Abstract
Cancer stem cells (CSCs) are known to be a major cause of metastasis, resistance and recurrence. Spheroid formation is one of the methods used to recruit CSCs utilizing an anchorage-independent environment in vitro. It was aimed to investigate the availability of spheroid formation culture methods in the research field of CSCs and resistance using 5-fluorouracil (5-FU)-resistant colorectal cancer cells. The wild type SNU-C5 and 5-FU-resistant SNU-C5 (SNU-C5/5-FUR) cells were cultured as usual (monolayer), and in 3-dimensional non-adhesive environments supplemented with fetal bovine serum (FBS) or growth factors, respectively. The characteristics of the spheroids were evaluated by morphometry, cell viability assay, western blotting, immunocytochemistry and enzyme-linked immunosorbent assay. Spheroid formation was induced in an environment supplemented with FBS, while SNU-C5/5-FUR cells only formed spheres in media supplemented with GFs. Sphere-formed cells showed slower cell proliferation than cells from monolayer, which coincided with an increased level of p21 and a decreased level of β-catenin. Markers for CSCs and drug resistance were not significantly changed after spheroid formation. Sphere-formed cells showed significantly increased levels of soluble E-cadherin, particularly in the environment supplemented with FBS. These results suggested that spheroid formation may be related to soluble E-cadherin, but is not related to CSCs or resistance markers.