BACKGROUND: Prosaposin overexpression and/or genomic amplification have been demonstrated in androgen-independent (AI) prostate cancer cell lines and tissues. Here, we explored the possibility for a functional relationship between prosaposin and androgen receptor (AR) in LNCaP cells. METHODS: The effect of prosaposin or its active molecular derivatives (e.g., saposin C) on expression and activity of androgen receptor (AR) and prostate-specific antigen (PSA) was examined by using immunoblotting, RT-PCR, transfection, and reporter gene assays, immunofluorescence staining, and inhibitors of signal transduction pathways. RESULTS: Prosaposin or saposin C, in an AI-manner, (a) increased AR mRNA and protein expression and nuclear AR content and its phosphorylation state; (b) increased PSA mRNA and protein expression; and (c) upregulated PSA- and an androgen-inducible probasin (PB)-reporter gene activity in LNCaP and AR-transfected PC-3 cells. Induction of PSA expression and reporter activity was substantially blocked or prevented with the antiandrogen bicalutamide, pertussis toxin, or inhibitors of MAPK- and PI3K/Akt-signaling pathways, indicating an androgen-agonistic effect for saposin C that involves AR and multiple signaling pathways. CONCLUSIONS: The results for the first time introduce prosaposin as an androgen-agonist in prostate cancer cells. This finding, together with the growth-promoting effect and overexpression of prosaposin, may support a growth advantage to AI prostate cancer cells. (c) 2006 Wiley-Liss, Inc.
BACKGROUND:Prosaposin overexpression and/or genomic amplification have been demonstrated in androgen-independent (AI) prostate cancer cell lines and tissues. Here, we explored the possibility for a functional relationship between prosaposin and androgen receptor (AR) in LNCaP cells. METHODS: The effect of prosaposin or its active molecular derivatives (e.g., saposin C) on expression and activity of androgen receptor (AR) and prostate-specific antigen (PSA) was examined by using immunoblotting, RT-PCR, transfection, and reporter gene assays, immunofluorescence staining, and inhibitors of signal transduction pathways. RESULTS:Prosaposin or saposin C, in an AI-manner, (a) increased AR mRNA and protein expression and nuclear AR content and its phosphorylation state; (b) increased PSA mRNA and protein expression; and (c) upregulated PSA- and an androgen-inducible probasin (PB)-reporter gene activity in LNCaP and AR-transfected PC-3 cells. Induction of PSA expression and reporter activity was substantially blocked or prevented with the antiandrogen bicalutamide, pertussis toxin, or inhibitors of MAPK- and PI3K/Akt-signaling pathways, indicating an androgen-agonistic effect for saposin C that involves AR and multiple signaling pathways. CONCLUSIONS: The results for the first time introduce prosaposin as an androgen-agonist in prostate cancer cells. This finding, together with the growth-promoting effect and overexpression of prosaposin, may support a growth advantage to AI prostate cancer cells. (c) 2006 Wiley-Liss, Inc.
Authors: Shalini Murthy; Min Wu; V Uma Bai; Zizheng Hou; Mani Menon; Evelyn R Barrack; Sahn-Ho Kim; G Prem-Veer Reddy Journal: PLoS One Date: 2013-02-20 Impact factor: 3.240
Authors: Azlena Ali; Laura Creevey; Yuan Hao; Damian McCartan; Peadar O'Gaora; Arnold Hill; Leonie Young; Marie McIlroy Journal: Breast Cancer Res Date: 2015-09-04 Impact factor: 6.466