MOLECULAR CHARACTERIZATION AND LIPOSOMAL TRANSFECTION OF A P53-MUTATED CELL-LINE ESTABLISHED FROM A POORLY DIFFERENTIATED LEIOMYOSARCOMA

A human cell line LMS6-93 has been established from a leiomyosarcoma ( LMS). Characteristics for ultrastructure, growth characteristics, cell cycle distribution, karyotype, protein expression detected by immunoh istochemistry (IHC), p53 mutational status and liposomal transfection behaviour were studied and determined. The primary tumor was clearly p ositive for cc-smooth muscle type actin and desmin in moderately diffe rentiated areas and indicated a loss of myogenic differentiation in ot her regions and therefore was classified as a poorly differentiated LM S. The cell line LMS6-93 contains mainly polymorphic spindle shaped or polygonal tumor cells which possess the characteristics of primitive mesenchymal cells, based on their morphology and positive reaction wit h an antibody to vimentin. IHC staining for S100, synaptophysin A, NSE , neurofilament proteins and cytokeratins were negative. Cytogenetic a nalysis revealed in the cell line diploid karyotypes comparatively clo se to several structural and numerical aberrations for chromosomes 2, 5, 6, 9, 10, 12, 14, 17, 18, 20, 22, and Y. IHC positivity was found f or the tumor suppressor protein Rb and the oncogene product MDM2. In a p53 mutational analysis a 1 bp insertional mutation in exon 6 (G inse rtion in codon 215) was detected and confirmed in the original primary tumor. The other p53 allele appears to be wild-type as indicated in W estern hybridization. Using different cationic lipid formulations comp lexed with a reporter expression vector (GFP) successful transfection into LMS6-93 cells was observed. The highest transfection rates (20-30 % GFP expression in the viable cell population) were obtained with lip ofectin. These results suggest that LMS6-93 functions as a good in vit ro model for transfection studies on an LMS cell line carrying a heter ozygous p53-frameshift mutation.