Mancini Caterina, Lori Giulia, Mattei Gianluca, Iozzo Marta, Desideri Dayana, Cianchi Fabio, Fortuna Laura, Passagnoli Federico, Massi Daniela, Ugolini Filippo, Messerini Luca, Piscuoglio Salvatore, Pezone Antonio, Magherini Francesca, Biagioni Alessio, Lottini Tiziano, Zambardino Demetra, Truglio Giuseppina Ivana, Petricci Elena, Magi Alberto, Arcangeli Annarosa, Maresca Luisa, Stecca Barbara, Pranzini Erica, Taddei Maria Letizia
Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy.
Department of Health Sciences Clinical Pharmacology and Oncology Unit, University of Florence, Florence, Italy.
J Exp Clin Cancer Res. 2025 Jul 10;44(1):198. doi: 10.1186/s13046-025-03447-y.
Phosphoglycerate dehydrogenase (PHGDH) is the rate-limiting enzyme in the de novo Serine synthesis pathway (SSP), a highly regulated pathway overexpressed in several tumors. Specifically, PHGDH expression is dynamically regulated during different stages of tumor progression, promoting cancer aggressiveness. Previously, we demonstrated that high Serine (Ser) availability, obtained by increased exogenous uptake or increased PHGDH expression, supports 5-Fluorouracil (5-FU) resistance in colorectal cancer (CRC). Beyond its metabolic role in sustaining Ser biosynthesis, different "non-enzymatic roles" for PHGDH have recently been identified. The present study aims to investigate non-enzymatic mechanisms through which PHGDH regulates 5-FU response in CRC.
Overexpression and gene silencing approaches have been used to modulate PHGDH expression in human CRC cell lines to investigate the role of this enzyme in 5-FU cellular response. Identified mechanisms have been validated in selected 5-FU resistant cell lines, CRC patients-derived tumor tissue samples, and patients-derived 3D organoids. Transcriptomic analysis was performed on wild-type and PHGDH-silenced cell lines, allowing the identification of pathways responsible for PHGDH-mediated 5-FU resistance. The relevance of identified genes was validated in vitro and in vivo in a CRC xenograft model.
PHGDH expression is highly variable among CRC tissues and patient-derived 3D organoids. A retrospective analysis of CRC patients highlighted a correlation between PHGDH expression and therapy response. Coherently, the modulation of PHGDH expression by gene silencing/overexpression affects 5-FU sensitivity in CRC cell lines. Transcriptomic analysis on CRC cell lines stably silenced for PHGDH evidenced down regulation in Hedgehog (HH) pathway. Accordingly, in vitro and in vivo studies demonstrated that the combined treatment of 5-FU and HH pathway inhibitors strongly hinders CRC cell survival and tumor growth in CRC xenograft models.
PHGDH sustains 5-FU resistance in CRC by mediating the upregulation of the HH signaling; targeting the here identified PHGDH-HH axis increases 5-FU susceptibility in different CRC models suggesting the 5-FU/HH-inhibitors combinatorial therapeutic strategy as a valid approach to counteract drug resistance in CRC.
磷酸甘油酸脱氢酶（PHGDH）是从头丝氨酸合成途径（SSP）中的限速酶，该途径受到高度调控且在多种肿瘤中过表达。具体而言，PHGDH的表达在肿瘤进展的不同阶段受到动态调控，促进癌症侵袭性。此前，我们证明通过增加外源性摄取或增加PHGDH表达获得的高丝氨酸（Ser）可用性可支持结直肠癌（CRC）对5-氟尿嘧啶（5-FU）的耐药性。除了其在维持丝氨酸生物合成中的代谢作用外，最近还发现了PHGDH的不同“非酶促作用”。本研究旨在探讨PHGDH调节CRC中5-FU反应的非酶促机制。
采用过表达和基因沉默方法来调节人CRC细胞系中PHGDH的表达，以研究该酶在5-FU细胞反应中的作用。已在选定的5-FU耐药细胞系、CRC患者来源的肿瘤组织样本和患者来源的3D类器官中验证了所确定的机制。对野生型和PHGDH沉默的细胞系进行转录组分析，从而确定负责PHGDH介导的5-FU耐药性的途径。在CRC异种移植模型中对体外和体内鉴定出的基因的相关性进行了验证。
PHGDH的表达在CRC组织和患者来源的3D类器官中高度可变。对CRC患者的回顾性分析突出了PHGDH表达与治疗反应之间的相关性。连贯地，通过基因沉默/过表达对PHGDH表达的调节会影响CRC细胞系中5-FU的敏感性。对稳定沉默PHGDH的CRC细胞系进行的转录组分析表明刺猬（HH）信号通路下调。因此，体外和体内研究表明，在CRC异种移植模型中，5-FU与HH信号通路抑制剂联合治疗可强烈阻碍CRC细胞存活和肿瘤生长。
PHGDH通过介导HH信号的上调维持CRC对5-FU的耐药性；靶向此处确定的PHGDH-HH轴可增加不同CRC模型中5-FU的敏感性，表明5-FU/HH抑制剂联合治疗策略是对抗CRC耐药性的有效方法。
