Reduction of brain metastases in plasminogen activator inhibitor-1-deficient mice with transgenic ocular tumors.
Plasminogen activator inhibitor-1 is known to play a paradoxical positive role in tumor angiogenesis, but its contribution to metastatic spread remains unclear. We studied the impact of plasminogen activator inhibitor (PAI)-1 deficiency in a transgenic mouse model of ocular tumors originating from retinal epithelial cells and leading to brain metastasis (TRP-1/SV40 Tag mice). PAI-1 deficiency did not affect primary tumor growth or vascularization, but was associated with a smaller number of brain metastases. Brain metastases were found to be differentially distributed between the two genotypes. PAI-1-deficient mice displayed mostly secondary foci expanding from local optic nerve infiltration, whereas wild-type animals displayed more disseminated nodules in the scissura and meningeal spaces. SuperArray GEarray analyses aimed at detecting molecules potentially compensating for PAI-1 deficiency demonstrated an increase in fibroblast growth factor-1 (FGF-1) gene expression in primary tumors, which was confirmed by reverse transcription-polymerase chain reaction and western blotting. Our data provide the first evidence of a key role for PAI-1 in a spontaneous model of metastasis and suggest that angiogenic factors, such as FGF-1, may be important for primary tumor growth and may compensate for the absence of PAI-1. They identify PAI-1 and FGF-1 as important targets for combined antitumor strategies.
Maillard
C M
CM
Laboratory of Tumor and Development Biology, GIGA-Cancer, Tour de Pathologie (B23), University of Liège, Sart-Tilman, B-4000 Liège, Belgium. cmaillard@ulg.ac.be
Bouquet
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Petitjean
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Mestdagt
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Frau
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Jost
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Masset
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Opolon
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Beermann
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Abitbol
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Foidart
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Perricaudet
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Noël
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