Abstract
Purpose: :
Uveal melanoma is the most common primary intraocular tumor in adults with a high rate of mortality due to metastasis. Rho-kinase is an intracellular signalling cascade effector, which is activated in a wide variety of tumor types. In this study, we evaluated the outcomes of Rho-kinase inhibition on the viability, proliferation and migration of the uveal melanoma cell line 92.1 as well as the expression of several metastatic proteins.
Methods: :
The 92.1 cells were cultured in DMEM/F-12 supplemented with 10% serum and treated with the specific pharmacological Rho-kinase inhibitor H1152 at a concentration range of 0.1-10 µM. Viability and proliferation were assessed by Live-Dead staining, MTT assay, and Ki-67 immunostaining. The organization of the actin cytoskeleton was evaluated by phalloidin staining. The extent of Rho-kinase activity was determined by an in vitro kinase assay. Migration was analyzed by the scratch assay on the confluent monolayers of cells grown in 6-well plates. The levels of beta-catenin, N-cadherin, and vimentin were determined by immunostainings on cells grown on fibronectin coated 8-well slides and by Western blot.
Results: :
H1152 resulted in a dose-dependent reduction in the Rho-kinase activity at the concentrations of 0.1 and 1 µM, whereas the administration of the inhibitor at 10 µM weakened this effect possibly due to the interference with other signalling pathways and resulted in a more aberrant, oncotic morphology together with a slight decrease in viability. H1152 at 1 µM significantly suppressed the proliferation of the 92.1 cells by 50% (p<0.05) without exerting any toxicity and interfered with the migration of the cells into the wound area after 2 days. The levels of vimentin and beta-catenin underwent a significant reduction of 20-30%, respectively, in response to 1 µM H1152 already after 1 day of incubation. Moreover, the weak immunoreactivity to N-cadherin was further reduced by 20% in the cells treated with 1 µM H1152 for 1 day.
Conclusions: :
These findings provide evidence to the involvement of Rho-kinase in the proliferation and migration of the 92.1 cells and demonstrate the efficacy of Rho-kinase inhibition in suppressing the metastatic potential of these cells as a novel alternative for the treatment of uveal melanoma.