Jingyi Li, Liang Feng, Lei Zhang, Weiguo Zhang, Yanting Zhang, Xiaoqin Liu, Qianqian Cai, Weiming Zhao, Gang Huang, Changlian Lu
{"title":"Saikosaponin D Mitigates Radioresistance in Triple-Negative Breast Cancer by Inducing MRE11 De-Lactylation via HIF1α/HDAC5 Pathway.","authors":"Jingyi Li, Liang Feng, Lei Zhang, Weiguo Zhang, Yanting Zhang, Xiaoqin Liu, Qianqian Cai, Weiming Zhao, Gang Huang, Changlian Lu","doi":"10.7150/thno.113517","DOIUrl":null,"url":null,"abstract":"<p><p><b>Background:</b> Triple-negative breast cancer (TNBC), the most aggressive breast cancer subtype, exhibits poor prognosis due to radiotherapy resistance. However, the underlying mechanisms and effective therapeutic agents remain elusive. <b>Methods:</b> We employed lactate/oxamate to assess DNA damage/repair in irradiated TNBC cell lines. Lentiviral vectors for MRE11/HDAC5 constructs and shRNA were used to explore lactylation via Western blot/Co-IP. TCGA data mining, tissue microarrays, proteomics-MS, and gene expression profiling were used to dissect Saikosaponin D (SSD)'s radiosensitizing mechanisms. Promoter luciferase assays and ChIP-qPCR were performed to map SSD-induced HIF1α binding sites on the HDAC5 promoter. <b>Results:</b> Elevated endogenous lactate in radioresistant TNBC cells promoted DNA repair via MRE11 Lys<sup>673</sup> lactylation, a critical modification conferring radioresistance. HDAC5 was identified as the key delactylase for MRE11 Lys<sup>673,</sup> validated by HADDOCK docking (hydrogen bond between MRE11 Lys<sup>673</sup> and HDAC5 Ser<sup>18</sup>) and Co-IP (HDAC5 overexpression reduced K<sup>673</sup> lactylation). TCGA and clinical tissue microarrays confirmed HDAC5 downregulation in TNBC. SSD inhibits the malignant phenotype of TNBC and enhances radiotherapy efficacy by inhibition on MRE11 lactylation via upregulating HDAC5. Mechanistically, SSD upregulated HIF1α to bind the HDAC5 promoter (-342bp to -20bp region) to activate its expression. <b>Conclusion:</b> Lactate-driven MRE11 Lys<sup>673</sup> lactylation mediates radioresistance, while SSD reverses this via HIF1α/HDAC5 axis activation. Our findings identify SSD as a radiosensitizer and HDAC5/MRE11 as potential therapeutic targets for TNBC.</p>","PeriodicalId":22932,"journal":{"name":"Theranostics","volume":"15 17","pages":"8935-8951"},"PeriodicalIF":13.3000,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12439262/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Theranostics","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.7150/thno.113517","RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/1/1 0:00:00","PubModel":"eCollection","JCR":"Q1","JCRName":"MEDICINE, RESEARCH & EXPERIMENTAL","Score":null,"Total":0}
引用次数: 0
Abstract
Background: Triple-negative breast cancer (TNBC), the most aggressive breast cancer subtype, exhibits poor prognosis due to radiotherapy resistance. However, the underlying mechanisms and effective therapeutic agents remain elusive. Methods: We employed lactate/oxamate to assess DNA damage/repair in irradiated TNBC cell lines. Lentiviral vectors for MRE11/HDAC5 constructs and shRNA were used to explore lactylation via Western blot/Co-IP. TCGA data mining, tissue microarrays, proteomics-MS, and gene expression profiling were used to dissect Saikosaponin D (SSD)'s radiosensitizing mechanisms. Promoter luciferase assays and ChIP-qPCR were performed to map SSD-induced HIF1α binding sites on the HDAC5 promoter. Results: Elevated endogenous lactate in radioresistant TNBC cells promoted DNA repair via MRE11 Lys673 lactylation, a critical modification conferring radioresistance. HDAC5 was identified as the key delactylase for MRE11 Lys673, validated by HADDOCK docking (hydrogen bond between MRE11 Lys673 and HDAC5 Ser18) and Co-IP (HDAC5 overexpression reduced K673 lactylation). TCGA and clinical tissue microarrays confirmed HDAC5 downregulation in TNBC. SSD inhibits the malignant phenotype of TNBC and enhances radiotherapy efficacy by inhibition on MRE11 lactylation via upregulating HDAC5. Mechanistically, SSD upregulated HIF1α to bind the HDAC5 promoter (-342bp to -20bp region) to activate its expression. Conclusion: Lactate-driven MRE11 Lys673 lactylation mediates radioresistance, while SSD reverses this via HIF1α/HDAC5 axis activation. Our findings identify SSD as a radiosensitizer and HDAC5/MRE11 as potential therapeutic targets for TNBC.
期刊介绍:
Theranostics serves as a pivotal platform for the exchange of clinical and scientific insights within the diagnostic and therapeutic molecular and nanomedicine community, along with allied professions engaged in integrating molecular imaging and therapy. As a multidisciplinary journal, Theranostics showcases innovative research articles spanning fields such as in vitro diagnostics and prognostics, in vivo molecular imaging, molecular therapeutics, image-guided therapy, biosensor technology, nanobiosensors, bioelectronics, system biology, translational medicine, point-of-care applications, and personalized medicine. Encouraging a broad spectrum of biomedical research with potential theranostic applications, the journal rigorously peer-reviews primary research, alongside publishing reviews, news, and commentary that aim to bridge the gap between the laboratory, clinic, and biotechnology industries.