84 COMBINATION THERAPY WITH 17-ALLYLAMINO-17-DEMETHOXYGELDANAMYCIN AND RITONAVIR INHIBITS EXPRESSION OF HEAT SHOCK FACTOR 1 IN RENAL CANCER CELLS

Abstract

You have accessJournal of UrologyKidney Cancer: Basic Research I1 Apr 201084 COMBINATION THERAPY WITH 17-ALLYLAMINO-17-DEMETHOXYGELDANAMYCIN AND RITONAVIR INHIBITS EXPRESSION OF HEAT SHOCK FACTOR 1 IN RENAL CANCER CELLS Akinori Sato, Takako Asano, Junichi Asakuma, Keiichi Ito, Akio Horiguchi, Makoto Sumitomo, and Tomohiko Asano Akinori SatoAkinori Sato More articles by this author , Takako AsanoTakako Asano More articles by this author , Junichi AsakumaJunichi Asakuma More articles by this author , Keiichi ItoKeiichi Ito More articles by this author , Akio HoriguchiAkio Horiguchi More articles by this author , Makoto SumitomoMakoto Sumitomo More articles by this author , and Tomohiko AsanoTomohiko Asano More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.132AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Phase II clinical trials have shown 17-allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of heat shock protein (HSP) 90, to be only a moderately effective anticancer agent because it generally increases the expression of HSPs. In the present study we combined 17-AAG with the protease inhibitor ritonavir and found that this combination therapy increases the effectiveness of 17-AAG against renal cancer cells by decreasing the expression of heat shock factor (HSF)-1, a transcription factor of HSPs. METHODS Renal cancer cells (769P, A498, ACHN, Caki-1) and renal proximal tubule epithelial cells (RPTEC) were treated with 17-AAG (0-1 μM) alone and in combination with ritonavir (0-50 μM). Cell viability and clonogenicity were assessed by MTS assay and colony formation assay, changes in cell cycle were evaluated by flow cytometry, and the expression of HSPs 27, 70, and 90; HSF-1; phosphorylated retinoblastoma protein (Rb); cyclin D1; cyclin-dependent kinase 4 (CDK4); histone deacetylases (HDACs) 1, 2, 3, and 6; acetylated histone; X-linked inhibitor of apoptosis (XIAP); and survivin was assessed by Western blot analysis. Apoptosis was assayed using flow cytometry and detecting active caspase 3 and cleaved poly(ADP-ribose) polymerase (PARP). RESULTS Combinations of 17-AAG and ritonavir inhibited the proliferation of renal cancer cells synergistically in a time- and dose-dependent manner and suppressed colony formation. They increased the sub-G1 fraction to as much as 64.2%, decreased the expression of survivin and XIAP, and increased active caspase 3 and cleaved PARP, thus leading to apoptosis. They inhibited the proliferation of RPTEC less than that of renal cancer cells and caused only small changes in the cell cycle of RPTEC. The combination caused Rb dephosphorylation and suppressed the expression of CDK4; cyclin D1; and HDACs 1, 2, and 6 in all the cancer cell lines and also induced histone acetylation in Caki-1 cells. Expression of HSPs 27, 70, and 90 was increased by 17-AAG alone but reduced by 17-AAG combined with ritonavir. Interestingly, the combination therapy decreased the expression of HSF-1, which may be one of the mechanisms of the combined effect. CONCLUSIONS Combination therapy with 17-AAG and ritonavir might be effective for treating renal cancer because ritonavir decreases the expression of HSF-1 and thereby suppresses the 17-AAG-induced increase of HSPs. Tokorozawa, Japan© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e35 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Akinori Sato More articles by this author Takako Asano More articles by this author Junichi Asakuma More articles by this author Keiichi Ito More articles by this author Akio Horiguchi More articles by this author Makoto Sumitomo More articles by this author Tomohiko Asano More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...