title: In vitroTumorsphere Formation Assays.
abstract: A tumorsphere is a solid, spherical formation developed from the proliferation of one cancer stem/progenitor cell. These tumorspheres (Figure 1a) are easily distinguishable from single or aggregated cells (Figure 1b) as the cells appear to become fused together and individual cells cannot be identified. Cells are grown in serum-free, non-adherent conditions in order to enrich the cancer stem/progenitor cell population as only cancer stem/progenitor cells can survive and proliferate in this environment. This assay can be used to estimate the percentage of cancer stem/progenitor cells present in a population of tumor cells. The size, which can vary from less than 50 micrometers to 250 micrometers, and number of tumorspheres formed can be used to characterize the cancer stem/progenitor cell population within a population ofin vitrocultured cancer cells and withinin vivotumors (Loet al., 2012; Liuet al.,2009). While several cell lines can be used for tumorsphere formation assay (e.g.primary mammary tumor cells fromHer2/neu-transgenic mice, MCF7, BT474 and HCC1954), some cell lines may not form typical tumorsphere structures and may be difficult to count or classify definitively as tumorspheres.
authors: Biological Sciences Department, University of South Carolina, Columbia, USA.
authors: Sara
authors: S
authors: Johnson
authors: Biological Sciences Department, University of South Carolina, Columbia, USA.
authors: Hexin
authors: H
authors: Chen
authors: Biological Sciences Department, University of South Carolina, Columbia, USA.
authors: Pang-Kuo
authors: PK
authors: Lo