SOMATOSTATIN AND VASOACTIVE-INTESTINAL-PEPTIDE RECEPTORS IN HUMAN MESENCHYMAL TUMORS - IN-VITRO IDENTIFICATION

Somatostatin and vasoactive intestinal peptide (VIP) have been shown t o be of diagnostic and therapeutic interest in several types of human epithelial tumors expressing the respective receptor, The present stud y evaluates the presence of somatostatin and VIP receptors in 64 prima ry or metastatic human mesenchymal tumors, In vitro receptor autoradio graphy on cryostat sections was performed using I-125-labeled [Tyr(3)] -octreotide as well as I-125-labeled [Leu(8),D-Trp(22),Tyr(25)]-somato statin-28 as radioligands for somatostatin receptors and I-125-labeled VIP as radioligand for VIP receptors. Somatostatin receptors were ide ntified in bone and vascular/perivascular tumors (3 of 3 osteosarcomas , 1 of 1 giant cell tumor, 2 of 2 angiosarcomas, and 4 of 4 hemangiope ricytomas), in 2 of 2 synovial sarcomas, in 2 of 5 histiocytomas, and in several muscle cell tumors (1 of 2 leiomyomas, 2 of 4 leiomyosarcom as, and 3 of 5 rhabdomyosarcomas) but were absent in 4 liposarcomas, 3 mesotheliomas, 3 chondrosarcomas, 10 Ewing sarcomas, 11 schwannomas, and 5 Wilms' tumors, VIP receptors were identified in 3 of 3 different iated liposarcomas, 2 of 2 angiosarcomas, ? of 4 hemangiopericytomas, 2 of 2 synovial sarcomas, 3 of 3 mesotheliomas, 5 of 5 Wilms tumors, a s well as in 2 of 5 histiocytomas, 1 of 2 leiomyomas, 2 of 4 leiomyosa rcomas, 3 of 3 intermediately differentiated rhabdomyosarcomas, and 1 of 3 osteosarcomas but not in chondrosarcomas, Ewing sarcomas, schwann omas, or undifferentiated rhabdomyosarcomas. The receptors were locate d on neoplastic cells, The somatostatin receptors were of high affinit y and of high specificity for biologically active somatostatin analogu es with high affinity for somatostatin-14 and somatostatin-28 as well as for octreotide, thus representing the sst(2) subtype; in a few case s of tumors having somatostatin receptors with low affinity for octreo tide, in situ hybridization techniques identified preferentially sst(1 ) mRNA. These data suggest that human mesenchymal tumors may be target s for somatostatin and/or VIP receptor ill vivo imaging; they may also be potential targets for somatostatin or VIP analogue therapy.