Role of protein kinase C isoforms in locomotion of Walker 256 carcinosarcoma cells

✍ Scribed by Andreas Wicki; Verena Niggli

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: French
• Weight: 102 KB
• Volume: 81
• Category: Article
• ISSN: 0020-7136
• DOI: 10.1002/(sici)1097-0215(19990412)81:2<255::aid-ijc15>3.0.co;2-d

✦ Synopsis

Treatment with low (nanomolar) concentrations of phorbol-12-myristate-13-acetate (PMA) for 5 to 30 min suppresses locomotion of Walker 256 carcinosarcoma cells, suggesting that activation of protein kinase C (PKC) is a stop signal for tumor cell locomotion. We have compared the effects of PMA on cell shape and motility with down-regulation of specific PKC isoforms. Using specific antibodies, we show that Walker carcinosarcoma cells express PKC isoforms ␣, ␤I, ␤II, ␥, , , and . Short-term incubation with PMA induced a marked shift of isoforms ␣, ␤I, ␤II, ␥ and to the particulate fraction. Long-term incubation with PMA (0.1 M, 6 hr) resulted in significant reduction of expression of conventional PKCs ␣, ␤I, ␤II and ␥ and of the novel PKC to 10% to 26% of controls. Down-regulation of PKC ␣, ␤I and ␤II by long-term incubation with PMA was reversible after removal of PMA, whereas that of isoforms ␥ and was not. The motile properties of cells after down-regulation of PKC isoforms were investigated. Concomitant with down-regulation of PKC isoforms, long-term incubation of cells with PMA resulted in recovery of the polar shape and the ability to migrate. Motility and polarized shape of the down-regulated cells were no longer susceptible to short-term treatment with PMA, showing that active PKC is indeed responsible for the inhibitory effects of PMA. Effects of long-term incubation with PMA on cell shape and motility were reversible. Our findings strongly suggest that PKCs ␣, ␤I and ␤II activated by PMA are involved in stopping Walker carcinosarcoma cell locomotion.