Y-27632, an inhibitor of Rho-associated protein kinase, suppresses tumor cell invasion via regulation of focal adhesion and focal adhesion kinase

Migration of rat ascites hepatoma (MM1) cells, invasion and phagokinetic mo vement were induced by the combination of lysophosphatidic acid (LPA) and f ibronectin (FN), Induction of migratory activity was tightly correlated wit h morphological change of MML cells from spherical or polygonal-shaped cell s to fusiform-shaped ones with pseudopodia, MM1 cells were mobile in a fusi form shape, whereas those of a spherical or polygonal shape were not. A sma ll GTPase Rho and one of its downstream effectors ROCK (Rho-associated coil ed-coil forming protein kinase), play essential roles in these processes, a s evidenced by suppression of migration and morphological change of MM1 cel ls by Clostridium botulinum C3 exoenzyme, an inhibitor of Rho, or by Y-2763 2, an inhibitor of ROCK, Y-27632 also suppressed the formation of fusiform- shaped pseudopodia-carrying MM1 cells that was induced by stimulation with the combination of LPA and PN, LPA and FN also evoked the formation of foca l adhesions and actin bundles, and tyrosine phosphorylation of focal adhesi on kinase (FAK) and paxillin, The inhibitory effect of Y-27632 on LPA-induc ed migration and morphological change of MM1 cells was considered to be med iated, at least in part, by impaired formation of focal adhesions and actin bundles. Y-27632 suppressed LPA-induced tyrosine phosphorylation of FAK an d paxillin, suggesting that ROCK regulates these molecules and Y-27632 inhi bits cellular migration and morphological change, at least in part, through this regulation.