CCRG-01. KAT5 ACTIVITY REGULATES G0-LIKE STATES IN HUMAN GLIOMAS

Abstract

Abstract Glioblastoma, the most aggressive type of primary brain cancer, benefits little from standard of care therapy. Over the past few decades not much advancement has been made in improving the recurrence-free survival after treatment, with a median survival period of 15 month from diagnostic. G0-like states are thought to act a reservoir for tumor recurrence after treatment in glioblastoma. Targeting G0 states in glioblastoma poses an attractive therapeutic approach, however, little progress has been made in the field, likely due to poorly understood mechanisms that regulate G0 ingress and egress. To find regulators of G0 states, we performed a genome-wide CRISPR-Cas9 screen of patient-derived glioblastoma stem cells. We identified KAT5, a histone acetyltransferase coding gene which is the catalytic subunit of the histone acetyltransferase complex NuA4, as an important candidate for regulating G0 ingress and egress. We found that in primary gliomas, KAT5-low cells display G0-like properties, while overall KAT5 activity increases from low to high grade tumors. To study G0 states in glioblastoma, we have engineered an inducible KAT5 system that functions as a fully tunable model system, where we can control expression of KAT5 and, therefore, effectively control glioma cell entry and exit from G0-like states. We provide evidence that G0-like states are characterized by hypoacetylated histones and low protein synthesis rates, which remarkably induces shifts in cell state reminiscent of dedifferentiation and acquisition of stem-like behavior. Our work demonstrates that regulation of G0 like states may be coupled to the generation of tumor heterogeneity and, more importantly, suggests a potential strategy whereby inhibiting KAT5 activity could effectively "down grade" GBM tumors by lengthening residence time in G0-like states, significantly increasing survival times. For these studies we will present a variety of techniques, including single cell RNA-seq to characterize cellular subpopulations in tumors and GBM stem-like cell cultures.