COEXPRESSION OF EGF RECEPTOR AND TGF-ALPHA MESSENGER-RNA AND PROTEIN OCCURS IN PRIMARY MENINGIOMAS

Meningiomas are benign brain tumors thought to arise by multi-step tum origenesis, involving both the activation of proto-oncogenes and the l oss 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 f or EGFR, is thought to act through autocrine stimulation of EGFR prese nt on the same and adjacent cells. Northern blot analysis revealed exp ression of EGFR mRNA in 9 of 11 (82%), and TGF alpha mRNA in 2 of 11 ( 18%), primary meningioma specimens. III situ hybridization verified EG FR and TGF alpha gene expression by meningioma cells. Immunocytochemis try using specific antibodies for EGFR and TGF alpha showed strong pos itivity amongst meningeal cells in the same meningioma samples. No EGF R or TGF alpha protein was detected in a sample of normal meninges. Th ese data indicate that the autocrine coexpression of EGFR and TGF alph a mRNA and protein may occur in only a small proportion of primary men ingiomas.