Differential effects of lectins on the in vitro growth of normal mouse lung cells and low- and high-cancer-derived cell lines.

The comparative aspects of cell growth, i.e., [3H]thymidine and [14C]leucine uptake of low-cancer (P4Bis) and high-cancer (P4BisT) cell lines and of their normal counterparts, have been studied in the presence and absence of concanavalin and Robinia lectins. These lectins have similar effects on cell growth, on thymidine and leucine uptake, and on incorporation of these precursors. The growth of normal cells is stimulated by both lectins, whereas the growth of transformed cells is inhibited. In all cases the uptake of both leucine and thymidine by cells is increased by the lectins, but the percentage of incorporation of the precursors is affected in a different manner. The percentage of thymidine incorporated by normal and transformed cells increases or decreases in direct proportion to cell growth; leucine incorporation is not affected significantly. The reversibility of these lectin effects by specific inhibitors shows that cell membranes are implicated in these phenomena. Our study with normal and transformed cells suggests that cell surface may play a role in the process of malignant transformation and that P4Bis cells are "transitory" between PB1 normal cells and P4BisT high-cancer cells.