Abstract 1121: Validation of FOXR2 and ARHGAP36 as oncogenes in medulloblastoma

Abstract

Abstract We are working to validate two putative oncogenes in medulloblastoma (MB), ARHGAP36 and FOXR2. These genes were identified as MB drivers using a Sleeping Beauty mutagenesis screen in mice and are overexpressed in subsets of human MB. We are using gain (GOF) and loss of function (LOF) studies both in vitro and in vivo to understand the roles of FOXR2 and ARHGAP36 in MB genesis. In GOF studies, both genes individually drove anchorage independent growth in a mouse cerebellar progenitor cell line (C17.2) and a human MB cell line (ONS76). When overexpressed individually in C17.2 cells, both FOXR2 and ARHGAP36 drove tumor formation in the flank of NU/J mice. We are also using an orthotopic injection model with C17.2 cells overexpressing either ARHGAP36 or FOXR2 individually to determine if these genes drive tumor formation in a more relevant setting. RNA sequencing and reverse-phase protein array analyses were also performed on WT and C17 cells overexpressing each oncogene to identify their effects in an unbiased manner. We are working to validate those effects using RT-PCR and Western analysis. In LOF studies, the CRISPR/Cas system is being used to create mutations in either the ARHGAP36 or FOXR2 locus in human MB cell lines (ONS76, MED8A, Daoy). This has been accomplished with ARHGAP36 in ONS76 cells, and we are currently characterizing those cells using proliferation, soft agar colony formation, and tumor formation assays. Lastly, we are working to create GOF and LOF mouse models of both FOXR2 and ARHGAP36 to characterize their oncogenic potential in vivo. We identified ARHGAP36 and FOXR2 as putative oncogenes in MB and our findings may elucidate novel targets for therapeutic efforts aimed at treating patients with MB. Citation Format: Pauline Jackson, Alex Larsson, Paramita Das, David Largaespada. Validation of FOXR2 and ARHGAP36 as oncogenes in medulloblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1121.