- Email: [email protected]
278 SECRETED FRIZZLED RELATED PROTEIN-1 IS A NEGATIVE REGULATOR OF ANDROGEN RECEPTOR SIGNALING IN PROSTATE CANCER
e112
THE JOURNAL OF UROLOGY姞
Vol. 185, No. 4S, Supplement, Sunday, May 15, 2011
Notch3 and Hey1 remained elevated in AI cells and could be reduced by Notch3 siRNA, but these cells were able to grow in androgen deprived medium regardless. CONCLUSIONS: Androgen deprivation upregulates Notch signaling mediated by Jag1 and Notch3 in parental LNCaP cells. Knockdown of Jag1 and/or Notch3 expression enabled further growth of these cells in androgen deficient medium. Our data supports the idea that Notch signaling has a tumor suppressive effect for androgenresponsive prostate cancer cells that is relieved in the AI state. Source of Funding: None
278 SECRETED FRIZZLED RELATED PROTEIN-1 IS A NEGATIVE REGULATOR OF ANDROGEN RECEPTOR SIGNALING IN PROSTATE CANCER Yoshiaki Kawano*, Soraya Diez, Pinar Uysal-Onganer, R. Siobhan Darrington, London, United Kingdom; Yoshihiro Wada, Wataru Takahashi, Masatoshi Eto, Kumamoto, Japan; Jonathan Waxman, Robert Kypta, London, United Kingdom INTRODUCTION AND OBJECTIVES: Secreted Frizzled-related protein-1 (sFRP1) associates with Wnt proteins and antagonizes Wnt/-catenin signaling. It is frequently downregulated in cancer including prostate cancer, but its function in prostate cancer is unclear. The transcriptional activity of Androgen receptor (AR) is regulated by interaction with various cofactors, which include -catenin. Therefore, we here investigated whether loss of sFRP-1 leads to increased AR transcriptional activity via activation of Wnt/-catenin signaling. METHODS: For transcription assays, all cells were transfected in triplicate in 24-well plates, and each well of the 24-well plate was transfected with 40ng pDM-Gal as an internal control, 200ng firefly luciferase gene driven by various promoter sequences and the expression plasmids as indicated. The total amount of DNA was brought to 400ng using empty pcDNA3.1. RESULTS: sFRP1 inhibited AR transcriptional activity in a dose-dependent manner. In addition, sFRP1 inhibited the proliferation of androgen-dependent LNCaP cells but not of an androgenindependent subline LNCaP-r, suggesting a role in androgen-dependent growth. The inhibition of AR by sFRP1 was unaffected by co-expression of Wnt3a or stabilised -catenin, suggesting it does not involve Wnt/-catenin signaling. Wnt5a also inhibited AR and expression of Wnt5a and sFRP1 together did not further inhibit AR, suggesting that Wnt5a and sFRP1 activate the same signal(s) to repress AR. However, sFRP1 inhibition of AR was unaffected by inhibitors of kinases involved in Wnt/Ca2⫹ and Wnt/planar cell polarity signaling. Interestingly, the cysteine-rich domain of sFRP1 interacted with Frizzled receptors expressed in prostate cancer cells, suggesting that sFRP1/Frizzled complexes activate a signal that leads to inhibition of AR signaling. CONCLUSIONS: These results highlight the function of -catenin-independent Wnt signalling in the control of AR activity and provide one explanation for sFRP1 downregulation in prostate cancer.
Source of Funding: The Joron Charitable Trust (YK, JW) and the Prostate Cancer Charity UK (RK). RK was also supported by the Department of Industry, Tourism and Trade of the Government of the Autonomous Community of the Basque Country (Etortek Research Programs 2005/2006), the Innovation Technology Department of Bizkaia County and the Ministry of Education and Science (SAF 2005-06122).
THE JOURNAL OF UROLOGY姞
Vol. 185, No. 4S, Supplement, Sunday, May 15, 2011
Notch3 and Hey1 remained elevated in AI cells and could be reduced by Notch3 siRNA, but these cells were able to grow in androgen deprived medium regardless. CONCLUSIONS: Androgen deprivation upregulates Notch signaling mediated by Jag1 and Notch3 in parental LNCaP cells. Knockdown of Jag1 and/or Notch3 expression enabled further growth of these cells in androgen deficient medium. Our data supports the idea that Notch signaling has a tumor suppressive effect for androgenresponsive prostate cancer cells that is relieved in the AI state. Source of Funding: None
278 SECRETED FRIZZLED RELATED PROTEIN-1 IS A NEGATIVE REGULATOR OF ANDROGEN RECEPTOR SIGNALING IN PROSTATE CANCER Yoshiaki Kawano*, Soraya Diez, Pinar Uysal-Onganer, R. Siobhan Darrington, London, United Kingdom; Yoshihiro Wada, Wataru Takahashi, Masatoshi Eto, Kumamoto, Japan; Jonathan Waxman, Robert Kypta, London, United Kingdom INTRODUCTION AND OBJECTIVES: Secreted Frizzled-related protein-1 (sFRP1) associates with Wnt proteins and antagonizes Wnt/-catenin signaling. It is frequently downregulated in cancer including prostate cancer, but its function in prostate cancer is unclear. The transcriptional activity of Androgen receptor (AR) is regulated by interaction with various cofactors, which include -catenin. Therefore, we here investigated whether loss of sFRP-1 leads to increased AR transcriptional activity via activation of Wnt/-catenin signaling. METHODS: For transcription assays, all cells were transfected in triplicate in 24-well plates, and each well of the 24-well plate was transfected with 40ng pDM-Gal as an internal control, 200ng firefly luciferase gene driven by various promoter sequences and the expression plasmids as indicated. The total amount of DNA was brought to 400ng using empty pcDNA3.1. RESULTS: sFRP1 inhibited AR transcriptional activity in a dose-dependent manner. In addition, sFRP1 inhibited the proliferation of androgen-dependent LNCaP cells but not of an androgenindependent subline LNCaP-r, suggesting a role in androgen-dependent growth. The inhibition of AR by sFRP1 was unaffected by co-expression of Wnt3a or stabilised -catenin, suggesting it does not involve Wnt/-catenin signaling. Wnt5a also inhibited AR and expression of Wnt5a and sFRP1 together did not further inhibit AR, suggesting that Wnt5a and sFRP1 activate the same signal(s) to repress AR. However, sFRP1 inhibition of AR was unaffected by inhibitors of kinases involved in Wnt/Ca2⫹ and Wnt/planar cell polarity signaling. Interestingly, the cysteine-rich domain of sFRP1 interacted with Frizzled receptors expressed in prostate cancer cells, suggesting that sFRP1/Frizzled complexes activate a signal that leads to inhibition of AR signaling. CONCLUSIONS: These results highlight the function of -catenin-independent Wnt signalling in the control of AR activity and provide one explanation for sFRP1 downregulation in prostate cancer.
Source of Funding: The Joron Charitable Trust (YK, JW) and the Prostate Cancer Charity UK (RK). RK was also supported by the Department of Industry, Tourism and Trade of the Government of the Autonomous Community of the Basque Country (Etortek Research Programs 2005/2006), the Innovation Technology Department of Bizkaia County and the Ministry of Education and Science (SAF 2005-06122).