Differentiation of mesothelioma cells is influenced by the expression of proteoglycans

The Role of RKIP in the Regulation of EMT in the Tumor Microenvironment

Simple Summary

Raf kinase inhibitor protein (RKIP) expression in cancer cells is significantly reduced and promoting cancer cells growth and invasiveness. Overexpresssion of RKIP has been reported to mediate pleiotropic anti-cancer activities including the inhibition of survival signaling pathways, sensitization to cell death by cytotoxic drugs, inhibition of invasion, EMT and metastasis. The molecular mechanism by which RKIP inhibits EMT is not clear. In this review, we have examined how RKIP inhibits the selected EMT gene products (Snail, vimentin, N-cadherin, laminin alpha) and found that it involves signaling cross-talks between RKIP and each of the EMT gene products. These findings were validated by bioinformatic analyses demonstrating in various human cancers a negative correlation between the expression of RKIP and the expression of the EMT gene products. These findings suggest that targeting RKIP induction in cancer cells will result in multiple hits by inhibiting tumor growth, metastasis and reversal of chemo-immuno resistance.

Abstract

The Raf Kinase Inhibitor Protein (RKIP) is a unique gene product that directly inhibits the Raf/Mek/Erk and NF-kB pathways in cancer cells and resulting in the inhibition of cell proliferation, viability, EMT, and metastasis. Additionally, RKIP is involved in the regulation of cancer cell resistance to both chemotherapy and immunotherapy. The low expression of RKIP expression in many cancer types is responsible, in part, for the pathogenesis of cancer and its multiple properties. The inhibition of EMT and metastasis by RKIP led to its classification as a tumor suppressor. However, the mechanism by which RKIP mediates its inhibitory effects on EMT and metastases was not clear. We have proposed that one mechanism involves the negative regulation by RKIP of the expression of various gene products that mediate the mesenchymal phenotype as well as the positive regulation of gene products that mediate the epithelial phenotype via signaling cross talks between RKIP and each gene product. We examined several EMT mesenchymal gene products such as Snail, vimentin, N-cadherin, laminin and EPCAM and epithelial gene products such as E-cadherin and laminin. We have found that indeed these negative and positive correlations were detected in the signaling cross-talks. In addition, we have also examined bioinformatic data sets on different human cancers and the findings corroborated, in large part, the findings observed in the signaling cross-talks with few exceptions in some cancer types. The overall findings support the underlying mechanism by which the tumor suppressor RKIP regulates the expression of gene products involved in EMT and metastasis. Hence, the development of agent that can selectively induce RKIP expression in cancers with low expressions should result in the activation of the pleiotropic anti-cancer activities of RKIP and resulting in multiple effects including inhibition of tumor cell proliferation, EMT, metastasis and sensitization of resistant tumor cells to respond to both chemotherapeutics and immunotherapeutics.

Chemosensitivity and resistance testing in malignant effusions with focus on primary malignant mesothelioma and metastatic adenocarcinoma

Cell based chemosensitivity and resistance testing is an attractive approach that offers functional measurement of drug response ex vivo with the ultimate goal to guide the choice of chemotherapy for various cancers. Thus, it has a great potential to select patients for the optimal treatment option, thereby offering a tool for personalized cancer therapy. Despite several decades of intensive scientific efforts ex-vivo tests are still not incorporated in the standard of care. Limited access to fresh tumor tissue, unsatisfactory models and single readout as endpoint constitute major hindrance. Thus, establishing and validating clinically useful and reliable model systems still remains a major challenge. Here we present malignant effusions as valuable sources for ex-vivo chemosensitivity and resistance testing. Accumulation of a malignant effusion in the pleura, peritoneum or pericardium is often the first diagnostic material for both primary malignant mesothelioma and a broad spectrum of metastatic adenocarcinoma originating from lung-, breast-, ovary- and gastro-intestinal organs as well as lymphoma. In contrast to biopsies, in these effusions malignant cells are easily accessible and often abundant. Effusion derived cells can occur dissociated or forming three-dimensional papillary structures that authentically recapitulate the biology of the corresponding tumor tissue and offer models for ex vivo testing. In addition, effusions have the advantage of being available prior to or concurrent with the pathological review, thus constituting an excellent source of viable cells for simultaneous molecular profiling, biomarker analysis and for establishing primary cells for studying tumor biology and resistance mechanisms. For a reliable test, however, a careful validation is needed, taking into account the inherited heterogeneity of malignant tumors, but also the complex interplay between malignant and benign cells, which are always present in this setting.

The Extracellular Matrix in Epithelial Ovarian Cancer - A Piece of a Puzzle

Epithelial ovarian cancer is the fifth leading cause of cancer-related deaths in women and the most lethal gynecological malignancy. Extracellular matrix (ECM) is an integral component of both the normal and tumor microenvironment. ECM composition varies between tissues and is crucial for maintaining normal function and homeostasis. Dysregulation and aberrant deposition or loss of ECM components is implicated in ovarian cancer progression. The mechanisms by which tumor cells induce ECM remodeling to promote a malignant phenotype are yet to be elucidated. A thorough understanding of the role of the ECM in ovarian cancer is needed for the development of effective biomarkers and new therapies.

Heparan sulfate proteoglycans and human breast cancer epithelial cell tumorigenicity

Heparan sulfate proteoglycans (HSPGs) are key components of the extracellular matrix that mediate cell proliferation, invasion, and cellular signaling. The biological functions of HSPGs are linked to their co-stimulatory effects on extracellular ligands (e.g., WNTs) and the resulting activation of transcription factors that control mammalian development but also associated with tumorigenesis. We examined the expression profile of HSPG core protein syndecans (SDC1-4) and glypicans (GPC1-6) along with the enzymes that initiate or modify their glycosaminoglycan chains in human breast cancer (HBC) epithelial cells. Gene expression in relation to cell proliferation was examined in the HBC cell lines MCF-7 and MDA-MB-231 following treatment with the HS agonist heparin. Heparin increased gene expression of chain initiation and modification enzymes including EXT1 and NDST1, as well as core proteins SDC2 and GPC6. With HS/Wnt interactions established, we next investigated WNT pathway components and observed that increased proliferation of the more invasive MDA-MB-231 cells is associated with activation of the Wnt signaling pathway. Specifically, there was substantial upregulation (>5-fold) of AXIN1, WNT4A, and MYC in MDA-MB-231 but not in MCF-7 cells. The changes in gene expression observed for HSPG core proteins and related enzymes along with the associated Wnt signaling components suggest coordinated interactions. The influence of HSPGs on cellular proliferation and invasive potential of breast cancer epithelial cells are cell and niche specific. Further studies on the interactions between HSPGs and WNT ligands may yield clinically relevant molecular targets, as well as new biomarkers for characterization of breast cancer progression.

Syndecans as modulators and potential pharmacological targets in cancer progression

Extracellular matrix (ECM) components form a dynamic network of key importance for cell function and properties. Key macromolecules in this interplay are syndecans (SDCs), a family of transmembrane heparan sulfate proteoglycans (HSPGs). Specifically, heparan sulfate (HS) chains with their different sulfation pattern have the ability to interact with growth factors and their receptors in tumor microenvironment, promoting the activation of different signaling cascades that regulate tumor cell behavior. The affinity of HS chains with ligands is altered during malignant conditions because of the modification of chain sequence/sulfation pattern. Furthermore, matrix degradation enzymes derived from the tumor itself or the tumor microenvironment, like heparanase and matrix metalloproteinases, ADAM as well as ADAMTS are involved in the cleavage of SDCs ectodomain at the HS and protein core level, respectively. Such released soluble SDCs "shed SDCs" in the ECM interact in an autocrine or paracrine manner with the tumor or/and stromal cells. Shed SDCs, upon binding to several matrix effectors, such as growth factors, chemokines, and cytokines, have the ability to act as competitive inhibitors for membrane proteoglycans, and modulate the inflammatory microenvironment of cancer cells. It is notable that SDCs and their soluble counterparts may affect either the behavior of cancer cells and/or their microenvironment during cancer progression. The importance of these molecules has been highlighted since HSPGs have been proposed as prognostic markers of solid tumors and hematopoietic malignancies. Going a step further down the line, the multi-actions of SDCs in many levels make them appealing as potential pharmacological targets, either by targeting directly the tumor or indirectly the adjacent stroma.

The role of syndecan-1 in cellular signaling and its effects on heparan sulfate biosynthesis in mesenchymal tumors

Proteoglycans (PGs) and in particular the syndecans are involved in the differentiation process across the epithelial-mesenchymal axis, principally through their ability to bind growth factors and modulate their downstream signaling. Malignant tumors have individual proteoglycan profiles, which are closely associated with their differentiation and biological behavior, mesenchymal tumors showing a different profile from that of epithelial tumors. Syndecan-1 is the main syndecan of epithelial malignancies, whereas in sarcomas its expression level is generally low, in accordance with their mesenchymal phenotype and highly malignant behavior. This proteoglycan is often overexpressed in adenocarcinoma cells, whereas mesothelioma and fibrosarcoma cells express syndecan-2 and syndecan-4 more abundantly. Increased expression of syndecan-1 in mesenchymal tumors changes the tumor cell morphology to an epithelioid direction whereas downregulation results in a change in shape from polygonal to spindle-like morphology. Although syndecan-1 plays major roles on the cell-surface, there are also intracellular functions, which are not very well studied. On the functional level, syndecan-1 affects mesenchymal tumor cell proliferation, adhesion, migration and motility, and the effect varies with the different domains of the core protein. Syndecan-1 may exert stimulatory or inhibitory effects, depending on the concentration of various mitogens, enzymes, and signaling molecules, the ratio between the shed and membrane-associated syndecan-1 and histological grade of the tumour. Growth factor signaling seems to be delicately controlled by regulatory loops involving the syndecan expression levels and their sulfation patterns. Overexpression of syndecan-1 modulates the biosynthesis and sulfation of heparan sulfate and it also affects the expression of other PGs. On transcriptomic level, syndecan-1 modulation results in profound effects on genes involved in regulation of cell growth.

Microenvironment-Dependent Phenotypic Changes in a SCID Mouse Model for Malignant Mesothelioma

Background and Aims: Malignant mesothelioma is an aggressive, therapy-resistant tumor. Mesothelioma cells may assume an epithelioid or a sarcomatoid phenotype, and presence of sarcomatoid cells predicts poor prognosis. In this study, we investigated differentiation of mesothelioma cells in a xenograft model, where mesothelioma cells of both phenotypes were induced to form tumors in severe combined immunodeficiency mice.

Methods: Xenografts were established and thoroughly characterized using a comprehensive immunohistochemical panel, array comparative genomic hybridization (aCGH) of chromosome 3, fluorescent in situ hybridization, and electron microscopy.

Results: Epithelioid and sarcomatoid cells gave rise to xenografts of similar epithelioid morphology. While sarcomatoid-derived xenografts had higher growth rates, the morphology and expression of differentiation-related markers was similar between xenografts derived from both phenotypes. aCGH showed a convergent genotype for both xenografts, resembling the original aggressive sarcomatoid cell sub-line.

Conclusion: Human mesothelioma xenografts from sarcomatoid and epithelioid phenotypes converged to a similar differentiation state, and genetic analyses suggested that clonal selection in the mouse microenvironment was a major contributing factor. This thoroughly characterized animal model can be used for further studies of molecular events underlying tumor cell differentiation.

Variation in drug sensitivity of malignant mesothelioma cell lines with substantial effects of selenite and bortezomib, highlights need for individualized therapy

Background

Malignant mesothelioma cells have an epithelioid or sarcomatoid morphology, both of which may be present in the same tumor. The sarcomatoid phenotype is associated with worse prognosis and heterogeneity of mesothelioma cells may contribute to therapy resistance, which is often seen in mesothelioma. This study aimed to investigate differences in sensitivity between mesothelioma cell lines to anti-cancer drugs. We studied two novel drugs, selenite and bortezomib and compared their effect to four conventional drugs. We also investigated the immunoreactivity of potential predictive markers for drug sensitivity; Pgp, MRP-1, ERCC1, RRM1, TS, xCT and proteasome 20S subunit.

Materials and methods

We treated six mesothelioma cell lines with selenite, bortezomib, carboplatin, pemetrexed, doxorubicin or gemcitabine as single agents and in combinations. Viability was measured after 24 and 48 hours. Immunocytochemistry was used to detect predictive markers.

Results

As a single agent, selenite was effective on four out of six cell lines, and in combination with bortezomib yielded the greatest response in the studied mesothelioma cell lines. Cells with an epithelioid phenotype were generally more sensitive to the different drugs than the sarcomatoid cells. Extensive S-phase arrest was seen in pemetrexed-sensitive cell lines. MRP-1 predicted sensitivity of cell lines to treatment with carboplatin and xCT predicted pemetrexed effect.

Conclusions

The observed heterogeneity in sensitivity of mesothelioma cell lines with different morphology highlights the need for more individualized therapy, requiring development of methods to predict drug sensitivity of individual tumors. Selenite and bortezomib showed a superior effect compared to conventional drugs, motivating clinical testing of these agents as future treatment regime components for patients with malignant mesothelioma.

Novel genes and pathways modulated by syndecan-1: implications for the proliferation and cell-cycle regulation of malignant mesothelioma cells

Malignant pleural mesothelioma is a highly malignant tumor, originating from mesothelial cells of the serous cavities. In mesothelioma the expression of syndecan-1 correlates to epithelioid morphology and inhibition of growth and migration. Our previous data suggest a complex role of syndecan-1 in mesothelioma cell proliferation although the exact underlying molecular mechanisms are not completely elucidated. The aim of this study is therefore to disclose critical genes and pathways affected by syndecan-1 in mesothelioma; in order to better understand its importance for tumor cell growth and proliferation. We modulated the expression of syndecan-1 in a human mesothelioma cell line via both overexpression and silencing, and followed the transcriptomic responses with microarray analysis. To project the transcriptome analysis on the full-dimensional picture of cellular regulation, we applied pathway analysis using Ingenuity Pathway Analysis (IPA) and a novel method of network enrichment analysis (NEA) which elucidated signaling relations between differentially expressed genes and pathways acting via various molecular mechanisms. Syndecan-1 overexpression had profound effects on genes involved in regulation of cell growth, cell cycle progression, adhesion, migration and extracellular matrix organization. In particular, expression of several growth factors, interleukins, and enzymes of importance for heparan sulfate sulfation pattern, extracellular matrix proteins and proteoglycans were significantly altered. Syndecan-1 silencing had less powerful effect on the transcriptome compared to overexpression, which can be explained by the already low initial syndecan-1 level of these cells. Nevertheless, 14 genes showed response to both up- and downregulation of syndecan-1. The "cytokine - cytokine-receptor interaction", the TGF-β, EGF, VEGF and ERK/MAPK pathways were enriched in both experimental settings. Most strikingly, nearly all analyzed pathways related to cell cycle were enriched after syndecan-1 silencing and depleted after syndecan-1 overexpression. Syndecan-1 regulates proliferation in a highly complex way, although the exact contribution of the altered pathways necessitates further functional studies.

Novel genes and pathways modulated by syndecan-1: implications for the proliferation and cell-cycle regulation of malignant mesothelioma cells

Malignant pleural mesothelioma is a highly malignant tumor, originating from mesothelial cells of the serous cavities. In mesothelioma the expression of syndecan-1 correlates to epithelioid morphology and inhibition of growth and migration. Our previous data suggest a complex role of syndecan-1 in mesothelioma cell proliferation although the exact underlying molecular mechanisms are not completely elucidated. The aim of this study is therefore to disclose critical genes and pathways affected by syndecan-1 in mesothelioma; in order to better understand its importance for tumor cell growth and proliferation. We modulated the expression of syndecan-1 in a human mesothelioma cell line via both overexpression and silencing, and followed the transcriptomic responses with microarray analysis. To project the transcriptome analysis on the full-dimensional picture of cellular regulation, we applied pathway analysis using Ingenuity Pathway Analysis (IPA) and a novel method of network enrichment analysis (NEA) which elucidated signaling relations between differentially expressed genes and pathways acting via various molecular mechanisms. Syndecan-1 overexpression had profound effects on genes involved in regulation of cell growth, cell cycle progression, adhesion, migration and extracellular matrix organization. In particular, expression of several growth factors, interleukins, and enzymes of importance for heparan sulfate sulfation pattern, extracellular matrix proteins and proteoglycans were significantly altered. Syndecan-1 silencing had less powerful effect on the transcriptome compared to overexpression, which can be explained by the already low initial syndecan-1 level of these cells. Nevertheless, 14 genes showed response to both up- and downregulation of syndecan-1. The "cytokine - cytokine-receptor interaction", the TGF-β, EGF, VEGF and ERK/MAPK pathways were enriched in both experimental settings. Most strikingly, nearly all analyzed pathways related to cell cycle were enriched after syndecan-1 silencing and depleted after syndecan-1 overexpression. Syndecan-1 regulates proliferation in a highly complex way, although the exact contribution of the altered pathways necessitates further functional studies.

Precision manufacturing for clinical-quality regenerative medicines

Innovations in engineering applied to healthcare make a significant difference to people's lives. Market growth is guaranteed by demographics. Regulation and requirements for good manufacturing practice-extreme levels of repeatability and reliability-demand high-precision process and measurement solutions. Emerging technologies using living biological materials add complexity. This paper presents some results of work demonstrating the precision automated manufacture of living materials, particularly the expansion of populations of human stem cells for therapeutic use as regenerative medicines. The paper also describes quality engineering techniques for precision process design and improvement, and identifies the requirements for manufacturing technology and measurement systems evolution for such therapies.

Altered expression of sialylated glycoproteins in breast cancer using hydrazide chemistry and mass spectrometry

Sialylation is one of the altered protein glycosylations associated with cancer development. The sialoglycoproteins in cancer cells, however, largely remain unidentified because of the lack of a method for quantitative analysis of sialoglycoproteins. This manuscript presents a high throughput method for quantitative analysis of N-linked sialoglycoproteins using conditional hydrazide chemistry, liquid chromatography, and tandem mass spectrometry. We further applied the sialoglycoproteomic method to the profiling of breast cancer tissues and compared findings with the results from the total glycoproteomic analysis using the original hydrazide chemistry method. We identified altered expression of sialoglycoproteins, as well as the total glycoprotein changes associated with breast cancer. Using lectin and Western blot analysis, we characterized one of the sialoglycoproteins, versican, and confirmed that versican was most sialylated and elevated in breast cancer. Furthermore, we showed that versican was detected in both cancer epithelial cells and peritumoral stromal cells using immunohistochemistry. Tissue microarray analysis revealed that epithelial expression of versican had significant relations to lymph node metastasis and pathological stages. This is the first quantitative sialoglycoproteomic and glycoproteomic analysis of breast cancer and noncancerous tissues. These findings present a significant addition of the method to the identification of altered expression of sialylated glycoproteins associated with breast cancer development.

Antithetic roles of proteoglycans in cancer

Proteoglycans (PGs), a family of complex post-translationally sculptured macromolecules, are fundamental regulators of most normal and aberrant cellular functions. The unparalleled structural-functional diversity of PGs endows them with the ability to serve as critical mediators of the tumor cells' interaction with the host microenvironment, while directly contributing to the organization and dynamic remodeling of this milieu. Despite their indisputable importance during embryonic development and in the adult organism, and their frequent dysregulation in tumor lesions, their precise involvement in tumorigenesis awaits a more decisive demonstration. Particularly challenging is to ascertain to what extent selected PGs may catalyze tumor progression and to what extent they may inhibit it, implying antithetic functions of individual PGs. Integrated efforts are needed to consolidate the routine use of PGs in the clinical monitoring of cancer patients and to broaden the exploitation of these macromolecules as therapeutic targets. Several PGs have the required attributes to be contemplated as effective antigens for immunotherapeutic approaches, while the tangible results obtained in recent clinical trials targeting the NG2/CSPG4 transmembrane PG urge further development of PG-based cancer treatment modalities.

New Cell-Based Therapy Paradigm: Induction of Bone Marrow-Derived Multipotent Mesenchymal Stromal Cells into Pro-Inflammatory MSC1 and Anti-inflammatory MSC2 Phenotypes

Cell-based therapies (CBTs) are quickly taking hold as a revolutionary new approach to treat many human diseases. Among the cells used in these treatments, multipotent mesenchymal stromal cells, also often and imprecisely termed mesenchymal stem cells (MSC), are widely used because they are considered clinically safe, unique in their immune-modulating capabilities, easily obtained from adult tissues, and quickly expanded as well as stored. However, despite these established advantages, there are limiting factors to employing MSCs in these therapeutic strategies. Foremost is the lack of a general consensus on a definition of these cells, marring efforts to prepare homogeneous lots and more importantly complicating their in vitro and in vivo investigation. Furthermore, although one of the most profound clinical effects of MSC intravenous administration is the modulation of host immune responses, no adequate ex vivo assays exist to consistently predict the therapeutic effect of each MSC lot in the treated patient. Until these issues are addressed, this very promising and safe new therapeutic approach cannot be used to its full advantage. However, these confounding issues do present exciting opportunities. The first is an opportunity to discover unknown aspects of host immune responses because the unique effect driven by MSC infusion on a patient's immunity has not yet been identified. In addition, there is an opportunity to develop methods, tests, and tools to better define MSCs and MSC-based therapy and provide consistency in preparation and effect. To this end, my laboratory recently developed a new approach to induce uniform pro-inflammatory MSC1 and anti-inflammatory MSC2 phenotypes from bone marrow-derived MSC preparations. I anticipate that MSC1 and MSC2 provide convenient tools with which to address some of these limitations and will help advance safe and effective CBTs for human disease.

Specific syndecan-1 domains regulate mesenchymal tumor cell adhesion, motility and migration

Background

Syndecans are proteoglycans whose core proteins have a short cytoplasmic domain, a transmembrane domain and a large N-terminal extracellular domain possessing glycosaminoglycan chains. Syndecans are involved in many important cellular processes. Our recent publications have demonstrated that syndecan-1 translocates into the nucleus and hampers tumor cell proliferation. In the present study, we aimed to investigate the role of syndecan-1 in tumor cell adhesion and migration, with special focus on the importance of its distinct protein domains, to better understand the structure-function relationship of syndecan-1 in tumor progression.

Methodology/Principal Findings

We utilized two mesenchymal tumor cell lines which were transfected to stably overexpress full-length syndecan-1 or truncated variants: the 78 which lacks the extracellular domain except the DRKE sequence proposed to be essential for oligomerization, the 77 which lacks the whole extracellular domain, and the RMKKK which serves as a nuclear localization signal. The deletion of the RMKKK motif from full-length syndecan-1 abolished the nuclear translocation of this proteoglycan. Various bioassays for cell adhesion, chemotaxis, random movement and wound healing were studied. Furthermore, we performed gene microarray to analyze the global gene expression pattern influenced by syndecan-1. Both full-length and truncated syndecan-1 constructs decrease tumor cell migration and motility, and affect cell adhesion. Distinct protein domains have differential effects, the extracellular domain is more important for promoting cell adhesion, while the transmembrane and cytoplasmic domains are sufficient for inhibition of cell migration. Cell behavior seems to depend also on the nuclear translocation of syndecan-1. Many genes are differentially regulated by syndecan-1 and a number of genes are actually involved in cell adhesion and migration.

Conclusions/Significance

Our results demonstrate that syndecan-1 regulates mesenchymal tumor cell adhesion and migration, and different domains have differential effects. Our study provides new insights into better understanding of the role of syndecans in tumor progression.

Chlamydophila pneumoniae attachment and infection in low proteoglycan expressing human lymphoid Jurkat cells

This study investigated the proteoglycan (PG)-dependent mechanism of Chlamydophila pneumoniae attachment to lymphocytic cells. Lymphoid Jurkat cells and epithelial HEp-2 cells were statically infected with C. pneumoniae (TW183). Transmission electron microscopy and assessment of inclusion-forming units indicated that the bacteria grew normally in Jurkat cells and were capable of producing secondary infection; however, they grew at a slower rate than in HEp-2 cells. RT-PCR analysis indicated that HEp-2 cells strongly expressed PG-core protein encoding genes, thereby sustaining glycosaminoglycans (GAGs), such as heparin, on the cellular surface. Similar gene expression levels were not observed in Jurkat cells, with the exception of glypican-1. Immunofluorescence analysis also supported strong heparin expression in HEp-2 cells and minimal expression in Jurkat cells, although heparan sulfate pretreatment significantly inhibited bacterial attachment to both cell types. Immunofluorescent co-staining with antibodies against chlamydial LPS and heparin did not identify bacterial and heparin co-localization on Jurkat cells. We also confirmed that when C. pneumoniae was statically infected to human CD4(+) peripheral blood lymphocytes known not expressing detectable level of heparin, the bacteria attached to and formed inclusion bodies in the cells. Thus, the attachment mechanism of C. pneumoniae to Jurkat cells with low PG expression is unique when compared with HEp-2 cells and potentially independent of GAGs such as heparin.

Concise review: mind the gap: challenges in characterizing and quantifying cell- and tissue-based therapies for clinical translation

There are many challenges associated with characterizing and quantifying cells for use in cell- and tissue-based therapies. From a regulatory perspective, these advanced treatments must not only be safe and effective but also be made by high-quality manufacturing processes that allow for on-time delivery of viable products. Although sterility assays can be adapted from conventional bioprocessing, cell- and tissue-based therapies require more stringent safety assessments, especially in relation to use of animal products, immune reaction, and potential instability due to extended culture times. Furthermore, cell manufacturers who plan to use human embryonic stem cells in their therapies need to be particularly stringent in their final purification steps, due to the unrestricted growth potential of these cells. This review summarizes the current issues in characterization and quantification for cell- and tissue-based therapies, dividing these challenges into the regulatory themes of safety, potency, and manufacturing quality. It outlines current assays in use, as well as highlights the limits of many of these product release tests. Mode of action is discussed, with particular reference to in vitro surrogate assays that can be used to provide information to correlate with proposed in vivo patient efficacy. Importantly, this review highlights the requirement for basic research to improve current knowledge on the in vivo fate of these treatments; as well as an improved stakeholder negotiation process to identify the measurement requirements that will ensure the manufacture of the best possible cell- and tissue-based therapies within the shortest timeframe for the most patient benefit.

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.

Syndecan-1 and FGF-2, but not FGF receptor-1, share a common transport route and co-localize with heparanase in the nuclei of mesenchymal tumor cells

Syndecan-1 forms complexes with growth factors and their cognate receptors in the cell membrane. We have previously reported a tubulin-mediated translocation of syndecan-1 to the nucleus. The transport route and functional significance of nuclear syndecan-1 is still incompletely understood. Here we investigate the sub-cellular distribution of syndecan-1, FGF-2, FGFR-1 and heparanase in malignant mesenchymal tumor cells, and explore the possibility of their coordinated translocation to the nucleus. To elucidate a structural requirement for this nuclear transport, we have transfected cells with a syndecan-1/EGFP construct or with a short truncated version containing only the tubulin binding RMKKK sequence. The sub-cellular distribution of the EGFP fusion proteins was monitored by fluorescence microscopy. Our data indicate that syndecan-1, FGF-2 and heparanase co-localize in the nucleus, whereas FGFR-1 is enriched mainly in the perinuclear area. Overexpression of syndecan-1 results in increased nuclear accumulation of FGF-2, demonstrating the functional importance of syndecan-1 for this nuclear transport. Interestingly, exogenously added FGF-2 does not follow the route taken by endogenous FGF-2. Furthermore, we prove that the RMKKK sequence of syndecan-1 is necessary and sufficient for nuclear translocation, acting as a nuclear localization signal, and the Arginine residue is vital for this localization. We conclude that syndecan-1 and FGF-2, but not FGFR-1 share a common transport route and co-localize with heparanase in the nucleus, and this transport is mediated by the RMKKK motif in syndecan-1. Our study opens a new perspective in the proteoglycan field and provides more evidence of nuclear interactions of syndecan-1.

Syndecan-1 supports integrin alpha2beta1-mediated adhesion to collagen

Several different receptor molecules act in concert to regulate cell adhesion. Among these are cell-surface proteoglycans and integrins, which collaborate extensively in mediating binding of cells to extracellular matrix molecules fibronectin and vitronectin. However, very little is known about possible functional synergism between proteoglycans and integrins during adhesion of cells to collagen, although collagen is the most abundant protein in the human body. Here we show that cell-surface heparan sulphate proteoglycans (HSPGs) support integrin alpha2beta1-mediated adhesion to collagen. Cells made devoid of HSPGs either by genetic means or by enzymatic digestions were unable to adhere to collagen via alpha2beta1 integrin. HSPG-deficient cells also displayed impaired spreading and actin organization on collagen. Among different HSPG molecules syndecan-1 was found to play an important role in supporting alpha2beta1 integrin-mediated adhesion. Using overexpression and knock-down experiments we demonstrated that syndecan-1, but not syndecan-2 or -4, enhanced binding of alpha2beta1 to collagen. Moreover, syndecan-1 co-localized with alpha2beta1 integrin and contributed to proper organization of cortical actin. Finally, crosstalk between syndecan-1 and alpha2beta1 integrin was found to enhance the transcription of matrix metalloproteinase-1 in response to collagen binding. Our findings thus suggest that a previously unknown link between integrin alpha2beta1 and syndecan-1 is important in regulating cell adhesion to collagen and in triggering integrin downstream signalling.

Estradiol-estrogen receptor: a key interplay of the expression of syndecan-2 and metalloproteinase-9 in breast cancer cells

Estrogens are related with the growth and development of target tissues and play a critical role in breast cancer progression. The effects of estrogens are mediated by the estrogen receptors ERalpha and ERbeta, which are members of the nuclear steroid receptor superfamily. To date, it is not known how these hormones elicit many of their effects on extracellular matrix molecules and how these effects can be connected with ER expression. For this purpose, the effect of estradiol on ER expression as well as on proteoglycan and metalloproteinase expression was studied. The effect of E2 on extracellular matrix molecule expression has been studied using ERalpha suppression in breast cancer cells. Our studies using ERalpha-positive MCF-7 cells show that estradiol affects the expression of syndecan-2, but not of syndecan-4, through ERalpha. Furthermore, the ability of estradiol to affect MMP-9 and TIMP-1 expression is connected with ERalpha status. Together, these data demonstrate the significant role of ERalpha on mediating the effect of estradiol on extracellular matrix molecules.

Elevate level of glycosaminoglycans and altered sulfation pattern of chondroitin sulfate are associated with differentiation status and histological type of human primary hepatic carcinoma

OBJECTIVES

The characteristics of glycosaminoglycans (GAGs) in many carcinomas have been reported to be different from those in normal tissues, which can be used as prognostic indices in some cancers. However, the difference in GAG characteristics among various differentiation status or histological types of the same cancer has not been described. The aim of this study was to investigate the relationship between GAG characteristics and human primary hepatic carcinomas of divers differentiation status or histological type.

METHODS

GAGs from intrahepatic cholangiocarcinomas and differently differentiated hepatocellular carcinomas were extracted, purified and enzymatically digested. Their content, relative molecular size distribution and disaccharide composition were analyzed and compared using electrophoresis and high-performance liquid chromatography.

RESULTS

A progressive increase in the content of chondroitin sulfate, low molecular size GAGs, and nonsulfated and disulfated chondroitin sulfate disaccharide units, together with a gradual decrease in heparan sulfate, have been found as the differentiation status of hepatocellular carcinoma became poorer. A significant increase in hyaluronic acid, which only slightly increased in hepatocellular carcinoma, was found in intrahepatic cholangiocarcinomas.

CONCLUSION

The alterations in GAG characteristics in primary hepatic carcinoma were associated with both the differentiation status and the histological type of the tumor.

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.

Targeted therapy--possible new therapeutic option for malignant mesothelioma?

Malignant Mesothelioma presents with a characteristic heterogeneous growth pattern. Response to treatment is often only partial, which may be related to tumor cell heterogeneity. Molecular screening methods have revealed profound differences in the driving mechanisms of the variously differentiated mesothelioma cells. Characterization of these differences has made it possible to identify novel drug targets which are effective for both phenotypes.

Quantification of alternative mRNA species and identification of thioredoxin reductase 1 isoforms in human tumor cells

The human selenoenzyme thioredoxin reductase 1 (TrxR1) is a very important enzyme for cell growth, differentiation, and the defense against oxidative stress. Several studies have shown that TrxR1 is up-regulated in tumor cells. The regulation of TrxR1 is very complex and involves the expression of different transcript forms of mRNA. We have, by quantitative polymerase chain reaction, investigated the total expression of TrxR1 mRNA and quantified the expression of alternative mRNA forms (alpha1/2, alpha6, alpha7/8, alpha10/11, alpha13, gamma2-4, and beta1) in six different human malignant mesothelioma cell lines of epithelioid, sarcomatoid, or mixed phenotype. The most abundant alpha-form was surprisingly alpha1/2 and not the expected alpha7/8. Selenium treatment resulted in increased expression of all alpha-variants, except the alpha10/11, where the levels were unaffected. The expression of protein isoforms was studied and the less abundant forms TrxR1v.2, TrxR1v.3, and TrxR1v.5 were detected in cell lysates and in human tumor tissue, using specific peptide antibodies. Furthermore, TrxR1v.3 and TrxR1v.5, previously not identified in human cells, were detected by mass spectrometry. Our data show differential expression of TrxR1 mRNA forms in malignant mesothelioma of different phenotype, and investigation of alternative transcript variants of TrxR1 could be a valuable tool in the diagnostics and characterization of tumors.

Versican expression in human cervical cancer

Versican expression may enhance tumour invasion and metastasis. However, the expressions of versican in cervical cancer have seldom been characterised. The aim of this study was to investigate versican expression in human cervical cancers. We immunohistochemically investigated the expression of versican protein in 174 cervical cancers and analysed the correlation with various clinicopathological features, including patient outcome. Stromal versican expression was significantly higher in patients with lymph node metastasis (p<0.0001). Epithelial versican expression was significantly higher in patients with non-squamous cell cercinoma (p=0.0003), lymph-vascular space invasion (p=0.046), lymph node metastasis (p=0.009) and ovarian metastasis (p=0.0001). Multivariate analysis showed that high epithelial versican expression was an independent prognostic factor for disease-free survival. Versican enrichment of the tumour tissue may be associated with progression in cervical cancer. Versican expression can serve as an indicator of poor prognosis in patients with cervical cancer.

Versican but not decorin accumulation is related to metastatic potential and neovascularization in testicular germ cell tumours

AIMS

To investigate the expression of versican and decorin in patients with testicular germ cell tumours (GCTs) and to correlate this with the clinicopathological findings. Matrix proteoglycans versican and decorin are frequently overexpressed in various malignancies and are involved in the progression of cancer.

METHODS AND RESULTS

Overexpression of versican and decorin was detected in GCTs by immunoblotting. Immunohistochemical staining for proteoglycans was performed on 71 cases of paraffin-embedded tissues. In most of the cases increased decorin and versican stromal staining was demonstrated. In both seminomas and non-seminomatous germ cell tumours (NSGCTs) strong staining of decorin was not found to be related to any of the clinicopathological variables. Accumulation of versican was found to be associated with vascular and lymphatic invasion, nodal metastasis and disease stage in seminomas and NSGCTs and, in addition, with tumour size and distant metastasis only in NSGCTs. Additionally, only the deposition of versican was linearly correlated with the number of microvessels in the tumour stroma in GCTs.

CONCLUSIONS

Ectopic versican and decorin expression is a frequent feature in GCTs. Versican but not decorin accumulation in GCTs is related to metastatic potential and neovascularization and might be a useful marker for testicular malignancy.

Prognostic significance of stromal versican expression in human endometrial cancer

BACKGROUND

Versican expression may enhance tumor invasion and metastasis. However, the expression of versican in human endometrial cancer has seldom been characterized. The aim of this study was to investigate versican expression in endometrial cancers.

PATIENTS AND METHODS

We immunohistochemically investigated the expression of versican protein in 167 endometrial cancers and analyzed the correlation with various observed clinicopathological features, including patient outcome.

RESULTS

Stromal versican expression was significantly higher in the advanced-stage (P = 0.010) and high-grade (P = 0.049) cancers, lymph node metastasis (P = 0.012), and ovarian metastasis (P = 0.024). Epithelial versican expression was significantly higher in patients with lymph node metastasis (P = 0.014) and lymph-vascular space involvement (P = 0.014). The disease-free survival (DFS) and overall survival (OS) rates of patients exhibiting high stromal versican expression were significantly lower than those of patients exhibiting low stromal versican expression (P < 0.0001). Multivariate analysis showed that high stromal versican expression was an independent prognostic factor for DFS and OS.

CONCLUSIONS

Versican enrichment of the stroma may be associated with tumor progression in endometrial cancer. Stromal versican expression can serve as an indicator of poor prognosis for patients with endometrial cancer.

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.

Tenascin-C induced signaling in cancer

Tenascin-C is an adhesion modulatory extracellular matrix molecule that is highly expressed in the microenvironment of most solid tumors. High tenascin-C expression reduces the prognosis of disease-free survival in patients with some cancers. The possible role of tenascin-C in tumor initiation and progression is addressed with emphasis on underlying signaling mechanisms. How tenascin-C affects malignant transformation, uncontrolled proliferation, angiogenesis, metastasis and escape from tumor immunosurveillance is summarized. Finally, we discuss how the phenotypes of tenascin-C knock-out mice may help define the roles of tenascin-C in tumorigenesis and how this knowledge could be applied to cancer therapy.

Expression of proteoglycan mRNA in patients with painful clicking and chronic closed lock of the temporomandibular joint

RT-PCR was used to analyze the expression of a series of mRNAs coding for proteoglycans aggrecan, versican, biglycan, decorin, fibromodulin and also hyaluronan synthase 1 in specimens obtained during discectomy of the temporomandibular joint in patients with unilateral signs and symptoms of chronic closed lock (eight patients) and painful clicking (seven patients). Regarding the disc, aggrecan expression was higher in patients with chronic closed lock. As for the posterior disc attachment specimens, patients with chronic closed lock showed a tendency for higher expression of biglycan and hyaluronan synthase 1. The degradation of matrix in patients with chronic closed lock of the temporomandibular joint seems not to be caused by a reduced synthesis and the degenerative process seen in these patients is one with low turnover similar to the situation in primary osteoarthrosis of hyaline cartilage. The results indicate that any treatment should intervene early in the disease process of chronic closed lock in order to prevent the development of a degenerative process.

Roles of membrane-type matrix metalloproteinase-1 in tumor invasion and metastasis

Degradation of extracellular matrix (ECM) is one of the first steps in tumor invasion and metastasis. Matrix metalloproteinases (MMP) have been strongly implicated in this step. Membrane-type MMP-1 (MT1-MMP) was first identified as an activator of proMMP-2 expressed on the surface of tumor cells and later, not only ECM macromolecules but also various biologically important molecules, were shown to serve as substrates for MT1-MMP. Accumulated lines of evidence have demonstrated that MT1-MMP expression level is closely associated with invasiveness and malignancy of tumors, suggesting that MT1-MMP is one of the most critical factors for tumor invasion and metastasis. Despite enthusiasm for MMP inhibitors, phase III trials have not yet demonstrated significance in overall survival and side-effects remain an issue. An understanding of the functions of MT1-MMP could supply clues for developing novel therapeutic strategies targeting MT1-MMP.

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.

Syndecan-4 is required for thrombin-induced migration and proliferation in human vascular smooth muscle cells

Thrombin is a mitogen and chemoattractant for vascular smooth muscle cells (SMCs) and may contribute to vascular lesion formation. We have previously shown that human SMCs, when stimulated with thrombin, release basic fibroblast growth factor (bFGF), causing phosphorylation of FGF receptor-1 (FGFR-1). Treatment with bFGF-neutralizing antibodies (anti-bFGF) or heparin inhibits thrombin-induced DNA synthesis. We concluded that thrombin may stimulate entry into the cell cycle via bFGF release and FGFR-1 activation. In the present study, we demonstrate a requirement for not only FGFR-1 but also syndecan-4, a transmembrane heparan-sulfate proteoglycan. Inhibition of syndecan-4 expression using small interfering RNA (siRNA) resulted in reduced DNA synthesis by human SMCs after stimulation with thrombin (10 nmol/liter). Anti-bFGF antibody, which inhibits DNA synthesis in control cells, had no inhibitory effect when syndecan-4 expression was reduced by siRNA. Thrombin- or bFGF-induced SMC migration, determined in Boyden chamber assays, was reduced in cells treated with syndecan-4 or FGFR-1 siRNA or by anti-bFGF. Thrombin induced phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 in a biphasic pattern. Although thrombin-mediated ERK phosphorylation at 5 min was not affected by syndecan-4 or FGFR-1 siRNA, ERK phosphorylation at later time points was reduced. We conclude that thrombin-released bFGF binds to syndecan-4 and FGFR-1, which is required for thrombin-induced mitogenesis and migration.

Excess biglycan causes eyelid malformation by perturbing muscle development and TGF-alpha signaling

Tissue morphogenesis during development is regulated by growth factors and cytokines, and is characterized by constant remodeling of extracellular matrix (ECM) in response to signaling molecules, for example, growth factors, cytokines, and so forth. Proteoglycans that bind growth factors are potential regulators of tissue morphogenesis during embryonic development. In this study, we showed that transgenic mice overexpressing biglycan under the keratocan promoter exhibited exposure keratitis and premature eye opening from noninfectious eyelid ulceration due to perturbation of eyelid muscle formation and the failure of meibomian gland formation. In addition, in vitro analysis revealed that biglycan binds to TGF-alpha, thus interrupting EGFR signaling pathways essential for mesenchymal cell migration induced by eyelid epithelium. The defects of TGF-alpha signaling by excess biglycan were further augmented by the interruption of the autocrine or paracrine loop of the EGFR signaling pathway of HB-EGF expression elicited by TGF-alpha. These results are consistent with the notion that under physiological conditions, biglycan secreted by mesenchymal cells serves as a regulatory molecule for the formation of a TGF-alpha gradient serving as a morphogen of eyelid morphogenesis.

Molecular characterization of tumour heterogeneity and malignant mesothelioma cell differentiation by gene profiling

Malignant mesothelioma is an aggressive tumour, characterized by a variable differentiation pattern and poor prognosis. At present, the clinical outcome in patients with malignant mesothelioma is mainly predicted by the morphological phenotype of the tumour. However, this conventional clinicopathological parameter is of limited value, partly because of the biological heterogeneity of this tumour and poor understanding of the regulatory mechanisms underlying the various patterns of growth. To elucidate the intrinsic molecular programmes that determine tumour differentiation, oligonucleotide arrays were used in an in vitro model of mesothelioma differentiation. The analysis of 2059 genes detected 102 genes that were significantly deregulated. Clustering of these genes into functional categories showed distinctive patterns for the two phenotypes, namely epithelioid and sarcomatoid. The molecular fingerprint of the sarcomatoid tumour component indicates overrepresentation of growth factor receptors and growth factor binding proteins, whereas epithelioid mesothelioma cells express other tumour-promoting factors involved in differentiation, metabolism, and regulation of apoptosis. These differences in the molecular phenotype may give a better basis for diagnosis and for designing novel therapies.

A sandwich ELISA for the estimation of human syndecan-2 and syndecan-4 in biological samples

Syndecans are integral membrane proteoglycans containing both chondroitin and heparan sulphate side chains. Syndecans are shed from the cell surface, and may be detected in cellular supernatant or body fluids. In this study, we wished to design ELISA methods for syndecan-2 and syndecan-4, with the future aim of analyzing syndecans in large number of patient materials. Briefly, sandwich ELISAs for human syndecan-2 and syndecan-4 were designed employing monoclonal mouse antibodies as capture and commercially available polyclonal rabbit anti-syndecan as secondary antibodies. Although no quantified standard was available, relative estimation of syndecan-2 and syndecan-4 levels was possible in a small pilot material. The paper presents the ELISA method for these proteoglycans. We suggest that this may be a useful tool in the analysis of patient materials and in the detection of syndecans during proteoglycan purification.

Cell protection, resistance and invasiveness of two malignant mesotheliomas as assessed by 10K-microarray

Malignant pleural mesothelioma (MPM) is an aggressive serosal tumor, strongly associated with former exposure to asbestos fibers and for which there is currently no effective treatment available. In human, MPM is characterized by a high local invasiveness, poor prognosis and therapeutic outcomes. In order to assess molecular changes that specify this phenotype, we performed a global gene expression profiling of human MPM. Using a 10,000-element microarray, we analyzed mRNA relative gene expression levels by comparing a mesothelioma cell line to either a pleural cell line or tumor specimens. To analyze these gene expression data, we used various bioinformatics softwares. Hierarchical clustering methods were used to group genes and samples with similar expression in an unsupervised mode. Genes of known function were further sorted by enzyme, function and pathway clusters using a supervised software (IncyteGenomics). Taken together, these data defined a molecular fingerprint of human MPM with more than 700 up- or down-regulated genes related to several traits of the malignant phenotype, specially associated with MPM invasiveness, protection and resistance to anticancer defenses. This portrait is meaningful in disease classification and management, and relevant in finding new specific markers of MPM. These molecular markers should improve the accuracy of mesothelioma diagnosis, prognosis and therapy.

Mesothelial progenitor cells and their potential in tissue engineering

The mesothelium consists of a single layer of flattened mesothelial cells that lines serosal cavities and the majority of internal organs, playing important roles in maintaining normal serosal integrity and function. A mesothelial 'stem' cell has not been identified, but evidence from numerous studies suggests that a progenitor mesothelial cell exists. Although mesothelial cells are of a mesodermal origin, they express characteristics of both epithelial and mesenchymal phenotypes. In addition, following injury, new mesothelium regenerates via centripetal ingrowth of cells from the wound edge and from a free-floating population of cells present in the serosal fluid, the origin of which is currently unknown. Recent findings have shown that mesothelial cells can undergo an epithelial to mesenchymal transition, and transform into myofibroblasts and possibly smooth muscle cells, suggesting plasticity in nature. Further evidence for a mesothelial progenitor comes from tissue engineering applications where mesothelial cells seeded onto tubular constructs have been used to generate vascular replacements and grafts to bridge transected nerve fibres. These findings suggest that mesothelial cell progenitors are able to switch between different cell phenotypes depending on the local environment. However, only by performing detailed investigations involving selective cell isolation, clonal analysis together with cell labelling and tracking studies, will we begin to determine the true existence of a mesothelial stem cell.

Mesothelial Differentiation as Reflected by Differential Gene Expression

Human mesothelial cells obtained from benign effusions retain their proliferative capacity and grow uniformly either with a fibroblastic or epithelioid morphology in vitro. These cultures therefore provide a model for the process of mesothelial differentiation in vivo. To study this differentiation, we isolated differentially expressed genes obtained by suppression subtractive hybridization. Of the nine genes found to be overexpressed in fibroblastic mesothelial cells, three are matrix-associated (integrin alpha5, collagen binding protein 2, human cartilage glycoprotein 39), whereas the others are associated with a proliferative cell type (14-3-3 epsilon, plexin B2, N33, and three genes encoding ribosomal elements). Seven of the eight genes upregulated in the epithelioid phenotype are related rather to specialized functions, such as metabolism (aldose reductase, lecithin:cholesterol acyltransferase, ATPase 6), cytoskeletal composition (cytokeratins 7 and 8), and regulation of differentiation (granulin, annexin II). Immunohistochemistry with available antibodies to six of the differentially expressed gene products confirmed the differences also in pleural tissues, where submesothelial cells displayed the fibroblastic markers, whereas surface cells displayed the epithelioid markers. In summary, this approach revealed a pattern of genes coordinately regulated during mesothelial differentiation and suggests that mesothelium may regenerate also by recruiting cells from the submesothelial layer. Some of the gene products may also be useful markers for differentiation and activation in serosal tissues.

Molecular analysis of transitional cell carcinoma using cDNA microarray

The incidence of transitional cell carcinoma (TCC), the fourth most common neoplasm diagnosed in men, is rising. Despite the development of several noninvasive diagnostic tests, none have gained full recognition by the clinicians. Gene expression profiling of tumors can identify new molecular markers for early diagnosis and disease follow-up. It also allows the classification of tumors into subclasses assisting in disease diagnosis and prognosis, as well as in treatment selection. In this paper, we employed expression profiling for molecular analysis of TCC. A TCC-derived cDNA microarray was constructed and hybridized with 19 probes from normal urothelium and TCC tissues. Hierarchical clustering analysis identified all normal urothelium samples to be tightly clustered and separated from the TCC samples, with 29 of the genes significantly induced (t-test, P<10(-5)) in noninvasive TCC compared to normal urothelium. The identified genes are involved in epithelial cells' functions, tumorigenesis or apoptosis, and could become molecular tools for noninvasive TCC diagnosis. Principal components analysis of the noninvasive and invasive TCC expression profiles further revealed sets of genes that are specifically induced in different tumor subsets, thus providing molecular fingerprints that expand the information gained from classical staging and grading.

Versican in epithelial ovarian cancer: relation to hyaluronan, clinicopathologic factors and prognosis

Versican, a proteoglycan previously reported to increase in other malignant tumours, was studied immunohistochemically in 299 primary epithelial ovarian cancers, their 43 metastases and 6 normal ovaries to evaluate its prognostic value and relation to hyaluronan, another extracellular matrix molecule increased in cancer and a binding partner of versican. The stainings were scored according to the area percentage of strong versican signal of total peri- and intratumoural stroma as low (<15%) or high (>or=15%). Epithelial staining of the tumours was scored as positive or negative. Low and high area percentage of strong stromal versican staining were observed in 133 and 166 carcinomas, respectively. A low area percentage of strong stromal versican staining correlated with mucinous histology (p = 0.019) and early International Federation of Gynecologists and Obstetritians (FIGO) stage (p < 0.0005), whereas a high percentage was associated with reduced 5-year survival rate of the patients (44% vs. 32%; p = 0.032). Versican was associated with the cancer cells in 151 tumours and correlated with clear cell histology (p < 0.0005), early FIGO stage (p = 0.049) and increased recurrence-free survival (63% vs. 47%; p = 0.032). However, in Cox's multivariate analyses with the conventional prognostic factors included, neither stromal nor cancer cell-associated versican reached a significant prognostic value. Versican is thus enriched in the malignant stroma surrounding and promoting the growth of ovarian cancer, probably acting with hyaluronan, and associates with unfavourable prognosis but does not constitute an independent indicator of patient survival.

Cleavage of syndecan-1 by membrane type matrix metalloproteinase-1 stimulates cell migration

The transmembrane heparan sulfate proteoglycan syndecan-1 was identified from a human placenta cDNA library by the expression cloning method as a gene product that interacts with membrane type matrix metalloproteinase-1 (MT1-MMP). Co-expression of MT1-MMP with syndecan-1 in HEK293T cells promoted syndecan-1 shedding, and concentration of cell-associated syndecan-1 was reduced. Treatment of cells with MMP inhibitor BB-94 or tissue inhibitor of MMP (TIMP)-2 but not TIMP-1 interfered with the syndecan-1 shedding promoted by MT1-MMP expression. In contrast, syndecan-1 shedding induced by 12-O-tetradecanoylphorbol-13-acetate treatment was inhibited by BB-94 but not by either TIMP-1 or TIMP-2. Shedding of syndecan-1 was also induced by MT3-MMP but not by other MT-MMPs. Recombinant syndecan-1 core protein was shown to be cleaved by recombinant MT1-MMP or MT3-MMP preferentially at the Gly245-Leu246 peptide bond. HT1080 fibrosarcoma cells stably transfected with the syndecan-1 cDNA (HT1080/SDC), which express endogenous MT1-MMP, spontaneously shed syndecan-1. Migration of HT1080/SDC cells on collagen-coated dishes was significantly slower than that of control HT1080 cells. Treatment of HT1080/SDC cells with BB-94 or TIMP-2 induced accumulation of syndecan-1 on the cell surface, concomitant with further retardation of cell migration. Substitution of Gly245 of syndecan-1 with Leu significantly reduced shedding from HT1080/SDC cells and cell migration. These results suggest that the shedding of syndecan-1 promoted by MT1-MMP through the preferential cleavage of Gly245-Leu246 peptide bond stimulates cell migration.

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.

Letrozole as a potent inhibitor of cell proliferation and expression of metalloproteinases (MMP-2 and MMP-9) by human epithelial breast cancer cells

P450 aromatase catalyzes the conversion of androgens to estrogens and plays a key role in the cell growth of hormone-dependent breast cancer in postmenopausal women. On the other hand, matrix metalloproteinases (MMPs), which can degrade almost all components of the extracellular matrix, play a crucial role in tumor cell invasion and cancer metastasis. In the present study the effect of letrozole on cell proliferation of estrogen receptor (ER)-positive MCF-7 human epithelial breast cancer and MCF-12A human mammary epithelial cells was studied. The effect of letrozole on the in vitro release of MMPs, particularly type IV collagenases (MMP-2 and MMP-9), by the ER-positive MCF-7 cells was also investigated, using a solid-phase method of high sensitivity and accuracy. Using RNA isolates from cell lines MCF-7 and MCF-12A, reverse transcriptase-polymerase chain reaction analysis revealed that only MCF-7 cells express the P450 aromatase gene. Study of the effects of letrozole alone and the hormones 17-beta-estradiol, testosterone and 4-androstene-3, 17-dione in the presence and absence of letrozole on cell growth at the DNA synthesis level showed that letrozole significantly suppressed the endogenous aromatase-induced proliferation of MCF-7 cells. The majority of MMPs secreted by MCF-7 cells were identified in their pro-forms, which was in accordance with the low metastatic potential determined for these cells. After treatment of cells with letrozole (10 nM) for 24 and 48 h, significant inhibition of MMP levels was obtained. Furthermore, concurrent treatment of MCF-7 cells with 17-beta-estradiol in the presence of letrozole significantly suppressed the estradiol-induced stimulation of MMP levels. The data obtained suggest that letrozole is a potent in vitro inhibitor of cell proliferation and of type IV collagenases expressed by ER-positive MCF-7 cells and may be of value for suppressing breast tumor growth and invasiveness.

Defects in keratinocyte activation during wound healing in the syndecan-1-deficient mouse

Mice lacking syndecan-1 are viable, fertile and have morphologically normal skin, hair and ocular surface epithelia. While studying the response of these mice to corneal epithelial and skin wounding, we identified defects in epithelial cell proliferation and regulation of integrin expression. mRNA profiling of corneal epithelial tissues obtained from wild-type and syndecan-1(-/-) mice suggest that these defects result from differences in overall gene transcription. In the cornea, syndecan-1(-/-) epithelial cells migrate more slowly, show reduced localization of alpha9 integrin during closure of wounds and fail to increase their proliferation rate 24 hours after wounding. In the skin, we did not document a migration defect after full thickness wounds but did observe cell proliferation delays and reduced localization of alpha9 integrin in the syndecan-1(-/-) epidermis after dermabrasion. Despite increased cell proliferation rates in the uninjured syndecan-1(-/-) epidermis and the corneal epithelium, morphologically normal epithelial thickness is maintained prior to injury; however, wounding is accompanied by prolonged hypoplasia in both tissues. Analyses of integrin protein levels in extracts from full thickness skin, revealed increased levels of alpha3 and alpha9 integrins both prior to injury and after hair removal in syndecan-1(-/-) mice but no increase 2 days after dermabrasion. These data for the first time show involvement of alpha9 integrin in skin wound healing and demonstrate essential roles for syndecan-1 in mediating cell proliferation and regulation of integrin expression in normal and wounded epithelial tissues.