Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) sensitizes LNCaP prostate cancer cells to TRAIL-induced apoptosis

Int J Oncol. 2012 Sep;41(3):818-28. doi: 10.3892/ijo.2012.1527. Epub 2012 Jun 25.

Abstract

Naturally occurring phenolic compounds have been shown to sensitize prostate cancer cells to tumour necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. TRAIL is a potent stimulator of apoptosis in cancer cells and an important immune effector molecule in the surveillance and elimination of developing tumours. However, many cancer cells are resistant to TRAIL-mediated death. In this study, we aimed to determine the mechanisms by which TRAIL resistance can be overcome in prostate cancer cells by 3,5-diprenyl-4-hydroxycinnamic acid (artepillin C). Artepillin C is a bioactive component of Brazilian green propolis that possesses antitumour and chemopreventive activities. TRAIL-resistant LNCaP prostate cancer cells were treated with TRAIL and artepillin C. Cytotoxicity was measured by MTT and lactate dehydrogenase (LDH) assays. Apoptosis was detected using Annexin V-FITC staining by flow cytometry and fluorescence microscopy. Death receptor (DR) (TRAIL-R1/DR4 and TRAIL-R2/DR5) expression was analyzed using flow cytometry. Mitochondrial membrane potential (∆ψm) was evaluated using DePsipher staining by fluorescence micro-scopy. The inhibition of NF-κB (p65) activation was confirmed with the ELISA-based TransAM NF-κB kit. Caspase-8 and caspase-3 activities were determined by colorimetric protease assays. The results showed that artepillin C sensitized the TRAIL-resistant LNCaP cells by engaging the extrinsic (receptor-mediated) and intrinsic (mitochondrial) apoptotic pathways. Artepillin C increased the expression of TRAIL-R2 and decreased the activity of NF-κB. Co-treatment with TRAIL and artepillin C induced the significant activation of caspase-8 and caspase-3, as well as the disruption of ∆ψm. These findings show that prostate cancer cells can be sensitized to TRAIL-mediated immunoprevention by artepillin C and confirm the role of phenolic compounds in prostate cancer immunochemoprevention.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Apoptosis Regulatory Proteins / metabolism
  • Caspase 3 / metabolism
  • Caspase 8 / metabolism
  • Cell Line, Tumor
  • Humans
  • Male
  • Membrane Potential, Mitochondrial / drug effects
  • Mitochondria / metabolism
  • NF-kappa B / metabolism
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Phenylpropionates / pharmacology*
  • Prostatic Neoplasms / physiopathology*
  • Prostatic Neoplasms / therapy
  • Receptors, Death Domain / metabolism
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / metabolism*
  • TNF-Related Apoptosis-Inducing Ligand / metabolism*

Substances

  • Apoptosis Regulatory Proteins
  • NF-kappa B
  • Nucleic Acid Synthesis Inhibitors
  • Phenylpropionates
  • Receptors, Death Domain
  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFSF10 protein, human
  • artepillin C
  • Caspase 3
  • Caspase 8