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Signature-based small molecule screening identifies cytosine arabinoside as an EWS/FLI modulator in Ewing sarcoma

Publication TypeJournal Article
AuthorsStegmaier, Kimberly, Wong Jenny S., Ross Kenneth N., Chow Kwan T., Peck David, Wright Renee D., Lessnick Stephen L., Kung Andrew L., and Golub Todd R.
AbstractBACKGROUND: The presence of tumor-specific mutations in the cancer genome represents a potential opportunity for pharmacologic intervention to therapeutic benefit. Unfortunately, many classes of oncoproteins (e.g., transcription factors) are not amenable to conventional small-molecule screening. Despite the identification of tumor-specific somatic mutations, most cancer therapy still utilizes nonspecific, cytotoxic drugs. One illustrative example is the treatment of Ewing sarcoma. Although the EWS/FLI oncoprotein, present in the vast majority of Ewing tumors, was characterized over ten years ago, it has never been exploited as a target of therapy. Previously, this target has been intractable to modulation with traditional small-molecule library screening approaches. Here we describe a gene expression-based approach to identify compounds that induce a signature of EWS/FLI attenuation. We hypothesize that screening small-molecule libraries highly enriched for FDA-approved drugs will provide a more rapid path to clinical application. METHODS AND FINDINGS: A gene expression signature for the EWS/FLI off state was determined with microarray expression profiling of Ewing sarcoma cell lines with EWS/FLI-directed RNA interference. A small-molecule library enriched for FDA-approved drugs was screened with a high-throughput, ligation-mediated amplification assay with a fluorescent, bead-based detection. Screening identified cytosine arabinoside (ARA-C) as a modulator of EWS/FLI. ARA-C reduced EWS/FLI protein abundance and accordingly diminished cell viability and transformation and abrogated tumor growth in a xenograft model. Given the poor outcomes of many patients with Ewing sarcoma and the well-established ARA-C safety profile, clinical trials testing ARA-C are warranted. CONCLUSIONS: We demonstrate that a gene expression-based approach to small-molecule library screening can identify, for rapid clinical testing, candidate drugs that modulate previously intractable targets. Furthermore, this is a generic approach that can, in principle, be applied to the identification of modulators of any tumor-associated oncoprotein in the rare pediatric malignancies, but also in the more common adult cancers.
Year of Publication2007
JournalPLoS Medicine
Volume4
Issue4
Pagese122 - e122
Date Published (YYYY/MM/DD)2007/04//
ISBN Number1549-1676
KeywordsAnimals, Antimetabolites, Antineoplastic, Antitumor, Bone Neoplasms, Cancer, Cell Line, Cytarabine, Drug Delivery Systems, Drug Screening Assays, Fluorescent Dyes, Fluorometry, Gene Amplification, Gene Expression Profiling, Gene Expression Regulation, Neop, Tumor