Ethics
This Ethics Committee of Nara Medical University approved this study (No. 1058). The study was conducted according to university guidelines. All procedures that involved human participants were conducted according to institutional and/or national research committee ethical standards and the 1964 Declaration of Helsinki and its subsequent alterations or equivalent ethical standards. All healthy volunteers in this study provided informed consent in accordance with Declaration of Helsinki tenets.
Cancer immunogram and GlioVis
The cancer immunogram is used for illustrating the condition of several simultaneous parameters that affect the interaction between a cancer and the immune system. The proposed immunogram is a radar plot where each axis acts as a scale to enumerate parameters (immunosuppressive regulators, immune cell infiltration and so on. Our immunogram analysis results of 9417 RNA-seq data from 9362 patients with 29 different solid cancers in The Cancer Genome Atlas (TCGA) dataset were obtained from the RNA sequencing (RNA-seq)-based Cancer Immunogram Web (https://yamashige33.shinyapps.io/immunogram/). Subgroups of patients with each cancer type or the entire TCGA cohort were normalized 31.
Characteristic immune cell marker (CD3, CD20, NKp46, CD11c, CD11b, TMEM) expression patterns in glioma were detected by examining glioma RNA-seq data from TCGA Database in the GlioVis data portal (http://gliovis.bioinfo.cnio.es/) 32.
Cell lines
We obtained the human GBM cell lines U87MG and LN-18 from American Type Culture Collection (Manassas, VA, USA). We obtained the T98G and U251MG GBM cells from RIKEN BioResource Center (Tsukuba, Japan) and JCRB Cell Bank (Osaka, Japan), respectively. The cell lines were authenticated and tested as mycoplasma-free. We maintained the cells in Dulbecco’s modified Eagle’s medium (DMEM; Life Technologies, Carlsbad, CA, USA) containing 100 µg/ml streptomycin, 100 U/ml penicillin (Thermo Fisher Scientific, Waltham, MA, USA), and 10% heat-inactivated fetal bovine serum (FBS; MP Biomedicals, Tokyo, Japan) at 37°C in a humidified atmosphere with 5% CO2.
Single guide RNAs
Two single guide RNAs (sgRNAs) targeting the exon 3 or 4 regions of the human CIS gene located on 3q13.31. The CIS exon 3 and 4 target sequences were as follows: CTCACCAGATTCCCGAAGGTTGG and CGTACTAAGAACGTGCCTTCTGG, respectively. The underlined sections indicate the protospacer adjacent motif (PAM) sequence. The negative control sgRNA was obtained from Integrated DNA Technologies (IDT, Coralville, IA, USA; https://sg.idtdna.com/site/order/designtool/index/CRISPR_PREDESIGN).
Induction of NK dCIS
The highly purified human NKCs were expanded as previously described 30. Peripheral blood mononuclear cells (PBMCs) were obtained from 16 mL heparinized peripheral blood from three healthy male volunteers (51, 47, and 43 years old). The PBMC CD3 fraction was depleted using RosetteSep™ Human CD3 Depletion Cocktail (STEMCELL Technologies, Vancouver, Canada). The CD3-depleted PBMCs (107 cells) were placed for 7 days in a T25 culture flask (Corning, Steuben, NY, USA) that contained 10 mL AIM-V medium (Life Technologies) with supplementation of 50 ng/mL recombinant human IL-18 (rhIL-18, Medical & Biological Laboratories Co., Ltd., Nagoya, Japan), 10% autologous plasma, and 3000 IU/mL rhIL-2 (Novartis, Basel, Switzerland) at 37°C in a humidified atmosphere with 5% CO2. The AIM-V medium containing 3000 IU/mL rhIL-2 was refilled as required.
Genome editing was conducted as previously described with minor modifications 33. Expanded NKCs (3 × 106) were electroporated to ribonucleoprotein (RNP) complexes [targeted sgRNA/transactivation CRISPR RNA (tracrRNA) and recombinant Cas9 (IDT)] using a Human NK Cell Nucleofector Kit (VPA-1005; Lonza, Basel, Switzerland) and electroporation program X-001. Subsequently, we resuspended the cells in AIM-V medium with 10% autologous plasma and 3000 IU/mL rhIL-2 and placed them for 7 days in a 12-well plate (Corning) at 37°C in a humidified atmosphere with 5% CO2.
Efficacy of CRISPR/Cas9 gene disruption
We harvested the genome-edited NKCs 7 days after electroporation, extracted their DNA with a QIAamp DNA mini kit (Qiagen, Hilden, Germany) and performed T7 endonuclease 1 (T7E1) mismatch detection assays using an Alt-R Genome Editing Detection Kit (IDT) as described previously 33,34. We amplified the on- and off-target (OT and OF, respectively) sites and adjacent sequences from the genomic DNA with KOD FX enzyme solution (TOYOBO, Osaka, Japan). The PCR conditions were as follows: one cycle at 94°C for 2 min, then 40 cycles at 98°C for 10 s, 63°C for 30 s, and 68°C for 30 s, and a final cycle at 68°C for 7 min. We performed the PCR on a LifeECO thermal cycler (Bioer Technologies Co. Ltd., Hangzhou, China). The PCR primers were obtained from Thermo Fisher Scientific.
The subsequent PCR was performed on the LifeECO thermal cycler with the following cycling conditions: 95°C for 5 min, decrease from 95°C to 85°C at a rate of 2°C per second, decrease from 85°C to 25°C at a rate of 0.1°C per second, then decreased to 4°C. We digested the rehybridized PCR products for 30 min with T7E1 and separated them for 20 min on 2% agarose gel. We visualized the DNA under a UV transilluminator (FAS-IV, Nippon Genetics Co. Ltd., Tokyo, Japan). OF mutagenesis, which was predicted with a gene homology-based off-targeting potential checking system (IDT) was detected in the same manner. The PCR primers used to amplify the target locus are listed in supplemental materials and methods 1.
Microarray-based gene expression
We examined mock NKCs (NK mock) and NK dCIS gene expression (National Center for Biotechnology Information Gene Expression Omnibus [NCBI GEO] accession no. GSE GSE229085) using the Clariom™ S array and deposited into NCBI GEO. We analyzed all CEL files using Transcriptome Analysis Console (TAC 4.1, Thermo Fisher Scientific). Gene set enrichment analysis (GSEA) was performed to establish whether a predefined set of genes differed statistically significantly between two biological states. We uploaded the microarray data to the GSEA website (https://www.gsea-msigdb.org/gsea/index.jsp).
String
Interacting genes were retrieved via the online STRING (Search Tool for the Retrieval of Interacting Genes) search tool 35 (https://string-db.org/).
Antibody staining and flow cytometry
We stained the cells with the appropriate antibodies and fixed them for 1 h in 1% paraformaldehyde-containing phosphate-buffered saline (PBS) at 4°C. We obtained the data using a BD FACSCalibur flow cytometer (BD Biosciences, San Jose, CA, USA) and analyzed it using FlowJo v10 (BD Biosciences). We determined CD107a expression with an IMMUNOCYTO CD107a Detection Kit (MBL, Nagoya, Japan) according to the instructions.
For intracellular cytokine staining, we stimulated the cells in a 96-well round-bottom plate with T98G GBM cells at 37°C for 4 h, then incubated them for 5 h at 37°C with Protein Transport Inhibitor Cocktail (Thermo Fisher Scientific). Then, we fixed and permeabilized the cells with BD Cytofix/Cytoperm Kit (BD Biosciences) and incubated them for 30 min with anti-cytokine antibodies on ice. Phosphorylation was detected with PerFix-EXPOSE (Beckman Coulter, Brea, CA, USA) according to the instructions. The Supplementary Materials and Methods list the antibodies used for the flow cytometry.
Western blotting
NKCs (106) were dissolved in RIPA Lysis and Extraction Buffer with Halt Protease Inhibitor Cocktail (Thermo Fisher Scientific) and sonicated by the ultrasound-based Sonifier 250 homogenizer (Branson, Hannover, Germany) according to the manufacturer’s instruction. We mixed the whole cell lysate with 4× Bolt LDS Sample Buffer (Thermo Fisher Scientific) and incubated it for 10 min at 70°C. Subsequently, we performed 4–12% sodium dodecyl sulfate–polyacrylamide gel electrophoresis using 5 µL (for glyceraldehyde-3-phosphate dehydrogenase [GAPDH]) to 40 µL (for CIS) lysate, then transferred the blots onto a PVDF membrane using the iBlot 2 Dry Blotting System (Thermo Fisher Scientific). We reacted the membranes at room temperature using iBind Automated Western Systems (Thermo Fisher Scientific). The primary antibodies were rabbit polyclonal IgGs against CIS (1:500 dilution, clone D4D9, Cell Signaling, Danvers, MA, USA) and GAPDH (1:1000 dilution, clone 14C10, Cell Signaling). The secondary antibody was horseradish peroxidase-conjugated anti-rabbit IgG antibody (1:200 dilution, Cell Signaling). The blots were developed with SuperSignal West Pico PLUS Chemiluminescent Substrate (Thermo Fisher Scientific). We determined the signal intensity with FUSION Solo and FUSION Solo 7S Edge (Vilber Bio Imaging, Paris, France).
Growth inhibition assays
We examined the inhibitory effects of the genome-edited NKCs on GBM cells with xCELLigence RTCA (real-time cell analysis) S16 and DP instruments (ACEA Biosciences, San Diego, CA, USA) as described previously 33,34,36. Briefly, we added 100 µL complete medium to each well on an E-plate 16 (ACEA Biosciences). We measured the background impedance at 37°C in a humidified atmosphere with 5% CO2. We seeded the GBM cells (2 × 104 T98G, LN-18, U251MG, U87MG cells/well) as the target (T) cells and recorded the impedance every 5 min for 72 h. After 24 h, we added the genome-edited NKCs to each well as effector (E) cells in E:T cell ratios of 1:1. We analyzed the data using RTCA version 1.2 (ACEA Biosciences) and calculated the relative growth inhibition as follows: (1 − normalized cell index of target cells co-cultured with each sample ÷ normalized cell index of target cells) × 100 (%).
Spheroid culture and CFSE-based cytotoxic assay
We seeded the GBM cells (300–6000 cells/well) onto nonadherent V-bottom 96-well plates (PrimeSurface 96U, MS-9096V, Sumitomo Bakelite, Tokyo, Japan) in DMEM supplemented with 10% FBS and cultured them at 37°C in a humidified atmosphere with 5% CO2 for 3 days. For fluorescence microscopy analysis, we suspended 5 × 105 NKCs in 1 mL 1 µg/mL carboxyfluorescein diacetate succinimidyl ester (CFSE; Dojindo Laboratories, Kumamoto, Japan) and incubated them at 37°C for 30 min. We co-cultured the spheroids derived from 300 T98G and U251MG cells for 24 h with 3 × 103 CFSE-labeled NKCs and observed them under a BZ-X700 all-in-one fluorescence microscope (Keyence, Osaka, Japan). We detected the CFSE-labeled NKCs with the green fluorescent protein filter (OP-87765, Keyence). The cells within all spheroids were visualized by recording merged Z-stack images using the BZ-X700 quick full-focus function.
For the flow cytometry-based apoptosis assay, we co-cultured 5 × 103 cell-derived spheroids for 24 h with 5 × 104 CFSE-labeled NKCs. Subsequently, we centrifuged and detached the cells with StemPro Accutase Cell Dissociation Reagent (Thermo Fisher Scientific) at 37°C for 60 min. Then, we stained the cells with an allophycocyanin (APC)-conjugated Annexin V Apoptosis Detection Kit as per the manufacturer’s instructions (BioLegend, San Diego, CA, USA). We detected apoptotic GBM cells with a BD FACSCalibur flow cytometer (BD Biosciences) and analyzed them using FlowJo v10 (BD Biosciences). To ensure that the analysis was accurate, we gated out the CFSE-positive fraction to assess GBM cell apoptosis.
In vivo orthotopic xenograft assays
We purchased 24 female non-obese diabetes/severe combined immunodeficiency/gc null (NOG) mice (6 weeks old) from the Central Institute for Experimental Animals (Kanagawa, Japan). The Institute of Animal Care and Use Committee of Nara Medical University approved all animal experiments. We anesthetized the mice with inhalation of isoflurane mixed with air (induction, 2.5%; maintenance, 1.5%) and fixed them on a stereotaxic instrument for mice (SR-6M-HT, Narishige, Tokyo, Japan). We infused the mice stereotactically with 2 µL native Hank’s buffered salt solution (HBSS) that contained 105 U87MG cells into the right thalamus (2 mm lateral and 2 mm posterior from the bregma and 3 mm dorsoventral from the outer cranium border) with a Hamilton syringe (33 S-gauge needle) mounted on an infusion syringe pump (Harvard Apparatus, Holliston, MA, USA). The mice were randomly assigned to three intracranial infusion groups (n = 8 mice per group): negative background (NB, HBSS only), NK mock, and NK dCIS (106 cells). The mice were directly infused intracranially with the cells and reagents prepared using the aforementioned settings and using the infusion syringe pump via the same burr hole used for implanting the U87MG cells. The infusion speed for both the U87MG cells and NKCs was 1 µL/min.
Histochemical analysis
We fixed the intracranial tumors in 10% neutral-buffered formalin, then embedded them in paraffin. We placed 5-µm thick sections on glass slides and stained them with hematoxylin–eosin (HE). We captured photographs at ×40 and ×400 magnification using a BX-710 microscope unit (Keyence). We performed the histochemical analyses using a BZ-X analyzer (Keyence).
Statistical analysis
We performed statistical analysis with GraphPad Prism 8 (GraphPad Software, San Diego, CA, USA) and report the values as the mean ± SD or SEM. We determined the statistical significance of differences with the unpaired t-test, Mann-Whitney test, or one- or two-way analysis of variance (ANOVA), followed by Tukey’s or Sidak’s test. Statistical significance was accepted at P < 0.05. We estimated survival in each group mated using the Kaplan–Meier method, which encompassed the medians and OS rates. We determined the statistical significance of differences with log rank testing.