title: Regulator of G-protein signaling 2 (RGS2) inhibits androgen-independent activation of androgen receptor in prostate cancer cells.
abstract: Hormones acting through G protein-coupled receptors (GPCRs) can cause androgen-independent activation of androgen receptor (AR) in prostate cancer cells. Regulators of G-protein signaling (RGS) proteins, through their GTPase activating protein (GAP) activities, inhibit GPCR-mediated signaling by inactivating G proteins. Here, we identified RGS2 as a gene specifically downregulated in androgen-independent prostate cancer cells. Expression of RGS2, but not other RGS proteins, abolished androgen-independent AR activity in androgen-independent LNCaP cells and CWR22Rv1 cells. In LNCaP cells, RGS2 inhibited G(q)-coupled GPCR signaling. Expression of exogenous wild-type RGS2, but not its GAP-deficient mutant, significantly reduced AR activation by constitutively activated G(q)Q209L mutant whereas silencing endogenous RGS2 by siRNA enhanced G(q)Q209L-stimulated AR activity. RGS2 had no effect on RGS-insensitive G(q)Q209L/G188S-induced AR activation. Furthermore, extracellular signal-regulated kinase 1/2 (ERK1/2) was found to be involved in RGS2-mediated regulation of androgen-independent AR activity. In addition, RGS2 functioned as a growth suppressor for androgen-independent LNCaP cells whereas androgen-sensitive LNCaP cells with RGS2 silencing had a growth advantage under steroid-reduced conditions. Finally, RGS2 expression level was significantly decreased in human prostate tumor specimens. Taken together, our results suggest RGS2 as a novel regulator of AR signaling and its repression may be an important step during prostate tumorigenesis and progression.
authors.affiliation: Department of Pharmacology, Creighton University School of Medicine, Omaha, NE 68178, USA.
authors.forename: X
authors.initials: X
authors.lastname: Cao
authors.forename: J
authors.initials: J
authors.lastname: Qin
authors.forename: Y
authors.initials: Y
authors.lastname: Xie
authors.forename: O
authors.initials: O
authors.lastname: Khan
authors.forename: F
authors.initials: F
authors.lastname: Dowd
authors.forename: M
authors.initials: M
authors.lastname: Scofield
authors.forename: M-F
authors.initials: MF
authors.lastname: Lin
authors.forename: Y
authors.initials: Y
authors.lastname: Tu
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000728:Androgens / Q000378:metabolism*; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D020710:RGS Proteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D000728:Androgens; D020710:RGS Proteins; C087182:RGS2 protein, human; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3