Abstract 5101: Characterization of a mouse model using the Sleeping Beauty transposon method to study diffuse intrinsic pontine glioma (DIPG)

Tumors in the brain-stem are difficult to diagnose and treat primarily owing to the location. Diffuse intrinsic pontine glioma (DIPG) is a fatal paediatric brain-stem tumor located in the ventral pons with 100% fatality. These tumors are often treated on the assumption that DIPGs are molecularly similar to adult high grade gliomas; however, they are molecularly distinct. The ACVR1G328V and the H3.1K27M mutations have been seen to recur in DIPGs and we hypothesis that these mutations play an important role in the disease progression. A mutation in the ACVR1 leads to kinase activation and induces downstream signal transduction by phosphorylation of Smads (1/5). H3.1K27M mutations cause genome wide H3K27me3 hypomethylation. We genetically engineered mouse DIPG models using the Sleeping Beauty Transposon (SBT) method to introduce plasmids containing NRASV12/p53-shRNA/ACVR1G328V or NRASV12/p53-shRNA/H3.1K27M into the 4th ventricle of 1-day old pups adjacent to the brain-stem. This generates DIPGs with specific genetic lesions. NRASV12 is a constitutively active oncogene belonging to the RAS family and p53-shRNA is a short hairpin for TP53 tumor suppressor gene. A control tumor model was engineered using plasmids encoding NRASV12 and p53-shRNA. Tumor growth is monitored periodically over time until animals become symptomatic due to tumor burden. At this time point, animals are euthanized and the tumors extracted. We characterized the model for upregulation of phospho-smad 1/5 and markers of neural precursor cells (nestin, Sox2, olig2, GFAP, PDGFRα). In conclusion, we generated a genetically engineered mouse model of DIPG which represents a novel platform to study the molecular pathways underlying disease pathogenesis. An understanding of the functions of mutations that lead up to the disease can help to develop novel therapies for DIPG. Citation Format: Ramya Ravindran, Flor M. Mendez, Felipe J. Nunez, Carl Koschmann, Marta Dzaman, Sheeba Pawar, Pedro R. Lowenstein, Maria G. Castro. Characterization of a mouse model using the Sleeping Beauty transposon method to study diffuse intrinsic pontine glioma (DIPG) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5101.