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Glutaminase Inhibitors Induce Thiol-Mediated Oxidative Stress and Radiosensitization in Treatment-Resistant Cervical Cancers
Journal article   Open access   Peer reviewed

Glutaminase Inhibitors Induce Thiol-Mediated Oxidative Stress and Radiosensitization in Treatment-Resistant Cervical Cancers

Ramachandran Rashmi, Kay Jayachandran, Jin Zhang, Vishnu Menon, Naoshad Muhammad, Michael Zahner, Fiona Ruiz, Sisi Zhang, Kevin Cho, Yuting Wang, …
Molecular cancer therapeutics, Vol.19(12), pp.2465-2475
12/2020
DOI: 10.1158/1535-7163.MCT-20-0271
PMCID: PMC8208465
PMID: 33087507
url
https://doi.org/10.1158/1535-7163.MCT-20-0271View
Published (Version of record) Open Access

Abstract

The purpose of this study was to determine if radiation (RT)-resistant cervical cancers are dependent upon glutamine metabolism driven by activation of the PI3K pathway and test whether PI3K pathway mutation predicts radiosensitization by inhibition of glutamine metabolism. Cervical cancer cell lines with and without PI3K pathway mutations, including SiHa and SiHa PTEN cells engineered by CRISPR/Cas9, were used for mechanistic studies performed in the presence and absence of glutamine starvation and the glutaminase inhibitor, telaglenastat (CB-839). These studies included cell survival, proliferation, quantification of oxidative stress parameters, metabolic tracing with stable isotope-labeled substrates, metabolic rescue, and combination studies with L-buthionine sulfoximine (BSO), auranofin (AUR), and RT. studies of telaglenastat ± RT were performed using CaSki and SiHa xenografts grown in immune-compromised mice. PI3K-activated cervical cancer cells were selectively sensitive to glutamine deprivation through a mechanism that included thiol-mediated oxidative stress. Telaglenastat treatment decreased total glutathione pools, increased the percent glutathione disulfide, and caused clonogenic cell killing that was reversed by treatment with the thiol antioxidant, N-acetylcysteine. Telaglenastat also sensitized cells to killing by glutathione depletion with BSO, thioredoxin reductase inhibition with AUR, and RT. Glutamine-dependent PI3K-activated cervical cancer xenografts were sensitive to telaglenastat monotherapy, and telaglenastat selectively radiosensitized cervical cancer cells and These novel preclinical data support the utility of telaglenastat for glutamine-dependent radioresistant cervical cancers and demonstrate that PI3K pathway mutations may be used as a predictive biomarker for telaglenastat sensitivity.

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