A comparative study of cell surface glycosyl determinants in cisplatin-sensitive and resistant L1210 murine leukemia cells

A comparison of cell surface carbohydrate determinants in two sublines of L1210 murine leukemic cells - one sensitive and one resistant to cisplatin - was conducted using lectins as molecular probes for distinct carbohydrate groups. It was found, that resistant cells were better agglutinated by different lectins without regard to their carbohydrate specificity. The most pronounced differences in cell agglutination were observed with D-mannospecific (concanavalin A, Pisum sativum and Leucojum vernum agglutinins) and D-galactospecific lectins (Ricinus communis and Arachis hypogaea agglutinins). The polypeptide patterns of the isolated plasma membranes studied by SDS-PAGE showed that Mr 94 kD polypeptide was more pronounced in cisplatin-sensitive cells, while 240 and 31 kD bands were more noticeable in cisplatin resistant cells. Isoelectrofocusing revealed distinct differences in polypeptide patterns under pH 5.5 and 7-7.5. The most peculiar feature of plasma membrane glycoprotein patterns revealed by horse-radish peroxidase-labelled lectins was the enhanced expression of Mr 240 kD PNA-binding glycoprotein in resistant cells. Less expressed but reproducible differences between glycoprotein patterns of the compared cell sublines were revealed with other lectins. Cell surface negative charge, as measured by cell electrophoresis, was substantially higher In resistant cells, The results obtained suggest that the resistance to cisplatin in L1210 murine leukemia cells is associated with an enhanced expression of distinct glycoproteins, mainly of O-type acidic high molecular weight glycoprotein, in plasma membrane of these tumor cells.