Role of GalNAc4S-6ST in astrocytic tumor progression

Intra-tumoral administration of CHST15 siRNA remodels tumor microenvironment and augments tumor-infiltrating T cells in pancreatic cancer

The dense stroma is one cause of poor efficacy of T cell-mediated immunotherapy in pancreatic ductal adenocarcinoma (PDAC). Carbohydrate sulfotransferase 15 (CHST15) is a proteoglycan-synthetic enzyme responsible for remodeling tumor stroma. Intra-tumoral injection of CHST15 small interfering RNA (siRNA) has been shown to increase the tumor-infiltrating T cells (TILs) in patients with unresectable PDAC. However, the mechanism underlying the enhanced accumulation of TILs is not fully explored. Here, we demonstrate that intra-tumoral injection of CHST15 siRNA locally and remotely diminishes myeloid-derived suppressor cells (MDSCs) and enhances TILs in mice. CHST15 was expressed by tumor cells and MDSCs in both tumor and tumor-draining lymph nodes (TDLNs), and CHST15 siRNA repressed stromal density, neutrophil extracellular traps, and Ly6C/G+ MDSCs in vivo. Remarkably, tumor growth inhibition was only observed in the immunocompetent KPC model, which is associated with enhanced TILs. In vitro, CHST15 siRNA significantly downregulated the levels of CHST15 and indoleamine 2,3-dioxygenase mRNA in CD33+ MDSCs derived from human peripheral blood mononuclear cells. These results suggest a dual role for intra-tumorally injected CHST15 siRNA on modulating the tumor immune microenvironment for T cell entry and remotely diminishing CHST15+ MDSCs, decreasing T cell suppression and expanding T cells in the TDLN, ultimately leading to an enhanced accumulation of TILs.

Silencing of tumoral carbohydrate sulfotransferase 15 reactivates lymph node pancreatic cancer T cells in mice

Limited intratumoral T-cell infiltration in pancreatic ductal adenocarcinoma (PDAC) is an obstacle to immunotherapy, yet the efficient approach to enhance tumor-infiltrating T cells is not fully established. Here, we show that tumor-specific knockdown of carbohydrate sulfotransferase 15 (CHST15), a tumor stromal proteoglycan-synthetic enzyme, suppresses tumor growth in a T-cell-dependent manner in a murine model of PDAC. Silencing of tumoral CHST15 unexpectedly expanded CD4+ and CD8+ T cells in tumor draining LN (TDLN), leading to accelerated accumulation of EdU+ proliferating CD4+ and CD8+ T cells and granzyme B+ CD8+ T cells in the tumor. RNA expression analysis indicated that tumoral CHST15 knockdown (KD) downregulated matrix remodeling-related genes, while upregulated anti-tumor T-cell activity-related genes in both tumor and TDLN. CHST15 KD significantly diminished intratumoral and TDLN Ly6C/G+ myeloid-derived suppressor cells prior to TDLN T-cell expansion, suggesting that tumoral CHST15 remotely regulated myeloid-derived suppressor cell mediated T-cell suppression in the TDLN. Our findings illustrate a novel immunotherapeutic potential of tumoral CHST15 blockage by reactivating T cells in immune suppressive TDLN of PDAC.

Functions of chondroitin/dermatan sulfate containing GalNAc4,6-disulfate

Chondroitin sulfate (CS) and dermatan sulfate (DS) containing GalNAc4,6-disulfate (GalNAc4S6S) were initially discovered in marine animals. Following the discovery, these glycosaminoglycans have been found in various animals including human. In the biosynthesis of CS/DS containing GalNAc4S6S, three groups of sulfotransferases are involved; chondroitin 4-sulfotransferases (C4STs), dermatan 4-sulfotransferase-1 (D4ST-1) and GalNAc 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST). GalNAc4S-6ST and its products have been shown to play important roles in the abnormal pathological conditions such as central nervous system injury, cancer development, abnormal tissue fibrosis, development of osteoporosis, and infection with viruses or nematodes. CS/DS containing GalNAc4S6S has been shown to increase with the functional differentiation of mast cells, macrophages and neutrophils. Genetic approaches using knockout or knockdown of GalNAc4S-6ST, blocking of the epitopes containing GalNAc4S6S by specific antibodies and chemical technology that enabled the synthesis of oligosaccharides with defined sulfation patterns have been applied successfully to these investigations. These studies contributed significantly to the basic understanding of the functional roles of CS/DS containing GalNAc4S6S in various abnormal conditions, and appear to provide promising clues to the development of possible measures to treat them.

Chondroitin sulfate E alleviates β-amyloid toxicity in transgenic Caenorhabditis elegans by inhibiting its aggregation

Chondroitin sulfate E (CS-E), which is characterized by oversulfated disaccharide units, has been shown to regulate neuronal adhesion, neurite outgrowth and exert neuroprotective effects. In view of these findings, here we investigated the anti-Alzheimer's disease (AD) activities of CSE by using transgenic Caenorhabditis elegans model of Alzheimer's disease. The behavioral experiments demonstrated that CSE at the concentration of 1 mg/ml significantly delayed the worm paralysis caused by Aβ aggregation as compared with control group. Western blot analysis revealed that the level of small oligomers in the transgenic C. elegans was significantly reduced upon treatment with CSE. The number of Aβ plaque deposits in transgenic worm was significantly decreased. In addition, CSE also protected the worms from oxidative stress and rescued chemotaxis dysfunction in transgenic strain CL2355. Taken together, these data suggested that CSE could protect against Aβ-induced toxicity in C. elegans. These results offer valuable evidence for the future use of CSE in the development of agents for the treatment of AD.

Glycomaterials to Investigate the Functional Role of Aberrant Glycosylation in Glioblastoma

Glioblastoma (GBM) is a stage IV astrocytoma that carries a dismal survival rate of ≈10 months postdiagnosis and treatment. The highly invasive capacity of GBM and its ability to escape therapeutic challenges are key factors contributing to the poor overall survival rate. While current treatments aim to target the cancer cell itself, they fail to consider the significant role that the GBM tumor microenvironment (TME) plays in promoting tumor progression and therapeutic resistance. The GBM tumor glycocalyx and glycan-rich extracellular matrix (ECM), which are important constituents of the TME have received little attention as therapeutic targets. A wide array of aberrantly modified glycans in the GBM TME mediate tumor growth, invasion, therapeutic resistance, and immunosuppression. Here, an overview of the landscape of aberrant glycan modifications in GBM is provided, and the design and utility of 3D glycomaterials are discussed as a tool to evaluate glycan-mediated GBM progression and therapeutic efficacy. The development of alternative strategies to target glycans in the TME can potentially unveil broader mechanisms of restricting tumor growth and enhancing the efficacy of tumor-targeting therapeutics.

Interactions of Pleiotrophin with a Structurally Defined Heparin Hexasaccharide

Pleiotrophin (PTN) is a potent cytokine that plays an important role in neural generation, angiogenesis, inflammation, and cancers. Its interactions with the polysaccharide glycosaminoglycan (GAG) are crucial to PTN’s biological activities. In this study, we investigated the interaction of selectively protonated PTN with the heparin hexasaccharide ΔUA2S-(GlcNS6S-IdoA2S)₂-GlcNS6S using solution NMR. The use of a structurally defined oligosaccharide and selectively protonated PTN enabled us to obtain intermolecular contacts using unfiltered NOESY experiments, significantly increasing the amount of high-resolution structural information obtainable. Our data showed that PTN’s arginines, lysines, and tryptophans in the two structured domains have strong interactions with the 2-O-sulfated uronate protons in the heparin hexasaccharide. Consistent with the NMR data is the observation that 2-O-desulfation and N-desulfation/N-acetylation significantly decreased heparin hexasaccharides’ affinity for PTN, while 6-O-desulfation only modestly affected the interactions with PTN. These results allowed us to hypothesize that PTN has a preference for sulfate clusters centered on the GlcNS6S-IdoA2S disaccharide. Using these data and the fact that PTN domains mostly bind heparin hexasaccharides independently, models of the PTN-heparin complex were constructed.

Differential gene expression identifies a transcriptional regulatory network involving ER-alpha and PITX1 in invasive epithelial ovarian cancer

Background

The heterogeneous subtypes and stages of epithelial ovarian cancer (EOC) differ in their biological features, invasiveness, and response to chemotherapy, but the transcriptional regulators causing their differences remain nebulous.

Methods

In this study, we compared high-grade serous ovarian cancers (HGSOCs) to low malignant potential or serous borderline tumors (SBTs). Our aim was to discover new regulatory factors causing distinct biological properties of HGSOCs and SBTs.

Results

In a discovery dataset, we identified 11 differentially expressed genes (DEGs) between SBTs and HGSOCs. Their expression correctly classified 95% of 267 validation samples. Two of the DEGs, TMEM30B and TSPAN1, were significantly associated with worse overall survival in patients with HGSOC. We also identified 17 DEGs that distinguished stage II vs. III HGSOC. In these two DEG promoter sets, we identified significant enrichment of predicted transcription factor binding sites, including those of RARA, FOXF1, BHLHE41, and PITX1. Using published ChIP-seq data acquired from multiple non-ovarian cell types, we showed additional regulatory factors, including AP2-gamma/TFAP2C, FOXA1, and BHLHE40, bound at the majority of DEG promoters. Several of the factors are known to cooperate with and predict the presence of nuclear hormone receptor estrogen receptor alpha (ER-alpha). We experimentally confirmed ER-alpha and PITX1 presence at the DEGs by performing ChIP-seq analysis using the ovarian cancer cell line PEO4. Finally, RNA-seq analysis identified recurrent gene fusion events in our EOC tumor set. Some of these fusions were significantly associated with survival in HGSOC patients; however, the fusion genes are not regulated by the transcription factors identified for the DEGs.

Conclusions

These data implicate an estrogen-responsive regulatory network in the differential gene expression between ovarian cancer subtypes and stages, which includes PITX1. Importantly, the transcription factors associated with our DEG promoters are known to form the MegaTrans complex in breast cancer. This is the first study to implicate the MegaTrans complex in contributing to the distinct biological trajectories of malignant and indolent ovarian cancer subtypes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08276-8.

Expression and function of chondroitin 4-sulfate and chondroitin 6-sulfate in human glioma

Key molecules promoting migration and invasion exist in the extracellular matrix, and include chondroitin 4-sulfate (C4S) and chondroitin 6-sulfate (C6S), functionally important carbohydrate chains of chondroitin sulfate proteoglycans that participate in regulating cancer development. Here, we show that C4S and C6S expression is upregulated in human glioma tissues, when compared to normal brain tissue, and that the extent of upregulation positively correlated with glioma malignancy. Treatment of cultured glioma cells with C4S and C6S enhanced cell viability, migration, and invasion, increased MMP-2 and MMP-9 levels, enhanced N-cadherin, but reduced E-cadherin expression. Inhibition of expression of the two CS synthetic enzymes chondroitin 4-O-sulfotransferase-1 (C4ST-1/CHST11) and chondroitin 6-O-sulfotransferase-1 (C6ST-1/CHST3) suppressed cell viability, migration and invasion, reduced MMP-2 and MMP-9 expression, and reduced N-cadherin expression, but increased E-cadherin levels. The C4S- and C6S-enhanced epithelial-to-mesenchymal transition and expression of MMP-2 occurred via activation of the PI3K/AKT signaling pathway, known to be involved in promoting cell migration and invasion. In immune-deficient larval zebrafish, C4S and C6S increased the numbers of viable tumor cells, thereby promoting glioma cell proliferation. The present observations point to a novel role of C4S and C6S in human glioma cell functions, thus possibly representing targets in glioma therapy.

Surfen-mediated blockade of extratumoral chondroitin sulfate glycosaminoglycans inhibits glioblastoma invasion

Invasive spread of glioblastoma (GBM) is linked to changes in chondroitin sulfate (CS) proteoglycan (CSPG)-associated sulfated glycosaminoglycans (GAGs) that are selectively up-regulated in the tumor microenvironment (TME). We hypothesized that inhibiting CS-GAG signaling in the TME would stem GBM invasion. Rat F98 GBM cells demonstrated enhanced preferential cell invasion into oversulfated 3-dimensional composite of CS-A and CS-E [4- and 4,6-sulfated CS-GAG (COMP)] matrices compared with monosulfated (4-sulfated) and unsulfated hyaluronic acid matrices in microfluidics-based choice assays, which is likely influenced by differential GAG receptor binding specificities. Both F98 and human patient-derived glioma stem cells (GSCs) demonstrated a high degree of colocalization of the GSC marker CD133 and CSPGs. The small molecule sulfated GAG antagonist bis-2-methyl-4-amino-quinolyl-6-carbamide (surfen) reduced invasion and focal adhesions in F98 cells encapsulated in COMP matrices and blocked CD133 and antichondroitin sulfate antibody (CS-56) detection of respective antigens in F98 cells and human GSCs. Surfen-treated F98 cells down-regulated CSPG-binding receptor transcripts and protein, as well as total and activated ERK and protein kinase B. Lastly, rats induced with frontal lobe tumors and treated with a single intratumoral dose of surfen demonstrated reduced tumor burden and spread compared with untreated controls. These results present a first demonstration of surfen as an inhibitor of sulfated GAG signaling to stem GBM invasion.-Logun, M. T., Wynens, K. E., Simchick, G., Zhao, W., Mao, L., Zhao, Q., Mukherjee, S., Brat, D. J., Karumbaiah, L. Surfen-mediated blockade of extratumoral chondroitin sulfate glycosaminoglycans inhibits glioblastoma invasion.

Upregulation of the solute carrier family 7 genes is indicative of poor prognosis in papillary thyroid carcinoma

Background

The solute carrier (SLC) 7 family genes comprise 14 members and function as cationic amino acid/glycoprotein transporters in many cells, they are essential for the maintenance of amino acid nutrition and survival of tumor cells. This study was conducted to analyze the associations of SLC7 family gene expression with mortality in papillary thyroid carcinoma (PTC).

Methods

Clinical features, somatic mutations, and SLC7 family gene expression data were downloaded from The Cancer Genome Atlas database. Linear regression model analysis was performed to analyze the correlations between SLC7 family gene expression and clinicopathologic features. Kaplan-Meier survival and logistic regression analyses were performed to characterize the associations between gene expression and patients’ overall survival.

Results

Patient mortality was negatively associated with age and tumor size but positively increased cancer stage and absence of thyroiditis in PTC patients. Kaplan-Meier survival analysis indicated that patients with high SLC7A3, SLC7A5, and SLC7A11 expression levels exhibited poorer survival than those with low SLC7A3, SLC7A5, and SLC7A11 expression levels (P < 0.05 for all cases). Logistic regression analysis showed that SLC7A3, SLC7A5, and SLC7A11 were associated with increased mortality (odds ratio [OR] 8.61, 95% confidence interval [CI] 2.3–55.91; OR 3.87, 95% CI 1.18–17.31; and OR 3.87, 95% CI 1.18–17.31, respectively.

Conclusion

Upregulation of SLC7A3, SLC7A5, and SLC7A11 expression was associated with poor prognosis in PTC patients, and SLC7 gene expression levels are potentially useful prognostic biomarkers.

Potential involvement of chondroitin sulfate A in the pathogenesis of ameloblastoma

Ameloblastoma is classified as a benign odontogenic tumor characterized by locally invasive behavior and high risk of recurrence. Here, we evaluate a potential role for glycosaminoglycan, a structural component of cell membranes and extracellular matrix, in ameloblstoma pathogenesis. We subjected formalin-fixed, paraffin-embedded tissue sections of 34 cases of ameloblastoma, 10 of odontogenic keratocyst, and 17 of dentigerous cyst to immunohistochemistry using monoclonal antibodies recognizing chondroitin sulfate A (CS-A), heparan sulfate (HS), and keratan sulfate (KS). Expression levels of CS-A in epithelial component and stroma of ameloblastoma were significantly higher than those in odontogenic keratocyst and dentigerous cyst. Moreover, CS-A in ameloblastoma was more strongly expressed in stellate reticulum-like cells than in amelobast-like cells with statistical significance. On the other hand, expression levels of HS and KS in epithelial component and stroma of ameloblastoma were lower compared with CS-A. These results overall reveal that among these odontogenic lesions, CS-A is preferentially expessed in ameloblastoma, suggesting potential pathogenetic role probably in cytodifferention of tumor cells to stellate reticulum-like cells.

Glioma Cell Invasion is Significantly Enhanced in Composite Hydrogel Matrices Composed of Chondroitin 4- and 4,6-Sulfated Glycosaminoglycans

Glioblastoma multiforme (GBM) is the most aggressive form of astrocytoma accounting for a majority of primary malignant brain tumors in the United States. Chondroitin sulfate proteoglycans (CSPGs) and their glycosaminoglycan (GAG) side chains are key constituents of the brain extracellular matrix (ECM) implicated in promoting tumor invasion. However, the mechanisms by which sulfated CS-GAGs promote brain tumor invasion are currently unknown. We hypothesize that glioma cell invasion is triggered by the altered sulfation of CS-GAGs in the tumor extracellular environment, and that this is potentially mediated by independent mechanisms involving CXCL12/CXCR4 and LAR signaling respectively. This was tested in vitro by encapsulating the human glioma cell line U87MG-EGFP into monosulfated (4-sulfated; CS-A), composite (4 and 4,6-sulfated; CS-A/E), unsulfated hyaluronic acid (HA), and unsulfated agarose (AG; polysaccharide) hydrogels within microfluidics-based choice assays. Our results demonstrated the enhanced preferential cell invasion into composite hydrogels, when compared to other hydrogel matrices (p<0.05). Haptotaxis assays demonstrated the significantly (p<0.05) faster migration of U87MG-EGFP cells in CXCL12 containing CS-GAG hydrogels when compared to other hydrogel matrices containing the same chemokine concentration. This is likely due to the significantly (p<0.05) greater affinity of composite CS-GAGs to CXCL12 over other hydrogel matrices. Results from qRT-PCR assays further demonstrated the significant (p<0.05) upregulation of the chemokine receptor CXCR4, and the CSPG receptor LAR in glioma cells within CS-GAG hydrogels compared to control hydrogels. Western blot analysis of cell lysates derived from glioma cells encapsulated in different hydrogel matrices further corroborate qRT-PCR results, and indicate the presence of a potential variant of LAR that is selectively expressed only in glioma cells encapsulated in CS-GAG hydrogels. These results suggest that sulfated CS-GAGs may directly induce enhanced invasion and haptotaxis of glioma cells associated with aggressive brain tumors via distinct mechanisms.

Mice deficient in N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase exhibit enhanced liver fibrosis and delayed recovery from fibrosis in carbon tetrachloride-treated mice

Background

Chondroitin/dermatan sulfate (CS/DS) rich in N-acetylgalactosamine 4,6-bissulfate (GalNAc(4,6SO₄)) residues is present as decorin and/or biglycan in mouse liver, and GalNAc(4,6SO₄) residues disappeared completely in N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST) knockout (KO) mice. The aim of this study was to investigate whether CS/DS rich in GalNAc(4,6SO₄) residues participate in the progression or resolution of liver fibrosis.

Methods

Wild type (WT) and GalNAc4S-6ST KO mice were treated with CCl₄ for 5 weeks. After discontinuation of CCl₄ administration, histochemical and biochemical changes and expression of genes related to matrix components were compared between WT and GalNAc4S-6ST KO mice.

Results and conclusion

On 2 days after cessation of CCl₄ administration, higher fibrosis was observed in KO mice than in WT mice by Sirius Red staining. Serum alanine aminotransferase activity was higher in KO mice than in WT mice. Hydroxyproline contents and Sirius Red staining showed that repair of liver fibrosis in the recovery stages appeared to be delayed in KO mice. Expression of mRNA of matrix metalloproteinase (MMP)-2, MMP-13 and versican peaked at 2 days after cessation of CCl₄ administration and was higher in KO mice than in WT mice. Expression of MMP-9 in the recovery stage was lower in KO mice than in WT mice. Our findings demonstrate that defect in GalNAc4S-6ST, which resulted in disappearance of CS/DS containing GalNAc(4,6SO₄), appear to contribute to progression of liver fibrosis, delayed recovery from fibrosis, and various changes in the expression of proteoglycans and MMPs in carbon tetrachloride–treated mice.

Inhibition of versican expression by siRNA facilitates tropoelastin synthesis and elastic fiber formation by human SK-LMS-1 leiomyosarcoma smooth muscle cells in vitro and in vivo

Versican is an extracellular matrix (ECM) molecule that interacts with other ECM components to influence ECM organization, stability, composition, and cell behavior. Versican is known to increase in a number of cancers, but little is known about how versican influences the amount and organization of the ECM components in the tumor microenvironment. In the present study, we modulated versican expression using siRNAs in the human leiomyosarcoma (LMS) smooth muscle cell line SK-LMS-1, and observed the formation of elastin and elastic fibers in vitro and also in vivo in a nude mouse tumor model. Constitutive siRNA-directed knockdown of versican in LMS cells resulted in increased levels of elastin, as shown by immunohistochemical staining of the cells in vitro, and by mRNA and protein analyses. Moreover, versican siRNA LMS cells, when injected into nude mice, generated smaller tumors that had significantly greater immunohistochemical and histochemical staining for elastin when compared to control tumors. Additionally, microarray analyses were used to determine the influence of versican isoform modulation on gene expression profiles, and to identify genes that influence and relate to the process of elastogenesis. cDNA microarray analysis and TaqMan low density array validation identified previously unreported genes associated with downregulation of versican and increased elastogenesis. These results highlight an important role for the proteoglycan versican in regulating the expression and assembly of elastin and the phenotype of LMS cells.

Chondroitin sulfate synthase 1 expression is associated with malignant potential of soft tissue sarcomas with myxoid substance

The glycosyltransferases chondroitin sulfate synthase 1 (CHSY1) and exostoses-like 3 (EXTL3) specifically function in biosynthesis of the glycans chondroitin sulfate and heparan sulfate, respectively. Although these glycans play important roles in pathogenesis of various tumors, their significance in soft tissue sarcoma remains unknown. Here, we asked whether CHSY1 or EXTL3 expression correlates with malignant potential of soft tissue sarcomas with myxoid substance. To do so, we examined 40 samples representing specific types, including 12 cases of myxoid liposarcoma, 14 of myxofibrosarcoma, 12 of malignant peripheral nerve sheath tumor, and 2 of low-grade fibromyxoid sarcoma. We performed immunohistochemistry with anti-CHSY1 and anti-EXTL3 antibodies and compared enzyme expression levels with tumor histologic grade as assessed by the Fédération Nationale des Centres de Lutte Contre le Cancer classification and with patient 5-year survival rate. CHSY1 and EXTL3 were expressed in 72.5% and 32.5% of all tumors, respectively. Notably, CHSY1 was strongly expressed in myxofibrosarcoma and malignant peripheral nerve sheath tumor compared with other tumors and significantly associated with higher- rather than lower-grade tumors (P < .01). High expression of CHSY1 was also significantly associated with poorer patient outcomes (P = .031) and higher stages assessed by American Joint Committee on Cancer staging system (P = .004). By contrast, EXTL3 expression was not correlated with histologic grade or patient prognosis. We conclude that CHSY1 expression is closely associated with malignant potential of soft tissue sarcomas with myxoid substance.

Isolation and characterization of monoclonal antibodies specific for chondroitin sulfate E

Chondroitin sulfate E (CSE) is a polysaccharide containing mainly disaccharide units of D-glucuronic acid (GlcA) and 4,6-O-disulfated N-acetyl-D-galactosamine (GalNAc) residues (E-unit) in the amount of ∼ 60%. CSE is involved in many biological and pathological processes. In this study, we established new monoclonal antibodies, termed E-12C and E-18H, by using CSE that contained more than 70% of E-units as an immunogen. These antibodies recognized CSE but not other CSs isomers or dermatan sulfate (DS). We evaluated the reactivities of the antibodies to 6-O-sulfated CSA (6S-CSA) and DS (6S-DS) that possessed ∼ 60% of GalNAc (4S, 6S) moieties in their structures. Neither of the antibodies reacted with 6S-DS. The antibodies strictly distinguished the structural difference of GlcA and L-iduronic acid in the polysaccharide. Binding affinities of the antibodies were determined by a surface plasmon resonance assay using CSE and 6S-CSA. The binding affinities were strongly associated with the molecular weight of CSE and the E-unit content of 6S-CSA. Moreover, we demonstrated that the antibodies are applicable to histochemical analysis. In conclusion, the new anti-CSE monoclonal antibodies specifically recognize the E-unit of CSE. The antibodies will become useful tools for the investigation of the biological and pathological significance of CSE.

Primary ovarian carcinomas and abdominal metastasis contain 4,6-disulfated chondroitin sulfate rich regions, which provide adhesive properties to tumour cells

High mortality in ovarian cancer patients is primarily caused through rapid metastasis of the tumour, but the underlying mechanisms are poorly understood. Glycosaminoglycans, are abundantly present in tumours and chondroitin sulfate-E (CSE), a highly 4,6-sulfated glycosaminoglycan, has been indicated to play a role in carcinogenesis. In this study we investigated the presence of CSE in ovarian cancer metastasis and studied its role in tumour cell adhesiveness and migration. CSE was studied immunohistochemically in primary ovarian carcinomas and abdominal metastases using the single chain antibody GD3G7. The role of CSE was studied in 2D (scratch assays) and 3D (collagen matrices, spheroids) systems using SKOV3 cells applying 1: overexpression of CSE by stable transfection with DNA encoding GalNAc4S-6 sulfotransferase, 2: enzymatic removal of CS, and 3: addition of CSE. In ovarian cancer tissue, CSE expression was predominantly seen in the stromal compartment of both primary ovarian carcinomas and metastases, with a comparable degree of intensity and extent. Overexpression of CSE disaccharide units by tumour cells increased their adhesive properties which was especially seen in tumour spheroid formation. Increased expression of CSE reduced cell migration. Addition of free CSE had similar effects. The data presented here indicate that CSE is associated with metastatic lesions and that it provides tumours with adhesive properties. CSE rich motifs are put forward as a potential target for ovarian cancer therapy.