What is Matrix Metalloproteinase 9?

Matrix metalloproteinase 9 (MMP9) is an enzyme found primarily in humans, encoded by matrix metalloproteinase (MMP) genes. Human proteins and enzymes from the MMP family breakdown cellular material as part of normal tissue remodeling and other biological processes. MMP enzymes also contribute to the progression of certain diseases by degrading collagens, breaking down extracellular matrixes, and assisting metastasis. Researchers believe MMP9 plays an integral role in the metastasis of certain types of cancers, as well as degrading collagens in certain types of arthritis.

While matrix metalloproteinase 9 is a naturally occurring, productive enzyme necessary for tissue repair and other processes, it is most commonly associated with the progression of cancer. Specifically, MMP9 breaks down the basement membranes of cells, giving tumors more space to grow. Cancer cells help direct MMP9 to degrade collagen IV, allowing the cancer to migrate, resulting in metastasis. In short, the natural purpose of such enzymes becomes beneficial to harmful cells.

For better study, researchers group MMP genes into four primary categories based on the function and purpose of each gene and the proteins or enzymes it produces. These categories are collagenases, gelatinases, stromelysins, and membrane types. In terms of matrix metalloproteinase 9, this enzyme falls primarily in the gelatinases category of MMPs. The MMP9 gene also conforms to certain behavioral and functional criteria of collagenases.

In scientific research, matrix metalloproteinase 9 also carries such names and classifications as Gelatinase B, 92 kDa Type IV collagenase, and 92 kDa gelatinase. Additional names include collagenase Type IV and collagenase Type IV-B. The HUGO Gene Nomenclature Committee (HGNC) assigned matrix metalloproteinase 9 the symbol MMP9 to replace the previous symbol of CLG4B. Official symbols provide consistency among researchers working in different laboratories, countries, and languages.

Looking at human chromosomes and DNA, the matrix metalloproteinase 9 gene is found on Chromosome 20. As listed by the HGNC, the exact location is 20q12-q13. Such coordinates indicate the gene's location on the 20th chromosome, in the region between q12 and q13. Consequently, researchers have found amplifications in this genetic area with regard to breast and ovarian cancer patients. Other studies link this genetic area with pituitary tumors, pseudohypoparathyroidism, and diabetes.

Structurally speaking, MMP9 bears striking resemblances to MMP2, another MMP gene scientist believe helps in cancer metastasis. In terms of homology, or the similarity of two structures, the amino acid sequences of MMP9 and MMP2 is such that both are commonly linked to aggressively invasive cancers. Both MMP9 and MMP2 enzymes degrade extracellular matrix proteins, with highly elevated expression of both appearing in cancers such as pancreatic, breast, and colorectal.