Insulin - like Growth Factor I Expression by Tumors of Neuroectodermal Origin with the t ( 1 I ; 22 ) Chromosomal Translocation

Expression of insulin-like growth factor I (IGF-I) mRNA by some tumor cell lines of neuroectodermal origin has been described. To further explore the significance of IGF-I mRNA expression in these tumors, a more extensive analysis was performed. Most (9 of 10) neuroectodermal tumor cell lines with a t(11;22) translocation (primitive neuroectodermal tumor IPNETI, Ewing's sarcoma, esthesioneuroblastoma) expressed IGF-I mRNA, whereas 0 of 15 cell lines without the translocation (PNET, neuroblastoma) expressed IGF-I. Furthermore, inasmuch as all neuroblastoma (12 of 12) cell lines examined expressed IGF-II RNA, the pattern of IGF expression could distinguish between these closely related tumors. CHP-100, a PNET cell line with the t(11;22) translocation, was shown to secrete both IGF-I protein and an IGF binding protein, IGFBP-2. This cell line also expressed the type I IGF receptor mRNA, and blockade of this receptor by a monoclonal antibody (aIR3) inhibited serum-free growth. These data demonstrate that IGF-I expression is a property of neuroectodermal tumors with a t(l 1;22) translocation and that interruption of an IGF-I autocrine loop inhibits the growth of these tumor cells. (J. Clin. Invest. 1990. 86:1806-1814.)