PRESENCE OF DOUBLE MINUTES AND MONOSOMY 17P IN XENOGRAFTED HUMAN OSTEOSARCOMAS

Cytogenetic analysis of 8 cases of xenografted human osteosarcomas are reported, including six newly diagnosed and two recurrent tumors. His tologically five were osteoblastic, two were chondroblastic, and one w as the microcellular type. All tumors were studied in short-term prima ry cultures between two and six days. Clonal and nonclonal abnormaliti es were present in the eight cases;four had a chromosome number in the hypotriploid range, two in the hyperdiploid, one in the hypodiploid, and one in the hypertetraploid range. All cases had complex karyotypes and the recognizable structural rearrangements clustered to chromosom e arms Ip, Iq, 3p, 5p, 6q, 11p, 13p, 14p, 15q, 16p, 16q, 20q, 21p, and 22q. Seven cases presented double monosomy 17 and six rumors showed d ouble minutes (dmin) or a homogeneously staining region (hsr). This fa ct has been described recently and its relation with the amplification of the MDM2 gene observed in osteosarcomas is as yet unknown.