Epigenetic repression of regulator of G-protein signaling 2 promotes androgen-independent prostate cancer cell growth

Dennis W. Wolff, Yan Xie, Caishu Deng, Zoran Gatalica, Mingjie Yang, Bo Wang, Jincheng Wang, Ming-Fong Lin, Peter W. Abel, Yaping Tu

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

G-protein-coupled receptor (GPCR)-stimulated androgen-independent activation of androgen receptor (AR) contributes to acquisition of a hormone-refractory phenotype by prostate cancer. We previously reported that regulator of G-protein signaling (RGS) 2, an inhibitor of GPCRs, inhibits androgen-independent AR activation (Cao et al., Oncogene 2006;25:3719-34). Here, we show reduced RGS2 protein expression in human prostate cancer specimens compared to adjacent normal or hyperplastic tissue. Methylation-specific PCR analysis and bisulfite sequencing indicated that methylation of the CpG island in the RGS2 gene promoter correlated with RGS2 downregulation in prostate cancer. In vitro methylation of this promoter suppressed reporter gene expression in transient transfection studies, whereas reversal of this promoter methylation with 5-aza-2′-deoxycytidine (5-Aza-dC) induced RGS2 reexpression in androgen-independent prostate cancer cells and inhibited their growth under androgen-deficient conditions. Interestingly, the inhibitory effect of 5-Aza-dC was significantly reduced by an RGS2-targeted short hairpin RNA, indicating that reexpressed RGS2 contributed to this growth inhibition. Restoration of RGS2 levels by ectopic expression in androgen-independent prostate cancer cells suppressed growth of xenografts in castrated mice. Thus, RGS2 promoter hypermethylation represses its expression and unmasks a latent pathway for AR transactivation in prostate cancer cells. Targeting this reversible process may provide a new strategy for suppressing prostate cancer progression by reestablishing its androgen sensitivity.

Original languageEnglish (US)
Pages (from-to)1521-1531
Number of pages11
JournalInternational Journal of Cancer
Volume130
Issue number7
DOIs
StatePublished - Apr 1 2012

Fingerprint

Epigenetic Repression
GTP-Binding Protein Regulators
Androgens
Prostatic Neoplasms
decitabine
Methylation
Growth
Androgen Receptors
CpG Islands
G-Protein-Coupled Receptors
Reporter Genes
Oncogenes
Heterografts
Small Interfering RNA
Transcriptional Activation
Transfection
Down-Regulation
Hormones
Phenotype
Gene Expression

Keywords

  • DNA methylation
  • G-protein-coupled receptors
  • RGS2
  • androgen receptor
  • prostate cancer progression

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Epigenetic repression of regulator of G-protein signaling 2 promotes androgen-independent prostate cancer cell growth. / Wolff, Dennis W.; Xie, Yan; Deng, Caishu; Gatalica, Zoran; Yang, Mingjie; Wang, Bo; Wang, Jincheng; Lin, Ming-Fong; Abel, Peter W.; Tu, Yaping.

In: International Journal of Cancer, Vol. 130, No. 7, 01.04.2012, p. 1521-1531.

Research output: Contribution to journalArticle

Wolff, DW, Xie, Y, Deng, C, Gatalica, Z, Yang, M, Wang, B, Wang, J, Lin, M-F, Abel, PW & Tu, Y 2012, 'Epigenetic repression of regulator of G-protein signaling 2 promotes androgen-independent prostate cancer cell growth', International Journal of Cancer, vol. 130, no. 7, pp. 1521-1531. https://doi.org/10.1002/ijc.26138
Wolff, Dennis W. ; Xie, Yan ; Deng, Caishu ; Gatalica, Zoran ; Yang, Mingjie ; Wang, Bo ; Wang, Jincheng ; Lin, Ming-Fong ; Abel, Peter W. ; Tu, Yaping. / Epigenetic repression of regulator of G-protein signaling 2 promotes androgen-independent prostate cancer cell growth. In: International Journal of Cancer. 2012 ; Vol. 130, No. 7. pp. 1521-1531.
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AB - G-protein-coupled receptor (GPCR)-stimulated androgen-independent activation of androgen receptor (AR) contributes to acquisition of a hormone-refractory phenotype by prostate cancer. We previously reported that regulator of G-protein signaling (RGS) 2, an inhibitor of GPCRs, inhibits androgen-independent AR activation (Cao et al., Oncogene 2006;25:3719-34). Here, we show reduced RGS2 protein expression in human prostate cancer specimens compared to adjacent normal or hyperplastic tissue. Methylation-specific PCR analysis and bisulfite sequencing indicated that methylation of the CpG island in the RGS2 gene promoter correlated with RGS2 downregulation in prostate cancer. In vitro methylation of this promoter suppressed reporter gene expression in transient transfection studies, whereas reversal of this promoter methylation with 5-aza-2′-deoxycytidine (5-Aza-dC) induced RGS2 reexpression in androgen-independent prostate cancer cells and inhibited their growth under androgen-deficient conditions. Interestingly, the inhibitory effect of 5-Aza-dC was significantly reduced by an RGS2-targeted short hairpin RNA, indicating that reexpressed RGS2 contributed to this growth inhibition. Restoration of RGS2 levels by ectopic expression in androgen-independent prostate cancer cells suppressed growth of xenografts in castrated mice. Thus, RGS2 promoter hypermethylation represses its expression and unmasks a latent pathway for AR transactivation in prostate cancer cells. Targeting this reversible process may provide a new strategy for suppressing prostate cancer progression by reestablishing its androgen sensitivity.

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