EXPRESSION OF PERIPHERAL-TYPE BENZODIAZEPINE RECEPTOR AND DIAZEPAM-BINDING INHIBITOR IN HUMAN ASTROCYTOMAS - RELATIONSHIP TO CELL-PROLIFERATION

The expression of peripheral-type benzodiazepine receptor (PER) and diazepam binding inhibitor (DBI) were studied in human astrocytic tumors using immunocytochemistry and in situ hybridization. Both PER and DBI were prominently expressed in neoplastic cells, whereas in normal brain their amount was low or undetectable. Immunocytochemical double staining demonstrated that PER and DBI were present in the same cells, suggesting that DBI may act in an autocrine manner in these cells. Analysis of 86 cases showed that PER expression was statistically significantly associated with tumor malignancy grade (P = 0.004) and the proliferative index as determined by immunocytochemistry with the MIB-1 antibody (P = 0.004). Patients having tumors with high levels of PBR-immunoreactive cells had a shorter life expectancy than patients whose tumors showed lower PER contents (P = 0.024). In conclusion, these results show that PER expression is higher in neoplastic cells than in normal brain tissue. They also suggest that PER immunocytochemistry might be useful in evaluating malignancy in brain tumors.