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β-catenin signalling is a potential therapeutic target for castrate-resistant prostate cancer
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Wnt/β-catenin signalling is a potential therapeutic target for castrate-resistant prostate cancer Eur Urol Suppl 2014;13;e3
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Kawano Y. 1 , Maeda Y. 1 , Takanobu M. 1 , Imamura T.2 , Takahashi W.1 , Wada Y. 1 , Kypta R.3 , Eto M. 1 1 Kumamoto
University Faculty of Life Sciences, Dept. of Urology, Kumamoto, Japan, 2 Kumamoto University Faculty of Life Sciences, Dept.
of Molecular Pathology, Kumamoto, Japan, 3 CIC BioGUNE, Cell Biology and Stem Cells Unit, Derio, Spain INTRODUCTION & OBJECTIVES: Wnt/β-catenin pathway is aberrantly activated in more than 30% of castration-resistant prostate cancer (CRPC), therefore targeting this pathway may be effective therapeutic option for substantial fraction of CRPC patients. We aimed to elucidate the effect of inhibiting Wnt/β-catenin pathway on prostate cancer cell growth and sensitising docetaxel-induced cytotoxicity in CRPC cells. MATERIAL & METHODS: LNCaP cells stably expressing β-catenin shRNA in a doxycycline-inducible manner (LNCaP/TR-βi) were established by sequential stable transfection with the tetracycline repressor gene (tetR) and β-catenin shRNA under the control of the tetracycline operator sequence directly upstream of the H1 promotor. Proliferation in vitro was assessed by crystal violet staining, cell counting, or WST-1 assay. For animal study, male BALB/c strain nude mice were injected subcutaneously with LNCaP/TR-βi cells, followed by doxycycline (dox) administration in drinking water for β-catenin shRNA induction. IWR-1 endo and CCT036477 were used to analyse the effect of chemical inhibition of Wnt/β-catenin signalling. RESULTS:
β-catenin shRNA induction by dox treatment markedly reduced LNCaP/TR-βi cell growth in vitro. LNCaP/TR-βi cells exhibited unexpected castration-resistant growth after transplantation into nude mice. However, β-catenin knockdown by dox administration significantly suppressed such in vivo growth as well. Such inhibitory effect of β-catenin knockdown against cellular proliferation was also observed in CRPC cell lines, such as DU145 and PC-3 cells, by siRNA transfection. These results suggest that Wnt/β-catenin plays a crucial role in proliferation of prostate cancer cells regardless of their androgen-dependence. Wnt/β-catenin inhibitors, IWR-1 endo and CCT036477, effectively phenocopied the depletion of β-catenin in prostate cancer cell, and augmented the cytotoxic effect of low-dose docetaxel in CRPC cells. Intriguingly, cell cycle analysis revealed that IWR-1 endo alone enriched G1 population but rather triggered mitotic catastrophe effectively in combination with low-dose docetaxel. CONCLUSIONS: This study provides proof of concept that a) inhibiting β-catenin, by either knockdown or chemical inhibitors, suppresses prostate cancer cell growth, and b) targeting Wnt/β-catenin signalling pathway is a valid therapeutic strategy for CRPC.
Wnt/β-catenin signalling is a potential therapeutic target for castrate-resistant prostate cancer Eur Urol Suppl 2014;13;e3
Print! Print!
Kawano Y. 1 , Maeda Y. 1 , Takanobu M. 1 , Imamura T.2 , Takahashi W.1 , Wada Y. 1 , Kypta R.3 , Eto M. 1 1 Kumamoto
University Faculty of Life Sciences, Dept. of Urology, Kumamoto, Japan, 2 Kumamoto University Faculty of Life Sciences, Dept.
of Molecular Pathology, Kumamoto, Japan, 3 CIC BioGUNE, Cell Biology and Stem Cells Unit, Derio, Spain INTRODUCTION & OBJECTIVES: Wnt/β-catenin pathway is aberrantly activated in more than 30% of castration-resistant prostate cancer (CRPC), therefore targeting this pathway may be effective therapeutic option for substantial fraction of CRPC patients. We aimed to elucidate the effect of inhibiting Wnt/β-catenin pathway on prostate cancer cell growth and sensitising docetaxel-induced cytotoxicity in CRPC cells. MATERIAL & METHODS: LNCaP cells stably expressing β-catenin shRNA in a doxycycline-inducible manner (LNCaP/TR-βi) were established by sequential stable transfection with the tetracycline repressor gene (tetR) and β-catenin shRNA under the control of the tetracycline operator sequence directly upstream of the H1 promotor. Proliferation in vitro was assessed by crystal violet staining, cell counting, or WST-1 assay. For animal study, male BALB/c strain nude mice were injected subcutaneously with LNCaP/TR-βi cells, followed by doxycycline (dox) administration in drinking water for β-catenin shRNA induction. IWR-1 endo and CCT036477 were used to analyse the effect of chemical inhibition of Wnt/β-catenin signalling. RESULTS:
β-catenin shRNA induction by dox treatment markedly reduced LNCaP/TR-βi cell growth in vitro. LNCaP/TR-βi cells exhibited unexpected castration-resistant growth after transplantation into nude mice. However, β-catenin knockdown by dox administration significantly suppressed such in vivo growth as well. Such inhibitory effect of β-catenin knockdown against cellular proliferation was also observed in CRPC cell lines, such as DU145 and PC-3 cells, by siRNA transfection. These results suggest that Wnt/β-catenin plays a crucial role in proliferation of prostate cancer cells regardless of their androgen-dependence. Wnt/β-catenin inhibitors, IWR-1 endo and CCT036477, effectively phenocopied the depletion of β-catenin in prostate cancer cell, and augmented the cytotoxic effect of low-dose docetaxel in CRPC cells. Intriguingly, cell cycle analysis revealed that IWR-1 endo alone enriched G1 population but rather triggered mitotic catastrophe effectively in combination with low-dose docetaxel. CONCLUSIONS: This study provides proof of concept that a) inhibiting β-catenin, by either knockdown or chemical inhibitors, suppresses prostate cancer cell growth, and b) targeting Wnt/β-catenin signalling pathway is a valid therapeutic strategy for CRPC.