beta-catenin signaling pathway and the tolerance of breast cancer cells to hypoxic conditions.

We have previously shown that Snail, a regulator of epithelial-mesenchymal transition, is activated in the hypoxia-resistant breast cancer cell line HBL100. The purpose of this study was to evaluate the role of beta-catenin signaling pathway in the maintenance of breast cancer cells 'tolerance to hypoxia. The breast cancer cell lines MCF-7 and HBL-100 were used in this study; HBL-100 cells were characterized by increased resistance to hypoxia. We have demonstrated that the transcription factor beta-catenin is activated in hypoxic conditions and the beta-catenin activity is supported by Snail, a regulator of epithelial-mesenchymal transition. The activated beta-catenin regulates the expression of genes of the cell response to hypoxia and thus, it maintains the growth of breast cancer in the reduced oxygen conditions. The coordinated activation of Snail/beta-catenin/HIF-1alpha proteins in cell may be considered as an important factor of tumor resistance to hypoxia.