1185 SENESCENCE AS CYTOSTATIC THERAPY: DRUG-INDUCED SENESCENCE IN PROSTATE CANCER CELLS REQUIRES SKP2-REGULATED P27KIP1 EXPRESSION

Abstract

You have accessJournal of UrologyProstate Cancer: Basic Research VI1 Apr 20101185 SENESCENCE AS CYTOSTATIC THERAPY: DRUG-INDUCED SENESCENCE IN PROSTATE CANCER CELLS REQUIRES SKP2-REGULATED P27KIP1 EXPRESSION Jonathan Ewald, Josh Desotelle, F. Michael Hoffman, and David Jarrard Jonathan EwaldJonathan Ewald More articles by this author , Josh DesotelleJosh Desotelle More articles by this author , F. Michael HoffmanF. Michael Hoffman More articles by this author , and David JarrardDavid Jarrard More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.686AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Traditional approaches to cancer treatment have relied on cytotoxic strategies. In contrast, cellular senescence is a terminal cytostatic phenotype induced in normal and transformed cells by stress. Drug-induced senescence in cancer may provide an effective therapeutic alternative to cytotoxic treatments by reducing toxicity and immune stimulation. The development of senescence for therapy has been hindered by a lack of compounds that efficiently induce this response in cancer as well as defined molecular pathways. METHODS We utilized a novel high-throughput whole cell assay to screen for agents from a 4600 compound library that induce senescence based on growth arrest, senescence-associated β-galactosidase(SA-β-gal) staining, and morphology(JBS 30;2009). We then examined AZQ-induced senescence in prostate cancer cell lines in vitro and DU145 xenograft tumors in vivo, monitoring cell/tumor growth, viability, and senescence. The role of cyclin-dependent kinase inhibitors (CDKI) inhibitors was tested in senescence. RESULTS The quinone diazequone(AZQ) was selected as a lead compound for its ability to induce senescence at low concentrations. In multiple prostate cancer cell lines, AZQ induced a terminal growth arrest, SA-β-gal and other senescence markers (Glb2, Cspg2 and BRAK). In all cell lines a consistent accumulation of the CDKI p27kip1 was identified with AZQ-induced senescence. The induction of p27kip1 resulted from decreased ubiquitylation mediated primarily by decreased Skp2, a ubiquitin ligase. Skp2 loss of expression was found after exposure to AZQ and other senescence-inducing compounds including doxorubicin and 5-azacytidine. Knockdown of Skp2 by siRNA in DU145 and PC3 cells increased p27Kip1 expression and decreased proliferation after 72 hours, while enforced expression of Skp2 disrupts the growth-inhibitory effects of AZQ. AZQ was found to be a potent inducer of senescence in prostate cancer xenografts and generated improved survival compared to controls(14 vs 8wk; p<0.5) with minimal side effects. CONCLUSIONS A novel high-throughput screen has generated a potent lead compound for further development. AZQ is a novel agent that induces senescence growth arrest in prostate cancer cells both in vitro and in xenograft tumors. Moreover, Skp2-regulated expression of p27Kip1 is a novel pathway regulating chemically-induced senescence in cancer. Madison, WI© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e459 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Jonathan Ewald More articles by this author Josh Desotelle More articles by this author F. Michael Hoffman More articles by this author David Jarrard More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...