Prognostic significance of Hsp-27 in astrocytic brain tumors: an immunohistochemical study.

Formalin-fixed paraffin-embedded tumor specimens from 95 patients with supratentorial astrocytic brain tumors were immunostained by a monoclonal antibody against the heat shock protein-27 (Hsp-27) using the streptavidin/peroxidase method. The immunohistochemical analysis was scored in a semiquantitative fashion incorporating both the intensity and distribution of specific staining (score): the immunohistochemical results were correlated with the histological grade of the tumors and patients' sex and age. Furthermore, Hsp-27 expression was studied in two groups into which the patients were further divided: group (a) previously untreated patients (n = 76) whose biopsy or surgical resection was related to their initial presentation and diagnosis and group (b) patients (n = 19) with reccurent disease who underwent radiotherapy and/or chemotherapy. Strong Hsp-27 cytoplasmic immunopositivity was observed in 42 out of 51 (82%) glioblastomas, in 8 out of 20 (40%) anaplastic astrocytomas and in 2 out of 24 (8%) astrocytomas. The mean Hsp-27 score was 45.2 in glioblastomas, 6.5 in anaplastic astrocytomas and 0.4 in astrocytomas. The expression of Hsp-27 immunoreactivity appeared to be independent of the age and sex of the patients. A non significant difference was defined between untreated patients and previously treated patients. Hsp-27 immunoreactivity was observed in the microvascular endothelial proliferations and in tumor blood vessels. Normal astrocytes were Hsp-27 negative. These findings indicate that, in contrast with the low Hsp-27 expression found in benign astrocytomas, the expression of Hsp-27 in a number of poorly differentiated tumors, including glioblastomas and anaplastic astrocytomas, is consistent and independent of previous treatment of the patients. We support the involvement of Hsp-27 in the growth of astrocytic brain tumors.