GRK3 Is a Direct Target of CREB Activation and Regulates Neuroendocrine Differentiation of Prostate Cancer Cells

Oncotarget. 2016 Jul 19;7(29):45171-45185. doi: 10.18632/oncotarget.9359.

Abstract

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that commonly arises through neuroendocrine differentiation (NED) of prostate adenocarcinoma (PAC) after therapy, such as radiation therapy and androgen deprivation treatment (ADT). No effective therapeutic is available for NEPC and its molecular mechanisms remain poorly understood. We have reported that G protein-coupled receptor kinase 3 (GRK3, also called ADRBK2) promotes prostate cancer progression. In this study, we demonstrate that the ADT-activated cAMP response element binding protein (CREB) directly targets and induces GRK3. We show GRK3 expression is higher in NEPC than in PAC cells and mouse models, and it positively correlates with the expression and activity of CREB in human prostate cancers. Notably, overexpression of GRK3 in PAC cells increased the expression of NE markers in a kinase activity dependent manner. Conversely, silencing GRK3 blocked CREB-induced NED in PAC cells, reversed NE phenotypes and inhibited proliferation of NEPC cells. Taken together, these results indicate that GRK3 is a new critical activator of NE phenotypes and mediator of CREB activation in promoting NED of prostate cancer cells.

Keywords: CREB; GRK3; androgen deprivation therapy; neuroendocrine prostate cancer.

MeSH terms

  • Adenocarcinoma / pathology
  • Androgen Antagonists / therapeutic use
  • Animals
  • Carcinoma, Neuroendocrine / pathology*
  • Cell Differentiation / drug effects
  • Cell Line, Tumor
  • Cyclic AMP Response Element-Binding Protein / physiology*
  • G-Protein-Coupled Receptor Kinase 3 / analysis
  • G-Protein-Coupled Receptor Kinase 3 / genetics
  • G-Protein-Coupled Receptor Kinase 3 / physiology*
  • Humans
  • Male
  • Mice
  • Prostatic Neoplasms / pathology*

Substances

  • Androgen Antagonists
  • CREB1 protein, human
  • Cyclic AMP Response Element-Binding Protein
  • G-Protein-Coupled Receptor Kinase 3
  • GRK3 protein, human