Abstract
Using the human ovarian cancer cell line HOCβI, we investigated the effects of urinary trypsin inhibitor (UTI) purified from human urine and its related synthetic peptides on the invasive potential of cancer cells in an in vitro assay. Invasiveness of tumor cells was determined using a modified Boyden chamber and a reconstituted basement membrane Matrigel. Three peptides (peptide 1, peptide 2, and peptide 3), representing sequences within UTI, were synthesized. HOCβI cells showed detectable and reproducible levels of expression of surface urokinaseβtype plasminogen activator (uPA) and plasminogen/plasmin by cell ELISAs and enzyme assays. UTI was found to strongly inhibit plasmin and human leukocyte elastase (HLE). Peptide 2 and peptide 3 specifically inhibit HLE and plasmin activity respectively. Peptide 1 has essentially no inhibitory activity. Treatment with UTI and peptide 3 reduces the incidence of invasion, whereas peptide 1 and peptide 2 do not affect invasion. The inhibitory effect on cell invasion is doseβdependent. The proteolytic enzyme plasmin may be involved in human ovarian cancer invasion in extracellular matrix degradation, and the use of UTI and peptide 3 that inhibits plasmin specifically reduces invasion by tumor cells. Β© 1994 WileyβLiss, Inc.