Targeting the NSUN2–DHODH Axis Reverses Ferroptosis Resistance and Oxaliplatin Resistance in Colorectal Cancer

Junyi Zhang¹Junxiao Shen²Tangye Zeng³Chang Gao⁴Biao Sheng⁴Junliang Li¹Weiqi Zeng¹Jieyi Shen¹Chong Shen¹Jiaojiao Wang^5,6*Jianwei Wang^1,7*

• ¹Department of Surgery, the Fourth Affiliated Hospital of School of Medicine, and International School of Medicine, International Institutes of Medicine, Zhejiang University, Yiwu, China
• ²Department of Urology, the Fourth Affiliated Hospital of School of Medicine, and International School of Medicine, International Institutes of Medicine, Zhejiang University, Yiwu, China
• ³Department of General Surgery, Sir Run Run Shaw Hospital, The Medicine School of Zhejiang University, Hangzhou, China
• ⁴Department of Oncology, the Fourth Affiliated Hospital of School of Medicine, and International School of Medicine, International Institutes of Medicine, Zhejiang University, Yiwu, China
• ⁵Department of Radiation Oncology, Zhejiang Cancer Hospital, Hangzhou, China
• ⁶Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, China
• ⁷Department of Colorectal Surgery and Oncology, Key Laboratory of Cancer Prevention and Intervention, Ministry of Education, 2nd Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China

Oxaliplatin (OXA) is a standard chemotherapy for advanced colorectal cancer (CRC), yet acquired resistance frequently limits its efficacy. Ferroptosis, an iron-dependent form of cell death driven by lipid peroxidation, represents a promising strategy to overcome chemoresistance. The RNA 5-methylcytosine (m5C) methyltransferase NSUN2 has been implicated in tumor progression, but its role in CRC chemoresistance remains unclear. Here, we investigated the functional and mechanistic involvement of NSUN2 in CRC progression and OXA response with a focus on ferroptosis-related pathways. Integrative analyses of bulk, single-cell, and spatial transcriptomic datasets, together with multi-cohort clinical validation, revealed that NSUN2 is upregulated in CRC and associated with poor prognosis. Functional assays, including colony formation, CCK-8 proliferation, migration, invasion, apoptosis, and xenograft experiments, showed that NSUN2 depletion suppressed CRC growth and enhanced sensitivity to OXA. NSUN2 knockdown increased lipid reactive oxygen species (ROS) accumulation, elevated malondialdehyde (MDA) levels, and induced mitochondrial damage, consistent with elevated ferroptotic stress. In vivo, NSUN2 depletion potentiated the antitumor activity of OXA in SW480 xenografts, and combining OXA with the ferroptosis inducer imidazole ketone erastin (IKE) further reduced tumor burden compared with OXA alone; in both contexts, tumor MDA was increased, consistent with enhanced lipid peroxidation. Mechanistically, NSUN2 stabilized dihydroorotate dehydrogenase (DHODH) mRNA through m5C modification, thereby increasing DHODH expression. Elevated DHODH acted as a ferroptosis suppressor independently of GPX4, whereas NSUN2 depletion disrupted this regulatory axis, promoting lipid peroxidation and ferroptosis sensitivity. DHODH restoration rescued ferroptosis and reversed the enhanced drug sensitivity caused by NSUN2 knockdown. Together, these findings define an NSUN2–DHODH epitranscriptomic axis that promotes CRC progression and OXA resistance by limiting ferroptosis, supporting NSUN2-targeting and ferroptosis-promoting strategies to improve chemotherapy response.