Expression Of RhoB In Clear Cell Renal Cell Carcinoma And Its Clinical Signiifcance And Its Influence On Renal Tumor Cell Proliferation, Cell Cycle And Apoptosis

Objective: Rho family(RhoA, RhoB,RhoC)belongs to the member of small G proteinfamily, is a set of relative molecular weight of about20-25kD GTP binding protein,plays an important role in signal transduction pathways, and affects the development oftumor. RhoB is a unique molecule in the family, although they share highly homologouswith RhoA and RhoC, its expression and function in different tissues and cells aredifferent. The present studies show RhoB acts as a suppressor gene in cancer. Renal cellcarcinoma is one of the most common tumors in the urinary carcinoma, mainlyoriginated from proximal tubule cells, and clear cell renal cell carcinoma (ccRCC)accounting for60%-80%of these tumors. Surgical resection is the mainly treatment forlocalized ccRCC. And ccRCC is both radiotherapy and conventional chemotherapyresistant. Thus, we hope to study the expression of RhoB in ccRCC and its biologicalfunctions in ccRCC, to explore a new avenue of cancer treatment.Methods:(1) RhoB expression in16pairs ccRCC tissues and matched adjacentnon-tumorous samples and3human ccRCC cell lines（786-O，769-P，Caki-1）andHuman renal proximal tubular epithelial cell line(HKC) were examined by western blot.We further examined10pairs ccRCC tissues and matched adjacent non-tumoroussamples and80ccRCC samples using immunohistochemistry method, and thecorrelation between RhoB expression and clinicopathological parameters of ccRCCpatients were analyzed.(2) A recombinant plasmid expression RhoB(pcDNA3.0-Flag-RhoB) was constructed, and transfected into786-O and Caki-1cells.We next investigated the biological efforts of RhoB in ccRCC cells proliferation, cellcycle, apotosis using MTS,colony formation assay and flow cytometry methods.Result:(1) The RhoB expression was decreased dramatically both in ccRCC tissues andrenal cancer cells, compared to their matched non-tumorous tissues and Human renal proximal tubular epithelial cell line (HKC)(P＜0.001). The immunohistochemistry datashowed that decreased RhoB expression was correlated with tumours T stage (P＜0.001), TNM stage (P=0.006). However, there was no significant correlation betweenRhoB expression and patients’ age and gender（P＞0.05.(2) Over-expression of RhoBremarkably inhibited cell proliferation, induced cell apotosis and cell cycle arrest inG2/M phase in786-O and Caki-1cells.Conclusion: The expression of RhoB was decreased dramatically both in ccRCCtissues and renal cancer cells, and its low expression level is negatively related to themalignance of ccRCC. Over-expression of RhoB remarkably inhibited renal tumor cellproliferation, induced cell apotosis and cell cycle arrest in G2/M phase. RhoB playsan suppressor gene role in ccRCC malignant, and which may provide a new thought formolecular targeted therapy of ccRCC.