title: Androgens suppress EZH2 expression via retinoblastoma (RB) and p130-dependent pathways: a potential mechanism of androgen-refractory progression of prostate cancer.
abstract: Androgens and the androgen receptor are important for both normal prostate development and progression of prostate cancer (PCa). However, the underlying mechanisms are not fully understood. The Polycomb protein enhancer of zeste homolog 2 (EZH2) functions as an epigenetic gene silencer and plays a role in oncogenesis by promoting cell proliferation and invasion. EZH2 has been implicated in human PCa progression, because its expression is often elevated in hormone-refractory PCa. Here, we demonstrated that expression of EZH2 is lower in androgen-sensitive LNCaP PCa cells compared with Rf and C4-2 cells, two androgen-refractory sublines that are derived from LNCaP cells. Androgen ablation by castration increased the level of EZH2 proteins in LNCaP xenografts in mice. In contrast, treatment of LNCaP cells in culture with the synthetic androgen methyltrieolone (R1881) at doses of 1 nm or higher suppressed EZH2 expression. Moreover, our data suggest that androgen repression of EZH2 requires a functional androgen receptor and this effect is mediated through the retinoblastoma protein and its related protein p130. We further showed that androgen treatment not only increases expression of EZH2 target genes DAB2IP and E-cadherin but also affects LNCaP cell migration. Our results reveal that androgens function as an epigenetic regulator in prostatic cells by repression of EZH2 expression through the retinoblastoma protein and p130-dependent pathways. Our findings also suggest that blockade of EZH2 derepression during androgen deprivation therapy may represent an effective tactic for the treatment of androgen-refractory PCa.
authors.affiliation: Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Laura R
authors.initials: LR
authors.lastname: Bohrer
authors.forename: Shuai
authors.initials: S
authors.lastname: Chen
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Hallstrom
authors.forename: Haojie
authors.initials: H
authors.lastname: Huang
mesh_terms: D000728:Androgens / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002465:Cell Movement; D047369:Chromatin Immunoprecipitation; D018450:Disease Progression; D000071221:Enhancer of Zeste Homolog 2 Protein; D015972:Gene Expression Regulation, Neoplastic; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D009919:Orchiectomy; D063151:Polycomb Repressive Complex 2; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism*; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism*; D050717:Retinoblastoma-Like Protein p130 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D000728:Androgens; C493838:Rbl2 protein, mouse; D011944:Receptors, Androgen; D016160:Retinoblastoma Protein; D050717:Retinoblastoma-Like Protein p130; D000071221:Enhancer of Zeste Homolog 2 Protein; C498410:Ezh2 protein, mouse; D011495:Histone-Lysine N-Methyltransferase; D063151:Polycomb Repressive Complex 2