The mechanism between epithelial mesenchymal transition in breast cancer and hypoxia microenvironment.

Hypoxia microenvironment widely exists in solid tumor tissues, which is mainly due to the rapid growth of cells within the tumor more than the speed of capillary in neoplasm, resulting in tumor tissue hypoxia. In hypoxia, hypoxia inducible factor 1 (HIF-1) is activated and regulate the expression of a series of hypoxia inducible genes, resulting in a series of hypoxia adaptation reaction. Researchs proved that, HIF-1 is closely related to the invasion, metastasis, prognosis of the tumor, and the expression of HIF-1 is higher in metastatic tissues compared with primary cancer tissues. In the evolution process of breast cancer, epithelial mesenchymal transition (EMT) define the characteristics of migration and invasion of breast cancer cells, which can also allow cancer cells to acquire the ability of self-renewing and stemness, so as to promote the generation of breast cancer stem cells. The incidence of EMT cancer stem cells are higher within the resistant to conventional treatment. This review focuses on breast cancer (stem cells), targeting the mechanism between hypoxia and EMT in tumor (stem cells), with the purpose of finding the new therapy to breast cancer.