Background. Cysteine proteases (cathepsin B [CATB] and cathepsin L [CA
TL]), the serine protease urokinase-type plasminogen activator (UPA),
and plasminogen activator inhibitor type-1 (PAI-1) are thought to play
an important part in cancer invasion and metastasis. The aims of this
study were to measure CATB, CATL, UPA, and PAI-1 in gastric cancer (G
C) and normal mucosa distant from the tumor (NORM); to evaluate whethe
r tissue levels are related to tumor stage, grade, or histotype; to as
sess their prognostic relevance; and to examine UPA and PAI-1 expressi
on immunohistochemically. Methods. Gastric cancer and NORM samples wer
e obtained from 25 patients with gastric cancer patients undergoing su
rgery (17 males, 8 females; mean age, 62 years; range, 31-84 years). A
ntigen concentrations were measured using the enzyme-linked immunosorb
ent assay method. Immunohistochemistry was performed using monoclonal
UPA and PAI-1 antibodies. Results. Significantly higher antigen levels
were found: (1) in GC vs. NORM (CATB, CATL, UPA, PAI-1) tissues; (2)
in GC with versus without metastasis (CATB, CATL, UPA); (3) in poorly
or moderately versus well differentiated GC; and (4) in diffuse versus
intestinal-type GC (CATB, CATL). Urokinase-type plasminogen activator
, PAI-1 and CATB levels had a significant prognostic impact. Cancer an
d stromal cells, showed immunoreactivity to anti-UPA and anti-PAI-1 an
tibodies. Conclusions. These results confirm the important role of CAT
B, CATL, UPA and PAI-1 in gastric cancer progression. Higher levels ar
e detected in GC with metastases, poorer differentiation, and diffuse
histotype, thus identifying patients with a worse prognosis.