Cell‐surface sulfoglycolipids are involved in the attachment of renal‐cancer cells to laminin

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Abstract
We investigated the role of sulfoglycolipids on human renal‐cell carcinoma cells (SMKT‐R3) in the attachment to a substrate adhesive protein, laminin. SMKT‐R3 cells over‐express sulfoglycolipids, including SM2, SM3 and SM4. When acidic glycolipid fractions were extracted from SMKT‐R3 cells, separated by HPTLC, and then overlaid with laminin, laminin bound specifically to SM3 and SM4. A monoclonal antibody, Sulph‐1, reacting with SM3 and SM4 inhibited attachment of the cells to laminin but not to fibronectin, in a dose‐dependent manner. In addition, when exogenous SM4 was incorporated into the cells, their attachment to laminin, but not to fibronectin, was enhanced. On the other hand, the incorporation of GalCer, which is a precursor of SM4, had no effect on adherence of the cells to laminin or to fibronectin. We also assayed haptotaxis, tumor‐cell migration along a gradient of substratum‐bound laminin. The incorporation of SM4 into the cells caused an approximately 3‐fold increase of the haptotactic response to laminin compared with non‐or GalCer‐incorporation. These results taken together suggest that sulfoglycolipids on renal‐cancer cells are involved in attachment to laminin and that they can modulate the metastatic potential of renal‐cell carcinoma cells.