Roles Of GTP-RhoA On Microtubule Polymerization-induced Cell Cycle Arrest In Renal Cell Carcinoma Treated With Taxol

Background:Renal cell carcinoma(RCC)is the most common neoplasm of the kidney in adults,accounting for 2%~3% of adult malignancies.Surgical resection remains the only definitive treatment for RCC.However,there is no uniform standard for postoperative adjuvant therapy.Taxol,a new type of microtubule(MT)resistant agent,can change cytoskeletal dynamics through promoting the role of MTs combination and stabilizing MTs,to inhibit tumor cell proliferation.It’s used in postoperative adjuvant therapy for advanced RCC.Reports showed that The expression of RhoA protein was up regulated in many cancer cells.RhoA is most involved in proliferation,invasion and migration of cancer cells and plays a key role.The present study firstly revealed cell cycle arresting by increasing GTP-RhoA levels via Taxol-induced MT polymerization in renal cell carcinoma.Methods: The RCC cell line OS-RC-2 was treated with 1μM Taxol and Alternatively,pretreated with 10 μM MT depolymerizing agent Colchicine(Col)or 2 μg/ml RhoA inhibitor C3 transferase.Cells were stained for MT and RhoA and examined under a confocal scanning microscope.Cell cycle was measured using a flow cytometer.The expression of RhoA and GTPRhoA protein was assayed by western blotting.Results: The present study revealed that Taxol-induced MT polymerization causes cell cycle arrest and an increase in GTP-RhoA protein expression.Disruption of Taxol-induced MT polymerization reversed GTP-RhoA expression and cell cycle arrest.The localization and redistribution of MTs and RhoA were consistent in cells with MT bundles and those without.Decreased GTP-RhoA had no marked effect on Taxol-induced MT bundling,however,it reduced the proportion of cells in G2/M phase.Conclusions: Taxol-induced MT polymerization regulated the protein expression levels of GTP-RhoA and cell cycle arrest.However,the alteration in GTP-RhoA expression did not influence MT arrangement,suggesting that GTP-RhoA serves a pivotal role in Taxol-induced MT polymerization and cell cycle arrest in RCC.Significance:The interaction among MTs,RhoA activity and cell cycle were investigated.We have got the pivotal role of GTP-RhoA in Taxol-induced MT polymerization and cell cycle arrest in RCC.In future,it may help understand the underlying mechanism of RCC tumorigenesis and enhance the curative effect of Taxol to improve patient survival.