Androgen-responsive serum response factor target genes regulate prostate cancer cell migration

Carcinogenesis. 2013 Aug;34(8):1737-46. doi: 10.1093/carcin/bgt126. Epub 2013 Apr 10.

Abstract

Progression of prostate cancer (CaP) relies on androgen receptor (AR) signaling, but AR-dependent events that underlie the lethal phenotype remain unknown. Recently, an indirect mechanism of androgen action in which effects of AR on CaP cells are mediated by Serum Response Factor (SRF) has been identified. This is the first mode of androgen action to be associated with aggressive CaP and disease recurrence. The manner in which androgen-responsive SRF activity controls aggressive CaP cell behavior is unknown. Here, the contribution of two representative SRF effector genes that are underexpressed, calponin 2 (CNN2), or overexpressed, sidekick-homolog 1 (SDK1), in clinical CaP specimens is studied. AR- and SRF- dependency of CNN2 and SDK1 expression was verified using synthetic and natural androgens, antiandrogens, and small interfering RNAs targeting AR or SRF, and evaluating the kinetics of androgen induction and SRF binding to endogenously and exogenously expressed regulatory gene regions in AR-positive CaP model systems that mimic the transition from androgen-stimulated to castration-recurrent disease. Small interfering RNA-mediated deregulation of CNN2 or SDK1 expression did not affect CaP cell proliferation or apoptosis but had marked effects on CaP cell morphology and actin cytoskeleton organization. Loss of CNN2 induced cellular protrusions and increased CaP cell migration, whereas silencing of SDK1 led to cell rounding and blunted CaP cell migration. Changes in cell migration did not involve epithelial-mesenchymal transition but correlated with altered β1-integrin expression. Taken together, individual androgen-responsive SRF target genes affect CaP cell behavior by modulating cell migration, which may have implications for therapeutic intervention downstream of AR and SRF.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actin Cytoskeleton / genetics
  • Actin Cytoskeleton / metabolism
  • Androgens / genetics*
  • Androgens / metabolism
  • Apoptosis / genetics
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism
  • Cell Growth Processes / genetics
  • Cell Line, Tumor
  • Cell Movement / genetics*
  • Disease Progression
  • Epithelial-Mesenchymal Transition / genetics
  • Humans
  • Integrin beta1 / genetics
  • Integrin beta1 / metabolism
  • Male
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism
  • Orchiectomy
  • Prostatic Neoplasms, Castration-Resistant / genetics*
  • Prostatic Neoplasms, Castration-Resistant / metabolism
  • Prostatic Neoplasms, Castration-Resistant / pathology*
  • Receptors, Androgen / genetics
  • Receptors, Androgen / metabolism
  • Serum Response Factor / genetics*
  • Serum Response Factor / metabolism

Substances

  • AR protein, human
  • Androgens
  • Cell Adhesion Molecules
  • Integrin beta1
  • Microfilament Proteins
  • Receptors, Androgen
  • SDK1 protein, human
  • SRF protein, human
  • Serum Response Factor