Expression of lumican in human colorectal cancer cells

Combined High-Throughput Proteomics and Random Forest Machine-Learning Approach Differentiates and Classifies Metabolic, Immune, Signaling and ECM Intra-Tumor Heterogeneity of Colorectal Cancer

Colorectal cancer (CRC) is a frequent, worldwide tumor described for its huge complexity, including inter-/intra-heterogeneity and tumor microenvironment (TME) variability. Intra-tumor heterogeneity and its connections with metabolic reprogramming and epithelial-mesenchymal transition (EMT) were investigated with explorative shotgun proteomics complemented by a Random Forest (RF) machine-learning approach. Deep and superficial tumor regions and distant-site non-tumor samples from the same patients (n = 16) were analyzed. Among the 2009 proteins analyzed, 91 proteins, including 23 novel potential CRC hallmarks, showed significant quantitative changes. In addition, a 98.4% accurate classification of the three analyzed tissues was obtained by RF using a set of 21 proteins. Subunit E1 of 2-oxoglutarate dehydrogenase (OGDH-E1) was the best classifying factor for the superficial tumor region, while sorting nexin-18 and coatomer-beta protein (beta-COP), implicated in protein trafficking, classified the deep region. Down- and up-regulations of metabolic checkpoints involved different proteins in superficial and deep tumors. Analogously to immune checkpoints affecting the TME, cytoskeleton and extracellular matrix (ECM) dynamics were crucial for EMT. Galectin-3, basigin, S100A9, and fibronectin involved in TME-CRC-ECM crosstalk were found to be differently variated in both tumor regions. Different metabolic strategies appeared to be adopted by the two CRC regions to uncouple the Krebs cycle and cytosolic glucose metabolism, promote lipogenesis, promote amino acid synthesis, down-regulate bioenergetics in mitochondria, and up-regulate oxidative stress. Finally, correlations with the Dukes stage and budding supported the finding of novel potential CRC hallmarks and therapeutic targets.

The response and resistance to drugs in ovarian cancer cell lines in 2D monolayers and 3D spheroids

Ovarian cancer is the most common type of gynecologic cancer. One of the leading causes of high mortality is chemoresistance, developed primarily or during treatment. Different mechanisms of drug resistance appear at the cellular and cancer tissue organization levels. We examined the differences in response to the cytotoxic drugs CIS, MTX, DOX, VIN, PAC, and TOP using 2D (two-dimensional) and 3D (three-dimensional) culture methods. We tested the drug-sensitive ovarian cancer cell line W1 and established resistant cell lines to appropriate cytotoxic drugs. The following qualitative and quantitative methods were used to assess: 1) morphology - inverted microscope and hematoxylin & eosin staining; 2) viability - MTT assay; 3) gene expression - a quantitative polymerase chain reaction; 4) identification of proteins - immunohistochemistry, and immunofluorescence. Our results indicate that the drug-sensitive and drug-resistant cells cultured in 3D conditions exhibit stronger resistance than the cells cultured in 2D conditions. A traditional 2D model shows that drug resistance of cancer cells is caused mainly by changes in the expression of genes encoding ATP-binding cassette transporter proteins, components of the extracellular matrix, "new" established genes related to drug resistance in ovarian cancer cell lines, and universal marker of cancer stem cells. Whereas in a 3D model, the drug resistance in spheroids can be related to other mechanisms such as the structure of the spheroid (dense or loose), the cell type (necrotic, quiescent, proliferating cells), drug concentrations or drug diffusion into the dense cellular/ECM structure.

Theranostic Applications of Glycosaminoglycans in Metastatic Renal Cell Carcinoma

Renal cell carcinoma (RCC) makes up the majority of kidney cancers, with a poor prognosis for metastatic RCC (mRCC). Challenges faced in the management of mRCC, include a lack of reliable prognostic markers and biomarkers for precise monitoring of disease treatment, together with the potential risk of toxicity associated with more recent therapeutic options. Glycosaminoglycans (GAGs) are a class of carbohydrates that can be categorized into four main subclasses, viz., chondroitin sulfate, hyaluronic acid, heparan sulfate and keratan sulfate. GAGs are known to be closely associated with cancer progression and modulation of metastasis by modification of the tumor microenvironment. Alterations of expression, composition and spatiotemporal distribution of GAGs in the extracellular matrix (ECM), dysregulate ECM functions and drive cancer invasion. In this review, we focus on the clinical utility of GAGs as biomarkers for mRCC (which is important for risk stratification and strategizing effective treatment protocols), as well as potential therapeutic targets that could benefit patients afflicted with advanced RCC. Besides GAG-targeted therapies that holds promise in mRCC, other potential strategies include utilizing GAGs as drug carriers and their mimetics to counter cancer progression, and enhance immunotherapy through binding and transducing signals for immune mediators.

GSK2126458 has the potential to inhibit the proliferation of pancreatic cancer uncovered by bioinformatics analysis and pharmacological experiments

BACKGROUND

Pancreatic cancer is one of the most serious digestive malignancies. At present, there is an extreme lack of effective strategies in clinical treatment. The purpose of this study is to identify key genes and pathways in the development of pancreatic cancer and provide targets for the treatment of pancreatic cancer.

METHODS

GSE15471 and GSE62165 were used to screen differentially expressed genes by GEO2R tool. Hub genes prognostic potential assessed using the GEPIA and Kaplan-Meier plotter databases. The drug susceptibility data of pan-cancer cell lines is provided by The Genomics of Drug Sensitivity in Cancer Project (GDSC). Finally, the effects of PI3K-Akt signaling pathway inhibitors on cell viability of pancreatic cancer cells were detected by cell proliferation and invasion assays.

RESULTS

A total of 609 differentially expressed genes were screened and enriched in the focal adhesion, phagosome and PI3K-Akt signaling pathway. Of the 15 hub genes we found, four were primarily associated with the PI3K-Akt signaling pathway, including COL3A1, EGF, FN1 and ITGA2. GDSC analysis showed that mTOR inhibitors are very sensitive to pancreatic cancer cells with mutations in EWSR1.FLI1 and RNF43. Cell proliferation and invasion results showed that mTOR inhibitors (GSK2126458) can inhibit the proliferation of pancreatic cancer cells.

CONCLUSIONS

This study suggested that the PI3K-Akt signaling pathway may be a key pathway for pancreatic cancer, our study uncovered the potential therapeutic potential of GSK2126458, a specific mTOR inhibitor, for pancreatic cancer.

Effects of lumican expression on the apoptosis of scleral fibroblasts: In vivo and in vitro experiments

Lumican serves an important role in the maintenance of sclera biomechanical properties. However, whether lumican expression is altered in myopia and the mechanisms of action involved are unknown. In the present study, the expression of lumican in cultured scleral fibroblasts and in the scleral tissue of a rat model of form-deprivation myopia was assessed. It was confirmed that diopter was decreased, whereas axial length was increased in modeled eyes relative to normal control eyes, indicating that the model of myopia was successfully established. These pathologic changes were accompanied by the upregulation of lumican and tissue inhibitor of metalloproteinases (TIMP)-2, as well as the downregulation of matrix metalloproteinase (MMP)-2 and MMP-14. The same trends in TIMP-2, MMP-2 and MMP-14 expression were observed when lumican was overexpressed in cultured scleral fibroblasts. Additionally, cell proliferation decreased whereas apoptosis increased compared with those of control cells. Inhibiting lumican expression had no effect on cell proliferation or apoptosis, but stimulated the expression of MMP-2 and MMP-14 while decreasing that of TIMP-2. The results suggested that lumican overexpression contributed to myopia by promoting apoptosis in scleral fibroblasts via the modulation of TIMP-2, MMP-2 and MMP-14 expression.

Lumican inhibits immune escape and carcinogenic pathways in colorectal adenocarcinoma

Lumican (LUM), a small leucine-rich proteoglycan, is a component of the extracellular matrix. Abnormal LUM expression is potentially associated with cancer progression. In the present study, we confirmed high LUM mRNA expression in colorectal adenocarcinoma (COAD) through the UALCAN database. The Kaplan-Meier method, univariate, and multivariate COX analysis showed that high LUM expression is an independent determinant of poor prognosis in COAD. A COX regression model was constructed based on clinical information and LUM expression. The receiver operating characteristic (ROC) curve indicated that this model was highly accurate in monitoring COAD prognosis. The co-expression network of LUM was determined by LinkedOmics, which showed that LUM expression was closely related to immune escape and the miR200 family. Furthermore, we studied the co-expression network of LUM and found that LUM could promote tumor metastasis and invasion. The Tumor Immune Estimation Resource website showed that LUM was closely related to immune infiltration and correlated with regulatory T cells, tumour-associated macrophages, and dendritic cells. We found that LUM cultivated cancer progression by targeting the miR200 family to promote epithelial-to-mesenchymal transition. These findings suggest that LUM is a potential target for inhibiting immune escape and carcinogenic pathways.

Fibroblasts in atherosclerosis: heterogeneous and plastic participants

PURPOSE OF REVIEW

Fibroblasts are very heterogeneous and plastic cells in the vasculature. A growing interest in fibroblasts in healthy and atherosclerotic vasculature is observed, next to macrophages, endothelial cells, and smooth muscle cells (SMCs). In this review, we discuss fibroblast presence, heterogeneity, origin, and plasticity in health and atherosclerosis based on latest literature.

RECENT FINDINGS

With help of single cell sequencing (SCS) techniques, we have gained more insight into presence and functions of fibroblasts in atherosclerosis. Next to SMCs, fibroblasts are extracellular matrix-producing cells abundant in the vasculature and involved in atherogenesis. Fibroblasts encompass a heterogeneous population and SCS data reveal several fibroblast clusters in healthy and atherosclerotic tissue with varying gene expression and function. Moreover, recent findings indicate interesting similarities between adventitial stem and/or progenitor cells and fibroblasts. Also, communication with inflammatory cells opens up a new therapeutic avenue.

SUMMARY

Because of their highly plastic and heterogeneous nature, modulating fibroblast cell function and communication in the atherosclerotic vessel might be useful in battling atherosclerosis from within the plaque.

Elevated Expression of Lumican in Lung Cancer Cells Promotes Bone Metastasis through an Autocrine Regulatory Mechanism

Background: The microarray analysis of whole-genome expression indicated that the gene encoding the protein lumican, which is associated with extracellular matrix (ECM) interaction, was highly expressed in osteotropic lung cancer cell lines with an enhanced capacity of bone metastasis. Methods: The expression of lumican in the osteotropic lung cancer cells was downregulated, and the in vitro migration, invasion, and adhesion of cancer cells to ECM components, and the in vivo bone metastasis capacity of these cells were examined. Exogenous lumican was provided to study the autocrine regulation mechanism of lumican in the bone metastasis of lung cancer cells. Results: Transfection with lumican-specific short hairpin RNA (shRNA) in the osteotropic lung cancer cells reduced the establishment of in vivo bone metastasis, but not lung metastasis. Reduction in the expression of lumican also decreased the attachment of lung osteotropic cancer cells to several components of the ECM and suppressed cell migration and invasion in vitro. Exogenous lumican restored these reduced capacities of lumican knockdown cells and promoted the seeding of lung cancer cells in the bone microenvironment. Conclusions: These results suggested that lumican promotes the metastasis of lung cancer cells to the bones via an autocrine regulatory mechanism, and blocking this interaction may provide a new therapeutic approach to reduce bone metastasis in cases of lung cancer.

Keratan Sulphate in the Tumour Environment

Keratan sulphate (KS) is a bioactive glycosaminoglycan (GAG) of some complexity composed of the repeat disaccharide D-galactose β1→4 glycosidically linked to N-acetyl glucosamine. During the biosynthesis of KS, a family of glycosyltransferase and sulphotransferase enzymes act sequentially and in a coordinated fashion to add D-galactose (D-Gal) then N-acetyl glucosamine (GlcNAc) to a GlcNAc acceptor residue at the reducing terminus of a nascent KS chain to effect chain elongation. D-Gal and GlcNAc can both undergo sulphation at C6 but this occurs more frequently on GlcNAc than D-Gal. Sulphation along the developing KS chain is not uniform and contains regions of variable length where no sulphation occurs, regions which are monosulphated mainly on GlcNAc and further regions of high sulphation where both of the repeat disaccharides are sulphated. Each of these respective regions in the KS chain can be of variable length leading to KS complexity in terms of chain length and charge localization along the KS chain. Like other GAGs, it is these variably sulphated regions in KS which define its interactive properties with ligands such as growth factors, morphogens and cytokines and which determine the functional properties of tissues containing KS. Further adding to KS complexity is the identification of three different linkage structures in KS to asparagine (N-linked) or to threonine or serine residues (O-linked) in proteoglycan core proteins which has allowed the categorization of KS into three types, namely KS-I (corneal KS, N-linked), KS-II (skeletal KS, O-linked) or KS-III (brain KS, O-linked). KS-I to -III are also subject to variable addition of L-fucose and sialic acid groups. Furthermore, the GlcNAc residues of some members of the mucin-like glycoprotein family can also act as acceptor molecules for the addition of D-Gal and GlcNAc residues which can also be sulphated leading to small low sulphation glycoforms of KS. These differ from the more heavily sulphated KS chains found on proteoglycans. Like other GAGs, KS has evolved molecular recognition and information transfer properties over hundreds of millions of years of vertebrate and invertebrate evolution which equips them with cell mediatory properties in normal cellular processes and in aberrant pathological situations such as in tumourogenesis. Two KS-proteoglycans in particular, podocalyxin and lumican, are cell membrane, intracellular or stromal tissue-associated components with roles in the promotion or regulation of tumour development, mucin-like KS glycoproteins may also contribute to tumourogenesis. A greater understanding of the biology of KS may allow better methodology to be developed to more effectively combat tumourogenic processes.

Knockdown of Lumican Inhibits Proliferation and Migration of Bladder Cancer

Lumican (LUM) is differentially expressed between normal and cancer tissues. The purpose of this study was to investigate the role of LUM in the proliferation and migration of bladder cancer (BCa) cells. Our study included 97 cases of BCa diagnosis from our hospital between June 2013 and June 2016. The expression of LUM was analyzed by immunohistochemistry and Western blot. To characterize the function of LUM, BCa cells were stably infected with a lentivirus against LUM, and cell proliferation, migration and cell cycle were investigated. In addition, xenograft experiments were performed in nude mice to evaluate the role of LUM in BCa. Our results showed that LUM was overexpressed in BCa tissues and cell lines in comparison to normal tissues. LUM expression was related to pathological type, T stage and N stage (P < .05). In addition, depletion of LUM inhibited the proliferation and migration of BCa cells by inactivating MAPK signaling. In conclusion, LUM promotes the proliferation and migration of BCa cells and may serve as a potential therapeutic target for BCa.

Keratan sulfate, a complex glycosaminoglycan with unique functional capability

From an evolutionary perspective keratan sulfate (KS) is the newest glycosaminoglycan (GAG) but the least understood. KS is a sophisticated molecule with a diverse structure, and unique functional roles continue to be uncovered for this GAG. The cornea is the richest tissue source of KS in the human body but the central and peripheral nervous systems also contain significant levels of KS and a diverse range of KS-proteoglycans with essential functional roles. KS also displays important cell regulatory properties in epithelial and mesenchymal tissues and in bone and in tumor development of diagnostic and prognostic utility. Corneal KS-I displays variable degrees of sulfation along the KS chain ranging from non-sulfated polylactosamine, mono-sulfated and disulfated disaccharide regions. Skeletal KS-II is almost completely sulfated consisting of disulfated disaccharides interrupted by occasional mono-sulfated N-acetyllactosamine residues. KS-III also contains highly sulfated KS disaccharides but differs from KS-I and KS-II through 2-O-mannose linkage to serine or threonine core protein residues on proteoglycans such as phosphacan and abakan in brain tissue. Historically, the major emphasis on the biology of KS has focused on its sulfated regions for good reason. The sulfation motifs on KS convey important molecular recognition information and direct cell behavior through a number of interactive proteins. Emerging evidence also suggest functional roles for the poly-N-acetyllactosamine regions of KS requiring further investigation. Thus further research is warranted to better understand the complexities of KS.

Prolonged exposure to extracellular lumican restrains pancreatic adenocarcinoma growth

We previously demonstrated that pancreatic stellate cells within pancreatic ductal adenocarcinoma (PDAC) stroma secrete lumican and its presence is associated with prolonged survival of patients with localized PDAC. Here, we observed that extracellular lumican decreases PDAC tumour cell growth in xenograft and syngeneic orthotopic animal models, and induces growth inhibition of low-passage human PDAC cells in a species-specific manner. PDAC cells grown in variant culture conditions and exposed to extracellular lumican display typical characterizations of cancer cell in a quiescent state, such as growth inhibition, apoptosis, G0/G1 arrest and chemoresistance. Importantly, extracellular lumican is associated with diminished ERK1/2 phosphorylation and increased p38 phosphorylation within PDAC cells. We further demonstrated that extracellular lumican physically binds with EGFR to trigger EGFR internalization and downregulation of EGFR and its downstream signal molecule ERK. Lumican enhances casitas B-lineage lymphoma expression, which stabilized the TGFβ Type II receptor sensitizing PDAC cells to TGFβ-mediated activation of p38 and SMAD signals. These provide a mechanism for the shift in signalling and phenotypic changes we observed after prolonged exposure to lumican. Together, our findings demonstrate that stromal lumican restrains PDAC cell growth through mediating cell entry into a quiescent state.

Lumican Inhibits SNAIL-Induced Melanoma Cell Migration Specifically by Blocking MMP-14 Activity

Lumican, a small leucine rich proteoglycan, inhibits MMP-14 activity and melanoma cell migration in vitro and in vivo. Snail triggers epithelial-mesenchymal transitions endowing epithelial cells with migratory and invasive properties during tumor progression. The aim of this work was to investigate lumican effects on MMP-14 activity and migration of Snail overexpressing B16F1 (Snail-B16F1) melanoma cells and HT-29 colon adenocarcinoma cells. Lumican inhibits the Snail induced MMP-14 activity in B16F1 but not in HT-29 cells. In Snail-B16F1 cells, lumican inhibits migration, growth, and melanoma primary tumor development. A lumican-based strategy targeting Snail-induced MMP-14 activity might be useful for melanoma treatment.

Extracellular lumican augments cytotoxicity of chemotherapy in pancreatic ductal adenocarcinoma cells via autophagy inhibition

Lumican, an extracellular matrix proteoglycan overexpressed by pancreatic stellate cells (PSCs) and pancreatic ductal adenocarcinoma cells (PDACs), drives the formation of a tumor-specific microenvironment. We recently showed that extracellular lumican inhibits pancreatic cancer cell growth and is associated with prolonged survival after surgery. Here we investigated the role of extracellular lumican in chemotherapy-mediated cancer therapy. Lumican secretion was increased by chemotherapeutic agents in PDAC, and especially in PSCs, and appeared to be linked to the extent of cells' response to chemotherapy-induced growth inhibition. In multiple PDAC models, including cell lines, patient-derived xenografts and lumican knockout mice, lumican significantly increased antitumor effect of chemotherapy. This effect was associated with DNA damage, apoptosis and inhibition of cell viability, glucose consumption, lactate production and vascular endothelial growth factor secretion. In PDAC cells, chemotherapeutic agents triggered autophagosome formation and increased LC3 expression through the reactive oxygen species-mediated AMP-activated kinase (AMPK) signaling pathway. Inhibition of gemcitabine-induced autophagy in cancer cells by treatment with AMPK inhibitor compound C, lysosomal inhibitor chloroquine or autophagy inhibitor 3MA enhanced gemcitabine-induced apoptosis, suggesting that autophagy is a protective cellular response to gemcitabine treatment. Importantly, lumican dramatically decreased AMPK activity, inhibiting chemotherapy-induced autophagy in both in vitro and in vivo PDAC models. Co-treatment of PDAC cells with lumican and gemcitabine increased mitochondrial damage, reactive oxygen species (ROS) production and cytochrome c release, indicating that lumican-induced disruption of mitochondrial function may be the mechanism of sensitization to gemcitabine. Together, our findings demonstrate that extracellular lumican augments cytotoxicity of chemotherapy in PDAC cells through inhibition of chemotherapeutic agent-induced autophagy.

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.

Lumican as a novel marker for differential diagnosis of Bowen disease and actinic keratosis

Lumican, a member of the small leucine-rich proteoglycan family, regulates the assembly and diameter of collagen fibers in the extracellular matrix of various tissues. Lumican expression correlates with pathological conditions, including skin fragility, corneal opacification, and corneal and cardiac wound healing. Lumican is overexpressed in tumor cells, including in the breast, colorectal, neuroendocrine cell, uterine cervical, and pancreatic cancers. Lumican expression also correlates with the growth and metastasis of various malignancies. For example, lumican expression is lower in the dermis of malignant melanoma cases than in early-stage melanomas. However, the expression patterns and roles of lumican in nonmelanoma skin cancer have not been elucidated. In this study, we used immunohistochemistry and in situ hybridization to examine the expression patterns of lumican in normal skin, Bowen disease, and actinic keratosis. In normal skin, lumican was expressed in the collagen fibers in the dermis, acrosyringium, follicular epithelium, and sebocytes but not in epidermal keratinocytes. In Bowen disease, lumican was expressed in 34 (91.8%) of 37 patients. Notably, all cases of actinic keratosis were negative for lumican. These findings suggest that lumican plays an important role in the pathogenesis of Bowen disease and actinic keratosis and might be useful as an adjunct to the diagnosis for subtypes of 2 diseases: bowenoid actinic keratosis and Bowen disease in sun-exposed areas.

Opticin, a small leucine-rich proteoglycan, is uniquely expressed and translocated to the nucleus of chronic lymphocytic leukemia cells

Background

Opticin (OPTC) is a member of the small leucine-rich proteoglycan (SLRP) family and is localized particularly in certain extracellular matrices. We have previously reported the unique expression of another SLRP, fibromodulin (FMOD) in the leukemic cells of patients with chronic lymphocytic leukemia (CLL). OPTC is located in the same region as FMOD on chromosome 1 (1q32.1). Cluster up-regulation of genes may be observed in malignancies and the aim of the present study was to analyze the expression of OPTC in CLL cells.

Methods

The expression of OPTC was tested by RT-PCR and realtime qPCR in PBMC from CLL patients, other hematological malignancies and healthy controls. The presence of OPTC protein, and its subcellular localization, was investigated using fractionation methods where the obtained lysate fractions were analyzed by Western blotting. Deglycosylation experiments were performed to investigate the glycosylation status of the CLL OPTC.

Results

OPTC was expressed at the gene level in all patients with CLL (n = 90) and in 2/8 patients with mantle cell lymphoma (MCL) but not in blood mononuclear cells of healthy control donors (n = 20) or in tumor samples from nine other types of hematological malignancies. OPTC was detected by Western blot in all CLL samples analyzed (n = 30) but not in normal leukocytes (n = 10). Further analysis revealed a CLL-unique unglycosylated 37 kDa core protein that was found to be located preferentially in the cell nucleus and endoplasmic reticulum (ER) of the CLL cells.

Conclusions

A 37 kDa unglycosylated OPTC protein was detected in ER and in the nucleus of CLL cells and not in healthy control donors. The function of this OPTC core protein remains unclear but its CLL-specific expression and subcellular localization warrants further investigations in the pathobiology of CLL.

A proline/arginine-rich end leucine-rich repeat protein (PRELP) variant is uniquely expressed in chronic lymphocytic leukemia cells

Proline/arginine-rich end leucine-rich repeat protein (PRELP) belongs to the small leucine-rich proteoglycan (SLRP) family, normally expressed in extracellular matrix of collagen-rich tissues. We have previously reported on another SLRP, fibromodulin (FMOD) in patients with chronic lymphocytic leukemia (CLL). PRELP is structurally similar to FMOD with adjacent localization on chromosome 1 (1q32.1). As cluster-upregulation of genes may occur in malignancies, the aim of our study was to analyze PRELP expression in CLL. PRELP was expressed (RT-PCR) in all CLL patients (30/30), as well as in some patients with mantle cell lymphoma (3/5), but not in healthy donor leukocytes (0/20) or tumor samples from other hematological malignancies (0/35). PRELP was also detected in CLL cell-lines (4/4) but not in cell-lines from other hematological tumors (0/9). PRELP protein was detected in all CLL samples but not in normal leukocytes. Deglycosylation experiments revealed a CLL-unique 38 kDa core protein, with an intact signal peptide. This 38 kDa protein was, in contrast to the normal 55 kDa size, not detected in serum which, in combination with the uncleaved signal peptide, suggests cellular retention. The unique expression of a 38 kDa PRELP in CLL cells may suggest involvement in the pathobiology of CLL and merits further studies.

Lumican effects in the control of tumour progression and their links with metalloproteinases and integrins

Lumican is a member of the small leucine-rich proteoglycan family. It is present in numerous extracellular matrices of different tissues, such as muscle, cartilage, and cornea. In skin, lumican is present as a glycoprotein. It plays a critical role in collagen fibrillogenesis, as shown by knocking out of its gene in mice. A direct link between lumican expression and melanoma progression and metastasis has been demonstrated. Lumican was shown to impede tumour cell migration and invasion by directly interacting with the α2β1 integrin. In addition, an active sequence of the lumican core protein, called lumcorin, was identified as being responsible for inhibition of melanoma cell migration. Lumican was also shown to exert angiostatic properties by downregulating the proteolytic activity associated with endothelial cell membranes, particularly matrix metalloproteinase (MMP)-14 and MMP-9. Globally, lumican appears to be a potent agent for inhibiting tumour progression rather than tumorigenesis. However, progressive changes in proteoglycans occur in the tumour environment. The complexity and diversity of proteoglycan structure might be responsible for a variety of functions that regulate cell behaviour. Through their core protein and their glycosaminoglycan chains, proteoglycans can interact with growth factors and chemokines. These interactions affect cell signalling, motility, adhesion, growth, and apoptosis. This review summarizes recent data concerning lumican control of tumour progression in different cancers, with a particular focus on its interactions with MMPs and integrins. Its potential therapeutic implications are discussed.

Lumican expression, localization and antitumor activity in prostate cancer

The stromal reaction surrounding tumors leads to the formation of a tumor-specific microenvironment, which may play either a restrictive role or a supportive role in the growth and progression of the tumors. Lumican, a small leucine-rich proteoglycan (SLRP) of the extracellular matrix (ECM), regulates collagen fibrillogenesis. Recently, lumican has also been shown to regulate cell behavior during embryonic development, tissue repair and tumor progression. The role of lumican in cancer varies according to the type of tumor. In this study we analyze the role of lumican in the pathogenesis of prostate cancer both in vivo and in vitro. Overall lumican up-regulation was observed in the primary tumors analyzed through both real-time PCR and immunostaining. The increase in lumican expression was observed in the reactive stroma surrounding prostate primary tumors with fibrotic deposition surrounding the acinar glands. In vitro analysis demonstrated that lumican inhibited both the migration and invasion of metastatic prostate cancer cells isolated from lymph node, bone and brain. Moreover, prostate cancer cells seeded on lumican presented a decrease in the formation of cellular projections, lamellipodia detected by a decreased rearrangement in ZO-1, keratin 8/18, integrin β1 and MT1-MMP, and invadopodia detected by disruption of α-smooth muscle actin, cortactin and N-WASP. Moreover, a significant increase in prostate cancer cell invasion was observed through the peritoneum of lumican knockout mice, further demonstrating the restrictive role lumican present in the ECM has on prostate cancer invasion. In conclusion, lumican present in the reactive stroma surrounding prostate primary tumors plays a restrictive role on cancer progression, and we therefore postulate that lumican could be a valuable marker in prostate cancer staging.

Extracellular matrix remodeling: the common denominator in connective tissue diseases. Possibilities for evaluation and current understanding of the matrix as more than a passive architecture, but a key player in tissue failure

Increased attention is paid to the structural components of tissues. These components are mostly collagens and various proteoglycans. Emerging evidence suggests that altered components and noncoded modifications of the matrix may be both initiators and drivers of disease, exemplified by excessive tissue remodeling leading to tissue stiffness, as well as by changes in the signaling potential of both intact matrix and fragments thereof. Although tissue structure until recently was viewed as a simple architecture anchoring cells and proteins, this complex grid may contain essential information enabling the maintenance of the structure and normal functioning of tissue. The aims of this review are to (1) discuss the structural components of the matrix and the relevance of their mutations to the pathology of diseases such as fibrosis and cancer, (2) introduce the possibility that post-translational modifications (PTMs), such as protease cleavage, citrullination, cross-linking, nitrosylation, glycosylation, and isomerization, generated during pathology, may be unique, disease-specific biochemical markers, (3) list and review the range of simple enzyme-linked immunosorbent assays (ELISAs) that have been developed for assessing the extracellular matrix (ECM) and detecting abnormal ECM remodeling, and (4) discuss whether some PTMs are the cause or consequence of disease. New evidence clearly suggests that the ECM at some point in the pathogenesis becomes a driver of disease. These pathological modified ECM proteins may allow insights into complicated pathologies in which the end stage is excessive tissue remodeling, and provide unique and more pathology-specific biochemical markers.

Extracellular matrix lumican promotes bacterial phagocytosis, and Lum-/- mice show increased Pseudomonas aeruginosa lung infection severity

Phagocytosis is central to bacterial clearance, but the exact mechanism is incompletely understood. Here, we show a novel and critical role for lumican, the connective tissue extracellular matrix small leucine-rich repeat proteoglycan, in CD14-mediated bacterial phagocytosis. In Psuedomonas aeruginosa lung infections, lumican-deficient (Lum(-/-)) mice failed to clear the bacterium from lungs, tissues, and showed a dramatic increase in mortality. In vitro, phagocytosis of nonopsonized gram-negative Escherichia coli and P. aeruginosa was inhibited in Lum(-/-) peritoneal macrophages (MΦs). Lumican co-localized with CD14, CD18, and bacteria on Lum(+/+) MΦ surfaces. Using two different P. aeruginosa strains that require host CD14 (808) or CD18/CR3 (P1) for phagocytosis, we showed that lumican has a larger role in CD14-mediated phagocytosis. Recombinant lumican (rLum) restored phagocytosis in Lum(-/-) MΦs. Surface plasmon resonance showed specific binding of rLum to CD14 (K(A) = 2.15 × 10(6) M(-1)), whereas rLumY20A, and not rLumY21A, where a tyrosine in each was replaced with an alanine, showed 60-fold decreased binding. The rLumY20A variant also failed to restore phagocytosis in Lum(-/-) MΦs, indicating Tyr-20 to be functionally important. Thus, in addition to a structural role in connective tissues, lumican has a major protective role in gram-negative bacterial infections, a novel function for small leucine-rich repeat proteoglycans.

Lumican inhibits angiogenesis by interfering with α2β1 receptor activity and downregulating MMP-14 expression

INTRODUCTION

Previous studies showed that lumican, a small leucine-rich proteoglycan that binds to α2 integrin I domain, is an efficient inhibitor of cell adhesion and migration. In this report, we tested its effect on angiogenesis in vitro and in vivo.

MATERIALS AND METHODS

Effect of lumican on angiogenesis was evaluated by in vitro capillary tube formation test performed between Fibrin II Gels or in Matrigel™ and in vivo by Matrigel(™) plug assay in BALB/c mice. Changes in matrix metalloproteinases expression caused by lumican were analyzed in endothelial cells by real-time PCR, Western immunoblotting and gelatin zymography.

RESULTS

In unchallenged endothelial cells, Matrigel™ induced robust capillary morphogenesis. In contrast, tube formation was dramatically reduced by lumican, and by siRNA to β1 integrin subunit mRNA but not by control siRNA. Similarly, lumican effectively inhibited neovascularization in vivo in assays using Matrigel™ plugs formed in BALB/c mice. Interestingly, lumican significantly reduced expression of matrix metalloproteinases, particularly MMP-14 that is known to activate other MMPs in close vicinity of endothelial cell membranes.

CONCLUSIONS

Our results provide strong evidence that lumican affects angiogenesis both by interfering with α2β1 receptor activity and downregulating proteolytic activity associated with surface membranes of endothelial cells.

Lumican reduces tumor growth via induction of fas-mediated endothelial cell apoptosis

Matrikines are important components of tumor microenvironments that integrate communication between extracellular matricies and membrane-bound receptors thereby regulating cellular behaviors. One such matrikine that is differentially expressed in cancer microenvironments is the extracellular matrix protein lumican; however its precise role in cancer remains ambiguous. To study the effects of lumican on cancer cells, we created lumican-overexpressing cell lines from murine fibrosarcoma (MCA102) and pancreatic adenocarcinoma (Pan02) cells. Lumican overexpression in Pan02 cells increased invasiveness, decreased soft agar colony size, and increased proliferation. Conversely in MCA102 cells, lumican decreased invasiveness, increased soft agar colony size, but did not influence proliferation. In contrast to these pleiotropic in vitro results, lumican overexpression within the in vivo tumor microenvironment produced uniformly smaller tumors. Importantly, reduced tumor size was correlated with reduced vascular density. Consistent with lumican's proposed anti-angiogenic activity, lumican increased endothelial cell apoptosis. Importantly, lumican was previously shown to influence Fas expression and our results show that lumican enhanced Fas mediated endothelial cell apoptosis although we were unable to detect any difference in Fas or Fas ligand expression between lumican-overexpressing and control cells. Interestingly, lumican had no effect on MCA102 apoptosis, suggesting that the observed reduction in tumor size is specifically due to endothelial cell apoptosis rather than a direct effect on the cancerous cells themselves. Therefore, this study is the first to demonstrate a causal relationship between tumor reduction and lumican's effect on angiogenesis as opposed to an effect on the cancerous cells themselves.

Lumican is required for neutrophil extravasation following corneal injury and wound healing

An important aspect of wound healing is the recruitment of neutrophils to the site of infection or tissue injury. Lumican, an extracellular matrix component belonging to the small leucine rich proteoglycan (SLRP) family, is one of the major keratan sulfate proteoglycans (KSPGs) within the corneal stroma. Increasing evidence indicates that lumican can serve as a regulatory molecule for several cellular processes, including cell proliferation and migration. In the present study, we addressed the role of lumican in the process of extravasation of polymorphonuclear leukocytes (PMNs) during the early inflammatory phase present in the healing of the corneal epithelium following debridement. We used Lum(-/-) mice and a novel transgenic mouse, Lum(-/-),Kera-Lum, which expresses lumican only in the corneal stroma, to assess the role of lumican in PMN extravasation into injured corneas. Our results showed that PMNs did not readily invade injured corneas of Lum(-/-) mice and this defect was rescued by the expression of lumican in the corneas of Lum(-/-),Kera-Lum mice. The presence of lumican in situ facilitates PMN infiltration into the peritoneal cavity in casein-induced inflammation. Our findings are consistent with the notion that in addition to regulating the collagen fibril architecture, lumican acts to aid neutrophil recruitment and invasion following corneal damage and inflammation.

Lumican, a small leucine-rich proteoglycan

Lumican belongs to the family of small leucine-rich repeat proteoglycans. Recent studies have shown that lumican participates in the maintenance of tissue homeostasis and modulates cellular functions including cell proliferation, migration, and differentiation. The expression of lumican has been correlated to the growth and metastasis of various malignancies; however, its exact role in tumorogenesis remains elusive. This review focuses upon the role of lumican in cell biology, providing insights into molecular mechanisms that lumican likely utilizes to control processes relevant to tumorogenesis.

Lumican affects actin cytoskeletal organization in human melanoma A375 cells

AIMS

Lumican, a small leucine-rich proteoglycan (SLRP), has attracted attention as a molecule of the extracellular matrix possibly involved in signalling pathways affecting cancer cell behaviour. The remodelling of the actin cytoskeleton, induced in response to external stimuli, is crucial for cell motility and intracellular signal transduction. The main goal of this study was to examine the effects of recombinant lumican on actin organization, the state of actin polymerization, actin isoform expression, and their sub-cellular distribution in the A375 human melanoma cell line.

MAIN METHODS

Fluorescence and confocal microscopy were used to observe actin cytoskeletal organization and the sub-cellular distribution of cytoplasmic beta- and gamma-actins. The ability of actin to inhibit DNaseI activity was used to quantify actin. Western blotting and real-time PCR were used to determine the expression levels of the actin isoforms.

KEY FINDINGS

A375 cells grown on lumican coatings changed in morphology and presented rearranged actin filament organization: from filaments evenly spread throughout the whole cell body to their condensed sub-membrane localization. In the presence of lumican, both actin isoforms were concentrated under the cellular membrane. A statistically significant increase in the total, filamentous, and monomeric actin pools was observed in A375 cells grown on lumican.

SIGNIFICANCE

Novel biological effects of lumican, an extracellular matrix SLRP, on the actin pool and organization are identified, which may extend our understanding of the mechanism underlying the inhibitory effect of lumican on the migration of melanoma cells.

Effect of morpholino antisense oligonucleotide against lumican mRNA in human embryonic kidney (HEK) 293 cells

Lumican is a member of the small-leucine-rich proteoglycan (SLRP) family and is overexpressed during wound healing of the cornea, in ischemic and reperfused heart, and in several cancer tissues. Lumican is considered to regulate the collagen fibril diameter and interfibrillar spacing. However, the effect of lumican on cell growth has not been adequately examined. In the present study, we attempted to clarify whether lumican contributes to human embryonic kidney (HEK) 293 cell growth, using the morpholino antisense oligonucleotide (m-anti oligo) against lumican mRNA. M-anti oligo is a novel oligonucleotide and exhibits a higher antisense activity, higher water solubility, and greater resistance to nucleases in target cells than phosphorothioate types of oligonucleotide. After delivery of m-anti oligo against lumican mRNA, the fluorescein 5-isothiocyanate (FITC) conjugated oligonucleotides were observed in the cytoplasm and nucleus of HEK 293 cells at 24 h by confocal laser microscopy. M-anti oligo for lumican mRNA strongly inhibited the synthesis of lumican protein in the HEK 293 cells, and the HEK cell growth rate was higher than those in the control groups. These findings may indicate that lumican protein has an inhibitory effect on HEK 293 cell growth in vitro.

Lumican expression is positively correlated with the differentiation and negatively with the growth of human osteosarcoma cells

Osteosarcoma is the most common primary bone tumour associated with childhood and adolescence. The possible role of the small leucine-rich proteoglycan, lumican, in the growth and metastasis of various cancer types has recently been investigated. In this study, the expression of lumican was examined in moderately differentiated (MG-63) and well-differentiated (Saos 2) human osteosarcoma cell lines of high and low metastatic capability, respectively. Real-time PCR, western blotting with antibodies against the protein core and keratan sulfate, and specific enzymatic digestions were the methods employed. The two human osteosarcoma cell lines were found to express and secrete lumican partly substituted with keratan sulfate glycosaminoglycans. Importantly, the non-metastatic, well-differentiated Saos 2 cells produced lumican at rates that were up to sevenfold higher than those of highly metastatic MG-63 cells. The utilization of short interfering RNA specific for the lumican gene resulted in efficient down-regulation of its mRNA levels in both cell lines. The growth of Saos 2 cells was inhibited by lumican, whereas their migration and chemotactic response to fibronectin were found to be promoted. Lumican expression was negatively correlated with the basal level of Smad 2 activation in these cells, suggesting that lumican may affect the bioavailability of Smad 2 activators. By contrast, these cellular functions of highly aggressive MG-63 cells were demonstrated not to be sensitive to a decrease in their low endogenous lumican levels. These results suggest that lumican expression may be positively correlated with the differentiation and negatively correlated with the progression of osteosarcoma.

Enhanced expression of keratinocyte growth factor and its receptor correlates with venous invasion in pancreatic cancer

Keratinocyte growth factor (KGF) and KGF receptor (KGFR) have been implicated in cancer growth as well as tissue development and repair. In this study, we examined whether KGF and KGFR have a role in human pancreatic ductal adenocarcinoma (PDAC). KGFR mRNA was expressed in eight pancreatic cancer cell lines, whereas the KGF mRNA was detected in seven of the cell lines and was absent in MIA PaCa-2 cells. KGFR and KGF immunoreactivity were localized in the cancer cells in 41.5 and 34.0% of patients, respectively. There was a significant correlation between KGFR or KGF immunoreactivity and venous invasion and a significant correlation between the presence of both markers and venous invasion, vascular endothelial growth factor (VEGF)-A expression, and poor prognosis. Exogenous KGF increased VEGF-A expression and release in MIA PaCa-2 cells, and PANC-1 cells stably transfected to overexpress KGF-exhibited increased VEGF-A expression. Moreover, short hairpin-KGFR transfection in MIA PaCa-2 cells reduced the stimulatory effect of exogenous KGF on VEGF-A expression. Short hairpin-KGF transfection in KLM-1 cells reduced VEGF-A expression in the cells. KGFR and KGF may act to promote venous invasion and tumor angiogenesis in PDAC, raising the possibility that they may serve as novel therapeutic targets in anti-angiogenic strategies in PDAC.

Transcriptome analysis of endothelial cell gene expression induced by growth on matrigel matrices: identification and characterization of MAGP-2 and lumican as novel regulators of angiogenesis

Remodeling of vascular microenvironments during normal and tumor-induced angiogenesis is an important, yet poorly understood mechanism by which endothelial cells (ECs) contribute to the activation or resolution of angiogenesis. We used microarray analyses to monitor changes in the transcriptome of ECs undergoing angiogenesis when cultured onto Matrigel matrices. This strategy identified 308 genes whose expression in ECs was altered at least 3-fold by angiogenesis, of which 63 genes were found to encode for secretory proteins. In vitro assays that modeled key steps in the angiogenic process showed that several identified genes possessed pro- or anti-angiogenic activities (e.g., SMOC-2, secreted modular calcium-binding protein-2; CRELD-2, cysteine-rich with EGF-like domains-1; MAGP-2, microfibril-associated glycoprotein-2; lumican; and ECM-1, extracellular matrix protein-1). In particular, MAGP-2 expression potentiated EC proliferation and p38 MAPK activation stimulated by the pro-angiogenic factors, basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF); it also stimulated EC invasion and angiogenic sprouting, and more importantly, promoted the development and infiltration of vessels into Matrigel plugs implanted into genetically normal mice. Conversely, lumican inhibited EC activation of p38 MAPK, as well as their invasion, angiogenic sprouting, and vessel formation in mice. Collectively, our findings provide new insights into how EC stromal remodeling regulates angiogenesis activation and resolution, as well as identify two novel EC-secreted stromal proteins that modulate angiogenesis both in vitro and in vivo.

Identification of transcripts modulated by ETV6 expression

Deletions at chromosome 12p12-13 are observed in 26-47% of childhood pre-B acute lymphoblastic leukaemia (ALL) cases, suggesting the presence of a tumour suppressor gene (TSG). Accumulating genetic and functional evidence points to ETV6 as being the most probable TSG targeted by the deletions. ETV6 is a ubiquitously expressed transcription factor of the ETS family with very few known targets. To understand its function and to elucidate the impact of its absence in leukaemia, we conducted a study to identify targeted genes. Following the induction of ETV6 expression, global expression was evaluated at different time points. We identified 87 modulated genes, of which 10 (AKR1C1, AKR1C3, IL18, LUM, PHLDA1, PTGER4, PTGS2, SPHK1, TP53 and VEGF) were validated by real-time quantitative reverse transcription-polymerase chain reaction. To assess the significance of the validated candidate genes in leukaemia, their expression patterns were determined, as well as that of ETV6, in pre-B ALL patients. The expression of IL18, LUM, PTGER4, SPHK1 and TP53 was significantly correlated with that of ETV6, further suggesting that ETV6 could regulate the expression of these genes in leukaemia. This work constitutes another step towards the understanding of the functions of ETV6 and the impact of its inactivation in childhood leukaemia.

Role of the small leucine-rich proteoglycan (SLRP) family in pathological lesions and cancer cell growth

The roles of lumican, a member of the small-leucine-rich-proteoglycan (SLRP) family, in pathological fibrosis, cancer tissues and tumor cell growth were reviewed. Lumican is predominantly localized in the areas of pathological fibrosis including the thickened intima of human coronary arteries, ischemic and reperfused hearts, and acute pancreatitis and chronic pancreatitis (CP)-like lesions adjacent to pancreatic cancer nests. In these lesions, lumican mRNA and protein were transiently and ectopically overexpressed in most of the vascular smooth muscle cells (VSMCs) that migrated into the thickened intima, myocardial cells adjacent to an ischemic lesion, acinar cells, islet cells and fibroblasts of pathological pancreatic tissues. The low expression level of lumican in breast cancer is associated with rapid progression and poor survival. Lumican mRNA in breast cancer is overexpressed in fibroblasts adjacent to cancer cells but not in cancer cells. Furthermore, the high expression level of lumican is associated with a high pathological tumor grade, a low estrogen receptor level in the cancer tissues, and young age of patients. The suppression of lumican expression in culture cells induces their cell growth. Lumican-transfected tumor cells are characterized by a strong suppression of their anchorage-independent growth and capacity of invasion. Lumican significantly suppressed subcutaneous tumor formation in syngenic mice, with a concomitant decrease in cyclin D1 expression level, and induced and/or enhanced the apoptosis of these cells. The autocrine mechanism in cancer cells and the paracrine mechanism in cancer cells and fibroblasts via transforming growth factor (TGF)-beta and Smad signals may play important roles in the regulation of tumor growth by SLRPs.

Downregulation of NDUFA1 and other oxidative phosphorylation-related genes is a consistent feature of basal cell carcinoma

Basal cell carcinoma (BCC) is the most common cutaneous malignancy that, like other tumours, possesses a heterogeneous genetic composition. In order to select genes with consistent changes in expression among these tumours, we analysed BCC microarray expression data by using a novel approach, termed correlative analysis of microarrays (CAM). CAM is a nested, non-parametric method designed to qualitatively select candidates based on their individual, similar effects upon an array-wide closeness measure. We applied the CAM method to expression data generated by two-channel cDNA microarray experiments, where 21 BCC and patient-matched normal skin specimens were examined. Fifteen candidate genes were selected, with six overexpressed and nine underexpressed in BCC vs. normal skin. Five of the nine consistently downregulated genes in the tumour samples are involved in mitochondrial function and the oxidative phosphorylation (OXPHOS) pathway. One of these genes was the 7.5-kDa subunit, NADH dehydrogenase (ubiquinone) alpha subcomplex-1 (NDUFA1), an accessory component of OXPHOS complex-I that is essential for respiratory activity. These findings support the hypothesis that irregularities in mitochondrial function are involved in neoplasia. Suppression of NDUFA1 expression could represent a key pathogenic mechanism in the development of BCC.

Keratocan, a cornea-specific keratan sulfate proteoglycan, is regulated by lumican

Lumican is an extracellular matrix glycoprotein widely distributed in mammalian connective tissues. Corneal lumican modified with keratan sulfate constitutes one of the major proteoglycans of the stroma. Lumican-null mice exhibit altered collagen fibril organization and loss of corneal transparency. A closely related protein, keratocan, carries the remaining keratan sulfate of the cornea, but keratocan-null mice exhibit a less severe corneal phenotype. In the current study, we examined the effect of lumican overexpression in corneas of wild type mice. These mice showed no alteration in collagen organization or transparency but had increased keratocan expression at both protein and mRNA levels. Corneas of lumican-null mice showed decreased keratocan. This coupling of keratocan expression with lumican also was observed after intrastromal injection of a lumican expression minigene into the corneal stroma of Lum-/- mice. Small interfering RNA knockdown of lumican in vitro reduced keratocan expression, whereas co-injection of a lumican-expressing minigene with a beta-galactosidase reporter driven by the keratocan promoter demonstrated an increase of keratocan transcriptional activity in response to lumican expression in Lum-/- corneas in vivo. These observations demonstrate that lumican has a novel regulatory role in keratocan expression at the transcriptional level. Such results help provide an explanation for the differences in severity of corneal manifestation found in Lum-/- and Kera-/- mice. The results also suggest a critical level of small proteoglycans to be essential for collagen organization but that overabundance is not detrimental to extracellular matrix morphogenesis.

Gene expression profile identifies a rare epithelioid variant case of pleomorphic liposarcoma carrying FUS-CHOP transcript

AIMS

To describe a tumour with morphological and immunophenotypic characteristics of epithelioid variant of pleomorphic liposarcoma. Pleomorphic liposarcoma is a very rare variant of liposarcoma defined morphologically by the presence of pleomorphic lipoblasts showing peculiar epithelial-like features that can be confused with primary or metastatic carcinoma.

METHODS AND RESULTS

Molecular analysis demonstrated for the first time the presence of FUS-CHOP transcript in this liposarcoma variant. Microarray analysis revealed a gene expression profile related to a more aggressive tumour type when compared with other myxoid/round cell liposarcomas.

CONCLUSIONS

The present data show that the epithelioid variant of pleomorphic liposarcoma represents a further variant of myxoid liposarcoma sharing the FUS-CHOP fusion transcript but carrying a distinct expression profile, in keeping with its aggressive clinical course.

Pancreatic tumor cells influence the composition of the extracellular matrix

The malignant behavior of cancers depends on the microenvironmental context. We investigated compositional alterations of the extracellular matrix (ECM) in pancreatic cancer, with special emphasis on the proteoglycans decorin, lumican, and versican. Compared with normal controls (n=18), marked overexpression of these proteoglycans was observed in pancreatic cancer tissues (n=30) by quantitative RT-PCR (p<0.0001). Immunohistochemistry revealed abundance of proteoglycans in the ECM of pancreatic cancer specimens, whereas tumor cells themselves were devoid of either decorin, lumican or versican. RT-PCR confirmed pancreatic stellate cells (PSCs) as the major source of these proteins. Interestingly, TGFbeta1 and conditioned medium derived from pancreatic cancer cell lines synergistically suppressed the expression of known anti-tumor factors decorin and lumican, but stimulated the expression of pro-metastatic factor versican in cultured PSCs. These findings indicate that malignant cells can actively influence the composition of the ECM through TGFbeta1 and other soluble factors, altering their microenvironment in a tumor-favorable way.

Involvement of stromal proteoglycans in tumour progression

Glycosaminoglycans (GAGs) and proteoglycans (PGs) belong to a class of extracellular macromolecules necessary for the growth of any multicellular structures, including tumours. Transformed cells induce stromal reaction either per se or by activation of the mesenchymal cells. Tumour stroma contains several chondroitin sulphate and heparan sulphate proteoglycans. These proteoglycans and their glycosaminoglycan chains modify cell behaviour by interacting with different molecules such as growth factors, cytokines, chemokines, proteinases and their inhibitors. This review describes the main proteoglycans of tumour stoma and discusses their implication in the regulation of the activity of extracellular proteins and peptides.

The small leucine-rich proteoglycan lumican inhibits melanoma progression

Lumican is a member of the small leucine-rich proteoglycan (SLRP) family. It contributes to the organisation of the collagen network and plays an important role in cell migration and tissue repair. The present study aimed to determine the influence of lumican expression on adhesion, anchorage-dependent and -independent growth, migration, in vitro invasion and in vivo melanoma growth. For that purpose, B16F1 mouse melanoma cells were stably transfected with an expression plasmid containing the complete lumican cDNA. Lumican expression by tumor cells did not change the proliferative activity of mouse melanoma cells in monolayer culture and did not influence either cell adhesion to extracellular matrix gel or type I collagen or cell spreading on these substrates. In contrast, lumican-transfected cells were characterized by a strong reduction of their anchorage-independent proliferation in agarose gel and capacity to invade extracellular matrix gel. After subcutaneous injections of transfected B16F1 cells in syngenic mice, lumican expression significantly decreased subcutaneous tumor formation in vivo, with a concomitant decrease of cyclin D1 expression. Lumican induced and/or increased the apoptosis of B16F1 cells. The results suggest that lumican is involved in the control of melanoma growth and invasion and may be considered, like decorin, as an anti-tumor factor from the extracellular matrix.