Establishment and characterization of a new Ewing's sarcoma cell line.

A new human Ewing's sarcoma cell line (CADO-ES1) was established from the malignant pleural effusion of a 19-year-old woman. These cells grew both anchorage dependently and anchorage independently. When cultured in bacteriologic dishes, they grew as tightly packed multicellular tumor spheroids; they were also capable of proliferating in soft agar. Flow cytometric DNA analysis demonstrated a nearly diploid DNA content (DNA index = 0.902). Chromosomal studies of cultured cells showed an isodicentric chromosome 8 in all examined cells, but t(11;22)(q24;q12), a translocation reported previously in Ewing's sarcoma, was not detected. Under normal culture conditions, no morphologic evidence of neural differentiation was detected. In addition, immunocytochemical studies showed that vimentin was intensely positive, whereas neurofilament (NF) and neuron-specific enolase (NSE) were weakly positive. Treatment with cyclic AMP (cAMP) induced pronounced morphologic evidence of neural differentiation and strong expression of NF in cultured cells. S-100 protein, glial fibrillary acidic protein (GFAP), desmin, cytokeratin, and epithelial membrane antigen were not detected immunohistochemically in either untreated or cAMP-treated cells, however. These data suggest that this cell line is derived from a highly undifferentiated neural cell with high chromosomal clonality, differentiating into neural features under certain conditions.