Growth factor- and phorbol ester-induced changes in cell morphology analyzed by digital image processing

Abstract

We have developed the computer-aided image processing analysis to visualize and quantitate the cell motility and morphological changes in living cultured cells. The effect of growth factors on cell motility and morphology has been analyzed by this method. Insulin, insulin-like growth factor-I (IGF-I), and epidermal growth factor (EGF) elicited membrane rufflings in rat embryo fibroblast 3Y1 cells as well as in human epidermoid carcinoma KB cells. Insulin and IGF-I also induced ruffling membranes in Balb/c-3T3 cells. The quantitative analysis by the programmed trace mode of the AVEC system has shown that the motion of the membrane rufflings was observed within 2 min, reached the maximum level within 4–8 min, and rapidly decreased within 10–15 min after the addition of these growth factors. The analysis also revealed the temperature- and growth factor concentration-dependent changes in the motion of membrane rufflings elicited by these growth factors. 12- O-Tetradecanoylphorbol-13-acetate, one of the well-known tumor promoters, rapidly induced cell rounding in Balb/c-3T3 cells. This change of cell morphology could be also quantified by the trace mode analysis. The fluorescent phalloidin staining experiment indicated that these growth factor- or phorbol ester-induced morphological changes were accompanied by the reorganization of filamentous actin. Furthermore, we were able to visualize actin stress fibers in living EBTr cells by enhancing the video image and to follow the reduction of stress fibers induced by cytochalasin B without any fixation or fluorescent probes.