Expression of insulin‐like growth factors I and II and their receptor mRNAs in primary human astrocytomas and meningiomas; in vivo studies using in situ hybridization and immunocytochemistry

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Abstract
These studies demonstrate the expression of IGF-I, IGF-II, and their respective receptor mRNAs in primary human astrocytomas and meningiomas. In situ hybridization and immunocy-tochemistry have localized a strong expression of both IGF-I and IGF-II mRNAs and of their protein products in the tumor cells of astrocytomas and meningiomas. The expression of IGF-I and IGF-II mRNAs in the tumor cells was accompanied by the co-expression of their respective type-I and type-II IGF receptor mRNAs. Control, non-malignant human brain expressed IGF-I mRNA and IGF-I and IGF-II receptor mRNAs. There was no significant expression of IGF-II mRNA in the control brain specimens. Control pachymeninges (dura mater) expressed low levels of IGF-I mRNA and IGF-I receptor mRNA. There was no significant expression of IGF-II and IGF-II receptor mRNAs in pachymeninges. The co-expression of IGFs and their receptors in brain tumors may contribute in their development and maintenance. The strong inappropriate expression of IGF-II mRNA and its protein product in the tumor cells of astrocytomas and meningiomas, but not in normal brain specimens, may serve as molecular markers for the early detection of these tumors.