Yang D, Ou YL, Wang SH, Jin HJ, Chen SH, Han R, Zhang H. Hypoxia facilitates triple-negative breast cancer stem cells enrichment and stemness maintenance through oxidized ataxia telangiectasia mutated-induced one-carbon metabolism. World J Stem Cells 2026; 18(1): 112278 [DOI: 10.4252/wjsc.v18.i1.112278]
Corresponding Author of This Article
Ran Han, Outpatient Department, Guizhou Provincial People’s Hospital, No. 83 Zhongshan East Road, Guiyang 550002, Guizhou Province, China. hanran105@sina.com
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Pathology
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Basic Study
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This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Jan 26, 2026 (publication date) through Jan 26, 2026
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World Journal of Stem Cells
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Yang D, Ou YL, Wang SH, Jin HJ, Chen SH, Han R, Zhang H. Hypoxia facilitates triple-negative breast cancer stem cells enrichment and stemness maintenance through oxidized ataxia telangiectasia mutated-induced one-carbon metabolism. World J Stem Cells 2026; 18(1): 112278 [DOI: 10.4252/wjsc.v18.i1.112278]
World J Stem Cells. Jan 26, 2026; 18(1): 112278 Published online Jan 26, 2026. doi: 10.4252/wjsc.v18.i1.112278
Hypoxia facilitates triple-negative breast cancer stem cells enrichment and stemness maintenance through oxidized ataxia telangiectasia mutated-induced one-carbon metabolism
Dan Yang, Yu-Lian Ou, Shu-Hui Wang, Hong-Jun Jin, Su-Hua Chen, Ran Han, Hua Zhang
Ran Han, Outpatient Department, Guizhou Provincial People’s Hospital, Guiyang 550002, Guizhou Province, China
Co-first authors: Dan Yang and Yu-Lian Ou.
Co-corresponding authors: Ran Han and Hua Zhang.
Author contributions: Yang D and Ou YL contributed equally to this manuscript and are co-first authors. Yang D, Ou YL, Han R, and Zhang H conceived and designed the study, and wrote the original draft; Yang D, Ou YL, and Chen SH performed the experiments and data analysis; Han R and Zhang H reviewed and edited the manuscript; Wang SH and Jin HJ provided supervision and project administration; Yang D and Han R acquired funding. Han R and Zhang H contributed equally to this manuscript and are co-corresponding authors. All authors have read and approved the final manuscript.
Institutional review board statement: This study didn’t include any human issues or animals.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
Data sharing statement: The data used to support the findings of this study are available from the corresponding author upon reasonable request.
Open Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Received: July 23, 2025 Revised: September 9, 2025 Accepted: December 2, 2025 Published online: January 26, 2026 Processing time: 181 Days and 21.1 Hours
Abstract
BACKGROUND
Cancer stem cells (CSCs) drive recurrence and therapeutic resistance in triple-negative breast cancer (TNBC), a highly aggressive breast cancer subtype. Intratumoral hypoxia, a common feature of solid tumors, promotes CSCs enrichment, yet the mechanisms sustaining CSCs stemness remain poorly understood. Hypoxia-induced reactive oxygen species can oxidatively activate ataxia telangiectasia mutated (ATM) kinase (oxidized ATM, p-ATM) independently of DNA breaks.
AIM
To investigate the role of hypoxia-induced oxidized ATM in sustaining TNBC-CSC stemness through c-Myc-mediated regulation of one-carbon metabolism.
METHODS
Hs578T and MDA-MB-231 TNBC cells were cultured under normoxia or hypoxia. CSC stemness was assessed by mammosphere assays and flow cytometry. ATM activity was assessed by pharmacological inhibition (Ku60019) and short hairpin RNA knockdown. c-Myc binding to serine hydroxymethyltransferase 2 (SHMT2) and methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) promoters was analyzed by dual-luciferase reporter assays and chromatin immunoprecipitation. NADPH/NADP+ ratios were quantified, and metabolic reprogramming was profiled by liquid chromatography-tandem mass spectrometry metabolomics.
RESULTS
Hypoxia significantly increased mammosphere formation in both Hs578T and MDA-MB-231 cells, as reflected by higher numbers of mammospheres (Hs578T: 214 ± 18; MDA-MB-231: 198 ± 16; both P < 0.01) and larger mean diameters (P < 0.01). Hypoxia also elevated CD44+/CD24- cell proportions and stemness gene expression (P < 0.01). Oxidized ATM was activated under hypoxia without γH2AX induction, confirming DNA damage independence. ATM inhibition reduced mammosphere growth and suppressed c-Myc, SHMT2, and MTHFD2. Luciferase and chromatin immunoprecipitation assays confirmed direct c-Myc binding to SHMT2 and MTHFD2 promoters, while mutation of the binding sites abolished promoter activity. NADPH/NADP+ ratios were significantly elevated under hypoxia but reduced following ATM inhibition (P < 0.05). Metabolomics revealed enrichment of serine/glycine one-carbon pathways.
CONCLUSION
Hypoxia-induced oxidized ATM maintains TNBC-CSC stemness by promoting c-Myc-dependent upregulation of MTHFD2 and SHMT2, linking hypoxia, redox signaling, and one-carbon metabolism. These findings suggest a potential therapeutic axis that could be exploited for TNBC treatment.
Core Tip: This study demonstrates that hypoxia activates oxidized ataxia telangiectasia mutated kinase, which plays a pivotal role in enhancing the stemness of triple-negative breast cancer stem cells. Through c-Myc-mediated transcriptional regulation, hypoxia promotes one-carbon metabolism and significantly upregulates key metabolic enzymes, including methylenetetrahydrofolate dehydrogenase 2 and serine hydroxymethyltransferase 2. These metabolic adaptations support redox balance and self-renewal capacity, highlighting a potential therapeutic axis targeting oxidized ataxia telangiectasia mutated-driven metabolic reprogramming in triple-negative breast cancer.
