INSULIN-LIKE GROWTH-FACTOR-1 (IGF-1) RECEPTORS, IGF-1, AND IGF-2 ARE EXPRESSED IN PRIMARY HUMAN SARCOMAS

A variety of bone and soft-tissue sarcoma cell lines have been shown t o express receptors for insulin-like growth factor-1 (IGF-1) and to re spond mitogenically to IGF-1 in vitro, We have recently demonstrated e vidence of IGF dependency in murine MGH-OGS and RIF-1 sarcomas, which express relatively high and intermediate levels of IGF-1 receptors, Ov erexpression of IGF-1 receptors and/or IGF ligands might, therefore, b e a mechanism by which human bone and soft-tissue sarcomas obtain a pr oliferative advantage over normal adjacent tissues, Therefore, we eval uated 29 human sarcoma specimens for expression of IGF-1 receptor, IGF -1, and IGF-2 by competitive binding and reverse-transcription polymer ase chain reaction (RT-PCR) techniques. Twelve of 29 sarcomas examined by RT-PCR and 13 of 25 examined by affinity-binding studies expressed IGF-1 receptor levels equal to or greater than levels determined in t he IGF-responsive MCF-7 breast carcinoma cell line, DNA amplification of the IGF-1 receptor gene was not identified in this group of sarcoma s that expressed high levels of IGF-1 receptor, Evaluation of IGF liga nd expression by RT-PCR revealed that 22 of 28 sarcomas expressed IGF- 1 levels comparable to or above those of the RPMI 7666 control line, a nd 17 of 27 sarcomas expressed significant levels of IGF-2 compared wi th the NCI H69 control cell line, These results suggest that autocrine /paracrine regulatory mechanisms might be responsible for the growth o f some sarcomas.