Role of SOX4 Transcription Factor in Immune Evasion by Glioblastoma

Abstract

Glioblastoma (GBM), defined as a stage IV glioma, is an invariably fatal disease with a 5-year survival rate of 5%. One of the defining characteristics of human GBM driving the disease resistance and recurrence is cellular heterogeneity. Specifically, a subpopulation of less differentiated cells displays striking plasticity and resistance to chemo- and radiotherapy. Single cell sequencing identified that two closely related SOXC transcription factors SOX4 and SOX11 are highly enriched in this population. SOX4 and SOX11, members of the SOXC transcription factor family, play critical roles in embryonic development, stem cell regulation, and oncogenesis. Here, we explore the immuno-evasive function of SOX4 and SOX11 in glioblastoma in both human and murine glioblastoma models. In human gliomasphere models, less differentiated cell state termed neural progenitor cell-like (NPC-like) cell state—where SOX4 and SOX11 are most highly expressed—exhibited immuno-evasive phenotype, namely resistance to interferon stimulation, and low cell surface expression of MHC class I and interferon receptors. Genetic knockdown or pharmacologic inhibition of SOX4 in these models resulted in a dramatic reduction of the NPC-like cell state and shift towards mesenchymal-like (MES-like) cell state. SOX4 knockdown gliomaspheres showed increased gene expression of immune-related genes and increased sensitivity to interferons, suggesting intrinsic immune activation. Type I and II interferon treatments also directly suppressed SOX4 protein levels and reduced the proportion of NPC-like cell state, linking inflammatory signaling with cell state transitions. Genetic disruption of Sox4 in mouse CT-2A and SB28-Ohlfest glioma cell lines revealed enhanced expression of interferon-stimulated genes and increased sensitivity to type I and II interferons, consistent with intrinsic immune activation. In the SB28-Ohlefst model, these effects were amplified in Sox4/Sox11 double knockout, with evidence of increased vulnerability to T cell-mediated killing in vitro and greater selection against dOVA model antigen-expressing cells in vivo. However, the lack of consistent in vivo response between experiments precluded us from demonstrating overall survival advantage of animals bearing Sox4/Sox11 double knockout tumors. Collectively, these findings identify SOX4 as a key regulator of immune evasion and cellular identity in human and murine glioblastoma. SOX11 is also relevant but has a less central role. Targeting of SOX4 could be used to decrease heterogeneity of GBM cell states and increase the sensitivity of GBM to immune attack.