Neutrophil elastase and cancer.

This mini-review summarizes our recent experimental and clinical studies on neutrophil elastase (NE) and cancer based on our original view point. Neoplasms metastasize as a result of a complex series of events. This process requires various degradative enzymes including proteases. NE has broad substrate specificity under physiological conditions, and excessive NE results in digestion of not only elastin, but also other extracellular matrix proteins. Several cell lines from human breast cancer and human lung cancer produce immunoreactive NE. The amount of immunoreactive NE in tumor tissue is an independent prognostic indicator of patients with breast cancer and lung cancer. Furthermore, a specific NE inhibitor completely suppressed growth of cancer cells transplanted into severe combined immunodeficiency mice. The use of NE inhibitor would seem to be a promising way to prevent the invasion and metastasis of cancer.