The growth-inhibitory effects of dexamethasone on renal cell carcinoma in vivo and in vitro.

Background: Recently, several kinase inhibitors have been reported to exert stronger growth inhibitory effects on metastatic renal cell carcinomas (RCCs) than cytokines such as interferons (IFNs) and interleukin-2 (IL-2). On the contrary, the adverse effects of these drugs are also severe. The aim of this study is to analyze the growth-inhibitory effects of DEXamethasone (DEX) on RCC in vivo and in vitro.

Methods: The MTT assay was performed using three RCC cell lines, OUR-10, Caki-1, and NC65. OUR-10 cells were subcutaneously transplanted to the dorsal area of nude mice. The nuclear translocation of glucocorticoid receptor (GR) and NF-kappa B was examined using appropriate antibodies. Concentrations of interleukin-6 (IL-6), IL-8, and vascular endothelial cell growth factor (VEGF) in the conditioned media and cytosol were measured by enzyme-linked immunosorbent assay (ELISA).

Results: All three RCC cell lines responded to DEX treatment. The growth of OUR-10 xenografts was significantly inhibited by administration of DEX. GR was translocated into the nucleus on DEX treatment. Intracellular IL-6, as well as IL-6 in the conditioned medium, decreased in OUR-10 cells following treatment with increasing amounts of DEX. Concentrations of IL-8 and VEGF in the conditioned medium of OUR-10 and NC65 cells also decreased following DEX treatment, with the inhibition of nuclear translocation of NF-kappa B.

Conclusion: DEX treatment is a candidate for advanced RCC therapy by inhibiting the activation of NF-kappa B and its downstream products such as IL-6, IL-8 and VEGF.