MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF AN UNDIFFERENTIATED SOFT-TISSUE SARCOMA CELL-LINE AND DERIVATIVE CLONES

From an undifferentiated soft tissue sarcoma (STS) a cell line designa ted US8-93 has been established. At subcloning the cell line US8-93 th ree different lines (US8-93A, B and C) could be set up. In a subsequen t study characteristics for ultrastructure, growth, cell cycle distrib ution, karyotype, protein overexpression detected by immunohistochemis try (IHC) and p53 mutational status were determined. The cell line US8 -93 as well as subclones contain mainly bipolar spindle-shaped cells a nd additionally some polygonal and multinucleated cells. Cells possess the characteristics of primitive mesenchymal cells based on their pos itive reactions with anti-vimentin and negative reactions for desmin, cytokeratin, myoglobin, S100, and NSE, implying a classification as an undifferentiated STS. Cytogenetic analysis revealed nearly diploid ce lls with several structural and numerical aberrations for chromosomes 1, 3, 4, 6, 9, 10, 12, 13, 15 and 18. IHC positivity was found for the tumor suppressor proteins p53 and Rb, the oncogene products Bcl-2, K- ras, N-ras, P-glycoprotein Mdr-1 and MDM-2. In the p53 gene a nonsense mutation in exon 4 was detected, that was confirmed in the original p rimary tumor and in three derivative clonal lines. The described STS c ell line represents a valuable supplementation to the relatively small number of human STS cell lines currently available and may also provi de a good in vitro model for studies of STS tumorigenesis in respect t o a mutated p53 gene.