Coexpression of EGF receptor and TGF alpha mRNA and protein occurs in primary meningiomas

Meningiomas are benign brain tumors thought to arise by multi-step tumorigenesis, involving both the activation of proto-oncogenes and the loss of tumor suppressor genes. The EGFR gene encodes a protooncogenic tyrosine kinase growth factor receptor implicated in the pathogenesis of several types of cancer, including gliomas. TGF alpha, the ligand for EGFR, is thought to act through autocrine stimulation of EGFR present on the same and adjacent cells. Northern blot analysis revealed expression of EGFR mRNA in 9 of 11 (82%), and TGF alpha mRNA in 2 of 11 (18%), primary meningioma specimens. III situ hybridization verified EGFR and TGF alpha gene expression by meningioma cells. Immunocytochemistry using specific antibodies for EGFR and TGF alpha showed strong positivity amongst meningeal cells in the same meningioma samples. No EGFR or TGF alpha protein was detected in a sample of normal meninges. These data indicate that the autocrine coexpression of EGFR and TGF alpha mRNA and protein may occur in only a small proportion of primary meningiomas.