Vitamin C enhances cisplatin sensitivity in bladder cancer via 5hmC-mediated epigenetic modulation of ATF4

  • Clin Epigenetics. 2025 Dec 19;17(1):203. doi: 10.1186/s13148-025-02011-x.
Chunru Xu  #  1  2  3 ,  Wenwei Ying  #  1  2  3 ,  Yuhui He  #  1  2  3 ,  Yucai Wu  1  2  3 ,  Tai Tian  1  2  3 ,  Jilong Zhang  1  2  3 ,  Shiming He  1  2  3 ,  Cuijian Zhang  4  5  6 ,  Xuesong Li  7  8  9 ,  Yanqing Gong  10  11  12
Affiliations
  • 1. Department of Urology, Peking University First Hospital, No 8 Xishiku Street, Xicheng District, Beijing, 100034, China.
  • 2. Institute of Urology, Peking University, Beijing, 100034, China.
  • 3. Beijing Key Laboratory of Urogenital Diseases (Male) Molecular Diagnosis and Treatment Center, Beijing, 100034, China.
  • 4. Department of Urology, Peking University First Hospital, No 8 Xishiku Street, Xicheng District, Beijing, 100034, China. [email protected].
  • 5. Institute of Urology, Peking University, Beijing, 100034, China. [email protected].
  • 6. Beijing Key Laboratory of Urogenital Diseases (Male) Molecular Diagnosis and Treatment Center, Beijing, 100034, China. [email protected].
  • 7. Department of Urology, Peking University First Hospital, No 8 Xishiku Street, Xicheng District, Beijing, 100034, China. [email protected].
  • 8. Institute of Urology, Peking University, Beijing, 100034, China. [email protected].
  • 9. Beijing Key Laboratory of Urogenital Diseases (Male) Molecular Diagnosis and Treatment Center, Beijing, 100034, China. [email protected].
  • 10. Department of Urology, Peking University First Hospital, No 8 Xishiku Street, Xicheng District, Beijing, 100034, China. [email protected].
  • 11. Institute of Urology, Peking University, Beijing, 100034, China. [email protected].
  • 12. Beijing Key Laboratory of Urogenital Diseases (Male) Molecular Diagnosis and Treatment Center, Beijing, 100034, China. [email protected].
  • # Contributed equally.
PMID: 41420190 DOI: 10.1186/s13148-025-02011-x
Abstract

Cisplatin resistance remains a major challenge in the clinical treatment of bladder Cancer (BC), and the epigenetic regulation of this resistance, particularly involving 5-hydroxymethylcytosine (5hmC), has not been fully elucidated. Here, we investigated the role of 5hmC and vitamin C (VC) in modulating cisplatin sensitivity in BC. Clinical analyses of 36 BC patients receiving cisplatin-based neoadjuvant chemotherapy showed that reduced 5hmC levels in pre-chemotherapy tumor tissues were significantly associated with cisplatin resistance (CR-BC) and poor prognosis, with low 5hmC correlating with shorter progression-free survival (PFS). In vitro, we established two cisplatin-resistant cell lines (T24-CR, UMUC-3-CR) that exhibited reduced 5hmC compared to parental cells. Treatment with 100 μM VC significantly restored 5hmC levels in CR-BC cells by activating TET Enzymes, inhibited cell proliferation, and enhanced cisplatin sensitivity; these effects were abrogated by the TET inhibitor Bobcat339, confirming VC acts in a TET-dependent manner. Mechanistically, genome-wide 850 K methylation array and RNA-seq analyses revealed that VC upregulated methylation specifically at the promoter of ATF4, a downstream effector of the MAPK pathway, thereby downregulating ATF4 expression. ATF4 knockdown in CR-BC cells increasing cisplatin sensitivity, while Bobcat339 reversed VC-induced ATF4 downregulation. In vivo, VC combined with cisplatin significantly inhibited tumor growth in T24-CR xenografts, and co-treatment with ATF4 knockdown further enhanced this effect, accompanied by elevated 5hmC and reduced Ki67 in tumors. Collectively, our findings identify reduced 5hmC as a hallmark of cisplatin-resistant BC and reveal a novel mechanism by which VC enhances cisplatin sensitivity. VC activates TET Enzymes to increase 5mC at the ATF4 promoter, downregulating ATF4 and modulating the MAPK pathway. This highlights VC as a potential epigenetic Adjuvant to overcome cisplatin resistance in BC.

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