Human head and neck squamous cell carcinoma cell lines are differentially radiosensitised by the honeybee product Propolis

Int J Radiat Biol. 2011 Mar;87(3):243-53. doi: 10.3109/09553002.2010.533248. Epub 2010 Dec 10.


Purpose: Propolis, a product of honeybees, has anti-tumoural, cytotoxic, anti-metastatic and anti-inflammatory properties. The aim of this study was the evaluation of the radiosensitising capacity of Propolis in human head and neck squamous cell carcinoma (HNSCC) cells.

Materials and methods: HNSCC cell lines (FaDu, UT-SCC15, UT-SCC45), fibroblasts (HSF2) and keratinocytes (HaCaT) were treated with Propolis (0-250 g/ml; 1, 4, 24 h) without and in combination with X-rays (0-6 Gy, single dose). Clonogenic survival, proliferation, apoptosis, expression and phosphorylation of different signalling proteins were determined. Liquid chromatography-mass spectrometry (LC-MS) was performed on Propolis.

Results: Propolis significantly (P < 0.01) reduced cell growth and clonogenic survival in a time- and concentration-dependent manner. Propolis-induced apoptosis and Caspase 3 cleavage, increased phosphorylation of Extracellular signal Regulated Kinase 1/2 (ERK1/2), protein kinase B/Akt1 (Akt1) and Focal adhesion kinase (FAK). While a 1-h Propolis pretreatment was ineffective, a 3-h pretreatment significantly (P < 0.05) radiosensitised FaDu cells. LC-MS analysis identified 14 compounds of Propolis.

Conclusions: Our data show that Propolis exerts cytotoxicity in a concentration- and time-dependent manner. In one out of three HNSCC cell lines, Propolis also caused an enhancement of radiosensitivity. Future studies on Propolis will shed further light on its potential as an adjuvant to radiotherapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Infective Agents / pharmacology
  • Apoptosis
  • Carcinoma, Squamous Cell / drug therapy*
  • Carcinoma, Squamous Cell / pathology*
  • Carcinoma, Squamous Cell / radiotherapy*
  • Cell Line, Tumor
  • Cell Survival
  • Chromatography, Liquid / methods
  • Dose-Response Relationship, Drug
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Head and Neck Neoplasms / drug therapy*
  • Head and Neck Neoplasms / pathology*
  • Head and Neck Neoplasms / radiotherapy*
  • Humans
  • Mass Spectrometry / methods
  • Phosphorylation
  • Propolis / pharmacology*
  • Radiation-Sensitizing Agents / pharmacology*
  • Spectrometry, Mass, Electrospray Ionization / methods
  • Time Factors


  • Anti-Infective Agents
  • Radiation-Sensitizing Agents
  • Propolis
  • Extracellular Signal-Regulated MAP Kinases