Arginine deprivation alters microglial polarity and synergizes with radiation to eradicate non-arginine-auxotrophic glioblastoma tumors
Nabil Hajji, … , Jose Luis Venero, Nelofer Syed
Nabil Hajji, … , Jose Luis Venero, Nelofer Syed
Published February 3, 2022
Citation Information: J Clin Invest. 2022;132(6):e142137. https://doi.org/10.1172/JCI142137.
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Research Article Oncology

Arginine deprivation alters microglial polarity and synergizes with radiation to eradicate non-arginine-auxotrophic glioblastoma tumors

Abstract

New approaches for the management of glioblastoma (GBM) are an urgent and unmet clinical need. Here, we illustrate that the efficacy of radiotherapy for GBM is strikingly potentiated by concomitant therapy with the arginine-depleting agent ADI-PEG20 in a non-arginine-auxotrophic cellular background (argininosuccinate synthetase 1 positive). Moreover, this combination led to durable and complete radiological and pathological response, with extended disease-free survival in an orthotopic immune-competent model of GBM, with no significant toxicity. ADI-PEG20 not only enhanced the cellular sensitivity of argininosuccinate synthetase 1–positive GBM to ionizing radiation by elevated production of nitric oxide (˙NO) and hence generation of cytotoxic peroxynitrites, but also promoted glioma-associated macrophage/microglial infiltration into tumors and turned their classical antiinflammatory (protumor) phenotype into a proinflammatory (antitumor) phenotype. Our results provide an effective, well-tolerated, and simple strategy to improve GBM treatment that merits consideration for early evaluation in clinical trials.

Authors

Nabil Hajji, Juan Garcia-Revilla, Manuel Sarmiento Soto, Richard Perryman, Jake Symington, Chad C. Quarles, Deborah R. Healey, Yijie Guo, Manuel Luis Orta-Vázquez, Santiago Mateos-Cordero, Khalid Shah, John Bomalaski, Giulio Anichini, Andreas G. Tzakos, Timothy Crook, Kevin O’Neill, Adrienne C. Scheck, Jose Luis Venero, Nelofer Syed

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Figure 1

ADI-PEG20 in combination with radiation significantly reduces the growth of ASS1-positive GBM neurospheres and inhibits tumor growth in syngeneic mice.

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ADI-PEG20 in combination with radiation significantly reduces the growth...
Five thousand cells were plated in low-attachment 96-well plates and incubated for 3 to 8 days to allow formation of neurospheres. Neurospheres were pretreated with ADI-PEG20 (1 μg/mL for human lines and 0.25 μg/mL for mouse line, GL261) for 24 hours before exposure to 2 Gy of ionizing radiation (IR). (A–C) Images were taken on indicated days after IR treatment and changes in neurosphere surface area measured using ImageJ software (upper and lower panels). (D) Epifluorescence (GFP intensity) was measured in whole brains using in vivo image analysis (IVIS). (E) Microscopic analysis of representative brain sections: transmitted light (TL), GFP, and H&E staining. Scale bars: 360 μm (A–C) and 430 μm (E). (F) Tumor size is represented as total radiant efficiency. (G) qPCR expression levels of GFP in tumor sections. The neurosphere results are presented as mean ± SD, n = 12. The in vivo results were obtained from 5 animals per group except for animals treated with ADI-PEG20 monotherapy, which only had 4 animals due to the premature death of 1 mouse. Data were analyzed using 1-way ANOVA (A–C and F) or 2-way ANOVA with Tukey’s multiple comparison test with adjusted P values reported (G). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. AU, arbitrary units.