Biosynthetic studies of proteoglycans in human melanoma cells with a monoclonal antibody to a core glycoprotein of chondroitin sulfate proteoglycans

Abstract

Monoclonal antibody (Mab) 9.2.27 was utilized in a combination of biosynthetic and biochemical investigations as an immunological probe for the study of chondroitin sulfate proteoglycans (CSP) in human melanoma cells. Pulse-chase and long-term intrinsic labeling immunoprecipitation experiments combined with the biosynthetic inhibitors monensin, cycloheximide, and paranitrophenol-beta-D-xyloside all suggest that Mab 9.2.27 recognizes a set of glycoprotein molecules ranging to a 250-kDa glycoprotein which serves as the core glycoprotein for CSP in human melanoma cells. Peptide maps comparing the 250-kDa and CSP molecule verify that the 250-kDa glycoprotein is the CSP core protein in human melanoma cells. Further studies document that the CSP released by melanoma cells and recognized by Mab 9.2.27 contains (2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-beta-4-O-sulfo-D-galactose and 2-acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-beta-6-O-sulfo-D-galactose saccharides and this CSP can interact with hyaluronic acid-Sepharose. Topographical studies indicate that this CSP has pericellular punctuated distribution on the melanoma cell surface and may play a role in cell-substrate interactions in the biology of metastatic human melanoma.