[The expression of plasminogen activator inhibitor-1 (PAI-1) gene in human astrocytomas].

OBJECTIVE

To investigate the expression of PAI-1 gene and its clinical significance in human astrocytomas.

METHODS

The mRNA and protein expression of PAI-1 were examined with Northern blot hybridization and ABC immunohistochemical methods in 36 cases of astrocytomas. The correlation between PAI-1 expression with clinicopathologic factors were studied.

RESULTS

All astrocytoma tissues expressed 3.0 kb and 2.2 kb transcripts of PAI-1 mRNA. The PAI-1 mRNA level in high grade astrocytomas were considerably higher than that in low grade astrocytomas (P < 0.01). Detectable levels of PAI-1 mRNA were not found in normal brain tissues. PAI-1 mRNA expression was positively correlated with necrosis (r = 0.51, P < 0.01), micro-blood vessel quantity (r = 0.33, P < 0.01) and brain edema (r = 0.27, P < 0.01) respectively. There was no correlation between PAI-1 mRNA expression and tumor size, sex or age of patients. Immunohistochemical staining for PAI-1 showed the distribution of PAI-1 protein was mainly in tumor cells of high grade astrocytomas, particularly in abundant areas of vascular proliferation and in remnant tumor cells surrounding necrotic foci, whereas it was only weakly expressed in low grade astrocytomas.

CONCLUSION

The expression of PAI-1 gene was closely associated with grade, necrosis, angiogenesis and brain edema, which may provide a molecular marker for determining the malignant degree of astrocytoma.