Hypoxia inducible factor 1α inhibits the expression of immunosuppressive tryptophan-2,3-dioxygenase in glioblastoma

• Verfasst von: Mohapatra, Soumya Ranjan [VerfasserIn]
• Verfasst von: Sadik, Ahmed [VerfasserIn]
• Verfasst von: Tykocinski, Lars-Oliver [VerfasserIn]
• Verfasst von: Dietze, Jørn [VerfasserIn]
• Verfasst von: Poschet, Gernot [VerfasserIn]
• Verfasst von: Heiland, Ines [VerfasserIn]
• Verfasst von: Opitz, Christiane [VerfasserIn]
• Titel: Hypoxia inducible factor 1α inhibits the expression of immunosuppressive tryptophan-2,3-dioxygenase in glioblastoma
• Verf.angabe: Soumya R. Mohapatra, Ahmed Sadik, Lars-Oliver Tykocinski, Jørn Dietze, Gernot Poschet, Ines Heiland and Christiane A. Opitz
• E-Jahr: 2019
• Jahr: 04 December 2019
• Umfang: 13 S.
• Teil: volume:10
• Teil: year:2019
• Teil: extent:13
• Fussnoten: Im Titel ist alpha als griechischer Buchstabe dargestellt ; Gesehen am 08.04.2020
• Titel Quelle: Enthalten in: Frontiers in immunology
• Ort Quelle: Lausanne : Frontiers Media, 2010
• Jahr Quelle: 2019
• Band/Heft Quelle: 10(2019) Artikel-Nummer 2762, 13 Seiten
• ISSN Quelle: 1664-3224
• DOI: doi:10.3389/fimmu.2019.02762
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: HIF1α
• Sach-SW: hypoxia
• Sach-SW: Immunosuppression
• Sach-SW: TDO2
• Sach-SW: Tryptophan
• K10plus-PPN: 1694253449

Abstract

Abnormal circulation in solid tumors results in hypoxia, which modulates both tumor intrinsic malignant properties as well as anti-tumor immune responses. Given the importance of hypoxia in glioblastoma (GBM) biology and particularly in shaping anti-tumor immunity, we analysed which immunomodulatory genes are differentially regulated in response to hypoxia in GBM cells. Gene expression analyses identified the immunosuppressive enzyme tryptophan-2,3-dioxygenase (TDO2) as the second most downregulated gene in GBM cells cultured under hypoxic conditions. TDO2 catalyses the oxidation of tryptophan to N-formyl kynurenine, which is the first and rate-limiting step of Trp degradation along the kynurenine pathway (KP). In multiple GBM cell lines hypoxia reduced TDO2 expression both at mRNA and protein levels. The downregulation of TDO2 through hypoxia was reversible as re-oxygenation rescued TDO2 expression. Computational modelling of tryptophan metabolism predicted reduced flux through the KP and lower concentrations of kynurenine and its downstream metabolite 3-hydroxyanthranilic acid under hypoxia. Metabolic measurements confirmed the predicted changes, thus demonstrating the ability of the mathematical model to infer tryptophan metabolite concentrations. Moreover, we identified hypoxia inducible factor 1α (HIF1α) to regulate TDO2 expression under hypoxic conditions, as the HIF1α-stabilising agents dimethyloxalylglycine (DMOG) and cobalt chloride reduced TDO2 expression. Knockdown of HIF1α restored the expression of TDO2 upon cobalt chloride treatment, confirming that HIF1α controls TDO2 expression. To investigate the immunoregulatory effects of this novel mechanism of TDO2 regulation, we co-cultured isolated T cells with TDO2-expressing GBM cells under normoxic and hypoxic conditions. Under normoxia TDO2-expressing GBM cells suppressed T cell proliferation, while hypoxia restored the proliferation of the T cells, likely due to the reduction in kynurenine levels produced by the GBM cells. Taken together, our data suggest that the regulation of TDO2 expression by HIF1α may be involved in modulating anti-tumor immunity in GBM.