Protein kinase C isoforms involved in regulation of cell shape and locomotion of human fibrosarcoma HT1080 cells

The role of protein kinase C (PKC) isoforms in the regulation of cell shape [switch between fibroblast-like and crescent shape (CS)] and of locomotion of human fibrosarcoma HT1080 cells has been investigated. The PKC activato r phorbol myristate acetate (PMA) induced the transition of elongated fibro blast-like cells into CS cells and stimulated locomotion. Both responses to PMA were inhibited by the PKC inhibitor Ro 31-8220. Analysis of the time c ourse showed that stimulation of shape changes (formation of CS cells) and locomotor activity (increase in the proportion and speed of locomoting cell s) was maximal in the early phase of the response (up to 2.5 hr) and signif icantly decreased later (15 to 21 hr). CS formation and stimulated locomoti on correlated closely with a marked redistribution from the cytosol to the membrane of PKC isoforms alpha, beta 1 and gamma in the early phase (0.5 to 2 hr) following activation with PMA. The subsequent reduction of the propo rtion of CS cells and of cell locomotion correlated with down-regulation of these isoforms in the second phase (16 to 21 hr). In contrast, the total a mount and distribution of PKC beta 2 remained almost unchanged with 10(-8) M PMA up to 21 hr. Furthermore, changes in shape and locomotion did not cor relate with the responses of PKC delta to PMA. Inhibition of PMA-stimulated locomotion by the more specific inhibitor Go 6976 is consistent with a rol e of PKC alpha and beta 1 in this response. Ro 31-8220 alone induced a mode rate down-regulation of PKC isoforms alpha and delta, but it also inhibited the more pronounced down-regulation of these isoforms by PMA. Our results indicate that activation of PKC isoforms alpha, gamma and beta 1, but not b eta 2 or delta, stimulates locomotion and formation of CS cells in human fi brosarcoma HT1080 cells. Int. J, Cancer 88:195-203, 2000. (C) 2000 Wiley-Li ss, Inc.