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 designated US8-93 has been established. At subcloning the cell line US8-93 three different lines (US8-93A, B and C) could be set up. In a subsequent study characteristics for ultrastructure, growth, cell cycle distribution, karyotype, protein overexpression detected by immunohistochemistry (IHC) and p53 mutational status were determined. The cell line US8-93 as well as subclones contain mainly bipolar spindle-shaped cells and additionally some polygonal and multinucleated cells. Cells possess the characteristics of primitive mesenchymal cells based on their positive 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 cells 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 primary tumor and in three derivative clonal lines. The described STS cell line represents a valuable supplementation to the relatively small number of human STS cell lines currently available and may also provide a good in vitro model for studies of STS tumorigenesis in respect to a mutated p53 gene.