IADR Abstract Archives

Propolis inhibits orosphere formation by HNSCC cells

Objectives: Cancer stem cells play an important role in the pathobiology of head and neck squamous cell carcinoma (HNSCC). We have shown that Propolis, a natural product from honeybee hives, inhibits proliferation of HNSCC cell lines (UM-SCC-17B, UM-SCC-74A) and primary human dermal microvascular endothelial cells (HDMEC) in vitro. However, the effect of Propolis on cancer stem cells is unknown. The goal of this study was to evaluate the effect of Propolis in the survival and stemness of head and neck cancer stem cells.

Methods: UM-SCC-17B cells were exposed to Propolis and analyzed by flow cytometry for the proportion of cancer stem-like cells, defined as ALDH+CD44+ cells. In addition, we sorted ALDH+CD44+ cells from UM-SCC-17B, plated them in ultralow attachment plates, treated with increasing concentrations of Propolis (0-50 µg/ml), and evaluated for generation of orospheres (defined as a non-adherent colony of ≥25 cells). Western blots were performed to evaluate the effect of Propolis on the expression of the self-renewal marker Bmi-1. One-way ANOVA followed by post-hoc tests were used to analyze data.

Results: Propolis decreased the number of orospheres (P=0.037) generated by ALDH+CD44+ cells cultured in ultralow attachment plates. This effect appears to be independent from changes in Bmi-1 expression levels. Surprisingly, Propolis enhanced the fraction of ALDH+CD44+ cells (P<0.001) in unsorted UM-SCC-17 cells cultured in standard cell culture plates.

Conclusion: Within the limitations of this in vitro study, we conclude that Propolis has an inhibitory effect on cancer stem cells cultured under non-adherent conditions.

IADR/AADR/CADR General Session
2013 IADR/AADR/CADR General Session (Seattle, Washington)
Seattle, Washington
2013
1464
Oral Medicine & Pathology
  • Nör, Felipe  ( University of Michigan, Ann Arbor, MI, USA )
  • Nör, Carolina  ( University of Michigan, Ann Arbor, MI, USA )
  • Bento, Leticia  ( University of Michigan, Ann Arbor, MI, USA )
  • Bretz, Walter A.  ( New York University, New York, NY, USA )
  • Nör, Jacques  ( University of Michigan, Ann Arbor, MI, USA )
    • Poster Session
    Oral Carcinogenesis and Diagnosis
    03/21/2013