Abstract 3816: DNA variation at BARD1 predicts response to aurora kinase inhibition in neuroblastoma.

Abstract

Abstract Background: Neuroblastoma remains responsible for a disproportionately high number of pediatric cancer deaths, necessitating novel treatment approaches. Our lab has previously reported DNA variations in the BRCA1-associated RING domain 1 (BARD1) gene to be significantly associated with high-risk neuroblastoma in an ongoing genome-wide association study (Capasso Nat Gen 2009). The expression of an oncogenic isoform, BARD1β, correlated with this disease associated common variation, and isoform specific depletion showed differential growth inhibition in a risk haplotype dependent manner (Bosse Can Res 2012). Furthermore, this isoform was shown to bind to and stabilized aurora kinase A and B in neuroblastoma cells, suggesting a mechanism for its oncogenicity and a potential therapeutic strategy. Methods: Short interfering RNAs (siRNAs) targeting AURKA, AURKB and BARD1β were tested individually in a panel of neuroblastoma cell lines (n=8) stratified by risk haplotype. Cell growth was measured by real time cell electronic sensing (RT-CES), and mRNA knockdown was confirmed by quantitative PCR. The pharmacologic inhibitors MLN8237, a selective aurora kinase A inhibitor; AZD1152, a selective aurora kinase B inhibitor; and CCT137690, a pan-aurora kinase A and B inhibitor were tested in vitro in an expanded neuroblastoma cell line panel (n=10), and cell viability was measured with a CellTiter-Glo(R) Luminescent Cell Viability Assay. Results: AURKB knockdown resulted in a trend of greater growth inhibition in neuroblastoma cell lines harboring a BARD1 risk haplotype, directly correlating with growth inhibition following BARD1β knockdown (R2=0.57, p=0.03). AURKA depletion showed significant growth inhibition (mean inhibition=45%, p<0.0001), but no correlation with BARD1 genotype was observed. Aurora A kinase inhibition with MLN8237 resulted in significant cytotoxicity (IC50 30 -750nM), and further analysis of published studies using MLN8237 in vivo on murine xenograft models of neuroblastoma showed that the cell lines with the BARD1 risk haplotype had significantly greater tumor reduction with this single agent therapy. AZD1152 and CCT137690 were less potent inhibitors of growth (IC50 30nM-10mM and 250nM-3mM, respectively). Conclusion: Taken together, these data support a model of BARD1 acting in a pathway involving the aurora kinase proteins in neuroblastoma cells, suggesting that BARD1 genotypes have the potential to be a biomarker of aurora kinase inhibitor activity, but the associations are complex and unlikely to be binary predictors of sensitivity or insensitivity. These data support the continued investigation of MLN8237 in clinical trials for high-risk neuroblastoma and further exploration of the mechanisms by which DNA variation at BARD1 influences neuroblastoma oncogenicity and therapeutic vulnerabilities. Citation Format: Vanessa M. Pineros, Kris R. Bosse, Lori S. Hart, Sharon J. Diskin, JulieAnn Rader, John M. Maris. DNA variation at BARD1 predicts response to aurora kinase inhibition in 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 3816. doi:10.1158/1538-7445.AM2013-3816