ESTABLISHMENT AND CHARACTERIZATION OF A CLEAR-CELL SARCOMA (MALIGNANT-MELANOMA OF SOFT PARTS) CELL-LINE

A clear cell sarcoma (CCS) cell line, designated as NCS-1, was establi shed in monolayer culture from a xenograft line originating from a met astatic CCS. Marked karyotypic aberrations and tumorigenicity in nude mice revealed the malignant derivation of the NCS-1 cell line. These c ells contained abundant glycogen and were amelanotic by light microsco py. By electron microscopy, however, melanosomes in various developmen tal stages were seen, and some of them were partially melanized, The e lectron microscopic dopa reaction revealed the presence of tyrosinase activity. Enzyme-linked immunoadsorbent assay revealed that NCS-1 cell s expressed a 75-kDa glyco-protein which was identified as a marker of highly differentiated melanoma cells. From these results, NCS-1 cells were found to retain both cytochemical and morphological properties o f CCS. Application of NCS-1 cells to a panel of monoclonal antibodies recognizing melanocytic differentiation antigens showed that they corr esponded approximately to highly differentiated melanoma cells. In con clusion, the present study strongly supports the close relationship be tween CCS and malignant melanoma.