Cell shape modulation alters glycosylation of a metastatic melanoma cell‐surface antigen

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Abstract
B16‐F1 melanoma cells cultivated in vitro as spheroids on a non‐adhesive substrate acquire in a reversible fashion an increase in lung colonization in vivo as compared to cells cultured as a monolayer. After neuraminidase treatment of protein blots, the spheroidal cells expressed an increased binding of 125I‐labelled peanut lectin (PNA) to a unique glycoprotein of Mr78,000 (gp78) which after desialylation migrated in SDS‐polyacrylamide gels as an Mr86,000 protein. Antibodies were generated against this glycoprotein purified on PNA‐Sepharose and its expression on the surface of viable B16‐F1 cells was demonstrated. Growth of B16‐F1 melanoma cells in suspension is associated with the altered glycosylation of gp78 which may be related to the increased metastatic ability of these cells. In vitro treatment of B16‐F1 cells with anti‐gp78 Fab fragments prior to their injection into the tail veins of syngeneic mice resulted in a 2‐fold increase in the appearance of tumor lung colonies.