Effects of concanavalin A on cellular dynamics and membrane transport.

How does Con A affect the cellular dynamics and cellular transport of various substances? It has been observed that following a 30 minute incubation with Con A (20-66 mug/ml) the tumor cells (Anaplastic carcinoma Type 15091a), unlike the normal cells, gradually retract their pseudopodia, take on a rounded shape and lose their motility. The maximum rounding of tumor cells takes place during the period of 200-250 min following the withdrawal of Con A from the incubating medium. All of these rounded cells later develop their regular pseudopodia. A partial synchrony of cell division is also observed. Associated with the rounding effect, there is a decrease in the rate of uptake of some specific amino acids by the tumor cells. The maximum reduction in the uptake coincides with the stage of maximum rounding. Con A also affects some of the electrical properties of tumor cells. In addition, the incorporation of radioactive thymidine into the nuclei is reduced to a much larger extent than can be accounted for by the reduction in the rate of entry of thymidine into cytoplasm. The saturation densities of both normal and tumor cells are not significantly altered by Con A. Tumor cells treated with Con A (chronically or acutely) are equally as potent as the untreated cells in yielding solid tumors when the host animals are injected with these cell subcutaneously. In conclusion, it is suggested that while Con A does not revert or destroy this particular line of tumor cells, this lectin has some interesting selective effects on the morphology and transport properties of tumor cells.