EGFR regulates the side population in head and neck squamous cell carcinoma

Laryngoscope. 2006 Mar;116(3):401-6. doi: 10.1097/01.mlg.0000195075.14093.fb.


Objective: To identify the presence of side population (SP) cells in established head and neck squamous carcinoma cell (HNSCC) lines and to determine the role of EGFR in the regulation of the side population of these cells.

Methods: SP cells were identified using flow cytometry analysis by the ability of these cells to extrude the Hoechst 33342 dye via the drug transporter BCRP1/ABCG2. Effect of EGFR on the side population was determined also by difference in Hoechst extrusion and by immunofluorescence. Immunohistochemical staining was performed to show the presence of the BCRP1/ABCG2 transporter and the phosphorylated form of EGFR in HNSCC tissue.

Results: SP cells are present in HNSCC cell lines. With the Hoechst 33342 extrusion assay, SP cells were found to comprise an average of 0.69% of the UMSCC10B cells and 0.91% of HN12 cells. Addition of the EGF ligand increased the SP population while inactivation of the EGFR kinase by Iressa significantly decreased SP.

Conclusion: In established head and neck squamous cell carcinoma cell lines, SP cells were found using methods that determine expression and function of the drug transporter BCRP1/ABCG2. Activation of EGFR, a gene implicated in tumorigenesis in HNSCC leads to increased SP, and conversely, inhibition of EGFR leads to decrease in SP. This finding could help explain the role of EGFR in regulating cancer stem cells and thus tumorigenesis in HNSCC.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily G, Member 2
  • ATP-Binding Cassette Transporters / metabolism
  • Antineoplastic Agents / pharmacology
  • Carcinoma, Squamous Cell / drug therapy
  • Carcinoma, Squamous Cell / metabolism*
  • Carcinoma, Squamous Cell / pathology
  • Cell Line, Tumor
  • Cell Proliferation
  • ErbB Receptors / antagonists & inhibitors
  • ErbB Receptors / biosynthesis*
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • Gefitinib
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Expression Regulation, Neoplastic / physiology*
  • Head and Neck Neoplasms / drug therapy
  • Head and Neck Neoplasms / metabolism*
  • Head and Neck Neoplasms / pathology
  • Humans
  • Immunohistochemistry
  • In Vitro Techniques
  • Neoplasm Proteins / metabolism
  • Quinazolines / pharmacology


  • ABCG2 protein, human
  • ATP Binding Cassette Transporter, Subfamily G, Member 2
  • ATP-Binding Cassette Transporters
  • Antineoplastic Agents
  • Neoplasm Proteins
  • Quinazolines
  • ErbB Receptors
  • Gefitinib