Cytogenetic, morphologic and oncogene analysis of a cell line derived from a heterologous mixed mullerian tumor of the ovary.

A cell line was established from a mixed mullerian tumor of the ovary and designated LN1. Histopathologic analysis of the fresh tumor specimen demonstrated a highly aneuploid heterologous tumor comprised of undifferentiated mesodermal components with carcinomatous cells present as a smaller population. Long-term in vitro culture resulted in the establishment of a cell line that exhibits an epithelial-like morphology and expresses epithelial antigens cytokeratin, epithelial membrane antigen, and carcinoma antigen TAG-72. These cells also express mesenchymal intermediate filaments, vimentin, and desmin. Karyotypic analysis revealed a basic triploid pattern with multiple chromosomal abnormalities, most notably an isochromosome of the short arm of five present in three copies. Analysis of oncogene expression revealed that LN1 cells constitutively express mRNA for c-ras, c-erbB2, and p53. The expression of mRNA for cellular oncogenes correlated with the presence of corresponding oncoproteins, p21H-ras, p21K-ras, and p185erB2 and mutant p53 protein. In summary, coexpression of epithelial and mesenchymal antigens by LN1 cells lends support to the hypothesis that epithelial and mesenchymal elements comprising mixed mullerian tumors of the ovary are derived from a common stem cell precursor. Furthermore, this cell line represents a functional in vitro model to evaluate the biologic activities of these unusual and highly aggressive ovarian malignancies.