BACKGROUND

Glioblastoma multiforme (GBM) remains the most aggressive and frequently occurring brain neoplasm. Members of the Rho family of small GTP-binding proteins, including Rho, Rac, and Cdc42, have been shown to participate in cell growth differentiation and motility. The mitogen-activated protein kinase (MAPK) pathway, which includes extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), has been shown to regulate cell growth, differentiation and motility. Here, the involvement of the Rho and Rho-associated protein kinase (ROCK) pathway, along with MAPK, was investigated to determine their roles in GBM cell migration and proliferation.

METHODS

In vitro studies utilized the human malignant glioblastoma cell line LN-18. The cells were treated with Y-27632, a ROCK inhibitor, and U0126, an upstream MAPK kinase inhibitor (MEK), alone or in combination with one another. Immunoblotting analysis established the levels of phosphorylated ERK1/2. Cell migration was determined by radial migration assay and cell proliferation by MTT.

RESULTS

Y-27632 reduced phosphorylation of ERK1/2 at 0.5 and 2 h. U0126 in combination with Y-27632 led to a more pronounced repression of platelet-derived growth factor (PDGF)- or fibronectin (FN)-induced ERK1/2 activation than U0126 treatment alone. Y-27632 treatment for 24 h suppressed GBM cell migration and resulted in a reduction in LN-18 cell proliferation. Furthermore, PDGF and FN-induced cell proliferation was suppressed by pre-treatment with Y-27632 or U0126, with the greatest reduction achieved by a combination of the two inhibitors.

CONCLUSIONS

Rho/ROCK signaling is involved in GBM cell migration and proliferation, and this pathway may be linked to ERK signaling.