The suppressive effect of Rho kinase inhibitor, Y-27632, on oncogenic Ras/RhoA induced invasion/migration of human bladder cancer TSGH cells

Urothelial cell carcinoma is the most common type of malignancy found in long-term dialysis patients and kidney transplant recipients in Taiwan. Surgical specimens of tumorous and non-tumorous bladder tissues were collected from 12 patients with bladder cancer. Increased expressions of Ras, RhoA, Akt, PI-3K were demonstrated in the tumors as compared to adjacent control tissues. To understand the impact of Ras over-expression on bladder cancer progression, human bladder cancer TSGH 8301 cells were transfected with Ras DNA. The Ras-transfected cells were then treated with either a PI-3K inhibitor (wortmannin) or Rho kinase inhibitor (Y-27632) and the expressions of Ras, PI-3K, Akt, NF-κB, and RhoA were analyzed. Fluorescent phalloidin staining demonstrated more intense F-actin staining in the Ras over-expressed cells than in the control cells, and the intensity of F-actin was inhibited by Y-27632. A gelatin zymography study demonstrated that the MMP-2 and MMP-9 expressions of the Ras-transfected cells were enhanced, and Y-27632 treatment reduced the levels of MMP-2 and MMP-9. Similarly, a wound healing assay revealed that the ability of cell migration was markedly increased by Ras transfection and the healing rate after treatment of Y-27632 was delayed. Our results provide evidence that Ras-induced RhoA and NF-κB activation was involved in the invasion/migration of bladder cancer. Through Ras and/or RhoA inhibition, there might be an opportunity for new therapeutic interventions in bladder cancer.