Endocrine Abstracts

The ability of local invasion and distant metastasis indicates malignancy. Focal adhesion complex plays an important role during cell invasion. This complex consists of integrins, focal adhesion kinase (FAK), vinculin, talin, α-actinin and paxillin. Activation of FAK regulates the assembly of focal adhesion and stress fiber formation via GTPase Rho and Rac, which is responsible for the migratory behavior of cells. In this study, we demonstrated the inhibitory effect of rottlerin on cell migration of an invasive follicular thyroid carcinoma CGTH W-2 cells via focal adhesion disassembly. Rottlerin treatment resulted in a two-fold decrease in the migratory activity of CGTH W-2 cells as estimated by both Transwell assay and wound healing assay. The protein expression levels of integrinβ1, active FAK, and active paxillin were decreased after rottlerin treatment. Consistent with these biochemical findings, disassembly of focal adhesions revealed by immunostaining for FAK, vinculin, and paxillin were noted. The disruption of actin stress fibers was seen, and was consistent with the reduced GTPase activities of Rac-1 and RhoA. This rottlerin-inhibited cell migration might not be attributed to the inhibition of PKCδ activity, since the inhibitory effect of rottlerin on cell migration could not be rescued by phorbol myristate acetate, which induced PKCδ activation and promoted the migration potential of CGTH W-2 cells. In summary, we demonstrated that rottlerin inhibits the migratory ability of CGTH W-2 by disassembly of focal adhesion complexes in a PKC δ-independent manner.