Expression of TGFalpha in meningiomas.

The objective of this study was to examine the expression of transforming growth factor alpha (TGFalpha), a mitogen for many cell types, and its receptor in basic subtypes of meningiomas as well as in meningiomas of varying grade. Formalin-fixed tissues from 26 meningiomas including 15 benign (5 meningothelial, 5 transitional, and 5 fibrous variants), 6 atypical, and 5 malignant examples were immunohistochemically examined for both TGFalpha protein and EGF/TGFalpha receptor protein. In addition, in situ hybridization (ISH) was used to detect TGFalpha mRNA expression. Immunostaining for TGFalpha was strongest in fibrous and atypical meningiomas, followed closely by transitional and malignant tumors. Only weak reactivity was observed in the meningothelial variant. In all but 4 tumors (2 fibrous, 2 atypical), ISH showed TGFalpha mRNA to be present, the signal being stronger in malignant than in conventional or atypical tumors. Lastly, immunostaining for EGF/TGFalpha receptor was positive in all tumors studied. Strong TGFalpha protein expression in meningiomas is commonly associated with fibrous morphology. Although the frequent detection of both TGFalpha protein and its mRNA, as well as of EGF/TGFalpha receptor within tumors of all type and grades, suggests that TGFalpha serves to promote tumor growth, its possible role in tumorigenesis or malignant progression is uncertain. In summary, demonstration of these substances is of no utility in the classification or grading of this common tumor because the differences in their expression among the various meningioma subtypes were not statistically significant.