Incorporation of the Four Core Genotype Transgenic Animal and a Newly Developed EGFRvIII-Based GBM Model into the existing Program Project Grant on Sex-Based Differences in Glioma

ABSTRACT Sex differences are present in many pathological conditions, including a number of non-reproductive cancers. These differences have been observed from an epidemiolocal perspective, and mechanistic studies have revealed broad-ranging differences between sexes at the genetic, epigenetic, and cellular levels. In glioblastoma, the most common primary malignant brain tumor, males present with disease nearly twice as often as females and experience a poorer prognosis given the same standard-of-care treatments. As part of a current Program Project Grant (parent award, P01 CA245705), we are focused on the cell-intrinsic and cell-extrinsic influences of sex differences, as well as their interplay, in glioblastoma. These efforts have focused on multiple mechanisms, including sex differences in the immune response, and found differences in the resident (microglial) and infiltrating (namely myeloid-derived suppressor cell) immune populations. While these initial observations were made using transplantable mouse glioblastoma models generated from genetically engineered or carcinogen- induced mouse models and validated in human samples, these models are not strongly representative of the human disease, as they lack key drivers, including mutation in the epidermal growth factor receptor (EGFR, namely EGFRvIII). Using in vivo electroporation approaches supported by the NCI IMAT program, more representative GBM models have been generated using Mosaic Analysis with Dual Recombinase (MADR) and Genome Editing of Synthetic Target Arrays for Lineage Tracing (GESTALT) technologies that leverage concomitant expression of key oncogenes such as EGFRvIII and deletion of key tumor suppressors such as NF1 and p53. The overall objective of this revision application is to enhance our program through the use of these more representative glioblastoma models to determine sex-specific immune response effects. In Aim 1, we will determine how the glioblastoma immune microenvironment is arranged as a function of the biological sex of the tumor. In parallel with these benchmarking studies, Aim 2 will take an unbiased, hypothesis-generating approach to determine how the neural cell composition of the tumor microenvironment is generated as a function of the biological sex of the developing glioblastoma. The MADR-GESTALT will be applied to wild-type mice, as well as Project 3-specific mouse models (junctional adhesion molecule-A) and the four-core genotype model that separates chromosomal and gonadal sex. The short-term goal of this application is to enhance Project 3 of the parent award and provide this new model for all projects through Core C, which houses experimental models. The long-term goal of this project is to leverage these more representative glioblastoma models for future functional and mechanistic studies on sex differences in glioblastoma.