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 [1-¹⁴C]-glucose and [1-¹⁴C]-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 ¹³C atoms after [U-¹³C]-glucose/[2-¹³C]-acetate labelling. Based on [1-¹⁴C]-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-¹³C]-glucose and [1-¹⁴C]-substrate labelling indicated high glycolytic capacity of tumour cells. However, the ratio of certain ¹³C-labelled metabolites showed detailed metabolic differences in the two selected cell lines in further characterisation. The detected differences of GAPDH, β-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 [2-¹³C]-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-1β, 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 ¹³C-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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

The biological activity of cisplatin and dibromodulcitol in combination therapy

The efficacy and modes of action of dibromodulcitol (DBD) and cisplatin (CDDP) were studied in several model systems. Combination treatments produced a longer survival time in mice bearing P388 solid lymphomas than either of the drugs alone. In the human metastatic melanoma HT-168 xenograft model the combined application of DBD and CDDP was also very effective, inducing a reduction in the number and volume of metastatic nodules. For V79 spheroids, DBD was mainly cytotoxic against the internal, quiescent cells, whereas cisplatin primarily killed cells in the proliferating, external regions of the spheroids. When combined, the drugs appeared to act synergistically throughout the spheroids. Studies on plasmid DNA showed that CDDP primarily generates cross-links, whereas single-strand breaks were dominant after DBD treatment. Upon using an assay for cleavage by restriction nuclease, antagonistic action of DBD and CDDP in combination may occur, nevertheless more strand breaks were always observed in these samples. These results suggest that the efficacy of combined DBD and CDDP is in part a result of 'spatial cooperation' by the drugs (i.e. affecting different cells) and in part the result of DNA damage produced by the combination treatments.

Antisense tumor therapy (a dream under construction)

Cancer, as a genetic disease, is a logical target for gene-oriented therapy--either by replacing the missing/nonfunctioning gene or by depressing the activity of an unwanted gene. The latter is really the inhibition of gene expression using oligonucleotide-based or "antisense" treatment. There are several strategies to achieve this: anti-gene or anti-code with triplex formation; ribozyme with endogenous catalytic RNase activity; antisense with oligonucleotides through steric inhibition or RNaseH activation; and sense strategy to inhibit or trap proteins by nucleic acids. There are two essential partners of the approach: targeted sequence in the unwanted gene/molecule and the complementary antisense oligo (-ribo- or -deoxyribonucleotide). The antisense sequences require chemical modifications (mostly on the phosphodiester backbone, less in the sugar or in the bases) to avoid nucleases, to form complexes for better delivery (in the organism and also in the cell). The activity of the unwanted target should be non-randomly associated with cancer (e.g. abl/ber). Both aspects of antisense treatment require further improvements to get longer lasting and real sequence-specific antitumor effect which could be competitive with the available therapeutic modalities.

[Proteoglycans (their structure, function and role in liver diseases)]

Proteoglycans are macromolecules containing a core protein to which glycosaminoglycan chains are covalently attached. The family contains several members with different structures and various functions. Some of them are elements of the extracellular matrix, while others are located to the cell surface playing important role in cell-cell and cell-extracellular matrix interactions. Present paper discusses the possible consequences of the alterations of proteoglycans observed in liver cirrhosis and liver tumors. It has to be emphasized however, that they are also involved in the pathomechanism of arteriosclerosis, Alzheimer-disease, immune diseases, arthritis, tumor progression and metastasis formation.

[Fibrogenesis in the liver--fibrosis, cirrhosis]

Liver fibrogenesis is a delicately balanced process, in which mainly the non-parenchymal liver cells are implicated. Either increased synthesis or decreased catabolism of matrix proteins results in the enhancement of ECM. As further consequence the formation of continuous diffusion and filtration barriers along the Disse space will hinder the bidirectional exchange of macromolecules. Normal structure of ECM is necessary to the normal function of hepatocytes. The quantitative and qualitative changes of ECM observed in liver fibrosis are able to inhibit the liver specific functions of hepatocytes. The mechanisms involved in this effect are not yet clearly understood. In animal experiments liver cirrhosis is reversible and theoretically the chance is open for humans, as well if we will be able to influence the specific steps of fibrogenesis.

[Pathology--on a molecular level (determination of nucleic acids from fixed embedded samples)]

Molecular biological techniques may open new avenues to pathological archives. Fixed and paraffin embedded blocks are a suitable source of nucleic acids, especially of DNA, for retrospective analysis. The quality of DNA depends mainly on the fixation procedure. High molecular weight DNA allows Southern hybridization, but fragmented DNA also became a target with the appearance of polymerase chain reaction (PCR). PCR has rising applicability and enables amplification of required sequence even from one section. Using these techniques on archieved materials a wide variety of informations, e.g. correlation between morphology, phenotypic expression and gene alteration, will be available.

Role of the modified (glycosaminoglycan producing) perisinusoidal fibroblasts in the CCl4-induced fibrosis of the rat liver

Development and regression of liver fibrosis and cirrhosis induced by CCl4 in male F-344 rats were strictly followed during and after an 8-week treatment. The relative amount of collagen was measured by morphometry and the number of glycosaminoglycan (GAG) containing fat storing cells was counted at each time point. The expression of proteoglycan genes (decorin, versican and BPG-5 HSPG) was studied in parallel with the development of cirrhosis. Collagen content of the liver as well as the number of GAG-containing mesenchymal (fat storing) cells increased in parallel until two weeks after the cessation of CCl4 treatment. Later, both the collagen content and the number of GAG-containing cells decreased in parallel and significantly. Proteoglycan gene expression in the nonparenchymal fraction of liver cells indicated an active proteoglycan synthesis in the course of the development of cirrhosis. It is concluded that modified Ito (fat storing) cells synthesize proteoglycans and play an important role in the formation of connective tissue fibers in liver fibrosis.

Modification of DENA-induced hepatocarcinogenesis by CCl4 cirrhosis. Comparison of the marker enzyme patterns

The modifying action of chronic liver injury on the process of hepatocarcinogenesis was investigated. To induce cirrhosis or fibrosis F344 rats received CCl4 alone or in combination with phenobarbital, either before (model 1) or after (model 2) the application of initiator, diethylnitrosamine (DENA). In these models, morphology, tumor incidence as well as polysubstrate monooxygenase system, gamma-glutamyltransferase (GGT) and glucose-6-phosphatase (G-6-Pase) were studied. The data presented show that in model 1 the tumor incidence was much lower than in rats treated with DENA alone. This reduction appeared to be associated with the decrease in cytochrome P450 content occurring in model 1 after DENA administration. Promotion of the hepatocarcinogenic process was observed when CCl4 injury followed the application of DENA (model 2). Comparison of marker enzymes in cirrhotic livers and in tumors either with or without cirrhosis indicated that changes in cytochrome P450 and G-6-Pase were rather the results of parenchymal damage, while GGT was elevated only in tumorous livers. In tumorous livers none of the xenobiotic metabolizing activities decreased as much as the cytochrome P450 content of the same samples. Thus conceivably the cytochrome P450 operates more rapidly in tumors than in normal livers.

Human clathrin heavy chain (CLTC): partial molecular cloning, expression, and mapping of the gene to human chromosome 17q11-qter

The nucleotide sequence of a 916-bp human cDNA clone isolated from a human colon lambda gt11 cDNA library was determined. Sequence analysis showed this cDNA to have 88% homology to the nucleotide sequence of the heavy chain of rat clathrin. The deduced amino acid sequence was 98.7% identical to the rat sequence, a change of only four amino acids. The mRNA identified in both human and rat cells with the human clathrin clone revealed transcripts of approximately 6.5 kb, which is consistent with the predicted 180 kDa molecular weight of the clathrin heavy chain. Southern analysis of human/rodent somatic cell hybrids localized the human clathrin heavy chain gene (CLTC) to chromosome 17. Additional analyses using panels of human/rodent somatic cell hybrids with specific chromosomal translocations and deletions mapped the human clathrin heavy chain gene locus to 17q11-qter.

Heparan sulfate proteoglycan of human colon: partial molecular cloning, cellular expression, and mapping of the gene (HSPG2) to the short arm of human chromosome 1

We have determined the sequence of two overlapping cDNA clones encoding a portion of the human heparan sulfate proteoglycan core protein (HSPG2) from a human colon library. The cDNA clones encompassed 1.34 kb of nucleotide sequence and showed approximately 85% homology to the murine heparan sulfate proteoglycan of the EHS tumor, BPG-5. The deduced amino acid sequence revealed an identity of 87% between the human and the murine species. Of the 57 different amino acids encoded in the human clones, 20 were substituted with a similar amino acid. Among the specific features that were highly conserved was the 32 cysteine residues with a distinctive repeat pattern characteristic of epidermal growth factor. Northern blotting revealed a single, approximately 12 kb transcript in a variety of cells including human colon carcinoma, endothelial, and fibroblastic cells. The size of this transcript correlated with the estimated molecular weight (approximately 400 kDa) of the protein core precursor. Southern blot analyses of DNA from 120 human/rodent somatic cell hybrids, including subclones with specific translocations or spontaneous breaks of human chromosome 1, demonstrated the presence of HSPG2 gene on the telomeric region of the short arm of chromosome 1 (1p34-pter). Two polymorphisms with TaqI and EcoRI restriction endonucleases, respectively, were also detected. The localization of this proteoglycan locus in the human genome and the availability of new RFLPs provide the tools for future studies of human diseases where the HSPG2 proteoglycan gene is suspected to be involved.

Modulation of extracellular matrix gene expression by heparin and endothelial cell growth factor in human smooth muscle cells

We have previously shown that human vascular smooth muscle cells grown for several passages in the presence of heparin and endothelial cell growth factor (ECGF) exhibit profound alterations in the synthesis of extracellular matrix proteins. In the present study, we demonstrate that the mRNA steady-state levels for various matrix macromolecules were altered in the presence of heparin and ECGF, but not ECGF alone. Specifically, the expression of types I and IV collagens, fibronectin, and decorin proteoglycan genes were markedly inhibited, whereas that of versican proteoglycan and beta-actin genes were unaffected. The effects were fully reversible. The suppression of the collagen gene expression was related to decreased collagen production by cells incubated with heparin and ECGF. Thus, heparin and ECGF synergistically elicit a coordinate and selective inhibition of matrix gene expression in human smooth muscle cells.

Alkaline phosphatase activity in human and rat liver tumors

Enzyme activity measurements of alkaline phosphatase in surgically removed human liver tumors showed elevated level of the enzyme in 6 focal nodular hyperplasias, reduction in 8 primary hepatocellular carcinomas, and no change in the 4 adenoma samples. The activity represented liver type of alkaline phosphatase nearly in all cases because it could be inhibited by L-homoarginine more extensively than by L- phenylalanine. Studies on polyacrylamide gel electrophoresis indicated the presence of a variant type isoenzyme only in one focal nodular hyperplasia and in two hepatocellular carcinomas, one of which showed a fibrolamellar structure whereas the other was associated to cirrhosis. The importance of the elevated amount of connective tissue in the tumor, resulting in an isoenzyme shift of alkaline phosphatase, received substantial support upon comparing chemically induced rat liver tumors with and without cirrhosis.

Fatty acylation of heparan sulfate proteoglycan from human colon carcinoma cells

A number of transmembrane proteins have been recently reported to be modified by the covalent addition of saturated fatty acids which may contribute to membrane targeting and specific protein-lipid interactions. Such modifications have not been reported in cell-associated heparan sulfate proteoglycans, although these macromolecules are known to be hydrophobic. Here, we report that a cell surface heparan sulfate proteoglycan is acylated with both myristate and palmitate, two long-chain saturated fatty acids. When colon carcinoma cells were labeled with [3H]myristic acid, a significant proportion of the label was shown to be specifically incorporated into the protein core of the proteoglycan. Characterization of fatty acyl moiety in the purified proteoglycan by reverse-phase high pressure liquid chromatography revealed that approximately 60% of the covalently bound fatty acids was myristate. We further show that this relatively rare 14-carbon fatty acid was bound to the protein core via a hydroxylamine- and alkali-resistant amide bond. The remaining 40% was the more common 16-carbon palmitate, which was bound via a hydroxylamine- and alkali-sensitive thioester bond. Palmitate appeared to be added post-translationally and derived in part from intracellular elongation of myristate, a process that occurred within the first two hours and was insensitive to inhibition of protein synthesis. Acylation of heparan sulfate proteoglycan represents a novel modification of this gene product and could play a role in a number of biological functions including specific interactions with membrane receptors and ligand stabilization.

Transforming growth factor beta alters the expression of heparan sulfate proteoglycan in human colon carcinoma cells

Transforming growth factor beta (TGF-beta) stimulated the synthesis of heparan sulfate proteoglycan in cultured human colon carcinoma cells without affecting its rates of intracellular degradation or secretion. The overall hydrodynamic size, electrophoretic mobility, and degree of sulfation of the TGF-beta-induced proteoglycan was indistinguishable from that of untreated cells. The synthesis of the protein core was significantly stimulated by TGF-beta, although total cellular protein was unaltered. The stimulatory effects of TGF-beta were prevented by the inhibitors of protein synthesis and DNA transcription, cycloheximide, or actinomycin D, respectively. Analysis of protein core mRNA levels using a murine cDNA encoding a basement membrane protein core, revealed a marked elevation of the steady state levels of mRNA for this gene product. In contrast, the mRNA levels for glyceraldehyde-3-phosphate dehydrogenase or beta-actin genes were not significantly affected by TGF-beta. Finally, nuclear run-off experiments showed increases in neither protein core-specific transcription nor in general transcriptional activity. Taken together, these results indicate that TGF-beta is a potent modulator of heparan sulfate proteoglycan expression in human colon carcinoma cells and that its effect is mediated primarily through an increase in mRNA levels encoding the protein core, perhaps a result of enhanced RNA stability. The TGF-beta-induced elevation of heparan sulfate proteoglycan may contribute to the control of stromal cell proliferation and matrix production by human colon carcinoma cells.

Ultrastructural localization and internalization of proteoglycan epitopes in a human non-Hodgkin (B) lymphoma

In a human non-Hodgkin (B) lymphoma xenograft (HT-117) heparan sulphate (HS) proved to be the main cell surface glycosaminoglycan, in contrast to the chondroitin sulphate dominance in normal lymphoid cells. Using anti-proteoglycan (PG) antibodies and immunoelectronmicroscopy, two heparan sulphate proteoglycans (transferrin receptor (TfR) and fibroblast membrane type) and one chondroitin sulphate proteoglycan (articular cartilage type) molecule were co-localized as random clusters on the surface of these lymphoma cells. Double labelling revealed that during internalization, which occurred via endosomes avoiding the lysosomal system, the different proteoglycan (PG) antigens became separated. The TfR and fibroblast membrane type HSPG epitopes reappeared on plasmalemmal vesicles derived most probably from the multivesicular endosomes, representing a unique form of exocytosis. It is suggested that different cell membrane PGs are integrated into subunits of yet unknown function in these human non-Hodgkin (B) lymphoma cells.

Altered glycosaminoglycan composition in reactive and neoplastic human liver

We have investigated the glycosaminoglycan composition of normal human liver, focal nodular hyperplasia, hepatic adenoma, and hepatocellular carcinoma. Uronic acid increased about 4 fold in the benign and reactive lesions, and greater than 7 fold in the carcinoma. Whereas in focal nodular hyperplasia and adenoma dermatan sulfate was the predominant glycosaminoglycan, in hepatocellular carcinoma chondroitin sulfate was the predominant species; it increased 24 fold over normal liver and 3-5 fold over all the other tissues. HPLC analysis of chondroitinase ABC or AC digests showed a 58 fold increase in Delta-Di-OS disaccharides in hepatocellular carcinoma, indicating significant undersulfation of chondroitin sulfate. Surprisingly, the normal-appearing liver surrounding the carcinoma showed glycosaminoglycan changes similar to adenoma and nodular hyperplasia. These results thus indicate that specific glycosaminoglycan changes occur in hepatocellular carcinoma, and suggest for the first time that proteoglycan metabolism is also altered in the non-cirrhotic, hepatic parenchyma adjacent to liver carcinoma.

Epitopes of cartilage core proteins and GAG pattern in human non-Hodgkin lymphoma xenografts

Glycosaminoglycan and core protein components of proteoglycans (PGs) have been studied in three human non-Hodgkin lymphoma xenografts of B cell origin. Lymphomas showed similar GAG content, but different composition of GAG subtypes. This variability was accompanied by an individual capacity to adhere to extracellular matrix elements. The core proteins identified by monoclonal antibodies raised against human cartilage chondroitin sulfate PG were also distinctly expressed and released. These proteins shared by different cell types may have biological significance.

[Pathobiology of human primary benign and malignant liver tumors]

Authors elaborated 35 surgically removed tumors of liver by morphological and biochemical methods. From tumors 5 proved to be hepatocellular adenoma (HCA), 12 to focal nodular hyperplasia (FNH) and 18 to hepatocellular cancer (HCC). On the basis of enzyme histochemical and biochemical examinations, HCA is characterised by "normal" enzyme pattern. By the above method, FNH can be divided into two groups, characterized with "normal" and "abnormal" (tumor-like) enzyme change, while HCC proved to be very heterogeneous. Majority of HCA and FNH cases, according to data gained by flow cytometer, were of diploid DNA content. In majority of HCC cases, DNA diploid was aneuploid, but in three cases normal DNA content was observed. The above mentioned examination revealed several different characteristics of human hepatic tumors, compared to experimentally created tumors of liver.

Two human melanoma xenografts with different metastatic capacity and glycosaminoglycan pattern

Two human melanoma xenografts were compared with respect to their in vivo growth and metastatic potentials as well as glycosaminoglycan patterns. The less differentiated HT 168 tumor showed faster growth at primary sites and a more pronounced capacity for metastasis into the liver. Although chondroitin sulfate was the dominant glycosaminoglycan subtype in both tumors, the more invasive xenograft had a higher heparan sulfate/chondroitin sulfate (HS/CS) ratio. We suggest that tumor progression is influenced by this ratio in this human melanoma system.

Chromatin alterations and gene function disorder in MC-29 virus-derived hepatoma

The disorder of gene expression in hepatomas was studied by following certain metabolic alterations (enzyme stimulation, nucleic acid labeling) after glucocorticoid treatment and analyzing the site of action of glucocorticoids. Compared to normal liver, the MC-29 virus-derived transplantable hepatoma (VTH) responded abnormally to glucocorticoids, which failed to stimulate the activity of certain enzymes (glucose-6-phosphatase, aryl hydrocarbon hydroxylase) or to inhibit DNA synthesis. Since the binding capacity of the cytosol steroid receptor was the same in liver and VTH but the interaction between the steroid receptor and DNA was reduced in VTH, it was concluded that structural alterations of chromatin nonhistones--including processed steroid receptor--may be responsible for the lack of physiological responses to steroids in VTH. Furthermore, the increased proportion or repetitive sequences in VTH DNA may be a feature of the disorder of gene regulation in malignant cells.

Morphological and biochemical studies on the effect of agents with liver protecting properties

The liver protective effect of Aicaphosphate in CC1(4)-induced acute, as well as CC1(4)-and thioacetamide-induced subacute and chronic liver damages is demonstrated. The effect of the protective drugs was studied in the forms of pre-, simultaneous and delayed treatment in acute and chronic liver damages induced by various toxic agents. The degree of liver damage was determined by morphological and biochemical methods, complementary to each other. For the completion of histological studies and morphometry used for the determination of the degree of fibrosis biochemical investigations are performed. In acute liver damage the determination of DNA, protein and lipid contents of the liver tissue and the radioactive aminoacid incorporation rate should be carried out with a simultaneous analysis of the serum enzymes. In chronic liver damage, the measurement of the hydroxyproline and DNA contents of the liver give useful data for the determination of the severity of the lesion and the effect of the protective drugs, respectively.

Biochemistry and enzyme induction in MC-29 virus-induced transplantable avian hepatoma

For the biochemical characterization of a new transplantable hepatoma derived from the MC-29 virus-induced liver tumor, the macromolecular content and the inducibility of glucose-6-phosphatase, glucose-6-phosphate dehydrogenase, and aryl hydrocarbon hydroxylase were compared in chicken liver and in this hepatoma. The alteration of the nucleocytoplasmic ratio was deduced from measurements of DNA, RNA, protein, and phospholipid contents of the whole cell homogenate and cell fractions. The increased nuclear and decreased cytoplasmic content of macromolecules suggests a dominancy of the nuclei in the tumor cells. Glucose-6-phosphatase and aryl hydrocarbon hydroxylase activities were lower by 60 and 80%, respectively, in the highly proliferating hepatoma than in the liver. In contrast, glucose-6-phosphate dehydrogenase activity increased in the hepatoma. However, enzyme inducers, such as methylcholanthrene, hydrocortisone, and insulin, were able to enhance the activity of these enzymes in the liver but had no stimulating effect on the hepatoma.