The androgen receptor induces integrin α6β1 to promote prostate tumor cell survival via NF-κB and Bcl-xL independently of PI3K signaling

Laura E. Lamb, Jelani C. Zarif, Cindy K. Miranti

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

Recent studies indicate that androgen receptor (AR) signaling is critical for prostate cancer cell survival, even in castration-resistant disease wherein AR continues to function independently of exogenous androgens. Integrin-mediated adhesion to the extracellular matrix is also important for prostate cell survival. AR-positive prostate cancer cells express primarily integrin α6β1 and adhere to a laminin-rich matrix. In this study, we show that active nuclear-localized AR protects prostate cancer cells from death induced by phosphoinositide 3-kinase (PI3K) inhibition when cells adhere to laminin. Resistance to PI3K inhibition is mediated directly by an AR-dependent increase in integrin α6β1 mRNA transcription and protein expression. Subsequent signaling by integrin α6β1 in AR-expressing cells increased NF-κB activation and Bcl-xL expression. Blocking AR, integrin α6, NF-κB, or Bcl-xL concurrent with inhibition of PI3K was sufficient and necessary to trigger death of laminin-adherent AR-expressing cells. Taken together, these results define a novel integrin-dependent survival pathway in prostate cancer cells that is regulated by AR, independent of and parallel to the PI3K pathway. Our findings suggest that combined targeting of both the AR/α6β1 and PI3K pathways may effectively trigger prostate cancer cell death, enhancing the potential therapeutic value of PI3K inhibitors being evaluated in this setting.

Original languageEnglish (US)
Pages (from-to)2739-2749
Number of pages11
JournalCancer Research
Volume71
Issue number7
DOIs
StatePublished - Apr 1 2011
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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