Prognostic significance of highly sulfated chondroitin sulfates in ovarian cancer defined by the single chain antibody GD3A11.

OBJECTIVE: The extracellular matrix (ECM) of ovarian cancer may provide a number of potential biomarkers. Chondroitin sulfate (CS), a class of sulfated polysaccharides, is abundantly present in the ECM of ovarian cancer. Structural alterations of CS chains (i.e. sulfation pattern) have been demonstrated to play a role in cancer development and progression. In this study we investigate the potential of highly sulfated CS as a biomarker in ovarian cancer using the single chain antibody GD3A11 selected by the phage display technology. METHODS: The specificity of the antibody was determined by an indirect ELISA. GD3A11 epitope expression was assessed by immunohistochemistry in healthy organs, benign and malignant ovarian tumors (N=359) and correlated to clinical parameters. The CHST15 gene, responsible for the biosynthesis of highly sulfated CS was evaluated for mutation and methylation status. RESULTS: The GD3A11 epitope was minimally expressed in normal organs. Intense expression was observed in the ECM of different ovarian cancer subtypes, in contrast to benign ovarian tumors. Expression was independent of tumor grade, FIGO stage, and the use chemotherapy. For the aggressive ovarian cancer phenotype, intense expression was identified as an independent predictor for poor prognosis. CHST15 gene analysis showed no mutations nor an altered methylation status. CONCLUSION: Specific highly sulfated CS motifs expressed in the tumoral ECM hold biomarker potential in ovarian cancer patients. These matrix motifs constitute a novel class of biomarkers with prognostic significance and may be instrumental for innovative diagnostic and therapeutic applications (e.g. targeted therapy) in management of ovarian cancer.

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.

Novel single-chain antibody GD3A10 defines a chondroitin sulfate biomarker for ovarian cancer.

AIMS: Ovarian cancer has the highest case-to-fatality-index of all gynecological cancers. In this study, tumor-related alterations in the extracellular matrix, especially regarding chondroitin sulfate glycosaminoglycans, are proposed as a novel biomarker in ovarian cancer. MATERIALS & METHODS: Phage display technology was applied to select antibody GD3A10, which was obtained by biopanning using embryonic glycosaminoglycans as a source for carcinogenic antigens. GD3A10 antigen specificity was studied in situ using glycosaminoglycan degrading enzymes. A patient cohort (n = 159) was immunohistochemically stained. Scoring was correlated with clinical prognostic parameters and survival. Normal rat organs were used to study normal antigen distribution. RESULTS: GD3A10 is a specific anti-chondroitin sulfate antibody and the epitope was absent or very restricted in normal rat organs, normal ovaries and benign ovarian tumors. Strong stromal expression was observed in malignant ovarian tumors, and correlated with poor prognostic factors such as subtype, tumor grade and recurrence. CONCLUSION: tumor-associated glycosaminoglycans are an interesting source of biomarkers in ovarian cancer, as shown here using chondroitin sulfate antibody GD3A10.

Sulfated sugars in the extracellular matrix orchestrate ovarian cancer development: 'when sweet turns sour'.

Considering the high mortality of ovarian cancer, novel approaches for diagnostics and therapy are urgently needed. Cancer initiation, progression, and invasion occur in a complex and dynamic microenvironment which depends on the interplay between host cell responses and tumor activity. Chondroitin sulfate (CS), a special highly sulfated sugar, forms an important intermediate player in this respect. Depending on the (micro)structural diversity of chondroitin sulfate chains, various ligands interact with this special group of glycosaminoglycans, making it a key molecule for many physiological and pathological processes, including cancer development. This review focuses on the various functions of chondroitin sulfate in tumor growth, angiogenesis, dissemination and immunosilencing of ovarian cancer. We also shed light on possible future diagnostic and therapeutic modalities for ovarian cancer based on the large variety in chondroitin sulfate microstructure and function. It is concluded that the class of chondroitin sulfate represents an attractive target to interfere with the process of ovarian tumorigenesis.

Extraction and structural analysis of glycosaminoglycans from formalin-fixed, paraffin-embedded tissues.

Glycosaminoglycans (GAGs) are long, anionic polysaccharides involved in many basic aspects of mammalian physiology and pathology. Here we describe a method to extract GAGs from formalin-fixed, paraffin-embedded tissues and found that they are structurally comparable with GAGs extracted from frozen tissues. We employed this method to structurally characterize GAGs in tissues, including laser-dissected layers of skin and pathological specimens. This method enables the use of the archival paraffin-embedded material for detailed (structural) analysis of GAGs.

Highly sulfated chondroitin sulfates, a novel class of prognostic biomarkers in ovarian cancer tissue.

OBJECTIVE: Clinical decision making in ovarian cancer needs new (prognostic) biomarkers. Although the search for biomarkers has traditionally focused on tumor cells, their surrounding contains important information as well. Glycosaminoglycans, heterogeneous polysaccharides which are abundantly present in the stromal compartment, are indicated in several pathological processes including cancer. In this study we investigated a specific glycosaminoglycan motif (4,6-disulfated chondroitin sulfate) for its potential as a prognostic biomarker in ovarian cancer. METHODS: 4,6-Disulfated chondroitin sulfate presence was studied immunohistochemically using the single chain antibody GD3G7 on 148 ovarian tumors including benign and malignant tumors, and tumors with low malignant potential. For comparative purposes p53 and Ki-67 were evaluated. X2 tests, univariate and multivariate Cox proportional hazards analyses were applied for statistical analysis. RESULTS: The stroma of malignant tumors showed significantly increased expression of 4,6-disulfated chondroitin sulfate (GD3G7 epitope) compared with benign tumors and tumors with LMP (p-values<0.000 and 0.002, respectively). Expression of GD3G7 in malignant tumors was significantly correlated with serous subtype, high tumor grade, advanced FIGO-stage and high CA-125 levels. In patients with advanced FIGO stage GD3G7 expression was significantly correlated with incomplete debulking and good response to platinum-based chemotherapy. GD3G7 surpassed both p53 and Ki-67 in statistical analysis. Multivariate survival analysis revealed GD3G7 expression as an independent predictor for progression free survival. CONCLUSION: Glycosaminoglycan motifs may form a new class of biomarkers for (ovarian) cancer, as indicated here for the GD3G7 epitope. Expression of GD3G7 may contribute in therapeutic decision making and constitutes a potential biomarker for poor prognosis.