Abstract 3275: PHGDH-mediated serine-glycine-one-carbon metabolism drives ferroptosis- and chemotherapy-resistance in colorectal cancer
Authors: Liang Guanzhan , Chen Jing , Wen Xiaofeng , Zhang Zongjin , Chen Zexian , Chen Yongle , Xian Zhenyu , He Xiaowen , Wu Xianrui , Lan Ping , Hu Tuo 
Published: March 2024

Abstract
Background and Aim: Ferroptosis is an iron-dependent form of programmed cell death characterized by lipid peroxidation, with the potential as a novel cancer therapy. The application of ferroptosis-inducers has been limited to preclinical studies due to toxic side effects and drug-resistance. Our study aims to explore the metabolic mechanism in regulating ferroptosis-resistance, thereby identifying combinational therapeutic target for ferroptosis-inducers.
Methods: The ferroptosis-resistant CRC cell lines were induced by chronic exposure to ferroptosis inducer Erastin and verified by cell viability assay. Metabolomics and transcriptomics were performed to identify the metabolic characteristics in ferroptosis-resistant CRC cells. Quantitative RT-PCR and western blot was applied to confirm the differentially expressed serine-glycine-one-carbon metabolism (SGOC) enzymes. The MTT cell viability assay, colony formation assay, 3D spheroid formation assay and cell derived xenograft (CDX) model were carried out to investigate the therapeutic effect of targeting SGOC key enzyme-phosphoglycerate dehydrogenase (PHGDH) in combination of ferroptosis inducers. Gene set enrichment analysis (GSEA) was performed to identify molecular mechanism for the upregulation of SGOC enzymes based on RNA-seq data from TCGA-COAD cohort.
Results: Metabolomic and transcriptomic data revealed that SGOC metabolism was significantly increased in ferroptosis-resistant CRC cells. Moreover, the mRNA and protein level of SGOC key enzyme-PHGDH were remarkably upregulated in ferroptosis-resistant CRC cells. PHGDH inhibitor NCT-503 or knockdown of PHGDH exhibited a great synergistic effect with ferroptosis inducers for CRC cells in vitro or in vivo. Additionally, targeting PHGDH could dramatically restore the sensitivity of ferroptosis-inducers in ferroptosis-resistant cells. The RNA methyltransferase-like 3 (METTL3) was identified as the upstream regulator responsible for the upregulation of PHGDH in an m6A-dependent manner. The ferroptosis stress induced deacetylation of METTL3, thereby promoting its nuclear translocation and enzyme activity.
Conclusions: In summary, we have uncovered that CRC cells resisted ferroptosis inducers via METTL3-PHGDH axis. Targeting PHGDH combined with ferroptosis inducers exhibited with synergistic effect for CRC in vitro and in vivo. Our findings identified the metabolic vulnerability in ferroptosis-resistant CRC cells, which could serve as a novel therapeutic target.
Citation Format: Guanzhan Liang, Jing Chen, Xiaofeng Wen, Zongjin Zhang, Zexian Chen, Yongle Chen, Zhenyu Xian, Xiaowen He, Xianrui Wu, Ping Lan, Tuo Hu. PHGDH-mediated serine-glycine-one-carbon metabolism drives ferroptosis- and chemotherapy-resistance in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3275.