SPECIFIC EXPRESSION OF INSULIN-LIKE GROWTH FACTOR-II IN RHABDOMYOSARCOMA TUMOR-CELLS

Insulin-like growth factor II (IGF-II) acts as autocrine growth and mo tility factor in human rhabdomyosarcoma cell lines, and Northern blot analysis of tumor biopsy specimens from both alveolar and embryonal rh abdomyosarcoma demonstrates high levels of IGF-II mRNA expression. To determine the frequency and site of expression of IGF-II in these tumo rs, the authors performed in situ hybridization. All tumor specimens e xamined expressed the gene for IGF-II, and this expression was localiz ed to the tumor cells themselves and not to the surrounding stroma. Th ese data suggest that the IGF-II autocrine loop may be operating not o nly in vitro but also in vivo.