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Introduction: RhoGDIs over expressioned lead to disruption of the actin cytoskeleton and inhibition of motility. Studies in cell lines suggest a correlation between decreased loss of expression of cell adhesion molecules and increased metastatic capabilitys. In particular, RhoGDIb mRNA expression is only observed in T24 bladder cancer cells compared with a more aggressive metastatic lineage T24T cells. The aim of present study was to analyze the protein expression of RhoGDIb in human bladder cancer and to correlate these findings with. We also examined RhoGDIb responses to different cancer therapies. Materials and Methods: The study comprised 61 of primary bladder cancer and metastasis from cystectomy and. 10 additionalmore specimens were from transurethral resection of bladder tumor (TURBT). TNM classification was done according to UICC standards. Immunohistochemical staining was performed with a monoclonal antibodyies against RhoGDIb ( BioSource, USA). The percentage of cell staining was scored as 0-∼15 per cent, 15-∼30 per cent, 30-∼60 per cent or over > 60 per cent cell staining. The staining intensity of tumor cells was scored according to four groupsas: negative (0), weak (+), moderate (++) and strong (+++). Level of RhoGDIb protein expression in human bladder cell lines 5637, TCC-sup, RT4, and T24 was determined by Western Blot., We determined the effect on RhoGDIb and E-cadherin expression by Western blot in TCC-sup cells and after exposure to the HDAC inhibitor FK228. effects on RhoGDIb in TCC-sup cells were tested. Changes in RhoGDIb expression responses in response to therapies with Raeloxifene or Raloxifene plus chemotherapy, Ad5/F35tk virus plus ganciclovir in combinatione with radiation therapy were detected assessed by IHC staining in xenografts specimens from nude mice implanted with human bladder cancer cells. Results: Strong RhoGDIb cytoplasmic staining was found within normal and hyperplasia bladder epithelium and, carcinoma in situ. Staining was primarily localized in cytoplasm. RhoGDIb immunoreactivity more than 30% with (++) to (+++) in 89% ofin Ta, 87% in of T1, 56% in of T2 and T3, 100% in of G1, 86% in of G2 and 43% in of G3 tumors. In metastasis, however, only 15% of tumor exhibited the staining moderately (++) or strongly (+++) positive staining in more than 30% cancer cells. The expression level of RhoGDIb wasis low in poorly differentiation differentiated cell lines (TCC-sup, T24) than incompared to the well differentiation cell line (RT4). Expression was intensive across T stage and G grades in the 10 TURBT specimens. RhoGDIb was down regulated by FK228 and E-cadherin was upregulated in dosees response fashion but there was no effect on expression with the Raloxifene or gene therapy treatments. Conclusion: Loss of RhoGDIb expression correlatesd with aggressive and metastatic phenotype in human bladder cancer suggesting its use as a prognostic marker and a potential target for therapy.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]