In vitro: |
Nat Med, 1999, 5(2), 221-225. | An essential part for Rho-associated kinase in the transcellular invasion of tumor cells.[Pubmed: 9930872] | Adhesion of tumor cells to host cell layers and subsequent transcellular migration are pivotal steps in cancer invasion and metastasis. The small GTPase Rho controls cell adhesion and motility through reorganization of the actin cytoskeleton and regulation of actomyosin contractility.
METHODS AND RESULTS:
Cultured rat MM1 hepatoma cells migrate through a mesothelial cell monolayer in vitro in a serum-dependent, Rho-mediated manners. Among several proteins isolated as putative target molecules of Rho, the ROCK (ROK) family of Rho-associated serine-threonine protein kinases are thought to participate in the induction of focal adhesions and stress fibers in cultured cells, and to mediate calcium sensitization of smooth muscle contraction by enhancing phosphorylation of the regulatory light chain of myosin. Transfection of MM1 cells with cDNA encoding a dominant active mutant of ROCK conferred invasive activity independently of serum and Rho. In contrast, expression of a dominant negative, kinase-defective ROCK mutant substantially attenuated the invasive phenotype. A specific ROCK inhibitor (Y-27632) blocked both Rho-mediated activation of actomyosin and invasive activity of these cells. Furthermore, continuous delivery of this inhibitor using osmotic pumps considerably reduced the dissemination of MM1 cells implanted into the peritoneal cavity of syngeneic rats.
CONCLUSIONS:
These results indicate that ROCK plays an essential part in tumor cell invasion, and demonstrate its potential as a therapeutic target for the prevention of cancer invasion and metastasis. | Neuron, 2000 May;26(2):431-41. | A critical role for a Rho-associated kinase, p160ROCK, in determining axon outgrowth in mammalian CNS neurons.[Pubmed: 9930872] | METHODS AND RESULTS: We tested the contribution of the small GTPase Rho and its downstream target p160ROCK during the early stages of axon formation in cultured cerebellar granule neurons. p160ROCK inhibition, presumably by reducing the stability of the cortical actin network, triggered immediate outgrowth of membrane ruffles and filopodia, followed by the generation of initial growth cone-ike membrane domains from which axonal processes arose. Furthermore, a potentiation in both the size and the motility of growth cones was evident, though the overall axon elongation rate remained stable. Conversely, overexpression of dominant active forms of Rho or ROCK was suggested to prevent initiation of axon outgrowth.
CONCLUSIONS:
Taken together, our data indicate a novel role for the Rho/ROCK pathway as a gate critical for the initiation of axon outgrowth and the control of growth cone dynamics. |
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