Roles and targeting of the HAS/hyaluronan/CD44 molecular system in cancer

Synthesis, deposition, and interactions of hyaluronan (HA) with its cellular receptor CD44 are crucial events that regulate the onset and progression of tumors. The intracellular signaling pathways initiated by HA interactions with CD44 leading to tumorigenic responses are complex. Moreover, HA molecules may perform dual functions depending on their concentration and size. Overexpression of variant isoforms of CD44 (CD44v) is most commonly linked to cancer progression, whereas their loss is associated with inhibition of tumor growth. In this review, we highlight that the regulation of HA synthases (HASes) by post-translational modifications, such as O-GlcNAcylation and ubiquitination, environmental factors and the action of microRNAs is important for HA synthesis and secretion in the tumor microenvironment. Moreover, we focus on the roles and interactions of CD44 with various proteins that reside extra- and intracellularly, as well as on cellular membranes with particular reference to the CD44-HA axis in cancer stem cell functions, and the importance of CD44/CD44v6 targeting to inhibit tumorigenesis.

Guidelines for the Cytopathologic Diagnosis of Epithelioid and Mixed-Type Malignant Mesothelioma: a secondary publication

OBJECTIVE

To provide practical guidelines for the cytopathologic diagnosis of malignant mesothelioma.

DATA SOURCES

Cytopathologists with an interest in the field involved in the International Mesothelioma Interest Group (IMIG) and the International Academy of Cytology (IAC) contributed to this update. Reference material includes peer-reviewed publications and textbooks.

RATIONALE

This article is the result of discussions during and after the IMIG 2012 conference in Boston, followed by thorough discussions during the 2013 IAC meeting in Paris. Additional contributions have been obtained from cytopathologists and scientists who could not attend these meetings, with final discussions and input during the IMIG 2014 conference in Cape Town.

Guidelines for the cytopathologic diagnosis of epithelioid and mixed-type malignant mesothelioma: Complementary Statement from the International Mesothelioma Interest Group, Also Endorsed by the International Academy of Cytology and the Papanicolaou Society of Cytopathology

OBJECTIVE

To provide practical guidelines for the cytopathologic diagnosis of malignant mesothelioma.

DATA SOURCES

Cytopathologists with an interest in the field involved in the International Mesothelioma Interest Group (IMIG) and the International Academy of Cytology (IAC) contributed to this update. Reference material includes peer-reviewed publications and textbooks.

RATIONALE

This article is the result of discussions during and after the IMIG 2012 conference in Boston, followed by thorough discussions during the 2013 IAC meeting in Paris. Additional contributions have been obtained from cytopathologists and scientists who could not attend these meetings, with final discussions and input during the IMIG 2014 conference in Cape Town.

Guidelines for cytopathologic diagnosis of epithelioid and mixed type malignant mesothelioma. Complementary statement from the International Mesothelioma Interest Group, also endorsed by the International Academy of Cytology and the Papanicolaou Society of Cytopathology

To provide practical guidelines for the cytopathologic diagnosis of malignant mesothelioma (MM). Cytopathologists involved in the International Mesothelioma Interest Group (IMIG) and the International Academy of Cytology (IAC), who have an interest in the field contributed to this update. Reference material includes peer-reviewed publications and textbooks. This article is the result of discussions during and after the IMIG 2012 conference in Boston, followed by thorough discussions during the 2013 IAC meeting in Paris. Additional contributions have been obtained from cytopathologists and scientists, who could not attend these meetings, with final discussions and input during the IMIG 2014 conference in cape town. During the previous IMIG biennial meetings, thorough discussions have resulted in published guidelines for the pathologic diagnosis of MM. However, previous recommendations have stated that the diagnosis of MM should be based on histological material only.[12] Accumulating evidence now indicates that the cytological diagnosis of MM supported by ancillary techniques is as reliable as that based on histopathology, although the sensitivity with cytology may be somewhat lower.[345] Recognizing that noninvasive diagnostic modalities benefit both the patient and the health system, future recommendations should include cytology as an accepted method for the diagnosis of this malignancy.[67] The article describes the consensus of opinions of the authors on how cytology together with ancillary testing can be used to establish a reliable diagnosis of MM.

Proteome screening of pleural effusions identifies galectin 1 as a diagnostic biomarker and highlights several prognostic biomarkers for malignant mesothelioma

Malignant mesothelioma is an aggressive asbestos-induced cancer, and affected patients have a median survival of approximately one year after diagnosis. It is often difficult to reach a conclusive diagnosis, and ancillary measurements of soluble biomarkers could increase diagnostic accuracy. Unfortunately, few soluble mesothelioma biomarkers are suitable for clinical application. Here we screened the effusion proteomes of mesothelioma and lung adenocarcinoma patients to identify novel soluble mesothelioma biomarkers. We performed quantitative mass-spectrometry-based proteomics using isobaric tags for quantification and used narrow-range immobilized pH gradient/high-resolution isoelectric focusing (pH 4–4.25) prior to analysis by means of nano liquid chromatography coupled to MS/MS. More than 1,300 proteins were identified in pleural effusions from patients with malignant mesothelioma (n = 6), lung adenocarcinoma (n = 6), or benign mesotheliosis (n = 7). Data are available via ProteomeXchange with identifier PXD000531. The identified proteins included a set of known mesothelioma markers and proteins that regulate hallmarks of cancer such as invasion, angiogenesis, and immune evasion, plus several new candidate proteins. Seven candidates (aldo-keto reductase 1B10, apolipoprotein C-I, galectin 1, myosin-VIIb, superoxide dismutase 2, tenascin C, and thrombospondin 1) were validated by enzyme-linked immunosorbent assays in a larger group of patients with mesothelioma (n = 37) or metastatic carcinomas (n = 25) and in effusions from patients with benign, reactive conditions (n = 16). Galectin 1 was identified as overexpressed in effusions from lung adenocarcinoma relative to mesothelioma and was validated as an excellent predictor for metastatic carcinomas against malignant mesothelioma. Galectin 1, aldo-keto reductase 1B10, and apolipoprotein C-I were all identified as potential prognostic biomarkers for malignant mesothelioma. This analysis of the effusion proteome furthers our understanding of malignant mesothelioma, identified galectin 1 as a potential diagnostic biomarker, and highlighted several possible prognostic biomarkers of this disease.

Determination of sodium hyaluronate in pharmaceutical formulations by HPLC-UV

A liquid chromatography (HPLC) method with UV detection was developed for determination of sodium hyaluronate in pharmaceutical formulation. Sodium hyaluronate is a polymer of disaccharides, composed of d-glucuronic acid and d-N-acetylglucosamine, linked via alternating β-1, 4 and β-1, 3 glycosidic bonds. Being a polymer compound it lacks a UV absorbing chromophore. In the absence of a UV absorbing chromophore and highly polar nature of compound, the analysis becomes a major challenge. To overcome these problems a novel method for the determination of sodium hyaluronate was developed and validated based on size exclusion liquid chromatography (SEC) with UV detection. An isocratic mobile phase consisting of buffer 0.05 M potassium dihydrogen phosphate, pH adjusted to 7.0 using potassium hydroxide (10%) was used. Chromatography was carried out at 25 °C on a BioSep SEC S2000, 300 mm×7.8 mm column. The detection was carried out using variable wavelength UV-vis detector set at 205 nm. The compounds were eluted isocratically at a steady flow rate of 1.0 mL/min. Sodium hyaluronate retention time was about 4.9 min with an asymmetry factor of 1.93. A calibration curve was obtained from 1 to 38 g/mL (r>0.9998). Within-day % RSD was 1.0 and between-day % RSD was 1.10. Specificity/selectivity experiments revealed the absence of interference from excipients, recovery from spiked samples for sodium hyaluronate was 99-102. The developed method was applied to the determination of sodium hyaluronate in pharmaceutical drug substance and product.

Hyaluronan and N-ERC/mesothelin as key biomarkers in a specific two-step model to predict pleural malignant mesothelioma

Purpose

Diagnosis of malignant mesothelioma is challenging. The first available diagnostic material is often an effusion and biochemical analysis of soluble markers may provide additional diagnostic information. This study aimed to establish a predictive model using biomarkers from pleural effusions, to allow early and accurate diagnosis.

Patients and Methods

Effusions were collected prospectively from 190 consecutive patients at a regional referral centre. Hyaluronan, N-ERC/mesothelin, C-ERC/mesothelin, osteopontin, syndecan-1, syndecan-2, and thioredoxin were measured using ELISA and HPLC. A predictive model was generated and validated using a second prospective set of 375 effusions collected consecutively at a different referral centre.

Results

Biochemical markers significantly associated with mesothelioma were hyaluronan (odds ratio, 95% CI: 8.82, 4.82–20.39), N-ERC/mesothelin (4.81, 3.19–7.93), CERC/mesothelin (3.58, 2.43–5.59) and syndecan-1 (1.34, 1.03–1.77). A two-step model using hyaluronan and N-ERC/mesothelin, and combining a threshold decision rule with logistic regression, yielded good discrimination with an area under the ROC curve of 0.99 (95% CI: 0.97–1.00) in the model generation dataset and 0.83 (0.74–0.91) in the validation dataset, respectively.

Conclusions

A two-step model using hyaluronan and N-ERC/mesothelin predicts mesothelioma with high specificity. This method can be performed on the first available effusion and could be a useful adjunct to the morphological diagnosis of mesothelioma.

Telomerase activity in effusions: a comparison between telomere repeat amplification protocol in situ and conventional telomere repeat amplification protocol assay

CONTEXT

We previously found telomere repeat amplification protocol (TRAP) in situ helpful in the diagnosis of malignancy in effusions, whereas varying sensitivities and specificities for malignancy were reported by investigators using extract-based TRAP.

OBJECTIVE

To compare the 2 methods and to elucidate the discrepancies between them.

DESIGN

Twenty-three effusions were analyzed. Telomerase activity of whole cell lysate was measured with a Telo TAGGG telomerase polymerase chain reaction ELISA PLUS kit with modifications to exclude polymerase chain reaction inhibitors. TRAP in situ was performed on cytospins. An estimate of total TRAP activity in the specimen was made based on the amount of positive cells, their fluorescence intensity, and the proportion of different cell types in the specimen. The estimate was compared with the level of telomerase activity in cell lysate-based TRAP.

RESULTS

TRAP in situ: Thirteen of 14 malignant cases and 2 of 2 equivocal cases showed moderate/strong reactivity. Five of 7 benign effusions were negative; in 2 of 7, mesothelial cells showed weak reactivity. Cell lysate-based TRAP assay: In 4 cases no internal standard was detected, indicating the presence of polymerase chain reaction inhibitors. The relative telomerase activities were 33.1 to 72.7 with a considerable overlap between malignant (48 +/- 9, mean +/- SD) and benign (43 +/- 9) cases.

CONCLUSIONS

The TRAP in situ results correlated to final diagnoses, whereas the cell lysate-based TRAP assay did not differentiate between malignant and benign cases. The varying proportions of positive cells and the variation in fluorescence intensity in the TRAP in situ slides explained some of the discrepancies. The problems encountered with TRAP performed on cell lysates are partly overcome using TRAP in situ.

Malignant mesothelioma--a connective tissue tumor with proteoglycan-dependent differentiation

Malignant mesothelioma (MM) is a connective tissue tumor with partial epithelioid differentiation. The pattern of proteoglycan (PG) expression by epithelioid and fibroblast-like (sarcomatoid) MM cells differ; cell surface PGs being more abundant in the former phenotype and matrix PGs in the latter. The differentiation as well as much of the malignant nature of these tumors is dependent on the expression of surface PGs. The syndecans, however, also translocate to the nucleus for an as yet unknown function.

Determination and distribution of N-acetyl- and N-glycolylneuraminic acids in culture media and cell-associated glycoconjugates from human malignant mesothelioma and adenocarcinoma cells

Sialic acids containing glycoconjugates are very common in human neoplasias and their expression frequently correlates with malignant phenotype and the tumor grade. The majority of tumor markers containing sialic acids in man involve changes in the amount of total sialic acids and in the presence of the two main sialic acid types, Neu5Ac and Neu5Gc, and their derivatives. The aim of the present study was to examine whether malignant mesothelioma cell lines synthesize sialic acid containing glycoconjugates at both the extracellular and cell membrane levels and particularly whether the type and the content of Neu5Ac and Neu5Gc are of biological importance for mesothelioma cell differentiation and evaluation of its prognosis. The study was performed in three human malignant mesothelioma cell lines, two with a fibroblast like phenotype (STAV-FCS and Vester) and one of epithelial differentiation (STAV-AB), which developed from the pleural effusions of patients with malignant mesothelioma and in one human adenocarcinoma cell line (Wart). Neu5Ac and Neu5Gc were determined following a mild hydrolysis step and a sample clean-up procedure. The determination was performed by reversed-phase HPLC after the NeuAc and NeuGc had been converted to per-O-benzoylated derivatives. It was found that Neu5Gc is the major sialic acid in the culture media of all cell lines examined. Molar ratios of Neu5Ac to Neu5Gc showed that Neu5Gc is the predominant sialic acid in the culture medium of the fibroblast-like mesothelioma cells. Neu5Ac is almost undetectable in the cell membrane, whereas Neu5Gc is present in considerable amounts. The obtained results suggest that the type and the content of Neu5Ac and Neu5Gc in culture media are of biological importance for mesothelioma cell differentiation and may be of value in the evaluation of prognosis.

The combination of CEA, EMA, and BerEp4 and hyaluronan analysis specifically identifies 79% of all histologically verified mesotheliomas causing an effusion

A previously tested antibody panel identified three criteria of major importance for distinguishing between mesothelioma and adenocarcinoma (ACA): carcinoembryonic antigen (CEA), BerEp4, and epithelial membrane antigen (EMA) accentuated at the cell membrane. An extended panel, consisting of CEA, BerEp4, EMA, vimentin, mesothelioma antibody (HBME-1), thrombomodulin, Ca125, and sialyl-Tn was applied to effusions from 86 ACAs and 21 mesotheliomas. The specificities and sensitivities of the previously identified reactivity patterns were tested on the new material and the effect of the added antibodies was evaluated. Further, hyaluronan analysis was added as a parameter. The previously selected criteria remained fully predictive for mesothelioma and ACA, respectively, also in the extended material (in all, 139 ACAs and 57 mesotheliomas). With the addition of the hyaluronan value, 79% of the cases was identified with 100% specificity. Among the new antibodies sialyl-Tn seemed the most promising because it specifically identified ACAs not expressing CEA.

Hyaluronan synthase expression in pleural malignant mesotheliomas

Hyaluronan (HA) is thought to play several important roles in tumor growth, tumorigenicity, and tumor dissemination and metastasis. Recently, three isoforms of hyaluronan synthase (HAS) have been cloned. Our objective was to determine which of the HAS isoforms were expressed in pleural malignant mesotheliomas, the most representative lesion of HA-producing tumors. We studied 10 cases of pleural malignant mesothelioma using novel antibodies of HAS. We compared HAS expression patterns of mesothelioma and pulmonary adenocarcinoma. Immunohistochemically, 9 of 10 (90%) cases of mesothelioma had extensive reaction to anti-HAS1 and anti-HAS2 antibodies, while HAS3 overexpression was present in 4 of 10 cases (40%). Of 20 cases of pulmonary adenocarcinoma, 5 overexpressed HAS1 (25%), 16 of 20 HAS2 (80%), and 4 of 20 HAS3 (20%). The expression level of HAS1 was significantly higher in mesotheliomas than in pulmonary adenocarcinoma (P=0.0036). Our data suggests that HAS1 might be a useful positive marker of malignant mesothelioma. However, a definitive conclusion should be based on further large-scale studies.

Telomere repeat amplification protocol (TRAP) in situ reveals telomerase activity in three cell types in effusions: malignant cells, proliferative mesothelial cells, and lymphocytes

Telomerase Repeat Amplification Protocol (TRAP) in situ was performed on cytospin preparations from 65 effusions from the serous cavities (45 pleural and 19 ascitic fluids and one pericardial fluid) submitted for routine diagnosis and the results were correlated to cytological morphology. Three types of cells with nuclear fluorescence were identified: malignant cells, hyperplastic mesothelial cell and lymphocytes. Of 38 cytologically malignant effusions, 12 showed strong reactivity in all malignant cells, three strong reactivity in part of the malignant population, whereas 12 showed moderate reactivity in the whole and five in part of the malignant population, respectively. In five malignant effusions weak reactivity was found in all (one case) and in scattered (four cases) malignant cells. Two effusions contained telomerase-negative malignant cells. Two pleural and two ascitic fluids contained proliferative mesothelial cells with weak or, in one case, moderate reactivity. Lymphocytes usually showed weak telomerase activity. Telomerase was expressed in almost all malignant tumours metastatic to serous cavities. Heterogeneity in tumour populations was demonstrated, which may have diagnostic implications, especially in cytology. Weak or moderate reactivity was found in lymphocytes and in some mesothelial proliferations and may explain the low specificity for malignancy sometimes obtained with the TRAP extract method. The weak reactivity found in lymphocytes may reduce the specificity when the extract method is used but causes no diagnostic problem with the TRAP in situ method.

Differentiation of mesothelioma from adenocarcinoma in serous effusions: The role of hyaluronic acid and CD44 localization

Differentiating cells of mesothelial origin from adenocarcinoma (ACA) based on morphology alone can be a diagnostic challenge, especially in cytological specimens. Malignant mesothelioma (MM) is characterized by accumulation of abundant intracellular hyaluronic acid (HA), a feature that is not reported in ACA. The purpose of this study was to evaluate the significance of cellular HA using an HA-specific binding peptide (HABP) and the expression of its principal receptor, the standard CD44 molecule (CD44S). Archival paraffin-embedded cell blocks of serous fluids from 28 cases of reactive mesothelial cells, 14 cases of MM, 20 cases of metastatic ovarian carcinomas, 17 cases of metastatic breast carcinomas, 12 cases of metastatic lung ACA, and 12 cases of metastatic gastrointestinal ACA were stained with HA using a biotinylated HABP and CD44S. Positive staining was defined as droplet to diffuse cytoplasmic staining for HA and uniform membranous staining for CD44S. All MMs and 93% (26/28) of the benign mesothelial cells were positive for intracytoplasmic HA vs. none of ACAs. CD44S was expressed in 100% (28/28) of mesothelial hyperplesia, 86% (12/14) of MMs, 70% (14/20) of ovarian carcinomas, 29% (5/17) of breast carcinomas, 25% (3/12) of gastrointestinal ACAs, and 8% (1/12) of lung ACAs. In MM and reactive mesothelial cells, CD44S stained cell membranes diffusely with highlights on the villous surfaces and in ACA it was focal and confined to cell membranes. Immunostaining with HA is a reliable marker that can distinguish between cells of mesothelial origin (reactive mesothelial cells and MM) and ACA. The CD44S staining pattern of cells of mesothelial origin is of diagnostic significance. CD44 may prove useful in conjunction with other stains in the differential diagnosis of mesothelioma and ADA.

Solid phase assays in glycoconjugate research: applications to the analysis of proteoglycans, glycosaminoglycans and metalloproteinases

Glycoconjugates are a class of macromolecules consisting of different constituents, one of which is sugar moieties. Glycoconjugates comprise the majority of tissue constituents, both intracellular and extracellular. Extracellular glycoconjugates (glycoproteins and proteoglycans) participate in a wide variety of interactions, through which they maintain tissue integrity. Therefore, their analysis or the study of their possible interactions would give evidence for the state of tissues. Since the amounts of some of the extracellular glycoconjugates are usually low or the amounts of tissue to be examined come from biopsies, specific analytical systems are developed for their study, the most familiar being solid phase assays, which have the advantages of analysis of multiple samples on the same time, cheap instrumentation and high specificity.

Proteoglycans and WT1 as markers for distinguishing adenocarcinoma, epithelioid mesothelioma, and benign mesothelium

Malignant mesothelioma is a tumour frequently accompanied by an effusion with elevated hyaluronan levels. To distinguish malignant mesothelioma, adenocarcinoma, and reactive benign mesothelium with cytological and histological methods including immunocytochemistry is a major diagnostic challenge. The Wilms' tumour susceptibility gene 1 (WT1), expressed during transition of mesenchyme to epithelial tissues, is regarded as a marker for the mesothelial lineage. Its effect on the cell phenotype may be regulated via the syndecans, i.e. proteoglycans on the cell surface. To determine how WT1, proteoglycans, and hyaluronan synthase are expressed in mesothelioma, adenocarcinoma, and reactive benign mesothelium, we studied these molecules at the mRNA and protein levels, with the additional purpose of finding diagnostic parameters. Adenocarcinoma cells produced more mRNA for syndecan-1, but cells derived from mesothelium expressed WT1, biglycan, and larger amounts of syndecan-2. The difference in gene expression of these two syndecans was best monitored by the ratio between them. Syndecan-4 was highly expressed in all malignant cell lines, this expression being 1.7-5 times greater than in benign mesothelial cells. Although hyaluronan synthase-1 and versican could not distinguish between the three conditions, versican expression was associated with a high rate of proliferation. These findings suggest that syndecan-1 and syndecan-2 together may be useful diagnostic markers, with stronger staining for the latter epitope in mesothelial tissues. The alternating appearance of these two syndecans can be shown not only by RT-PCR and FACS in vitro, but also by immunohistochemistry on clinical material.

Effects of glycosaminoglycans on proliferation of epithelial and fibroblast human malignant mesothelioma cells: a structure-function relationship

Proteoglycans interact with other effective macromolecules regulating a variety of cellular events via their glycosaminoglycan (GAG) chains. The effects of all known glycosaminoglycans (GAGs) produced by normal cells and tissues on the proliferation of two human malignant mesothelioma cell lines, one with fibroblast-like morphology and the other with epithelial differentiation - both able to produce hyaluronan (HA), galactosaminoglycans (GalAGs) and heparan sulphate (HS) containing proteoglycans - have been studied. Cell proliferation was assessed by measuring [3H]thymidine incorporation and cell number. GalAGs, i.e. chondroitin sulphates (CSs) and dermatan sulphate (DS), strongly stimulate the proliferation of fibroblast-like cells in a dose-dependent manner (170-250% at 100 microg/ml), independently of their sulphation pattern. In epithelial cells, however, only DS stimulates cell proliferation. The effects of CSs on proliferation of epithelial cells are not depended on their sulphation pattern. Thus, CSs either with -[GlcA-GalNAc-(-6-O-SO(3)-)]- or -[GlcA-GalNAc-(-4-O-SO(3)-]- as the commonest unit, had no significant effect. L-Iduronic acid (IdoA)-rich heparin and fast-moving HS (fm-HS), a HS fraction with a heparin-like structure, had significant antiproliferative effects on mesothelioma cells of both types (30-70% at 1.0 microg/ml and 85-90% at 100 microg/ml, respectively). GlcA-rich HS, however, had no significant effects. HA inhibits only the proliferation of fibroblast-like cells by 25% at 50 and 100 microg/ml. Keratan sulphate suppresses cell proliferation (10-30%) in both cell lines. In the view of these findings, a structure-function relationship of GAGs on cell proliferation of the two human malignant mesothelioma cell lines is discussed. Other factors, such as chain conformation and geometry, as well as interactions of growth factors with GAGs, possibly involved in the regulation of cell proliferation, are also discussed.

Advances in analysis of glycosaminoglycans: its application for the assessment of physiological and pathological states of connective tissues

Glycosaminoglycans are a class of biological macromolecules found mainly in connective tissues as constituents of proteoglycans, covalently linked to their core protein. Hyaluronan is the only glycosaminoglycan present under its single form and possesses the ability to aggregate with the class of proteoglycans termed hyalectans. Proteoglycans are localised both at the extracellular and cellular (cell-surface and intracellular) levels and, via either their glycosaminoglycan chains or their core proteins participate in and regulate several cellular events and (patho)physiological processes. Advances in analytical separational techniques, including high-performance liquid chromatography, capillary electrophoresis and fluorophore assisted carbohydrate electrophoresis, make possible to examine alterations of glycosaminoglycans with respect to their amounts and fine structural features in various pathological conditions, thus becoming applicable for diagnosis. In this review we present the chromatographic and electromigration procedures developed to analyse and characterise glycosaminoglycans. Moreover, a critical evaluation of the biological relevance of the results obtained by the developed methodology is discussed.

Capillary electrophoresis for the analysis of glycosaminoglycans and glycosaminoglycan-derived oligosaccharides

Glycosaminoglycans are a family of polydisperse, highly sulfated complex mixtures of linear polysaccharides that are involved in many life processes. Defining the structure of glycosaminoglycans is an important factor in elucidating their structure-activity relationship. Capillary electrophoresis has emerged as a highly promising technique consuming an extremely small amount of sample and capable of rapid, high-resolution separation, characterization and quantitation of analytes. Numerous capillary electrophoresis methods for analysis of intact glycosaminoglycans and glycosaminoglycan-derived oligosaccharides have been developed. These methods allow for both qualitative and quantitative analysis with a high level of sensitivity. This review is concerned with separation methods of capillary electrophoresis, detection methods and applications to several aspects of research into glycosaminoglycans and glycosaminoglycan-derived oligosaccharides. The importance of capillary electrophoresis in biological and pharmaceutical samples in glycobiology and carbohydrate biochemistry and its possible applications in disease diagnosis and monitoring chemical synthesis are described.

Analysis of glycosaminoglycan-derived disaccharides in biologic samples by capillary electrophoresis and protocol for sequencing glycosaminoglycans

Glycosaminoglycans are biologically significant carbohydrates which either as free chains (hyaluronan) or constituents of proteoglycans (chondroitin/dermatan sulfates, heparin, heparan sulfate and keratan sulfate) participate and regulate several cellular events and (patho)physiological processes. Capillary electrophoresis, due to its high resolving power and sensitivity, has been successfully used for the analysis of glycosaminoglycans. Determination of compositional characteristics, such as disaccharide sulfation pattern, is a useful prerequisite for elucidating the interactions of glycosaminoglycans with matrix effective molecules and, therefore, essential in understanding the biological functions of proteoglycans. The interest in the field of characterization of such biologically important carbohydrates is soaring and advances in this field will signal a new revolution in the area of glycomics equivalent to that of genomics and proteomics. This review focuses on the capillary electrophoresis methods used to determine the disaccharide pattern of glycosaminoglycans in various biologic samples as well as advances in the sequence analysis of glycosaminoglycans using both chromatographic and electrophoretic techniques.

Hyaluronan content in pleural fluid as a prognostic factor in patients with malignant pleural mesothelioma

BACKGROUND

Regardless of the modality of therapy used, malignant pleural mesothelioma is a highly treatment-resistant and invariably fatal disease. Identification of prognostic variables are important for future investigational therapeutic studies.

METHODS

The prognostic significance of various clinical variables, including hyaluronan levels in pleural fluid, was evaluated in a retrospective analysis in 100 patients with histologically confirmed malignant pleural mesothelioma.

RESULTS

The overall median survival was 11.5 months. Univariate analyses identified histologic subtype, i.e., epithelial or mixed, and elevated content of hyaluronan in the pleural effusion as significant prognostic variables. A multivariate analysis confirmed the independent predictive power of histologic subtype, and an elevated concentration of hyaluronan in the pleural fluid also indicated longer survival in older patients and in patients receiving therapy other than supportive.

CONCLUSIONS

The prognostic value of histologic subtype and the concentration of hyaluronan in pleural effusions should be considered when designing and evaluating treatment trials for patients with malignant pleural mesothelioma.

An optimized battery of eight antibodies that can distinguish most cases of epithelial mesothelioma from adenocarcinoma

An immunocytochemical battery comprising 9 antibodies specifically distinguishes 80% of the epithelial malignant mesotheliomas from adenocarcinomas. The discriminatory power of antibodies to calretinin was tested together with this battery to determine whether the performance thereby could be improved. The study comprises 119 mesotheliomas of epithelial or mixed phenotype and 57 adenocarcinoma metastases in the pleural cavity. The differences between the 2 groups were highly significant for all recorded parameters, but typical reactivity for all parameters was seen in only 6 (5.0%) of the 119 mesotheliomas. An algorithm based on stepwise logistic regression was used to interpret divergent reaction patterns. Most diagnostic information was obtained with 8 of the parameters studied. The resulting algorithm identified almost 90% of the mesotheliomas with high specificity. The battery can be performed in 2 steps: several adenocarcinomas first are diagnosed with a few antibodies, applying the rest of the battery on the remaining unresolved cases.

Use of tumor markers for differential diagnosis of mesothelioma and secondary pleural malignancies

STUDY OBJECTIVE

The aim of the study was to assess diagnosis value of tumor markers for differential diagnosis between mesothelioma and other pleural tumors.

DESIGN AND METHODS

Prospective study of 85 patients attending our hospital with malignant pleural effusion. The diagnostic approach involved routine pleurocentesis followed by pleural needle. When precise diagnosis was not achieved, thoracoscopy with pleural biopsies was performed. Carcinoembryonic antigen (CEA), hyaluronic acid, tissue polypeptide antigen and cyfra 21 to 1 were measured in serum and pleural fluid.

RESULTS

By using receiver operating characteristics curves and area under curves, the best diagnostic characteristics were obtained with pleural and serum CEA concentrations. The area under the curve was larger for pleural ACE than for serum ACE. The sensitivity and specificity of a pleural CEA level exceeding 3 ng/mL for ruling out the diagnosis of mesothelioma were 100% and 77%, respectively.

CONCLUSION

A CEA level above 3 ng/mL in pleural fluid eliminated the diagnosis of mesothelioma, whereas the other markers were not sufficiently discriminant. However, despite a negative predictive value of 100% at a cutoff of 3 ng/mL, CEA assay in pleural fluid only avoids a small number of diagnostic thoracoscopies.

Reactivity of six antibodies in effusions of mesothelioma, adenocarcinoma and mesotheliosis: stepwise logistic regression analysis

Anti-CEA, anti-vimentin, CAM5.2, BerEp4, Leu-M1 and anti-EMA were applied to effusions from 36 mesotheliomas, 53 adenocarcinomas and 24 reactive mesothelial proliferations. Stepwise logistic regression analysis selected three criteria of major importance for distinguishing between adenocarcinoma and mesothelioma: BerEp4, CEA and EMA accentuated at the cell membrane (mEMA), these three being of similar diagnostic value. The pattern BerEp4-, CEA- and mEMA+ was fully predictive for mesothelioma (sensitivity 47%), whereas the opposite pattern was fully predictive for adenocarcinoma (sensitivity 80%). Only EMA seemed to distinguish between mesotheliosis and mesothelioma. Comparison of reactivity in cytological and histological material from the same mesotheliomas showed similar staining frequencies for CEA and CAM5.2, with some random variation for Leu-M1 and EMA, whereas vimentin and BerEp4 reactivity was more frequent in cytological specimens.

Strategies for analysis and structure characterization of glycans/proteoglycans by capillary electrophoresis. Their diagnostic and biopharmaceutical importance

Proteoglycans are key biological macromolecules that, via their glycan constituents, participate and regulate several cellular events and physiopathological processes. Refined structures of their highly anionic glycan chains, involving sulphation pattern and uronic acid distribution through the polymeric chain, determine the interactions of proteoglycans with matrix effector molecules and are responsible for numerous effects. Analysis and structural characterization of glycans are, therefore, essential in understanding the biological functions of proteoglycans. Capillary electrophoresis with its high resolving power and sensitivity may successfully be used for the fine chemical characterization of components present in low amounts and to overcome limitations due to low amount/volume of biologic samples available. This technique is also friendly to the user and to the environment, since a very small amount of solvents (a few microL) is required. In this review the strategies used to analyse and characterize the structure of glycan chains of proteoglycans are summarized. They involve capillary electrophoretic analysis of depolymerized acidic glycan chains using specific enzymes and analysis of intact chains. The importance of this type of analysis in biologic samples and tissues and its possible diagnostic and biopharmaceutical use are also discussed.

A survey of methodological challenges for glycosaminoglycan/proteoglycan analysis and structural characterization by capillary electrophoresis

Proteoglycans participate and regulate several physiological processes via their glycosaminoglycan constituents. For a deeper understanding of how they interact with extracellular ligands as well as with cell bound effector molecules, the fine chemical structures of their glycosaminoglycan chains must be elucidated. Lately developed capillary electrophoretic techniques is a powerful analytical tool for the analysis of glycosaminoglycans, combining a high resolving power with sensitive detection. In this review we describe how depolymerized and intact glycosaminoglycans/proteoglycans can be characterized by capillary electrophoresis, relating these analyses to their possible biological significance. Conditions for running these separations and the detection systems for particular applications are also summarized.

Optimization of a battery using nine immunocytochemical variables for distinguishing between epithelial mesothelioma and adenocarcinoma

A battery of immunocytochemical analyses, previously established to distinguish between malignant mesothelioma and metastatic adenocarcinoma, was extended by analysing the same cases with three other commercially available antibodies. Altogether, 11 antibodies were studied in mesotheliomas diagnosed by other means, using 14 different immunocytochemical parameters. Logistic regression analysis indicated that the following parameters were of importance for this diagnostic problem: vimentin reactivity in epithelial cells (1), cytokeratin (CAM 5.2) reactivity in spindle-shaped (fibrous) cells (2), cell membrane-associated reactivity of EMA (3), HBME-1 (4) and thrombomodulin (5), and absence of reactivity to CEA (6), CD15 (7), BerEp4 (8) and Sialyl-TN (9). The analysis gave an algorithm with which a specific diagnosis of mesothelioma could be made in 80% of the cases-i.e., some improvement compared to the 55% sensitivity using the previous battery.

Utility of hyaluronic acid in pleural fluid for differential diagnosis of pleural effusions: likelihood ratios for malignant mesothelioma

The level of hyaluronic acid (HA) was determined in the pleural fluid of 99 patients, including 19 with malignant mesothelioma, 27 with lung cancer, 1 with breast cancer, 1 with mediastinal tumor and 51 with non-malignant diseases. With a cut-off level at 100 micrograms/ml, the pleural fluid concentration of HA was high in 36.8% of patients (7 of 19) with malignant mesothelioma and 1.3% of patients (1 of 80) with lung cancer and other malignant and non-malignant diseases. The mean concentration of pleural fluid HA was significantly higher in patients with mesothelioma than in those with lung cancer and other malignant and non-malignant diseases. The pre-test probability of MM was 5.9% in this series. The LRs for > or = 100, 50-99 and < or = 49 micrograms/ml are 28.3, 3.3 and 0.5, respectively; these put the post-test probabilities at 64, 17 and 3%, respectively. Indeed, in cases of uncommon disease such as MM, the post-test probability is low even if the cut-off level of HA is > or = 100 micrograms/ml. The discrimination between malignant mesothelioma and lung cancer needs special attention. In these two diseases, the LRs of MM for pleural fluid CEA > 30, 10-30 and < 10 ng/ml were 0.2, 1.9 and 2.4, respectively. The pre-test probability of MM for HA > or = or 100 micrograms/ml is 64%. Furthermore, because the LR for CEA is < 10 ng/ml, the post-test probability is 81%. When the combination of two markers is considered, the high level of HA and the low level of CEA may be useful for the differential diagnosis of MM from pleuritis carcinomatosa.

High-performance capillary electrophoretic analysis of hyaluronan in effusions from human malignant mesothelioma

A procedure to quantify hyaluronan in effusions from human malignant mesothelioma using a highly sensitive and reproducible high-performance capillary electrophoresis (HPCE) method is presented. Following ethanol precipitation, hyaluronan and galactosaminoglycans were degraded to delta 4,5-disaccharides with a mixture of chondroitinases ABC and AC. Heparan sulphate and proteins/glycoproteins were separated by ultrafiltration on a Centricon 3 membrane, and hyaluronan-derived disaccharides were analysed by direct injection of the filtrate into a HPCE system. Determination of hyaluronan in effusions from five healthy individuals and three patients with mesothelioma gave values comparable to those found using the HPLC method. One of the advantages of the HPCE method as compared to HPLC is the low solvent consumption. The much lower detection limit (attomole level) of the HPCE method may also allow the analysis of hyaluronan content in serum. The contribution of HPCE in diagnosis of a neoplasm, such as human malignant mesothelioma, illustrates the great potential of this technique in the field of life sciences.

Effect of insulin and epidermal growth factors on the synthesis of glycosaminoglycans/proteoglycans in cultured human malignant mesothelioma cells of different phenotypic morphology

Two human malignant mesothelioma cell sublines, one with a fibroblast-like and the other with an epithelial differentiation, were examined for their capacity to synthesize glycosaminoglycans in the presence of IGF-I, EGF, and their combination. This synthesis depends on the morphology of the mesothelioma cells, with many-fold higher amounts of both hyaluronan and proteoglycans being produced by the cells with epithelial morphology than by those of the fibroblast phenotype. In both cell lines this synthesis was affected in a dose-dependent fashion by the exogenously added growth factors and exposure to IGF-I and EGF in combination showed a synergistic effect. This effect of those factors seems to be mediated via protein tyrosin kinase-dependent receptors and was different in the fibroblast-like and epithelial cells. The synthetic rates of the various glycosaminoglycans formed (hyaluronan, galactosaminoglycans and heparan sulfate) were also variously affected by these factors, indicating differences in how the synthesis of the various glycosaminoglycans is regulated. The results obtained suggest a close correlation between the presence of the appropriate growth factor(s), the process of cell differentiation and the synthesis of glycosaminoglycans in these cells.

Mechanisms of carcinogenesis and clinical features of asbestos-associated cancers

Exposure to asbestos, particularly members of the amphibole subgroup (crocidolite, amosite), is associated with the development of malignant mesothelioma and lung cancer. Although management of asbestos in buildings and increased regulation of asbestos in workplace settings are viable approaches to the prevention of disease, the prognosis of asbestos-associated tumors is generally dismal. Moreover, although a vast amount of information is available on the responses of cells and tissues to fibers, understanding the pathogenesis of asbestos-associated malignancies is hampered by the complexity of and differences between various fiber types. Multiple interactions between components of cigarette smoke and asbestos may be important in the development of lung cancer. In this article, the general properties of asbestos fibers will be discussed with an emphasis on chemical and physical features implicated in tumorigenesis. We will then provide a brief overview of the clinical features and treatment of cancers associated with exposure to asbestos. Finally, we will review recent experimental data providing some insight into the cellular and molecular mechanisms of carcinogenesis by asbestos.

Determination of hyaluronan and galactosaminoglycan disaccharides by high-performance capillary electrophoresis at the attomole level. Applications to analyses of tissue and cell culture proteoglycans

A rapid, highly sensitive and reproducible HPCE method is described for the determination of all non- and variously sulphated disaccharides present in hyaluronan and vertebrate chondroitin sulphates and dermatan sulphates. Following chondroitinase digestion of glycosaminoglycans or proteoglycans, the non-, di- and tri-sulphated delta-disaccharides are completely separated and readily determined within 14 min on a fused-silica capillary in 15 mM sodium dihydrogen orthophosphate, pH 3.00, using reversed polarity at 20 kV and detection at 232 nm. The determination of the various delta-disaccharides derived from either glucuronic or iduronic acid and the presence of glucuronic and iduronic clustered structures in dermatan sulphate can also easily be made, using digests with chondroitinase AC or B. A linear detector response was obtained for the entire interval tested (up to 10 mg/l of delta-disaccharides). Concentrations as small as 32, 65, 100 and 250 pmol/l (22, 38, 50 and 98 ng/l) of tri-, di- and nonsulphated delta-disaccharides, respectively, can be reliably detected.

Glycosaminoglycans from two human malignant mesothelioma cell lines: determination, distribution, and effect of platelet-derived growth factor on their synthesis

The synthesis and distribution of glycosaminoglycans (GAGs) were studied in two human malignant mesothelioma cell lines: one with fibroblast-like morphology and the other with epithelial differentiation. Analyses using highly sensitive high-pressure liquid chromatography techniques and agarose gel electrophoresis showed that these cells produce not only hyaluronan (HA) but also galactosaminoglycans (GalAGs, chondroitin sulfate and (or) dermatan sulfate) and heparan sulfate (HS). In both cell lines most of the HA (87-90%) and GalAGs (57-66%) are secreted into the extracellular matrix. Although HS is mainly bound to the cell surface in fibroblast-differentiated cells (75%), in epithelial type cells only 40% occurs in the cell-associated fraction. The amounts of secreted GAGs are 6- to 8-fold higher in epithelial than in fibroblast-like mesothelioma cultures. In cells with the fibroblast phenotype, the beta-homodimer of platelet-derived growth factor (PDGF) in a concentration of 1.5 ng/mL stimulates HA and GalAG synthesis 5-fold and that of HS 10-fold, whereas higher concentrations suppress this stimulatory effect. The stimulatory effect, observed at low concentrations of this growth factor, was completely blocked by the addition of antibodies against this factor. In epithelially differentiated cells, the production of all GAGs was suppressed after addition of this factor, even at low concentrations. We therefore suggest that mesothelioma cells can produce GAGs, the synthesis of which is dependent on the presence and concentration of PDGF beta-homodimer. The differences between the two cell lines regarding the effect of this growth factor on GAG synthesis indicates that the regulation of this synthesis is complex, other factors also being important.

Immunohistochemical reactivity in mesothelioma and adenocarcinoma: a stepwise logistic regression analysis

Histological sections from 103 malignant mesotheliomas and 43 adenocarcinoma metastases in pleural biopsies were investigated for reactivity against a panel of 11 different antibodies. The size of the material allowed the evaluation by stepwise logistic regression analysis, which selected five parameters of major importance: vimentin reactivity in epithelial cells, reactivity to low-molecular-weight keratins in fibrous cells, strong membrane accentuation of EMA reactivity, and lack of reactivity to LeuM1 and BerEp4. Three of these criteria were sufficient to identify a mesothelioma with high specificity and with a sensitivity of approximately 70%. Whilst the monoclonal anti-CEA tested was the most valuable single parameter, it did not add any diagnostic information to the combination of criteria selected by the stepwise logistic regression analysis. However, this antibody can be used to exclude most of the adenocarcinomas from further analysis with the more extensive panel.