The cysteine protease legumain (asparaginyl endopeptidase, AEP) plays important roles in normal physiology but is also associated with several disorders, such as atherosclerosis, osteoporosis, cancer and neurodegenerative diseases.
Asparagine endopeptidase (AEP), also called legumain, is highly expressed in various solid tumors, promoting cancer cell invasion, migration, and metastasis.
Activities of both cysteine cathepsins and legumain, possible target enzymes associated with cancer cell invasion and metastasis, were down-regulated in cell homogenates following cystatin C uptake.
Although all the cancer tissues were positive for legumain, 2 staining patterns were observed in the cytoplasm: diffuse cytoplasmic and vesicular positivity.
Importantly, increased legumain expression was validated by real-time PCR and Western blots, correlated positively with an increased malignancy of ovarian tumors (P < 0.01).