exons 9,11,13,17 and 18. In this cutaneous melanoma cohort KIT mutation frequency was found to be 34/79 (43.04%) with a significantly higher rate in acrolentiginous melanoma (ALM) as compared to UV-induced common variants (20/34, 58.8% versus 14/45, 31.1%, p = 0.014). In the double wild type mucosal melanoma cohort the KIT mutation frequency was found to be comparable (41.2%). The actual frequency of KIT mutation in the original 227 patient cutaneous melanoma cohort was 34/227, 14.9%. Exon 11 was the most frequent mutation site (44.7%) followed by exon 9 (21.1%) equally characterizing UV-induced common histotypes and ALM tumors. In mucosal melanoma exon 9 was the most frequently involved exon followed by exon 13 and 17. KIT mutation hotspots were identified in exon 9 (c482/491/492), in exon 11 (c559,c572, c570), in exon 13 (c642), in exon 17 (c822) and in exon 18 (c853). The relatively high KIT mutation rate in cutaneous melanoma in this central-European cohort justifies regular testing of this molecular target in this entity, not only in mucosal variants.

Characterisation of bioenergetic pathways and related regulators by multiple assays in human tumour cells.

BACKGROUND: Alterations in cellular metabolism are considered as hallmarks of cancers, however, to recognize these alterations and understand their mechanisms appropriate techniques are required. Our hypothesis was to determine whether dominant bioenergetic mechanism may be estimated by comparing the substrate utilisation with different methods to detect the labelled carbon incorporation and their application in tumour cells. METHODS: To define the bioenergetic pathways different metabolic tests were applied: (a) measuring CO2 production from [1-(14)C]-glucose and [1-(14)C]-acetate; (b) studying the effect of glucose and acetate on adenylate energy charge; (c) analysing glycolytic and TCA cycle metabolites and the number of incorporated (13)C atoms after [U-(13)C]-glucose/[2-(13)C]-acetate labelling. Based on [1-(14)C]-substrate oxidation two selected cell lines out of seven were analysed in details, in which the highest difference was detected at their substrate utilization. To elucidate the relevance of metabolic characterisation the expression of certain regulatory factors, bioenergetic enzymes, mammalian target of rapamycin (mTOR) complexes (C1/C2) and related targets as important elements at the crossroad of cellular signalling network were also investigated. RESULTS: Both [U-(13)C]-glucose and [1-(14)C]-substrate labelling indicated high glycolytic capacity of tumour cells. However, the ratio of certain (13)C-labelled metabolites showed detailed metabolic differences in the two selected cell lines in further characterisation. The detected differences of GAPDH, ß-F1-ATP-ase expression and adenylate energy charge in HT-1080 and ZR-75.1 tumour cells also confirmed the altered metabolism. Moreover, the highly limited labelling of citrate by [2-(13)C]-acetate-representing a novel functional test in malignant cells-confirmed the defect of TCA cycle of HT-1080 in contrast to ZR-75.1 cells. Noteworthy, the impaired TCA cycle in HT-1080 cells were associated with high mTORC1 activity, negligible protein level and activity of mTORC2, high expression of interleukin-1ß, interleukin-6 and heme oxygenase-1 which may contribute to the compensatory mechanism of TCA deficiency. CONCLUSIONS: The applied methods of energy substrate utilisation and other measurements represent simple assay system using (13)C-acetate and glucose to recognize dominant bioenergetic pathways in tumour cells. These may offer a possibility to characterise metabolic subtypes of human tumours and provide guidelines to find biomarkers for prediction and development of new metabolism related targets in personalized therapy.

Microarray profiling reveals that placental transcriptomes of early-onset HELLP syndrome and preeclampsia are similar.

BACKGROUND: The involvement of the placenta in the pathogenesis of preeclampsia and HELLP syndrome is well established, and placental lesions are also similar in these two syndromes. Here we aimed to examine the placental transcriptome and to identify candidate biomarkers in early-onset preeclampsia and HELLP syndrome. METHODS: Placental specimens were obtained at C-sections from women with early-onset preeclampsia and HELLP syndrome, and from controls who delivered preterm or at term. After histopathological examination, fresh-frozen placental specimens were used for microarray profiling and validation by qRT-PCR. Differential expression was analysed using log-linear models while adjusting for gestational age. Gene ontology and pathway analyses were used to interpret gene expression changes. Tissue microarrays were constructed from paraffin-embedded placental specimens and immunostained. RESULTS: Placental gene expression was gestational age-dependent among preterm and term controls. Out of the 350 differentially expressed genes in preeclampsia and 554 genes in HELLP syndrome, 224 genes (including LEP, CGB, LHB, INHA, SIGLEC6, PAPPA2, TREM1, and FLT1) changed in the same direction (elevated or reduced) in both syndromes. Many of these encode proteins that have been implicated as biomarkers for preeclampsia. Enrichment analyses revealed similar biological processes, cellular compartments and biological pathways enriched in early-onset preeclampsia and HELLP syndrome; however, some processes and pathways (e.g., cytokine-cytokine receptor interaction) were over-represented only in HELLP syndrome. CONCLUSION: High-throughput transcriptional and tissue microarray expression profiling revealed that placental transcriptomes of early-onset preeclampsia and HELLP syndrome largely overlap, underlying a potential common cause and pathophysiologic processes in these syndromes. However, gene expression changes may also suggest a more severe placental pathology and pronounced inflammatory response in HELLP syndrome than in preeclampsia.

Leptin-based glycopeptide induces weight loss and simultaneously restores fertility in animal models.

AIM: To design, manufacture and test a second generation leptin receptor (ObR) agonist glycopeptide derivative. The major drawback to current experimental therapies involving leptin protein is the appearance of treatment resistance. Our novel peptidomimetic was tested for efficacy and lack of resistance induction in rodent models of obesity and appetite reduction. METHODS: The glycopeptide containing two additional non-proteinogenic amino acids was synthesized by standard solid-phase methods. Normal mice were fed with peanuts until their blood laboratory data and liver histology showed typical signs of obesity but not diabetes. The mice were treated with the peptidomimetic at 0.02, 0.1 or 0.5 mg/kg/day intraperitoneally side-by-side with 0.1 mg/kg/day leptin for 11 days. After termination of the assay, the blood cholesterol and glucose amounts were measured, the liver fat content was visualized and quantified and the remaining mice returned to normal diet and were allowed to mate. In parallel experiments normal rats were treated intranasally with the glycopeptide at 0.1 mg/kg/day for 10 days. RESULTS: The 12-residue glycosylated leptin-based peptidomimetic E1/6-amino-hexanoic acid (Aca) was designed to target a principal leptin/ObR-binding interface. E1/Aca induced leptin effects in ObR-positive cell lines at picomolar concentrations and readily crossed the blood-brain barrier (BBB) following intraperitoneal administration. The peptide initiated typical leptin-dependent signal transduction pathways both in the presence and absence of leptin protein. The peptide also reduced weight gain in mice fed with high-fat peanut diet in a dose-dependent manner. Obese mice receiving peptide E1/Aca at a 0.5 mg/kg/day dose lost weight, corresponding to a net 6.5% total body weight loss, while similar mice treated with leptin protein did not. Upon cessation of the weight loss treatment, several obesity-related pathologies (i.e. abnormal metabolic profile and liver histology as well as infertility) normalized in peptide-, but not leptin-treated, mice. Peptide E1/Aca added intranasally to growing normal rats decelerated normal weight gain corresponding to a net 6.8% net total body weight loss with statistical significance. CONCLUSIONS: No resistance induction to peptide E1/Aca or toxicity in either obese or healthy rodents was observed, indicating the potential for widespread utility of the peptidomimetic in the treatment of leptin-deficiency disorders. We provide additional proof for the hypothesis that difficulties in current leptin therapies reside at the BBB penetration stage, and we document that by either glycosylation or intranasal peptide administration we can overcome this limitation.

Effect of syndecan-1 overexpression on mesenchymal tumour cell proliferation with focus on different functional domains.

OBJECTIVES: Syndecan-1 is a transmembrane proteoglycan involved in various biological processes. Its extracellular, transmembrane and cytoplasmic domains may all participate in signal transduction. The aim of this study was to investigate the biological roles of these domains of syndecan-1. MATERIALS AND METHODS: We transfected cells of two mesenchymal tumour cell lines with a full-length syndecan-1 construct and three truncated variants, namely 78 construct lacking the EC domain with exception of DRKE sequence; 77 construct lacking extracellular the whole domain and RMKKK corresponding to a short cytoplasmic motif. Subcellular distribution was revealed using confocal laser microscopy. Overexpression of the constructs was verified using real-time RT-PCR and by FACS analysis and effects of syndecan-1 on cell behaviour were explored. Cell cycle analysis allowed for dissection of mechanisms regulating cell proliferation. RESULTS: Overexpression of syndecan-1 influenced expression profile of the other syndecan members, and decreased tumour cell proliferation significantly by two mechanisms, as follows: increased length of G0/G1 phase was the most evident change in RMKKK and 77 transfectants, whereas prolonged S phase was more obvious in full-length transfectants. Overexpression of syndecan-1 changed the tumour cell morphology in an epithelioid direction. CONCLUSIONS: Both full-length and truncated syndecan-1 inhibited proliferation of the mesenchymal tumour cells, providing new insights into the importance for cancer growth of different functional domains of this proteoglycan.

Detection of high-risk HPV (16, 18, 33) in situ cancer of the cervix by PCR technique.

OBJECTIVE: The purpose of this study was to collect data about the incidence of high-risk HPV (16, 18, 33) types in in situ cervical cancers, and to evaluate the reliability of the morphological signs of HPV infection by comparing the presence of these signs to the PCR-proven HPV virus infection. METHODS: Fifty patients who underwent conisation at the Department of Obstetrics and Gynecology of Semmelweis University, Budapest, Hungary because of in situ cervical cancer were examined retrospectively for the presence of HPV infection by the PCR technique. The direct and indirect morphological signs of HPV infection identified in the histological and cytological samples were compared to the actual results of virus DNA amplification by PCR in the identical histological sections. The evaluation of the cytological smears and the histological sections was accomplished independently by two different pathologists. RESULTS: E6 open reading frame of HPV 16, 18 or 33 was detected by PCR in 56% (28 cases) of the histological sections of the 50 examined patients with in situ cancer. In 92% (26 patients) of the 28 HPV positive patients one HPV type was detected, while in one of the remaining two cases two HPV types (16/33), or all three types could be detected. The direct morphological signs for HPV infection proved to be 75% sensitive and 50% specific when compared to the results of PCR. Their predictive value for HPV infection was 65%. For the indirect HPV signs the sensitivity was 64% and specificity 31%. The predictive value, prognosticating the presence of HPV 16, 18, 33 infection was 54% in the same sections. Using significance analysis no significant relationship (p = 0.7728) could be detected between the positivity of indirect signs and the presence of HPV 16, 18, 33 infection, while in case of direct signs the relationship was almost significant (p = 0.0675). The joint testing of the direct and indirect signs did not improve the results (p = 0.1338). During the review of the cytological smears the specificity of the cytology in predicting true HPV infections was found to be 68% and sensitivity was 20%. The predictive value was only 50%. A significance analysis was not accomplished by this diagnostic method because of the missing data (see text). CONCLUSION: The method of Nawa et al. seems to be a reliable approach for the detection of HPV DNA in paraffin-embedded material. The three main types of HPV (16, 18, 33) are probably represented in lower percentages in CIN III in Hungary, but a larger survey is needed to obtain reliable data. The direct and indirect morphological signs of HPV infection failed to show a significant relationship with the PCR proven presence of HPV 16, 18, 33.

Increased risk for cancer in multiple myeloma patients and their first-degree relatives.

Analyzing data of 125 multiple myeloma patients, the authors found a 40-fold increased tumor incidence among the patients and their first-degree relatives as compared to the average population. These tumors were the same as those usually found among Hungarians. There was no difference as to the patient's blood group antigens in the families of myeloma patients with or without other tumor. IgA-type disease was found to be relatively more frequent in the group of patients who had tumor besides myeloma. In a prospective study, authors could not find mutation of suppressor gene p53 in 14 patients and their 16 healthy first-degree relatives. This may indicate that there is no p53 suppressor gene alteration responsible for the high-risk condition for tumorgenesis in this population.

Expression of decorin, transforming growth factor-beta 1, tissue inhibitor metalloproteinase 1 and 2, and type IV collagenases in chronic hepatitis.

Decorin is a small extracellular matrix proteoglycan. It binds and modulates transforming growth factor (TGF)-beta 1 action, the major stimulator of fibrogenesis. Its role in the pathogenesis of human liver cirrhosis is unknown. Therefore, we studied the relationship of the 2 proteins in normal human liver and in 43 chronic hepatitis and liver cirrhosis specimens. To understand the mechanism that maintains matrix deposition in stage IV hepatitis, we studied expression of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2, as well as the activities of type IV collagenases. Gene expression was analyzed on messenger RNA and protein level by morphologic and biochemical approaches. Decorin proved to be an early marker of fibrogenesis, and its deposition increased parallel to that of TGF-beta 1 and to inflammatory activity. Liver fibrosis progressed despite high temporospatial expression of decorin with TGF-beta 1. Neither decorin nor TGF-beta 1 protein deposition increased further in cirrhosis with low inflammatory activity, suggesting that impaired extracellular matrix catabolism rather than active production plays a role in this stage. This possibility was supported by high message levels of metalloproteinase inhibitors, no 72-kd collagenase activities, and low 92-kd collagenase activities.

Expression of a decorin-like moleculein human melanoma.

Decorin, a member of the family of small leucin-rich proteoglycans, has originally been described as a secreted proteoglycan component of the connective tissues, and has been implicated in the negative regulation of cell proliferation directly or via interactions with TGF-beta. It was reported to be generally absent from tumor cells. Here we show that human melanoma cell lines express a decorin-like molecule. We detected decorin mRNA by RT-PCR in 7 out 7 human melanoma lines characterized by various metastatic potential. Using polyclonal antiserum against the core protein of decorin, the typical 80-120 kD glycanated form as well as a high molecular weight aberrant version (200-210 kD) of decorin were demonstrated by Western blot technique in the culture supernatants as well as in lysates of human melanoma cells. Finally, decorin epitope was also demonstrated immunohistochemically in human melanoma xenografts, as well as in tumor cells of surgically resected melanomas but not in melanocytes of nevi. The expression of this aberrant decorin did not inhibit the in vitroor in vivogrowth of human melanoma cells, and it was independent of their metastatic potential. Human melanoma cell lines expressing aberrant decorin retained sensitivity to the antiproliferative and gelatinase-stimulatory effects of exogenous TGF-beta.

Cytokine regulation of syndecan expression in cells of liver origin.

Syndecan-1 and syndecan-2-two cell surface heparan sulfate proteoglycans-were described in normal human liver. Proteoglycans can modulate the effect of cytokines, and cytokines can influence the expression of proteoglycans. In the present work the regulatory effect of IL-1beta, IL-6, TNF-alpha, IFN-gamma and TGF-beta1 on syndecan-1 and syndecan-2 expression of hepatocytes, hepatoma cell lines, liver and skin fibroblasts has been studied. All cytokines were able to influence the steady state level of syndecan-1 and syndecan-2 mRNA. Their action was target cell specific resulting in either up- or downregulation except TGF-beta1 that was stimulatory in all cell types examined.

Effect of heparin and liver heparan sulphate on interaction of HepG2-derived transcription factors and their cis-acting elements: altered potential of hepatocellular carcinoma heparan sulphate.

Proteoglycan assembly in malignant tumours is subject to profound changes. The significance of these alterations is not well understood; especially, their role in nuclear regulation is a topic for debate. The capacity of heparin and liver carcinoma heparan sulphate (HS) to alter DNA-transcription factor interactions has been studied to provide further evidence concerning the regulatory potential of glycosaminoglycan (GAG) in the nucleus. Experiments both in vitro and in vivo indicated that heparin and HS are capable of inhibiting the interaction of transcription factors with their consensus oligonucleotide elements. Among five transcription factors studied, AP-1, SP-1, ETS-1 and nuclear factor kappaB proved to be sensitive to heparin and heparan sulphate, whereas TFIID was hardly inhibited in either in vitro or in vivo systems. Interestingly, HS from peritumoral liver was five times more effective than heparin. Liver carcinoma HS was less effective than liver HS, but its activity was comparable with that of heparin. These results indicate that the structural differences of GAG chains strongly influence their biological behaviour. The loss of their recognized functional activity in malignant tumours might promote the development of uncontrolled growth and gene expression favouring the neoplastic process.

Decorin and actin expression and distribution in patients with chronic hepatitis C following interferon-alfa-2b treatment.

BACKGROUND/AIMS: Chronic hepatitis C can lead to cirrhosis and hepatocellular carcinoma. Interferon-alfa therapy may prevent the progression of the disease. The expressions of decorin and alfa-smooth muscle cell actin of the extracellular matrix play a central role in liver fibrosis. We set out to assess the expressions of these proteins in chronic hepatitis C patients, and to evaluate how they can be modified by interferon-alfa therapy. METHODS: Twenty chronic hepatitis C patients received interferon-alfa-2b therapy for 6 months (group I) or 12 months (group II). Liver biopsy samples were taken before and after the therapy. The alfa-smooth muscle actin-positive cells were determined with a monoclonal antibody, and decorin expression was detected with a polyclonal antibody. The cells were evaluated with a semiquantitative scoring method. For statistical analysis, non-parametric methods were used. RESULTS: Before the therapy, alfa-smooth muscle actin-labeled cells and marked decorin expression were present throughout all the acinar zones. Interferon-alfa-2b therapy resulted in significant decreases in both the number of alfa-smooth muscle actin-positive cells and the decorin expression. The alfa-smooth muscle actin-positive cells and decorin expression correlated with the histological activity index (R=0.72, p<0.03, R=0.68, p<0.05). CONCLUSIONS: This study demonstrates that a large number of alfa-smooth muscle actin-positive cells and a marked decorin expression are frequent findings in chronic hepatitis C. Treatment with interferon-alfa-2b for 12 months reduced the number of labeled cells and the decorin expression. The results suggest that interferon-alfa-2b is capable of interfering with fibrogenesis in an early and presumably still reversible phase of chronic hepatitis C.

Experimental and human liver fibrogenesis.

In this work, we provide an overview of our results obtained by studying the role of transforming growth factor beta1 and proteoglycans in liver fibrogenesis. It has been found that transforming growth factor beta1 is one of the most important stimulators of extracellular matrix synthesis in the liver. In chronic liver injury, desmin-positive non-parenchymal liver cells expressed transforming growth factor beta1. The extracellular localization of the growth factor correlated well with types I, III and IV procollagen-alpha, which were detected in the fibrous septa of chronically injured livers. A similar distribution pattern was observed in human specimens. To identify the role of transforming growth factor beta1 in liver extracellular matrix protein synthesis, transforming growth factor beta1-positive transgenic mice were generated. Animals expressing the growth factor in their liver showed spontaneous liver fibrosis. Proteoglycans also participate in fibrogenesis. The majority of liver-specific heparan sulfate proteoglycans, such as syndecan-1 and fibroglycan, are produced by hepatocytes. The extracellular matrix proteoglycans decorin and perlecan are synthesized by non-parenchymal liver cells. The amount of the latter is very low in normal liver, but increases dramatically in liver fibrosis. The effect of regulatory factors on liver proteoglycans seems to be cell type-specific. In contrast to previous observations, elevated amounts of decorin did not inhibit the action of transforming growth factor beta1 in the liver.

Human and experimental hepatocarcinogenesis.

Human liver cancer is increasing worldwide, including in Hungary. The detection of liver tumors in premalignant or early malignant states is essential for successful treatment. MC-29 virus-induced chicken hepatoma and rodent, fish and monkey models for chemical hepatocarcinogenesis were studied and compared to humans. Changes in phenotypic enzyme alterations and in the expression of certain oncogens and growth factors characterize the experimentally induced hepatomas, and might also be characteristic of human premalignant and malignant focal liver lesions. Fish hepatocarcinogenesis is useful for studying compounds in environmental pollution. Increased expression of transforming growth factor á can be observed both in experimental and human liver tumors. Increased tumor incidence was detected in transgene mice containing both transforming growth factor alpha and c-myc genes. Animal models of hepatocarcinogenesis help to understand the development of liver tumors. Methods applied in studies using those models are useful in the study of premalignant and malignant human liver lesions.

Inhibition of DNA topoisomerase I activity by heparan sulfate and modulation by basic fibroblast growth factor.

Eukaryotic DNA topoisomerase I catalyzes changes in the superhelical state of duplex DNA by transiently breaking single strands thereby allowing relaxation of both positively and negatively supercoiled DNA. Topoisomerase I is a nuclear enzyme localized at active sites of transcription, and abnormal levels of the enzyme have been observed in a variety of neoplasms. Because the enzyme binds heparin and, given the presence of heparan sulfate within the nuclei of mammalian cells, we sought to investigate the interaction between topoisomerase I and sulfated glycosaminoglycans isolated from normal and neoplastic human liver. The results demonstrated that low concentrations (approximately 100 nM) of heparan sulfate from normal liver but not from its malignant counterpart effectively blocked relaxation of supercoiled DNA driven by either purified holoenzyme or topoisomerase I activity present in nuclear extracts of three malignant cell lines. Heparin acted at even lower (approximately 10 nM) concentrations. Moreover, we show that basic fibroblast growth factor could interfere with this heparan sulfate/heparin-driven inhibition and that both basic fibroblast growth factor and heparin-binding sites co-localized in the nuclei of U937 leukemic cells. Our results suggest that DNA topoisomerase I activity may be modulated in vivo by specific heparan sulfate moieties present in normal cells but markedly reduced or absent in their transformed counterparts.

Role of sinusoidal heparan sulfate proteoglycan in liver metastasis formation.

Previous studies have indicated that the predominant sites of tumor cell extravasation in the liver are the sinusoidal vessels, where tumor cells contact the sinusoidal endothelium and the subendothelial extracellular matrix containing the basic components of the basement membrane. We studied the role of sinusoidal extracellular matrix in metastatsis formation by 3LL-HH murine tumor cells selected for their preferential liver colonization. 3LL-HH tumor cells did not efficiently adhere to cryosections of the liver, but they recognized the sinusoids and vessel walls. Pre-treatment of the mice with polyclonal anti-basement membrane antibodies [anti-laminin, anti-fibronectin and anti-heparan sulfate proteoglycan (HSPG)] significantly modulated the organ distribution of tumor cell colonies following intracardial injection: all 3 antibodies inhibited kidney colonization; anti-laminin and anti-fibronectin antibodies inhibited lung colonization; and only anti-HSPG antibody inhibited liver colonization. In several organs such as the heart, stomach, pancreas and bladder, anti-basement membrane antibody treatment did not alter the process of colonization. Immunofluorescence studies showed that anti-HSPG antibody recognized the basement membranes of sinusoids and blood vessels. Our data suggest a specific involvement of sinusoidal HSPG in the liver colonization of 3LL-HH cells.

Expression of syndecan-1 in human B cell chronic lymphocytic leukaemia.

Syndecan-1 is considered an important transmembrane proteoglycan in cell-microenvironment interactions, but its exact function in normal or in transformed B cells is still unknown. In this study, RNA was isolated from peripheral cells of chronic lymphocytic leukaemia (B-CLL) and 'normal', non-leukaemic patients, as controls. Reverse PCR showed no or very low syndecan-1 mRNA expression in controls, while in 11/13 B-CLL the circulating leukaemic cells expressed syndecan-1. Similar results were obtained for interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6). Furthermore, syndecan-1 protein was detected in the majority of circulating B-CLL cells by flow cytometry and immunocytochemistry using anti-syndecan-1 MAb. Control cells were practically negative. Further study is required to understand the biological significance of syndecan-1 on B-CLL cells.

Syndecan-1 - A new piece in B-cell puzzle.

Syndecans are transmembrane proteoglycans, with core proteins mainly decorated with heparan sulfate chains. Syndecan-1 is expressed in a tissue-, cell-and differentiation-specific manner. Its extra-cellular domain can bind via HS chains to matrix elements, to growth factors (especially "heparin-binding" proteins) and to certain biological agents. The ectodomain released by proteolysis can also be functionally active. The cytoplasmic domain can take part in signaling processes as well as in modifying cell shape. In hematopoietic cells syndecan-1 is expressed in normal pre-B-cells and plasma cells, as well as in plasmocytoid and lymphoplasmocytoid malignancies. According to our study syndecan-1 is expressed in B-CLL cells both in tissue environment and in circulation.

Proteoglycan gene expression in rat liver after partial hepatectomy.

Liver regeneration is regulated by several factors. Among these extracellular matrix plays a crucial role in the restoration of normal structure. Proteoglycans are major components of extracellular matrix and they are able to bind growth factors implicated in liver growth. We studied syndecan, perlecan, fibroglycan, and decorin expression after partial hepatectomy in rats by Northern blot analysis. A strong early upregulation was observed at 30 min in decorin expression which was followed by the first syndecan and perlecan peaks at 2 and 4 hours after hepatectomy. At 24 hours, which is the peak of hepatocyte DNA synthesis, all these three proteoglycans had elevated steady state transcript level. Fibroglycan message decreased after partial hepatectomy and remained low during the experimental period. The different expression pattern of the proteoglycans suggests that these extracellular matrix components may selectively influence the regeneration process.

Expression of extracellular matrix proteoglycans perlecan and decorin in carbon-tetrachloride-injured rat liver and in isolated liver cells.

Proteoglycans are important components of the extracellular matrix. They are involved in liver regeneration as well as in liver fibrosis. The distribution and cellular source of proteoglycans under normal as well as pathological conditions is still under debate. Localization of decorin and perlecan was studied in normal, acutely damaged, and cirrhotic liver by histochemistry. Furthermore, their synthesis was analyzed in different liver cell populations isolated from normal rat liver. In normal liver, decorin positivity was observed in the perisinusoidal space and in the portal area. Perlecan was clearly detectable in the portal area (blood vessels and bile ducts); a moderate reaction was also seen along the sinusoids. Strong positivity for both proteoglycans was detectable in the necrotic areas of acutely damaged liver. Chronic liver damage was characterized by the deposition of decorin and perlecan in the fibrotic septa. Immunocytochemical reactions were positive for perlecan and decorin in cultured Ito and endothelial cells but not in hepatocytes and Kupffer cells. Northern hybridization confirmed the capacity of Ito cells and endothelial cells to express the two genes. Interestingly, although rat skin fibroblasts expressed strong messages for both proteoglycans, rat aortic smooth muscle cells did not synthesize decorin.