PKC MEDIATES 12(S)-HETE-INDUCED CYTOSKELETAL REARRANGEMENT IN B16A MELANOMA-CELLS

The fatty acid 12(S)-HETE may be a new second messenger capable of act ivating PKC. In tumor cells 12(S)-HETE stimulates cytoskeleton-depende nt cellular responses such as adhesion and spreading. Analysis of 12(S )-HETE effects on B16a melanoma cell cytoskeleton revealed reversible rearrangement of microtubules, microfilaments, the actin-binding prote ins, vinculin, myosin heavy (MHC) and light chains (MLC), as well as b undling of vimentin intermediate filaments. The alterations in microfi laments and intermediate filaments occurred very rapidly, i.e., 5 min after exposure of tumor cells to 12(S)-HETE. The 12(S)-HETE-induced cy toskeletal alterations were accompanied by centrifugal organelle-trans location. Interestingly, MLC exhibited clear association with the- cyt oplasmic organelles. Biochemical analysis of the 12(S)-HETE effect ind icated a PKC-mediated reversible hyperphosphorylation of MLC, vimentin , and a 130 kD cytoskeletal-associated protein. Optimal effects were o btained after 5 min treatment with 12(S)-HETE at 0.1 muM concentration . 12(S)-HETE pretreatment induced tumor cell spreading on a fibronecti n matrix which required the intactness of all three major cytoskeletal components. The spreading process was dependent upon the activity of PKC. Our data suggest that 12(S)-HETE is a physiological stimulant of PKC. Further, it induces rearrangement of the cytoskeleton of tumor ce lls in interphase resulting in the stimulation of cytoskeleton-depende nt cell activity such as spreading. (C) 1993 Wiley-Liss, Inc.