Clement, M.; Gibbs, A.; Begum, A.; Siebzehnrubl, D.; Kaushik, S.; Singh, N.; Gupta, B.; Eftychidis, V.; Siebzehnrubl, F. A.

Glioblastomas are incurable and lethal brain cancers. Immunotherapies offer new and promising treatment options for glioblastoma patients, but the highly immunosuppressive nature of these cancers presents a challenging clinical obstacle. Glioblastoma immune evasion is driven by cell-cell interactions in the tumor microenvironment and recent studies have identified astrocytes as important contributors to immune silencing [1, 2]. Cell plasticity is a key feature of reactive astrocytes that drives heterogeneous, pro- or anti-inflammatory states [3], but the molecular regulators of astrocyte-immune interactions remain incompletely understood. Here, we investigate whether cell plasticity of glioblastoma-associated astrocytes promotes or opposes tumor progression and show that loss of astrocyte plasticity results in T-cell recruitment and immune activation. We evaluate how astrocytic cell plasticity contributes to immune functions in the glioblastoma microenvironment using single cell sequencing from preclinical models, in vivo genetic perturbations and in vitro mouse and human experimental systems. We show that astrocytes surrounding glioblastoma express the stem cell-associated transcription factor, ZEB1, and that conditional-inducible astrocytic deletion of Zeb1 remarkably reduces glioblastoma growth and extends survival. Increased recruitment and activation of T cells in astrocytic Zeb1-deficient mouse models is linked to increased expression of the immunoattractant cytokine CXCL14, and viral delivery of CXCL14 in experimental glioblastoma models increases survival. Our data support that CXCL14 is a candidate therapeutic target for reprogramming the tumor microenvironment that can restrict and reduce glioblastoma growth and progression.