Glucocorticoid up-regulates transforming growth factor-beta (TGF-beta) type II receptor and enhances TGF-beta signaling in human prostate cancer PC-3 cells

Endocrinology. 2006 Nov;147(11):5259-67. doi: 10.1210/en.2006-0540. Epub 2006 Aug 3.

Abstract

Previous studies have shown that dexamethasone (Dex) induces the expression of TGF-beta1 in androgen-independent prostate cancer both in vitro and in vivo. However, it is not clear whether Dex has a direct effect on the expression of TGF-beta receptors. In this study, using the androgen-independent human prostate cancer cell line, PC-3 cells, we demonstrated that Dex increased the expression of TGF-beta receptor type II (TbetaRII), but not TGF-beta receptor type I (TbetaRI) in a time- and dose-dependent manner. The up-regulation of TbetaRII expression by Dex was mediated by glucocorticoid receptor and occurred at the transcriptional level. Dex also enhanced TGF-beta1 signaling and increased the expression of cyclin-dependent kinase inhibitors p15(INK4B) (p15) and p27(KIP1) (p27), which are the target genes of TGF-beta1 and have been identified as inducers of cell cycle arrest at the G1 checkpoint. The antiproliferative effect of Dex was partially blocked by anti-TbetaRII antibody, indicating that elevated TbetaRII and TGF-beta1 signaling were involved in the antiproliferative effect of Dex. Because the TGF-beta1 pathway could not fully explain the antiproliferative effect of Dex, we further examined the effects of Dex on the transcriptional activity of nuclear factor-kappaB (NF-kappaB) and the expression of IL-6 and found that Dex suppressed the transcriptional activity of NF-kappaB and IL-6 mRNA expression in PC-3 cells. These results demonstrated that glucocorticoid inhibited the proliferation of PC-3 cells not only through enhancing growth-inhibitory TGF-beta1 signaling, but also through suppressing transcriptional activities of NF-kappaB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cyclin-Dependent Kinase Inhibitor p15 / genetics
  • Cyclin-Dependent Kinase Inhibitor p27 / genetics
  • Dexamethasone / pharmacology*
  • Gene Expression Regulation / drug effects*
  • Humans
  • Interleukin-6 / genetics
  • Male
  • NF-kappa B / antagonists & inhibitors
  • Promoter Regions, Genetic
  • Prostatic Neoplasms
  • Protein Serine-Threonine Kinases
  • RNA, Messenger / analysis
  • Receptor, Transforming Growth Factor-beta Type II
  • Receptors, Transforming Growth Factor beta / genetics*
  • Signal Transduction / drug effects*
  • Transforming Growth Factor beta1 / pharmacology*
  • Up-Regulation

Substances

  • Cyclin-Dependent Kinase Inhibitor p15
  • Interleukin-6
  • NF-kappa B
  • RNA, Messenger
  • Receptors, Transforming Growth Factor beta
  • Transforming Growth Factor beta1
  • Cyclin-Dependent Kinase Inhibitor p27
  • Dexamethasone
  • Protein Serine-Threonine Kinases
  • Receptor, Transforming Growth Factor-beta Type II