Isolation and characterization of a side population in thyroid cancer cell lines
Dai Cui · Universitätsbibliothek der FU Berlin Hochschulschriftenstelle u. Dokumentenserver · 2007
The identification of cancer stem cells in leukemia, as well as in brain tumor and breast cancer renews the interest in the hypothesis that cancers may arise from adult stem/progenitor cells. Recently, the Hoechst 33342 staining based method has been successfully applied to identify stem-like "side population" cells in a number of unrelated human cancers and their normal tissue sources. In this study, using the Hoechst staining method and Fluorescence-activated Cell Sorting (FACS), we identified a small fraction of side population cells in various human anaplastic thyroid cancer cell lines. These cancer side population cells possess some intrinsic stem cell properties as they preferentially express stem cell markers Oct4 and ABC transporter genes--ABCG2 and MDR1, and can generate both side population and non-side population cells in vitro. Clonal formation analysis and Matrigel invasion assay revealed that these cancer side population cells were more clonogenic and displayed higher invasive potential than non-side population cells. In addition, the cancer side population cells exhibited elevated gene expression of some proteinases which may promote tumor invasion and metastasis. Interestingly, in serum-free medium with epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), the cancer side population cells can be enriched and proliferate as spheres. Taken together, these findings suggest that the side population in thyroid cancer cell lines is enriched with stem-like cancer cells that may serve as a valuable model to study thyroid carcinogenesis and thus contribute to a novel therapy of highly malignant anaplastic thyroid cancer.