The involvement of various growth factors, growth factor receptors, and proliferative markers in the molecular pathogenesis of astrocytic neoplasms is being studied extensively. Epidermal growth factor receptor (EGFR) gene overexpression occurs in nearly 50% of cases of glioblastoma. As EGFR and MIB-1 are involved in mitogenic signal transduction and cellular proliferation pathway, we studied the correlation between the expression of EGFR and MIB-1 labeling index (LI) in astrocytic tumors.Materials and methods
We investigated the immunohistochemical expression of EGFR and MIB-1 using the appropriate monoclonal antibodies in 30 cases of astrocytic tumors of which fifteen were grade IV (glioblastoma), five cases were grade III or anaplastic astrocytomas, seven cases were grade II or diffuse astrocytomas, and only three cases were grade I or pilocytic astrocytomas.Results
Both the EGFR expression and MIB-1 LI increased with increasing grades of astrocytomas, with a significantly higher percentage of cells showing positive staining for both EGFR and MIB-1 in glioblastoma multiforme and grade III astrocytomas compared with grade II astrocytomas. The expression levels of both EGFR and MIB-1 were low in grade I or pilocytic astrocytomas.Conclusion
A significant correlation was found between EGFR overexpression and MIB-1 LI in grade II, grade III, and gliobastoma multiform. These may suggest that tumor proliferation, at least in the higher grades of astrocytomas, depends up to some extent on epidermal growth factor and EGFR-related signaling pathways.