Abstract 3027: Role of BCOR in retinoblastoma

Abstract Retinoblastoma, which is usually initiated by the biallelic mutational inactivation of RB1, is the most common primary eye cancer in children and is fatal if left untreated. While retinoblastoma is initially sensitive to chemotherapy, it demonstrates a strong propensity for therapeutic escape, which is a leading cause of ocular morbidity, eye loss, and reduced survival. This problem is exacerbated by a poor understanding of how retinoblastoma progresses after the initial loss of RB1. Genomic analysis of primary retinoblastoma tumors has revealed the corepressor BCOR as the second most common target of mutations in retinoblastoma. Here, we explored the role of BCOR in normal retinal development to provide insights into its role in retinoblastoma. Mass spectrometry following immunoprecipitation of wildtype BCOR in primary retinoblastoma cells revealed novel BCOR interacting proteins in the Polycomb and MiDAC epigenetic complexes. Subsequent studies revealed potential functional consequences of BCOR mutation that may promote retinoblastoma progression. This work reveals new insights the role of epigenetic deregulation in retinoblastoma progression, and they nominate new candidates for therapeutic intervention. Citation Format: Michelle Garying Zhang, Dawn Owens, Stefan Kurtenbach, Jeffim Kuznetsov, Matthew Fields, Daniel Pelaez, James W. Harbour. Role of BCOR in retinoblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3027.