ADAR1-mediated RNA editing links ganglioside catabolism to glioblastoma stem cell maintenance
Li Jiang, … , Xiang-Dong Fu, Jeremy N. Rich
Li Jiang, … , Xiang-Dong Fu, Jeremy N. Rich
Published February 8, 2022
Citation Information: J Clin Invest. 2022;132(6):e143397. https://doi.org/10.1172/JCI143397.
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Research Article Oncology Stem cells

ADAR1-mediated RNA editing links ganglioside catabolism to glioblastoma stem cell maintenance

Abstract

Glioblastoma (GBM) is the most common and lethal primary malignant brain tumor, containing GBM stem cells (GSCs) that contribute to therapeutic resistance and relapse. Exposing potential GSC vulnerabilities may provide therapeutic strategies against GBM. Here, we interrogated the role of adenosine-to-inosine (A-to-I) RNA editing mediated by adenosine deaminase acting on RNA 1 (ADAR1) in GSCs and found that both ADAR1 and global RNA editomes were elevated in GSCs compared with normal neural stem cells. ADAR1 inactivation or blocking of the upstream JAK/STAT pathway through TYK2 inhibition impaired GSC self-renewal and stemness. Downstream of ADAR1, RNA editing of the 3′-UTR of GM2A, a key ganglioside catabolism activator, proved to be critical, as interference with ganglioside catabolism and disruption of ADAR1 showed a similar functional impact on GSCs. These findings reveal that RNA editing links ganglioside catabolism to GSC self-renewal and stemness, exposing a potential vulnerability of GBM for therapeutic intervention.

Authors

Li Jiang, Yajing Hao, Changwei Shao, Qiulian Wu, Briana C. Prager, Ryan C. Gimple, Gabriele Sulli, Leo J.Y. Kim, Guoxin Zhang, Zhixin Qiu, Zhe Zhu, Xiang-Dong Fu, Jeremy N. Rich

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Figure 2

ADAR1 promotes GSC proliferation and self-renewal.

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ADAR1 promotes GSC proliferation and self-renewal. See also Table 1 and ...
See also Table 1 and Supplemental Figures 2 and 3. (A) ADAR1 expression levels in GBM (TCGA) and normal brain in the Genotype-Tissue Expression (GTEx) database. *P < 0.05. TPM, transcripts per million. (B) Immunoblotting of ADAR1 in paired GSCs and DGCs. GFAP and SOX2 serve as markers of differentiated and stem/progenitor cells. β-Actin served as loading control. (C) Immunofluorescence analysis of ADAR1 and SOX2. Scale bar: 50 μm. (D) Percentage of ADAR1+ cells among SOX2+ versus SOX2– cells performed in C. Data were compared by Student’s t test and shown as mean ± SD. ****P < 0.0001. (E) ADAR1 expression of GSCs transduced with shCONT or shADAR1. n = 4. Data was determined by ANOVA and shown as mean ± SD. **P < 0.01, ***P < 0.001. (F) Immunoblotting for ADAR1, PARP, and cleaved caspase-3 in GSCs transduced with shCONT or shADAR1. β-Actin served as loading control. Arrowheads indicate cleaved PARP. (G) Proliferation of GSCs transduced with shCONT or shADAR1. Data was determined by 2-way ANOVA with Dunnett’s multiple-comparison testand shown as mean ± SD. n = 5. ****P < 0.0001. (H) Immunofluorescence analysis of Ki67 of GSCs transduced with shCONT or shADAR1. Scale bars: 20 μm. (I) Extreme limiting dilution analysis (ELDA) for sphere formation of GSCs transduced with shCONT or shADAR1. Data was determined by pairwise tests. n = 24. ***P < 0.001. (J) Proliferation of GSCs transduced with vector, ADAR1 wt, or ADAR1 E912A. Data was determined as in G. n = 5. ****P < 0.0001. (K) Immunoblotting for ADAR1 and cleaved caspase-3 in GSCs transduced as in J. β-Actin served as loading control. (L) ELDA for sphere formation of GSCs transduced as in J. n = 24. *P < 0.05, **P < 0.01, ***P < 0.001.