The role of matrix metalloproteinases in squamous cell carcinomas of the head and neck

The ability of tumors to infiltrate the surrounding tissue is one of the major characteristics of a malignancy. This process is based on the tumors ability to destroy the extracellular matrix (ECM) including the basement membrane (BM). Several previous studies identified matrix metalloproteinases (MMPs), a family of zinc-dependent endopeptidases to be keyplayers in this process. Since then multiple investigations focused on the expression and activation levels of their extracellular regulators and to a lesser extent of their transcriptional modulators. However, the exact diagnostic and prognostic values of these regulators still remain unclear. Squamous cell carcinomas of the head and neck (HNSCC) are known for their infiltrative growth and there is strong evidence that at least some members of the MMP-family play a crucial role in this process. It turned out that MMP-2, -9, -13 and to a lesser extent MMP-7 are related to the metastatic potential of HNSCC but further studies will be required to establish the exact role of MMPs in HNSCC. This Review will discuss the current literature concerning the role of MMPs in HNSCC.