Matrix Metalloproteases in Breast Cancer

As breast cancer continues to be a considerable burden, claiming numerous lives worldwide every year, researchers are striving to unravel molecular targets in the tumor microenvironment (TME) and associated pathways to devise novel therapeutic strategies for improving the prognosis of breast cancer patients. Proteases, which are essential for the breakdown of various proteins under normal homeostatic conditions, often lead to detrimental effects in cancer, such as increased tumor progression, invasion, and metastasis. It has recently been discovered that proteases effectuate these phenomena by breaking down extracellular matrix (ECM) components and altering various signal transduction pathways. In the TME, different types of cells, including cancer cells and infiltrating immune cells, produce matrix metalloproteases (MMPs), which constitute a distinct class of zinc-dependent endopeptidases. They predominantly cleave ECM components and modulate signaling pathways associated with cell growth, proliferation, apoptosis, and epithelial-mesenchymal transition (EMT). In this chapter, we specifically explore the role of MMPs in breast cancer, analyze the associated signal transduction pathways, and delineate MMP-targeted therapies for treating breast cancer.