RRM1 competes with NEDD4 to stabilize USP19 by blocking K387 ubiquitination and suppresses autophagy-mediated chemoresistance in colorectal cancer.

Authors

Lingxiao Wang, Weixing Zhang, Yifan Kang, Yingjia Wang, Shenghuai Hou, Fan Wang, Yuqiao Bai, Ruijun Ma, Jian Yang, Yaoping Li

Published in

Cellular oncology (Dordrecht, Netherlands). Jun 29, 2026. Epub Jun 29, 2026.

Abstract

Resistance to 5-fluorouracil (5-FU) remains a major clinical challenge in colorectal cancer (CRC) treatment. This study investigates the non-canonical role of ribonucleotide reductase subunit M1 (RRM1) in regulating autophagy-mediated chemoresistance.
A comprehensive multi-omics strategy, including metabolomics, transcriptomics and proteomics analyses, was employed to study 5-fluorouracil-resistant colorectal cancer tissues from patients and matched drug-resistant cell models. Protein-protein interactions, ubiquitination events and functional consequences were validated via complementary assays including Co-IP, GST pull-down, in vivo ubiquitination, structure-guided molecular docking, site-directed mutagenesis, and subcutaneous xenograft mouse models. Structure-based virtual screening was conducted to identify candidate compounds targeting the RRM1-USP19 interaction, with in vivo anti-tumor activity verified in 5-FU-resistant CRC xenografts.
RRM1 is significantly downregulated in 5-FU-resistant CRC tissues, and low RRM1 expression correlates with poor clinical prognosis. Mechanistically, RRM1 directly binds USP19 via conserved E647/R648 residues, competitively blocking NEDD4-mediated USP19 K387 ubiquitination and subsequent proteasomal degradation. Loss of RRM1 destabilizes USP19, impairs autophagic substrate deubiquitination, hyperactivates autophagic flux and thereby induces 5-FU resistance. Restoration of RRM1 or expression of the ubiquitination-defective USP19-K387R mutant re-sensitizes resistant CRC cells to 5-FU. The peptide GAGGVGKSAL, identified via virtual screening, specifically disrupts the RRM1-USP19 interface, inhibits excessive autophagy and potently suppresses tumor progression in 5-FU-resistant CRC xenograft models.
This study identifies the novel RRM1-USP19-NEDD4 regulatory axis as a core mediator of autophagy-driven 5-FU resistance in CRC, uncovers a non-canonical, metabolism-independent role of RRM1 as a USP19 stabilizer via competitive inhibition of NEDD4-mediated ubiquitination, and validates GAGGVGKSAL as a promising lead compound targeting this axis to reverse 5-FU resistance. The RRM1-USP19-NEDD4 axis represents a novel therapeutic target for overcoming chemoresistance in CRC.

PMID:
42371362
Bibliographic data and abstract were imported from PubMed on 29 Jun 2026.

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