Expression of insulin-like growth factor-1 receptor in synovial sarcoma: Association with an aggressive phenotype

It is I Fell known that insulin-like growth factor-1 receptor (IGF-IR) play s a crucial role in proliferation and survival of transformed cells. Overex pression of TGF-IR in certain tumors has been reported, but there is still little known about its importance ia vivo. Here, we evaluated the IGF-IR le vels in 35 human synovial sarcoma tumors by Western blot and reverse transc riptase-PCR. In Ig of these, IGF-IR was detectable by Western blot, whereas 17 were nondetectable. There was a significant association between the amo unt of receptor proteins and mRNA transcripts. Furthermore, we found that t he IGF-1R Western blot-positive tumors were associated with a high incidenc e of lung metastases. Eleven of 18 (61%) developed metastases in the IGF-1R detectable group, compared to 3 of 17 (18%) in the nondetectable group (P = 0.01). Moreover, in the detectable group of IGP-1R, 12 of 18 (67%) exhibi ted a high tumor cell proliferative rate, compared to 5 of 16 (31%) in the nondetectahle group (P = 0.04). On the other hand, no association was found between the IGF-1R and type of fusion gene transcript (SYT-SSX1 or SYT-SSX 2). Our results suggest that expression of IGF-IR can underlie an aggressiv e phenotype in synovial sarcoma.