Expression of fibronectin and adhesion to fibronectin in myeloma cell lines.

Fibronectin (FN) expression in six myeloma, two mature B-cell lines, and four T-cell lines was analyzed. All myeloma cell lines expressed FN at various levels, while mature B- and T-cell lines apparently had less FN. Moreover, an extramedullary plasmacytoma-derived myeloma cell line, KHM7, was found to secrete FN into the culture medium. Fibronectin receptors, VLA4 or VLA5, were expressed at various levels on all myeloma cell lines. An adhesion assay revealed three of six myeloma cell lines bound to FN. However, there was no correlation between binding to FN and FN receptor expression, indicating a complicated FN binding pathway. The mechanism and pathological significance of FN expression and FN binding in myeloma cells are discussed.