TBLR1 as an androgen receptor (AR) coactivator selectively activates AR target genes to inhibit prostate cancer growth.
Androgen receptor (AR), a steroid hormone receptor, is critical for prostate cancer growth. However, activation of AR by androgens can also lead to growth suppression and differentiation. Transcriptional cofactors play an important role in this switch between proliferative and anti-proliferative AR target gene programs. Transducin β-like-related protein 1 (TBLR1), a core component of the nuclear receptor corepressor complex, shows both corepressor and coactivator activities on nuclear receptors, but little is known about its effects on AR and prostate cancer. We characterized TBLR1 as a coactivator of AR in prostate cancer cells and determined that the activation is dependent on both phosphorylation and 19S proteosome. We showed that TBLR1 physically interacts with AR and directly occupies the androgen-response elements of the affected AR target genes in an androgen-dependent manner. TBLR1 is primarily localized in the nucleus in benign prostate cells and nuclear expression is significantly reduced in prostate cancer cells in culture. Similarly, in human tumor samples, the expression of TBLR1 in the nucleus is significantly reduced in the malignant glands compared with the surrounding benign prostatic glands (P<0.005). Stable ectopic expression of nuclear TBLR1 leads to androgen-dependent growth suppression of prostate cancer cells in vitro and in vivo by selective activation of androgen-regulated genes associated with differentiation (e.g. KRT18) and growth suppression (e.g. NKX3-1), but not cell proliferation of the prostate cancer. Understanding the molecular switches involved in the transition from AR-dependent growth promotion to AR-dependent growth suppression will lead to more successful treatments for prostate cancer.
Department of Pathology, New York University School of Medicine, New York, New York, USA Department of Pathology, Mount Sinai School of Medicine, New York, New York, USA NYU Cancer Institute, Department of Urology, Department of Pharmacology, New York Harbor Healthcare System, New York University School of Medicine, New York, New York, USA.
Garrett
G
Daniels
Yirong
Y
Li
Lan Lin
LL
Gellert
Albert
A
Zhou
Jonathan
J
Melamed
Xinyu
X
Wu
Xinming
X
Zhang
David
D
Zhang
Daniel
D
Meruelo
Susan K
SK
Logan
Ross
R
Basch
Peng
P
Lee
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D048708:Cell Growth Processes / Q000235:genetics; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D006801:Humans; D008297:Male; D008819:Mice, Nude; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism*; D012334:RNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D046888:Tissue Array Analysis; D014158:Transcription, Genetic
C410798:AR protein, human; D009687:Nuclear Proteins; D012334:RNA, Neoplasm; D011944:Receptors, Androgen; D018160:Receptors, Cytoplasmic and Nuclear; D012097:Repressor Proteins; C473691:TBL1XR1 protein, human
androgen; androgen receptor; gene expression; gene transcription; prostate