PM-20 COMPARATIVE PROTEOME PROFILING OF IN VIVO AND IN VITRO MODELS OF DIPG

BACKGROUND: Diffuse intrinsic pontine glioma is one of the least understood pediatric tumors. We have recently identified two molecular subtypes of DIPGs (sonic hedgehog and N-Myc). Despite the existence of in vitro and in vivo models of the disease, molecular characterization of these models and their proximity to representing the disease has not been established. Here, we have done comparative protein profiling of a number of DIPG primary cells as well as protein profiles of a single specimen and specimens derived from its' in vivo and in vitro models. METHODS: Human primary DIPG (n = 4) and normal human cells derived from hindbrain (n = 2) were processed for protein profiling. Total protein was extracted and analyzed using SDS PAGE, and analyzed using Q Exactive mass spectrometer (ThermoFisher, CA, USA). Data and pathway analysis were done using the SequestHT and Ingeniuty Pathway Analysis software respectively. Protein was also extracted from a single human DIPG specimen, and its' in vitro and in vivo derived cells. Protein profiling of this specimens was performed as described above. RESULTS: In this study, we first investigated the protein profiles of four widely used DIPG primary lines, all H3.3K27M mutant. We show the overlap of the protein profile of these cells with established human DIPG subtypes. We further investigated the protein profile of a single DIPG tissue to its in vitro and in vivo models. We describe the fidelity of each model with respect to the molecular entity of the original tumor. The largest number of proteins were shared between primary tumor and murine model (846 proteins, 44%), where the primary tumor and cultured cells shared 30% (721) proteins. CONCLUSIONS: Established human DIPG cells represent tumor biology at the protein level. However, differences in molecular pathway of in vitro and in vivo models representing the disease exist.