Cancer metastasis is characterised by the spread of cancer cells to distant organs and tissues, which relies on changes in cell-cell and cell-extracellular matrix (ECM) interactions. Proteoglycans are major components of the ECM and cell surface, where they have been shown to mediate some of these cell-ECM interactions. Hence changes in the expression levels and structures of these complex molecules are likely to affect cancer cell progression. Studies have shown that both perlecan, an extracellular heparan sulphate proteoglycan, and a chondroitin sulphate proteoglycan 4 (CSPG4), a cell surface proteoglycan and thought to be decorated with chondroitin sulphate, are capable of modulating the metastatic potential of malignant cells making them attractive potential immunotherapeutic targets to control metastasis. Thus, this study aims to investigate the expression levels and structures of CSPG4 and perlecan produced by the human colon carcinoma cancer cell line, WiDr, to assess their glycosaminoglycan structure.
WiDr cells expressed CSPG4 on their cell surface, which was not secreted into the ECM while perlecan was produced and secreted into the culture medium but not laid down in the ECM. We hypothesise that perlecan and CSPG4 work cooperatively interacting with integrins and the surrounding environment to instruct cells to adhere, migrate, and proliferate. In WiDr cells, perlecan was colocalised with the α2β1 integrin while CSPG4 colocalised with the β1 integrin chain but not the α2 component. Scratch assays, that were used as model of cell expansion, have shown that anti-integrin β1 antibodies reduced cell expansion on both tissue culture polystyrene (TCPS) and collagen coated TCPS. Interestingly, anti-CSPG4 monoclonal antibodies (clone 9.2.27) were able to reduce cell expansion on type I collagen coated TCPS, but not TCPS suggesting a link between the substratum that the cells are exposed to, the expression of CSPG4 and specific integrins. We plan to investigate the role of glycosminoglycans decorating proteoglycans and whether these carbohydrate structures modulate the interactions with the integrins, affecting cell adhesion.