Tumor Treating Fields dually activate STING and AIM2 inflammasomes to induce adjuvant immunity in glioblastoma
Dongjiang Chen, … , Maryam Rahman, David D. Tran
Dongjiang Chen, … , Maryam Rahman, David D. Tran
Published February 24, 2022
Citation Information: J Clin Invest. 2022;132(8):e149258. https://doi.org/10.1172/JCI149258.
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Tumor Treating Fields dually activate STING and AIM2 inflammasomes to induce adjuvant immunity in glioblastoma

Abstract

Tumor Treating Fields (TTFields), an approved therapy for glioblastoma (GBM) and malignant mesothelioma, employ noninvasive application of low-intensity, intermediate-frequency, alternating electric fields to disrupt the mitotic spindle, leading to chromosome missegregation and apoptosis. Emerging evidence suggests that TTFields may also induce inflammation. However, the mechanism underlying this property and whether it can be harnessed therapeutically are unclear. Here, we report that TTFields induced focal disruption of the nuclear envelope, leading to cytosolic release of large micronuclei clusters that intensely recruited and activated 2 major DNA sensors — cyclic GMP-AMP synthase (cGAS) and absent in melanoma 2 (AIM2) — and their cognate cGAS/stimulator of interferon genes (STING) and AIM2/caspase 1 inflammasomes to produce proinflammatory cytokines, type 1 interferons (T1IFNs), and T1IFN-responsive genes. In syngeneic murine GBM models, TTFields-treated GBM cells induced antitumor memory immunity and a cure rate of 42% to 66% in a STING- and AIM2-dependent manner. Using single-cell and bulk RNA sequencing of peripheral blood mononuclear cells, we detected robust post-TTFields activation of adaptive immunity in patients with GBM via a T1IFN-based trajectory and identified a gene panel signature of TTFields effects on T cell activation and clonal expansion. Collectively, these studies defined a therapeutic strategy using TTFields as cancer immunotherapy in GBM and potentially other solid tumors.

Authors

Dongjiang Chen, Son B. Le, Tarun E. Hutchinson, Anda-Alexandra Calinescu, Mathew Sebastian, Dan Jin, Tianyi Liu, Ashley Ghiaseddin, Maryam Rahman, David D. Tran

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Figure 1

TTFields-induced cytosolic micronuclei clusters recruit cGAS and AIM2 in patient-derived GSCs.

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TTFields-induced cytosolic micronuclei clusters recruit cGAS and AIM2 in...
(See Supplemental Figures 1–7). (A) 3D confocal images showing immunofluorescence staining (IF) for cGAS and AIM2 and counterstained with DAPI for DNA in CA1, CA3, and CA7 GSCs either nontreated (NT) (top) or treated with TTFields at 200 kHz (TTF) (bottom) for 24 hours. Large micronuclei clusters extend directly from the true nuclei through a narrow bridge. Each square is 30 μm2; z height is 15 μm. (B) A bar plot showing percentages of GSCs with cGAS and AIM2-recruited cytosolic large micronuclei clusters and nuclear protrusions over the total cells counted in the experiments in A. Fisher’s exact test was used to compare 2 groups within each cell line. ***P < 0.001. (C) Representative confocal images showing IF of LAMINAC and DAPI counterstain in CA1 and L2 GSCs either NT or TTF for 24 hours, showing a focal rupture (CA1) and scattered perforations (L2) of the nuclear envelope leading to a large micronuclei cluster (broken yellow oval) and several nuclear protrusions, respectively. Scale bars: 10 μm. (D) A bar plot showing percentages of GSCs with cGAS and AIM2-recruited cytosolic large micronuclei clusters over the total cells counted, following pretreatment with either the vehicle or ribociclib (4.5 μM) to induce G1 arrest, followed by TTFields treatment for 24 hours, demonstrating that S-phase entry is required for TTFields-induced cytosolic micronuclei clusters. L2 cells are relatively resistant to ribociclib. Fisher’s exact test with adjustments for multiple comparisons was used. ***P < 0.001. NS, not significant. All data are representative of at least 3 independent experiments.