INSULIN-LIKE GROWTH-FACTOR-II IN THE PATHOGENESIS OF HUMAN NEUROBLASTOMA

Insulin-like growth factor II (IGF-II) acts as an autocrine growth fac tor for many in vitro tumor cell lines including neuroblastoma. To exa mine the role of IGF-II in tumor biology we have analyzed a total of 5 6 primary neuroblastoma tumor samples for the presence of IGF-II using a combination of mRNA and protein analysis. A group of 21 samples was examined for the presence of IGF-II mRNA by slot blot and a separate group of 37 samples was examined for IGF-II immunoreactivity. IGF-II w as detected in 48% of the total tumor specimens analyzed. IGF-II immun oreactivity was observed in cells resembling developing neuroblasts an d was confined to the cytoplasm and proximal neurites. The appearance of IGF-II mRNA and protein did not correlate with tumor prognostic fea tures including stage, histology, or N-myc amplification. These data s uggest that the expression of IGF-II is not confined to a specific sta ge of the disease but may have a broader role in the pathogenesis of n euroblastoma.