2. Academic Validation
  3. PCK2 promotes invasion and epithelial-to-mesenchymal transition in triple-negative breast cancer by promoting TGF-β/SMAD3 signaling through inhibiting TRIM67-mediated SMAD3 ubiquitination

PCK2 promotes invasion and epithelial-to-mesenchymal transition in triple-negative breast cancer by promoting TGF-β/SMAD3 signaling through inhibiting TRIM67-mediated SMAD3 ubiquitination

  • Cancer Biol Ther. 2025 Dec;26(1):2478670. doi: 10.1080/15384047.2025.2478670.
Tsung-Ming Chang 1 2,  Wei-Yu Fang 1,  Hui-Ping Hsu 3,  Pei-Yi Chu 1 4 5,  Shih Sheng Jiang 1,  Kuo-Wei Huang 1,  Wen-Chun Hung 1,  Hui-You Lin 1,  Hui-Jen Tsai 1 6 7
Affiliations

Affiliations

  • 1 National Institute of Cancer Research, National Health Research Institutes, Tainan, Taiwan.
  • 2 Department of Medical Laboratory Science, College of Medical Science and Technology, I-Shou University, Kaohsiung, Taiwan.
  • 3 Department of Surgery, National Cheng Kung University Hospital, Tainan, Taiwan.
  • 4 Department of Pathology, Show Chwan Memorial Hospital, Taiwan.
  • 5 Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, Taichung, Taiwan.
  • 6 Department of Oncology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
  • 7 Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
PMID: 40081967 DOI: 10.1080/15384047.2025.2478670
Abstract

PCK2, which encodes mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M), is upregulated in various cancers. We demonstrated high expression of PEPCK-M in approximately half of triple-negative breast cancers (TNBCs) previously. TNBC is associated with an aggressive phenotype and a high metastasis rate. In this study, we investigated the role of PCK2 in TNBC. PCK2 knockdown suppressed proliferation and mTOR signaling in TNBC cells. In addition, cell invasion/migration ability and the expression of epithelial-to-mesenchymal transition (EMT) markers were positively correlated with PCK2 expression in TNBC cells via regulation of transforming growth factor-β (TGF-β)/SMAD3 signaling. SMAD3 was positively regulated by PCK2 in TNBC cells. Knockdown of SMAD3 in PCK2-overexpressing TNBC cells reduced the expression levels of EMT markers, Snail and Slug, and suppressed cell invasion/migration. In addition, PCK2 knockdown attenuated the stimulatory effect of TGF-β on SMAD3 phosphorylation in TNBC cells. PEPCK-M promotes the protein and mRNA expression of SMAD3 via competitive binding to tripartite motif-containing 67 (TRIM67), an E3 ubiquitin Ligase, to reduce SMAD3 ubiquitination, which leads to promoting nuclear translocation of SMAD3 and autoregulation of SMAD3 transcription. Moreover, high PCK2 mRNA expression was significantly associated with poor survival in TNBC patients. In conclusion, our study revealed for the first time that PCK2 activates TGF-β/SMAD3 signaling by regulating the expression and phosphorylation of SMAD3 by inhibiting TRIM67-mediated SMAD3 ubiquitination and promoting the stimulatory effect of TGF-β to promote TNBC invasion. The regulatory effect of PCK2 on mTOR and TGF-β/SMAD3 signaling suggests that PCK2 is a potential therapeutic target for suppressing TNBC progression.

Keywords

Epithelial-to-mesenchymal transition (EMT); PCK2; TGF-β/SMAD3; TRIM67; mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M); triple-negative breast cancer.

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