Overexpression of MMP-9 and HIF-1α in Breast Cancer Cells under Hypoxic Conditions.

Purpose: Hypoxia, which is a loss of oxygen in tissues, is a common condition in solid tumors due to the tumor outgrowing existing vasculature. Under hypoxic conditions, hypoxia-inducible factor (HIF)-1α rapidly accumulates and transactivates hundreds of genes, such as matrix metalloproteinases (MMPs). MMPs contribute to invasion and metastasis of tumor cells by degrading the surrounding basement membrane and extracellular matrix barriers, which enables the easy migration and spread of cancer cells.