Berberine from Tibetan Medicine Dracocephalum tanguticum Maxim Suppresses Colorectal Tumor Growth and Inhibits CD8⁺ T Cells Ferroptosis via the NRF2–SLC7A11–GPX4 Axis

Yating Wang, Yanning Zhang, Qiang Wang, Linfan Zheng, Yan Liu Department of Traditional Chinese Medicine, School of Medicine, Qinghai University, Xining, Qinghai, 810006, People’s Republic of ChinaCorrespondence: Yan Liu, Department of Traditional Chinese Medicine, School of Medicine, Qinghai University, Xining, Qinghai, 810006, People’s Republic of China, Email [email protected]: This study aimed to identify berberine as the candidate active constituent of Dracocephalum tanguticum Maxim (D. tanguticum) and to investigate whether it suppresses colorectal tumor growth by inhibiting ferroptosis in cytotoxic T lymphocytes via the NRF2–SLC7A11–GPX4 axis.Methods: The antitumor activity of D. tanguticum ethanol extract (DME) was evaluated in CT-26 murine colorectal cancer cells using CCK-8, wound healing, and colony formation assays. Flow cytometry was used to determine the proportion of CD8+ T cells in tumor-bearing mice and to assess exhaustion markers on tumor-infiltrating CD8+ T cells. Transcriptomic sequencing and molecular docking were performed to identify the interaction between berberine (BBR), tentatively identified as a candidate active constituent of DME, and GPX4, and the effect of BBR on erastin-induced ferroptosis in CD8⁺ T cells was subsequently validated.Results: BBR, a putatively annotated candidate metabolite putatively annotated from DME, attenuated ferroptosis in tumor-infiltrating CD8⁺ T cells, as confirmed by rescue assays using ferroptosis inducers. Accordingly, BBR treatment increased the proportion of functional CD8⁺ T cells while reducing exhausted T-cell populations in both in vitro and in vivo models. Mechanistically, BBR activated the NRF2–SLC7A11–GPX4 axis, leading to GPX4 upregulation and ferroptosis suppression in CD8⁺ T cells.Conclusion: Berberine, a candidate metabolite derived from D. tanguticum, enhances CD8+T cells function and suppresses ferroptosis via the NRF2–SLC7A11–GPX4 pathway, supporting its further development as a novel immunotherapeutic agent for colorectal cancer.Keywords: Dracocephalum tanguticum Maxim, colorectal cancer, CD8+ T cells, ferroptosis, berberine