Tissue plasminogen activator is required for the growth, invasion, and angiogenesis of pancreatic tumor cells.
OBJECTIVE
Overexpression of tissue-type plasminogen activator (t-PA) in exocrine pancreatic tumors might be a determinant of the aggressive biological behavior of these tumors.


METHODS
Endogenous t-PA production was suppressed by antisense oligonucleotides or transcripts in CAPAN-1 and RWP-1 cell lines. Reciprocally, the t-PA non-expressing BxPC-3 and PANC-1 cells were stably transfected to overexpress t-PA. Recombinant t-PA and chemical inhibitors were also used on these cells. Clones were assayed for invasion and growth in vitro and in vivo.


RESULTS
In vitro, specific inhibition of t-PA expression or activity significantly inhibited the proliferation of t-PA-producing RWP-1, CAPAN-1, and SK-PC-1 cells. Antisense constructs were used to generate RWP-1 clones stably suppressed for t-PA expression (AS clones). These clones had a significantly reduced invasion and proliferation on plastic and in soft agar. The addition of recombinant t-PA rescued the growth of the AS clones to parental levels and was mitogenic for other independent pancreas cell lines. This effect did not require plasmin activity. In athymic mice, RWP-1 AS clones produced tumors fivefold smaller than control clones. AS tumors contained a significantly reduced number of Ki67-positive nuclei, fewer mitotic cells, and a remarkably reduced angiogenic network. Finally, the generation of tetracycline-repressed t-PA transfectants in PANC-1 cells confirmed the activity of t-PA in invasion and proliferation in vitro and in vivo.


CONCLUSIONS
t-PA, in addition to its known role in invasion, plays other critical roles in pancreas tumor progression, stimulating cancer cell proliferation and tumor-associated angiogenesis.
Díaz
Víctor M
VM
Unitat de Recerca Biomedica, Hospital Materno-Infantil, Hospitals Vall d'Hebron, Instituto de Biologia Molecular, Barcelona, Spain.
Planaguma
Jesús
J
Thomson
Timothy M
TM
Reventós
Jaume
J
Paciucci
Rosanna
R
D000818:Animals; D016375:Antisense Elements (Genetics); D001798:Blood Proteins / Q000494:pharmacology; D002448:Cell Adhesion / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D005341:Fibrinolysin / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000473:pathology / Q000503:physiopathology*; D010190:Pancreatic Neoplasms / Q000473:pathology / Q000503:physiopathology*; D010957:Plasmids; D010959:Tissue Plasminogen Activator / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000502:physiology
D016375:Antisense Elements (Genetics); D001798:Blood Proteins; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin