SK-NEP-1 and Rh1 are Ewing family tumor lines.

The utility of preclinical models of childhood cancers is contingent upon reliably classifying them with their corresponding clinical counterparts. Molecular tools such as gene expression profiling allow researchers to confirm the similarity between clinical tumors and preclinical models. We describe the use of gene expression profiling to show that SK-NEP-1, a cell line previously thought to represent anaplastic Wilms tumor, is instead related to Ewing sarcoma. RT-PCR confirmed that SK-NEP-1 expresses EWS-FLI1 gene fusion transcripts characteristic of Ewing sarcoma, and DNA sequencing demonstrated the joining of exon 7 of EWS with exon 5 of FLI1 for these transcripts. Rh1, which was previously categorized as an alveolar rhabdomyosarcoma cell line, also has a gene expression profile suggestive of Ewing sarcoma and expresses EWS-FLI1 fusion transcripts in which exon 7 of EWS is joined with exon 6 of FLI1. These examples illustrate the importance of molecularly characterizing pediatric preclinical models used for testing new agents.