MP39-18 SEQUENTIAL INHIBITION OF HEAT SHOCK PROTEINS 90 AND 70 ENHANCES CYTOTOXICITY IN BLADDER CANCER CELLS

Abstract

You have accessJournal of UrologyBladder Cancer: Basic Research IV1 Apr 2014MP39-18 SEQUENTIAL INHIBITION OF HEAT SHOCK PROTEINS 90 AND 70 ENHANCES CYTOTOXICITY IN BLADDER CANCER CELLS Alice H. Cavanaugh, John F. Danella, and Heinric Williams Alice H. CavanaughAlice H. Cavanaugh More articles by this author , John F. DanellaJohn F. Danella More articles by this author , and Heinric WilliamsHeinric Williams More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.1333AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The overexpression of heat shock proteins (HSP) has been reported in numerous cancers. The inhibition of HSPs is associated with the degradation of known oncogenic proteins shown to be active in bladder cancer, suggesting that HSP inhibition may have a significant contribution to the treatment of bladder cancer. We tested the effect of second generation HSP90 inhibitors on the proliferation, apoptosis and oncogenic signaling pathways in 3 human bladder cancer cell lines. We also tested the ability of the sequential inhibition of HSP90 and 70 to inhibit cell proliferation. METHODS Human bladder cancer cell lines, T-24, TCCSUP and UMUC3 were treated for 4 to 96H with 17-AAG (first generation HSP90 inhibitor) as well as STA9090 and AUY922 (second generation inhibitors). Cells were also treated with the HSP70 inhibitor VER 155008 alone and in combination with a HSP90 inhibitor. Cell proliferation rates were determined by MTT assays, while the expression of HSPs, apoptotic and cell signaling markers were determined by Western analysis. RESULTS UMUC3 cells showed the most sensitivity of all cell lines. Fifty percent growth inhibition occurred within 48H of treatment using 10 nM of the second generation inhibitors. This same degree of inhibition required 10-fold higher concentrations of 17-AAG. STA9090 exhibited the highest efficacy showing 80% growth inhibition at 100 nM for all the cell lines tested. All cell lines showed a 5-10 fold increase in the expression of HSP70 within 24 H of treatment with HSP90 inhibitors. In addition there was also a 50% increase in the expression of HSP40, 60 and 110. Since the overexpression of other HSPs may compensate for the inhibition of HSP90, we sequentially inhibited the expression of HSP90 with STA9090, and HSP70 with VER 155008, and determined the effects on cell proliferation. The combination of drugs showed a synergistic inhibition of growth with 78% inhibition at 24H compared to 68% inhibition with VER155008 alone, or 43% inhibition with STA9090 alone. HSP90 inhibition induced apoptosis as demonstrated by increased expression of cleaved caspase 3 and downregulation of mediators of several oncogenic signaling pathways including EGFR, ErbB2, cyclin D1, pAKT, pSTAT3/5, pS6, p4EBP1 in the cell lines tested. CONCLUSIONS HSP inhibitors as monotherapy have shown promising preclinical efficacy but this has not been replicated in clinical trials. Data from this study suggests that combination HSP90/70 inhibition is superior to either alone in a bladder cancer cytotoxicity model and the significance of this in the clinical setting remains to be seen. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e432-e433 Peer Review Report Advertisement Copyright & Permissions© 2014MetricsAuthor Information Alice H. Cavanaugh More articles by this author John F. Danella More articles by this author Heinric Williams More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...