1. ¹Department of Pediatrics, Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Research Foundation, University of Cincinnati College of Medicine, Cincinnati, OH, USA
2. ²Department of Pediatrics, Division of Developmental Biology, Cincinnati Children's Hospital Research Foundation, University of Cincinnati College of Medicine, Cincinnati, OH, USA
3. ³Department of Pediatrics, Division of Hematology/Oncology, Cincinnati Children's Hospital Research Foundation, University of Cincinnati College of Medicine, Cincinnati, OH, USA
4. ⁴Department of Pediatrics, Division of Pathology, Cincinnati Children's Hospital Research Foundation, University of Cincinnati College of Medicine, Cincinnati, OH, USA

Correspondence: Professor N Ratner, Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Research Foundation, 3333 Burnet Avenue, MLC 7013, Room S7.244, Cincinnati, OH 45229-3039, USA. E-mail: nancy.ratner@cchmc.org

⁵These authors contributed equally to this work.

Received 2 July 2009; Revised 1 September 2009; Accepted 23 September 2009; Published online 9 November 2009.

Abstract

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas without effective therapeutics. Bioinformatics was used to identify potential therapeutic targets. Paired Box (PAX), Eyes Absent (EYA), Dachsund (DACH) and Sine Oculis (SIX) genes, which form a regulatory interactive network in Drosophila, were found to be dysregulated in human MPNST cell lines and solid tumors. We identified a decrease in DACH1 expression, and increases in the expressions of PAX6, EYA1, EYA2, EYA4, and SIX1–4 genes. Consistent with the observation that half of MPNSTs develop in neurofibromatosis type 1 (NF1) patients, subsequent to NF1 mutation, we found that exogenous expression of the NF1-GTPase activating protein-related domain normalized DACH1 expression. EYA4 mRNA was elevated more than 100-fold as estimated by quantitative real-time PCR in most MPNST cell lines. In vitro, suppression of EYA4 expression using short hairpin RNA reduced cell adhesion and migration and caused cellular necrosis without affecting cell proliferation or apoptotic cell death. MPNST cells expressing shEYA4 either failed to form tumors in nude mice or formed very small tumors, with extensive necrosis but similar levels of proliferation and apoptosis as control cells. Our findings identify a role of EYA4 and possibly interacting SIX and DACH proteins in MPNSTs and suggest the EYA4 pathway as a rational therapeutic target.