Autophagy modulators sensitize prostate epithelial cancer cell lines to TNF-alpha-dependent apoptosis

Claudia Giampietri, Simonetta Petrungaro, Fabrizio Padula, Alessio D'Alessio, Elettra Sara Marini, Antonio Facchiano, Antonio Filippini, Elio Ziparo

Research output: Contribution to journalArticlepeer-review

Abstract

TNF-alpha levels in prostate cancer correlate with the extent of disease and are significantly elevated in the metastatic stage. TNF receptor superfamily controls two distinct signalling cascades, leading to opposite effects, i.e. apoptosis and survival; in prostate cancer TNFalpha-mediated signalling induces cell survival and resistance to therapy. The apoptosis of prostate epithelial cancer cells LNCaP and PC3 was investigated upon treatment with the autophagy inhibitor 3-methyladenine and the autophagy inducer rapamycin, in combination with TNFalpha. Cells were exposed to these molecules for 18, 24 and 48 h. Autophagy was assessed via LC3 Western blot analysis; propidium iodide and TUNEL stainings followed by flow cytometry or caspase-8 and caspase-3 activation assays were performed to evaluate apoptosis. TNF-alphainduced apoptosis was potentiated by 3-methyladenine in the androgen-responsive LNCaP cells, whereas no effect was observed in the androgen-insensitive PC3 cells. Interestingly such pro-apoptosis effect in LNCaP cells was associated with reduced c-Flip levels through proteasomal degradation via increased reactive oxygen species production and p38 activation; such c-Flip reduction was reversed in the presence of either the proteasome inhibitor MG132 or the reactive oxygen species scavenger N-acetyl-cysteine. Conversely in PC3 but not in LNCaP cells, rapamycin stimulated TNF-alpha-dependent apoptosis; such effect was associated with reduced c-Flip promoter activity and FoxO3a activation. We conclude that TNF-alpha-induced apoptosis may be potentiated, in prostate cancer epithelial cells, through autophagy modulators. Increased sensitivity to TNF-alpha-dependent apoptosis correlates with reduced c-Flip levels which are consequent to a post-transcriptional and a transcriptional mechanism in LNCaP and PC3 cells respectively.

Original languageEnglish
Pages (from-to)1210-1222
Number of pages13
JournalApoptosis
Volume17
Issue number11
DOIs
Publication statusPublished - Nov 2012

Keywords

  • Apoptosis
  • Autophagy
  • c-Flip
  • Prostate cancer

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Biochemistry, medical
  • Cancer Research
  • Pharmaceutical Science
  • Pharmacology

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