EFFECT OF PH ON PROTEINASE SECRETION BY TRANSFORMED FIBROBLAST POPULATIONS

Effect of pH on secretion of proteolytic enzymes in cell cultures of t hree clonal lines of transformed fibroblasts (K2, T15 and K4) was stud ied by C-14-labelled denatured proteins as substrate. One using line o f malignant macrophages derived from mouse reticulum cell sarcoma (J77 4.1) was used for comparison. The relative motility index of all cell lines was derived by computer analysis of quantitative estimations of cell dispersion in single-cell-derived colonies. Cultivation at pH 6.5 decreased the growth rate in most experiments as compared with that a t pH 7.4, and stimulated cell motility to a different extent. The popu lation of mouse malignant macrophages produced several-fold higher ext racellular proteolytic activity than the fibroblast lines. Secretion o f proteinases by the malignant macrophages was significantly stimulate d by the lower pH, Enzyme secretion by two of the three fibroblast der ivatives was also stimulated by acidic pH but to a lesser extent than the secretion of the malignant macrophages. The assessment of motility done by measurement of dispersion of cells in colony proved a positiv e correlation between motility and proteinase secretion in J774.1 cell s and one transformed fibroblast clone (T15) but not in the two other clonal lines.