Nuclear Accumulation of ß-Catenin in Cancer Stem Cell Radioresistance and Stemness in Human Colon Cancer.

BACKGROUND/AIM: The aim of this study was to examine whether the Wnt/ß-catenin signal activation is a cause of radioresistance in colon cancer by assessing the ß-catenin localization and its correlation with cancer stem cells (CSCs). MATERIALS AND METHODS: The nuclear levels of ß-catenin, the hallmark of Wnt activation, were analyzed in HCT116 and SW480 cells by immunohistochemistry, before and after irradiation. Further, we assessed CSC populations by staining for aldehyde dehydrogenase-1 (ALDH1) and CD44. RESULTS: ß-catenin was localized predominantly in the nucleus and plasma membrane in SW480 and HCT116 cells, respectively. Compared to HCT116 cells, SW480 cells displayed higher Wnt activation. At 24 h after irradiation, most of the DSBs in SW480 cells were repaired, but were still present in HCT116 cells. Additionally, compared to HCT116 cells, a significantly higher proportion of SW480 cells were ALDH1- and CD44-positive. CONCLUSION: Colon cancers with nuclear ß-catenin accumulation demonstrated greater radio-resistance with a higher number of CSCs.