Cathepsin D

Cathepsin D is an estrogen-regulated, lysosomal acidic protease associated with tissue breakdown. Elevated levels of Cathepsin D are indicative of breast cancer recurrence in both node-negative and node-positive disease. Over-expression of Cathepsin D is also linked to tumorigenesis in prostate cancer and to aggressive forms of colorectal cancer and lung adenocarcinoma. In addition, Cathepsin D is associated with amyloid formation in Alzheimer's plaques as is possibly linked to lung tissue damage in cigarette smokers.