EXPRESSION OF THE GALACTOSE BINDING-PROTEIN MAC-2 BY HUMAN-MELANOMA CELL-LINES

The Mac-2 protein is a lectin specific for galactose-containing glycoc onjugates. Present in some normal cells, it was also associated with t he metastatic potential of some carcinoma cells. We studied Mac-2 expr ession in three human melanoma cell lines and in five variants and clo nes from one of them. By using the M3/38 rat monoclonal antibody, Mac- 2 was demonstrated on cell surface by flow cytometry as well as in the cytoplasm and in the nucleus by confocal microscopy. The expression o f Mac-2 was not correlated with that of terminal unsialylated Gal beta 1-3 GalNac structures on metastatic melanoma cell lines. However, the presence of extracellular Mac-2 containing vesicles was observed in c ell lines with metastatic potency. Western blot analysis of cell lysat es, in reducing or non-reducing conditions, revealed two bands of 34-3 6 and 93-98 kDa apparent M(r), also found in HL60 and P388.D1 cell lin es used as positive controls.