LECTIN HISTOCHEMISTRY OF ASTROCYTIC TUMORS AND IN-VITRO CHARACTERIZATION OF LECTIN-INDUCED MODIFICATIONS ON THE PROLIFERATION OF THE SW1088, U373 AND U87 HUMAN ASTROCYTIC CELL-LINES

The role of lectins as biosignalling molecules or as markers of human astrocytic tumors remains relatively unexplored. The aim of the presen t work is to investigate (1) whether or not human astrocytic tumors ex press specific glycans, evidenced experimentally by means of lectin hi stochemistry, and (2) whether, in turn, these lectins can significantl y modulate astrocytic tumor cell proliferation. Using a cell image pro cessor, we therefore began by quantitatively measuring the histochemic al binding pattern of 5 lectins (WGA, PNA, PHA-L, GSA-IA4 and Con A) i n 5 astrocytomas, 5 anaplastic astrocytomas and 5 glioblastomas. Secon dly, we measured the influence of these 5 lectins on the proliferation of 3 astrocytic tumor cell lines (SW1088, U373 and U87) growing in vi tro as monolayers. Cell proliferation was assessed by means of the col orimetric MTT assay. The histochemical lectin staining markedly varied intra- and inter-group. However, some constant results were obtained. Indeed, the staining increased markedly from GSA-IA4 and PHA-L throug h WGA and PNA to Con A in the three histopathological groups. The asse ssment of cell proliferation demonstrated that WGA, Con A and PHA-L ve ry significantly decreased proliferation in the 3 astrocytic cell line s in a dose-dependent manner. Astrocytic tumor cells in the confluent growth phase were less sensitive to the WGA, Con A and PHA-L lectin-in duced effects than cells in the log growth phase. The GSA-IA4 and PNA lectins had globally very weak effects on the proliferation of the ast rocytic tumor cell lines. Increasing the fetal calf serum from 1% to 1 0% in the culture media significantly antagonized the WGA-, Con A- and PHA-L-induced cell proliferation decrease in the 3 astrocytic cell li nes. In conclusion, the present data strongly suggest that some lectin s (including WGA, Con A and PHA-L) significantly influence the prolife ration of astrocytic tumor cells.