IDH1 Mutation Impacts DNA Repair Through ALKBH2 Rendering Glioblastoma Cells Sensitive to Artesunate

<b>Background</b>: Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are enzymes that catalyze the oxidative decarboxylation of isocitrate to alpha-ketoglutarate (α-KG), which is essential for many metabolic processes, including some steps in DNA repair. In tumors, notably in gliomas, <i>IDH1</i> and <i>IDH2</i> are frequently mutated. The mutation found in different cancers is functionally active, causing, instead of α-KG, the formation of 2-hydroxyglutarate (2-HG), which inhibits α-KG-dependent enzymes. Gliomas harboring mutated <i>IDH1/2</i> show a better prognosis than <i>IDH1</i> wild-type (wt) tumors of the same grade, which might result from the inhibition of DNA repair functions. A DNA repair enzyme dependent on α-KG is alkB homolog 2 (ALKBH2), which removes several lesions from DNA. These findings prompted us to investigate the response of glioma cells to artesunate (ART), a plant ingredient with genotoxic and anticancer activity currently used in several trials. <b>Materials and Methods</b>: We used isogenic glioblastoma cell lines that express IDH1 wild-type or, based on a TET-inducible system, the IDH1 mutant (mt) protein, and treated them with increasing doses of artesunate. We also treated glioblastoma cells with 2-HG, generated ALKBH2 knockout cells, and checked their sensitivity to the cytotoxic effects of artesunate. <b>Results</b>: We show that the cell-killing effect of ART is enhanced if the IDH1 mutant (R132H) is expressed in glioblastoma cells. Further, we show that 2-HG imitates the effect of IDH1mt as 2-HG ameliorates the cytotoxicity of ART. Finally, we demonstrate that the knockout of ALKBH2 causes the sensitization of glioblastoma cells to ART. <b>Conclusions</b>: The data indicate that ALKBH2 protects against the anticancer effect of ART, and the mutation of IDH1/2 commonly occurring in low-grade gliomas sensitizes to ART via an ALKBH2-dependent mechanism. The data support the use of ART in the therapy of <i>IDH1/2</i>-mutated cancers both in combination with chemotherapy and adjuvant treatment.