Brazilian Green Propolis Extract Synergizes with Protoporphyrin IX-mediated Photodynamic Therapy via Enhancement of Intracellular Accumulation of Protoporphyrin IX and Attenuation of NF-κB and COX-2

Molecules. 2017 May 4;22(5):732. doi: 10.3390/molecules22050732.

Abstract

Brazilian green propolis (BGP) is noted for its impressive antitumor effects and has been used as a folk medicine in various cultures for many years. It has been demonstrated that BGP could enhance the cytotoxic effect of cytostatic drugs on tumor cells. Photodynamic therapy (PDT) is a therapeutic approach used against malignant cells. To assess the synergistic effect of BGP extract on protoporphyrin IX (PpIX)-mediated photocytotoxicity, MTT assays were performed using A431 and HeLa cells. TUNEL assay and Annexin V-FITC/PI staining were performed to confirm the induction of apoptosis. Western blotting analysis was performed to examine the pro-apoptotic proteins, anti-apoptotic proteins and inflammation related proteins in A431 cells. Intracellular accumulation of PpIX was examined by flow cytometry. The synergistic effect of BGP extract in PpIX-PDT was also evaluated with a xenograft model. Our findings reveal that BGP extract increased PpIX-mediated photocytotoxicity in A431 and HeLa cells. PpIX-PDT with BGP extract treatment resulted in a decrease in Bcl-xL and an increase in NOXA, Bax and caspase-3 cleavage. The protein expression levels of p-IKKα/β, NF-κB and COX-2 were upregulated by PpIX-PDT but significantly attenuated when in combination with BGP extract. BGP extract was also found to significantly enhance the intracellular accumulation of PpIX in A431 cells. BGP extract increased PpIX-mediated photocytotoxicity in a xenograft model as well. Our findings provide evidence for a synergistic effect of BGP extract in PpIX-PDT both in vitro and in vivo.

Keywords: Brazilian green propolis; apoptosis; cancer; inflammation; photodynamic therapy; synergy.

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Brazil
  • Cell Line, Tumor
  • Chromatography, High Pressure Liquid
  • Cyclooxygenase 2 / metabolism*
  • Drug Synergism
  • Flow Cytometry
  • Heterografts
  • Humans
  • Mice, Inbred BALB C
  • Mice, Nude
  • NF-kappa B / metabolism*
  • Photochemotherapy*
  • Propolis*
  • Protoporphyrins / pharmacokinetics
  • Protoporphyrins / pharmacology*
  • Spectrophotometry, Ultraviolet

Substances

  • NF-kappa B
  • Protoporphyrins
  • Propolis
  • protoporphyrin IX
  • Cyclooxygenase 2