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 [PNET], 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 (alpha IR3) inhibited serum-free growth. These data demonstrate that IGF-I expression is a property of neuroectodermal tumors with a t(11;22) translocation and that interruption of an IGF-I autocrine loop inhibits the growth of these tumor cells.
D Yee, R E Favoni, G S Lebovic, F Lombana, D R Powell, C P Reynolds, N Rosen
Guidelines: The Editorial Board will only consider letters that we deem relevant and of interest to our readers. We will not post data that have not been subjected to peer review, nor will we post letters that are essentially a reiteration of another letter. All accepted letters will be posted on our website within one week of acceptance. We reserve the right to edit any letter for length, content, and clarity. Authors of all accepted letters will be asked to preview any changes. Authors will be notified by e-mail if their letters were not accepted. As this is a final decision, no appeals will be considered.
Specific requirements: All letters must be 400 words or fewer. You may enter the letter as plain text or HTML. The author's name and e-mail address are required, and will be posted with the letter. All possible conflicts of interest must be noted, even if they are not posted. If you wish to include a figure (keep in mind that non-peer-reviewed data will not be posted), please contact the editors directly at email@example.com.