ヒト脳腫瘍におけるinsulin-like growth factor I （IGF-I）受容体の発現に関する検討—定量的autoradiography法によるIGF-Iおよびepidermal growth factor受容体の測定およびその比較

EXPRESSION OF INSULIN-LIKE GROWTH FACTOR I RECEPTORS IN HUMAN BRAIN TUMORS: COMPARISON WITH EPIDERMAL GROWTH FACTOR RECEPTOR BY USING QUANTITATIVE AUTORADIOGRAPHY

　抄録　定量的autoradiography法を用いて，ヒトgliomaにおけるinsulin-like growth factor I （IGF-I）やepidermal growth factor （EGF）の受容体発現の有無について検討した。その結果，高親和性IGF-I受容体がmedulloblastomaを含む全glioma例に存在し，特にglioblastomaに高濃度の発現傾向がみられた。また，EGF受容体はmedulloblastomaでは測定限界以下であったが，low grade astrocytomaにおいても対照群に比べ高濃度発現が認められた。このことは，EGFのみならず，IGF-Iもgliomaの増殖，分化に深く関与することを示唆し，殊にglioblastomaに高濃度のIGF-I受容休の発現傾向がみられることは，gliomaの悪性化に何らかの役割を果たしていると思われた。腫瘍における成長因子受容体の検索は，特異抗体やantagonistを用いた新たな治療法の開発に寄与すると思われる。

By using quantitative autoradiographic tech-niques, receptors for insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF) were analyzed in 13 samples of human brain tumors (4 low grade astrocytomas, 7 glioblastomas, 1 anaplatic ependymoma and 1 medulloblastoma). High number of specific binding sites for IGF-I and EGF were homogeneously present in tissue sections derived from glioblastoma. In low grade astrocytoma, relatively high numbers of bindingsite for EGF were observed, but there was no significant difference in concentrations of IGF-I binding sites between tumors and control cortex. In medulloblastoma, only IGF-I binding sites were present.

These observations might indicate that both IGF-I and EGF are involved in the growth modulation of human gliomas possibly through paracrine or autocrine mechanisms. Antagonists to growth factors or monoclonal antibody against those receptors could have the way for thera-peutic application for gliomas.