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 monocl onal antibody against the heat shock protein-27 (Hsp-27) using the str eptavidin/peroxidase method. The immunohistochemical analysis was scor ed in a semiquantitative fashion incorporating both the intensity and distribution of specific staining (score); the immunohistochemical res ults were correlated with the histological grade of the tumors and pat ients' sex and age. Furthermore, Hsp-27 expression was studied in two groups into which the patients were further divided: group (a) previou sly untreated patients (n=76) whose biopsy or surgical resection was r elated to their initial presentation and diagnosis and group (b) patie nts (n=19) with recurrent disease who underwent radiotherapy and/or ch emotherapy. Strong Hsp-27 cytoplasmic immunopositivity was observed in 42 out of 51 (82%) glioblastomas, in 8 out of 20 (40%) anaplastic ast rocytomas 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 a strocytomas. The expression of Hsp-27 immunoreactivity appeared to be independent of the age and sex of the patients. A non significant diff erence was defined between untreated patients and previously treated p atients. Hsp-27 immunoreactivity was observed in the microvascular end othelial proliferations and in tumor blood vessels. Normal astrocytes were Hsp-27 negative. These findings indicate that, in contrast with t he low Hsp-27 expression found in benign astrocytomas, the expression of Hsp-27 in a number of poorly differentiated tumors, including gliob lastomas and anaplastic astrocytomas, is consistent and independent of previous treatments of the patients. We support the involvement of Hs p-27 in the growth of astrocytic brain tumors.