C-ERBB-2 IN ASTROCYTOMAS - INFREQUENT OVEREXPRESSION BY IMMUNOHISTOCHEMISTRY AND ABSENCE OF GENE AMPLIFICATION BY FLUORESCENCE IN-SITU HYBRIDIZATION

Recent studies suggest that aberrations of c-erbB-2 may be involved in astrocytic brain rumours. We screened immunohistochemically c-erbB-2 protein (p185) expression in 94 astrocytic grade 1-4 neoplasms of the brain. The amplification of the c-erbB-2 oncogene was investigated in protein overexpression cases by dual colour fluorescence in situ hybri disation (FISH). p185 overexpression was correlated with p53 and epide rmal growth factor receptor (EGFR) expression; as well as with clinico pathological features. Only two anaplastic (grade 3) astrocytomas and one gliobastoma (grade 4) showed overexpression of p185 protein by imm unohistochemistry (monoclonal MAb1 antibody TA250), whereas none of th e grade 1-2 astrocytomas was positive. Interestingly, the expression o f p185 was confined solely to the cytoplasm of neoplastic astrocytic c ells and not to the cell membranes as found in malignancies with ampli fication of the c-erbB-2 oncogene. Two the three overexpression cases were also positive by EGFR. No amplification of the c-erbB-2 gene was observed by FISH in the three rumours with immunohistochemical p185 ov erexpression or seven weakly positive/negative tumours. In conclusion, our results suggest that p185 overexpression is infrequent in astrocy tomas, that it is of no important diagnostic or prognostic value and t hat c-erbB-2 oncogene amplification is not seen in the few cases in wh ich there is overexpression.