Expression of epidermal growth factor receptors and c-erbB-2 proteins in human astrocytic tumors

Tumorigenesis is the result of sequential or multiple genetic alterations. The overexpression or amplification of various oncogenes in diverse human brain tumors have been observed. While numerous studies on the immunohistochemical demonstration of EGFR-overexpression have been reported, little has been found in the literature about the c-erbB-2 protein in human astrocytic tumors. In the present study, we evaluated the expression of EGFR and c-erbB-2 protein in 33 astrocytic tumors with immunohistochemistry. According to the World Health Organization brain tumor classification, the study included 9 low-grade astrocytomas (grade 2), 15 anaplastic astrocytomas (grade 3), and 9 glioblastomas multiforme (grade 4). The positive EGFR immunoreactivity was detected in 28 (85%) of 33 tumors. The expression of EGFR increased with the grade of malignancy in low-grade astrocytomas (67%), anaplastic astrocytomas (87%), and glioblastomas (100%). For the expression of c-erbB-2 protein, 17 (51.5%) of 33 tumors were positive immunostain, including 3 low-grade astrocytomas (37.5%), 9 anaplastic astrocytomas (81.8%), and 5 glioblastomas (62.5%). Different degrees of immunoreactivity for c-erbB-2 protein were found in variant grades of astrocytomas. However, the positive immunostain of EGFR displayed moderate or strong reactivity. The coexpression of EGFR and c-erbB-2 protein was found in 17 (15.5%) of 33 tumors. The results emphasize that the overexpression of EGFR parallels astrocytoma progession and higher frequency of c-erbB-2 immunoreactivity was seen in snaplastic astrocytomas and glioblastomas than in low-grade astrocytomas.