Sesquiterpene lactone parthenolide suppresses tumor growth in a xenograft model of renal cell carcinoma by inhibiting the activation of NF‐κB

The transcription factor nuclear factor‐κB (NF‐κB) has been shown to be constitutively activated in various human malignancies, including leukemia, lymphoma and a number of solid tumors. NF‐κB regulates the transcriptional of genes important for tumor invasion, metastasis and chemoresistance. The sesquiterpene lactone parthenolide, an inhibition of NF‐κB, has been used conventionally to treat migraines and inflammation. In this study, renal cancer cell lines OUR‐10 and ACHN were used for in vitro experiments to evaluate growth‐inhibitory effects of parthenolide. An OUR‐10 xenograft model in nude mice was also used to investigate the in vivo growth‐inhibitory effects of parthenolide. Apoptosis in response to treatment of OUR‐10 cells with parthenolide was confirmed. Localization of NF‐κB in response to parthenolide treatment was examined of by immunofluorostaining of OUR‐10 cells with antibody against NF‐κB p65 and by Western blot analysis of OUR‐10 cell and tumor nuclear and cytosol fraction. Parthenolide effectively inhibited proliferation of cultured OUR‐10 cells and triggered apoptosis in vitro. Subcutaneous injection or oral administration of parthenolide showed significant tumor growth inhibition in the xenograft model via decreased production of interleukin‐8 (IL‐8) or vascular endothelial growth factor (VEGF). Immunohistochemistry and Western blot analysis showed decreased nuclear localization of NF‐κB and phosphorylated NF‐κB protein and subsequently expression of MMP‐9, Bcl‐xL and Cox‐2 in response to parthenolide treatment. These results indicate that parthenolide is a useful in the treatment of renal cell carcinoma and acts via inhibition of NF‐κB. © 2007 Wiley‐Liss, Inc.