Targeting Histone H3.3-K27M Mutation for the Treatment of DIPGs

The major goals of this project are to determine whether the H3.3-K27M mutant promotes DIPG tumor growth and provides a novel therapeutic target for treating this cancer. We will determine whether H3.3-K27M confers sensitivity to a specific histone H3K27 demethylase inhibitor, GSK-J4, in preclinical models of pediatric brainstem gliomas. This project will be the first time to provide proof-of-principle for pharmacologic targeting of histone H3K27 methylation as a therapeutic target for cancer, and furthermore indentify a specific compound which may be useful for glioma patients with a specific histone H3F3A gene mutation (H3.3-K27M). We will test the hypothesis that the H3.3-K27M mutation alters gene expression in such a way that promotes cell growth, while additionally conferring cell sensitivity to GSK-J4. To address these hypotheses, we propose the following: Aim 1: Determine whether GSK-J4 treatment alters the expression of genes that promote cell proliferation and differentiation in H3.3-K27M mutant DIPG cells. This aim will determine the extent to which GSK-J4 alters gene expression in K27M mutant DIPG cells, and will identify critical mediators of pro-tumorigenic effects of K27M mutant. We will perform ChIP-sequence, as well as gene expression array analysis, using K27M mutant DIPG cells before and after GSK-J4 treatment. Candidate genes that are suppressed in response to GSK-J4 treatment will be investigated as pro-tumorigenic mediators of the K27M mutation using siRNA treatments of tumor cells, with results interpreted by extent of growth inhibition Aim 2: Determine whether the H3.3-K27M mutation correlates with GSK-J4 sensitivity in human DIPG brainstem xenografts. We will test the anti-tumor activity of GSK-J4 in human orthotopic DIPG xenografts. Intracranial (brainstem) tumor growth and response to therapy will be quantitatively measured by BLI, and efficacy will be assessed by survival analysis.