HUMAN NEUROECTODERM-DERIVED CELL-LINE SECRETES FIBRONECTIN THAT SHARES THE HNK-1/10C5 CARBOHYDRATE EPITOPE WITH NEURAL CELL-ADHESION MOLECULES

A human malignant melanoma cell line, Melur, secretes several glycoproteins that contain a unique carbohydrate epitope shared by neural cell adhesion molecules and recognized by the monoclonal antibodies HNK‐1, L2, and 10C5. In this report, we present evidence that one of the major melanoma glycoproteins containing the HNK‐1/10C5 epitope is the cell adhesion molecule, fibronectin, or a fibronectin‐like molecule. Melanoma‐derived fibronectin was isolated from serum‐free conditioned medium by gelatin‐Sepharose affinity adsorption and shown to react with monoclonal antibodies HNK‐1 and 10C5 in Western blot analysis. HNK‐1‐containing fibronectin was purified on a gelatin‐Sepharose column followed by an affinity column using a monoclonal antibody against the HNK‐1 carbohydrate. The purified HNK‐1‐fibronectin then could be incorporated into the extracellular matrix of hamster fibroblasts in vitro, and such a matrix was detectable using the HNK‐1 monoclonal antibody in an immunofluorescence assay. Of the seven neuroectoderm‐derived tumor cell lines tested, only the Melur melanoma cell secreted fibronectin containing the HNK‐1 carbohydrate. Identification of human neuroectoderm‐derived fibronectin as a potential carrier of the HNK‐1 carbohydrate suggests a new role for fibronectin in neural development and regeneration, and represents a new model for studying the function of this carbohydrate domain in neural cell adhesion. Copyright © 1990, Wiley Blackwell. All rights reserved