Tumor-associated trypsin participates in cancer cell-mediated degradation of extracellular matrix.
We have recently demonstrated that many cancer cell lines produce a novel trypsinogen isoenzyme called tumor-associated trypsinogen 2 (TAT-2). It was found during a search of the target protease for tumor-associated trypsin inhibitor (TATI). We now show that degradation of subendothelial cell extracellular matrix (ECM) by four different cell lines (COLO 205 colon carcinoma, K-562 erythroleukemia, CAPAN-1 pancreatic carcinoma, and HT 1080 fibrosarcoma) can be partially inhibited by TATI or neutralizing trypsin antibodies. When cells were cultured in serum-free medium on ECM, TATI and trypsin antibodies inhibited the release of immunoreactive fibronectin fragments from ECM by 47-54 and 40%, respectively. Degradation of isotopically labeled ([3H]serine, [3H]proline, and [35S]sulfate) ECM was also significantly prevented by TATI. At its maximum, it exerted a 57% inhibition on the degradation of [3H]serine-labeled ECM. Plasminogen added exogenously to the culture medium further potentiated the proteolysis of ECM. Interestingly, addition of enteropeptidase, an activator of TAT-2, also enhanced cell-mediated proteolysis as assessed by degradation of purified fibronectin coated onto the surface of wells. Immunoblot analysis showed that enteropeptidase-mediated proteolysis generated a pattern of fibronectin fragments similar to that obtained by digestion of purified fibronectin by TAT-2. These results demonstrate the existence of a proteolytic system in tumor cells which is dependent on the activation of TAT-2. We suggest that TAT-2 is involved in a protease cascade-stimulating tumor cell invasion and degradation of extracellular matrix.
Koivunen
E
E
Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Finland.
Ristimäki
A
A
Itkonen
O
O
Osman
S
S
Vuento
M
M
Stenman
U H
UH
D005109:Extracellular Matrix / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D009361:Neoplasm Invasiveness; D009369:Neoplasms / Q000201:enzymology*; D014357:Trypsin / Q000502:physiology*; D014361:Trypsin Inhibitors / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000201:enzymology
D005353:Fibronectins; D014361:Trypsin Inhibitors; D014357:Trypsin