Abstract 3822: COUP-TF1 is a novel biomarker of therapy response in high-risk neuroblastoma.

High-risk neuroblastoma (HR NB) is a lethal pediatric solid tumor derived from sympathetic neuroblasts. Most NBs take up the norepinephrine analogue 131I-meta-iodobenzylguanidine (MIBG) that is used radiologically to stage disease. Results from a Children9s Oncology Group HR NB trial showed patients with MIBG positive NB at diagnosis had worse overall survival compared to patients with MIBG negative NB (3 year OS: 65% vs 85%; Parisi 2010) but biologically we do not know why. MIBG (-) NBs are more undifferentiated pathologically and often fail to secrete the catecholamines HVA and VMA. We hypothesized that MIBG (-) and MIBG (+) HR NBs arise at different stages of neuroblast development and thus harbor different gene expression profiles that affect therapy response. We interrogated published microarrays (GSE19724, GSE3960) of primary HR NBs for gene expression changes based on norepinephrine transporter (NET) expression as NBs take up MIBG through this neural transporter. Twenty-one genes had > 3-fold significant change in expression based on NET expression. Genes involved in neural development (ALK, PHOX2B, TLX2, DBH, DDC) were significantly decreased in NET “low” NBs, supporting our hypothesis. NET “low” NBs also had a >3-fold increase in COUP-TF1, a transcription factor necessary for retinoic acid (RA) induced differentiation in some cancers. COUP-TF1’s role in NB is unknown. Microarrays containing prognostic data confirmed HR NBs with medium/high COUP-TF1 expression had superior patient survival compared to those with low COUP-TF1, independent of NET (p=.0004, http://home.ccr.cancer.gov/oncology/oncogenomics). In vitro, NB cell lines with high COUP-TF1 protein (SMS-SAN) were very sensitive to RA induced differentiation and shRNA inhibition of COUP-TF1 in SMS-SAN caused RA resistance. Similarly, overexpression of COUP-TF1 restored RA sensitivity in RA resistant, low COUP-TF1 expressing IMR5. RA treatment increased COUP-TF1 expression in NB coincident with RARβ induction, suggesting COUP-TF1 is critical to RA response. shRNA inhibition of COUP-TF1 (shCOUP) rendered SMS-SAN resistant to doxorubicin, with SMS-SAN-shCOUP growing in doxorubicin doses that killed > 70% of wild type SMS-SAN, suggesting COUP-TF1 is necessary for cytotoxic response as well. We have identified a transcription factor that is associated with improved patient survival and in vitro studies suggest this is through mediation of therapy response. COUP-TF1 enhances RA induced differentiation in NB and we are the first to show COUP-TF1 also mediates cytotoxic response in cancer. This supports using COUP-TF1 as a biomarker for therapy response to improve risk stratification and treatment choice in HR NB. If COUP-TF1 impacts prognosis through chemosensitization and RA pathway effects, efforts to define the mechanism and therapeutically enhance COUP-TF1 expression will be critical to reverting therapy resistance to improve patient survival. Citation Format: Haneen Abdella, Srilatha Nalluri, Susan K. Peirce, Kelly C. Goldsmith. COUP-TF1 is a novel biomarker of therapy response in high-risk neuroblastoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3822. doi:10.1158/1538-7445.AM2013-3822