Androgen deprivation-induced senescence promotes outgrowth of androgen-refractory prostate cancer cells

PLoS One. 2013 Jun 28;8(6):e68003. doi: 10.1371/journal.pone.0068003. Print 2013.

Abstract

Androgen deprivation (AD) is an effective method for initially suppressing prostate cancer (PC) progression. However, androgen-refractory PC cells inevitably emerge from the androgen-responsive tumor, leading to incurable disease. Recent studies have shown AD induces cellular senescence, a phenomenon that is cell-autonomously tumor-suppressive but which confers tumor-promoting adaptations that can facilitate the advent of senescence-resistant malignant cell populations. Because androgen-refractory PC cells emerge clonally from the originally androgen-responsive tumor, we sought to investigate whether AD-induced senescence (ADIS) affects acquisition of androgen-refractory behavior in androgen-responsive LNCaP and LAPC4 prostate cancer cells. We find that repeated exposure of these androgen-responsive cells to senescence-inducing stimuli via cyclic AD leads to the rapid emergence of ADIS-resistant, androgen-refractory cells from the bulk senescent cell population. Our results show that the ADIS phenotype is associated with tumor-promoting traits, notably chemoresistance and enhanced pro-survival mechanisms such as inhibition of p53-mediated cell death, which encourage persistence of the senescent cells. We further find that pharmacologic enforcement of p53/Bax activation via Nutlin-3 prior to establishment of ADIS is required to overcome the associated pro-survival response and preferentially trigger pervasive cell death instead of senescence during AD. Thus our study demonstrates that ADIS promotes outgrowth of androgen-refractory PC cells and is consequently a suboptimal tumor-suppressor response to AD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Androgens / genetics*
  • Androgens / metabolism*
  • Cell Death / genetics
  • Cell Line, Tumor
  • Cellular Senescence / genetics*
  • Gene Expression Regulation, Neoplastic / genetics
  • Humans
  • Male
  • Prostatic Neoplasms / genetics*
  • Prostatic Neoplasms / metabolism
  • Prostatic Neoplasms / pathology*
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • bcl-2-Associated X Protein / genetics
  • bcl-2-Associated X Protein / metabolism

Substances

  • Androgens
  • Tumor Suppressor Protein p53
  • bcl-2-Associated X Protein

Grants and funding

This work was funded by a Florida Biomed Bankhead Coley New Investigator Award, a University of Miami/Sylvester Comprehensive Cancer Center Pap Corps Developmental Cancer Research Grant and a University of Miami/Stanley Glaser Foundation award (to PR). MGG was partially supported by a Sylvester Comprehensive Cancer Center Summer Undergraduate Research Award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.