Coincidence of EGF receptors and somatostatin receptors in meningiomas but inverse, differentiation-dependent relationship in glial tumors.

Somatostatin (SS) receptors as well as EGF receptors have been shown to be present in various brain tumors such as meningiomas or glia-derived tumors. Using receptor autoradiography for both receptors, their localization on adjacent tumor sections was investigated and a correlation was attempted. In glia-derived tumors, there was an inverse relationship for the incidence of the two receptors in individual tumors: in a majority of cases (five of eight) of well-differentiated astrocytomas (I-II), SS receptors were present, but in none of the cases (zero of eight) EGF receptors were detected. In undifferentiated glioblastomas, the reverse situation was observed, no SS receptors were found (0 of 14) but EGF receptors were present in a majority of tumors (8 of 14). In astrocytomas III both types of receptors were normally seen. These data suggest that in glia-derived tumors, SS receptors are markers for the well-differentiated cases as opposed to EGF receptors. In meningiomas, SS receptors are found in all (27 of 27) tumors and EGF receptors in a large percentage (23 of 27) of the same tumors. However, in some cases a coincidence of both receptors on the same cell can be excluded. Furthermore, no effect of the SS analog SMS 201-995 on basal or EGF-stimulated growth of meningiomas in culture could be detected. Nevertheless, the coexistence of the two receptor types in meningiomas may be suggestive for a potential functional interaction between EGF and SS.