✍🏼Xiao Ding, Nick Lung-Ngai Ting, Chi Chun Wong, Pingmei Huang, Nata Bakuradze, Lanping Jiang, Chuanfa Liu, Yufeng Lin, Shiyu Li, Yujie Liu, Mingxu Xie, Weixin Liu, Kai Yuan, Luyao Wang, Xinyue Zhang, Yanqiang Ding, Qing Li, Yang Sun, Yinglei Miao, Lanqing Ma, Xiang Gao, Weixun Li, William K.K. Wu, Joseph J.Y. Sung, Sunny Hei Wong, Jun Y

🏠 Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China

📑 Cell Host & Microbe (2025)

Abstract
Chemoresistance is a main cause of colorectal cancer (CRC) treatment failure. We identified that Bacteroides fragilis is enriched in patients with CRC resistant to chemotherapy in two independent cohorts, and its abundance is associated with poor survival. Consistently, administration of B. fragilis to CRC xenografts and ApcMin/+- and AOM/DSS-induced CRC mice all significantly attenuated the antitumor efficacy of 5-FU and OXA. Mechanistically, B. fragilis colonized colon tumors and mediated its effect via its surface protein SusD/RagB binding to the Notch1 receptor in CRC cells, leading to activation of the Notch1 signaling pathway and the induction of epithelial-to-mesenchymal transition (EMT)/stemness to suppress chemotherapy-induced apoptosis. Either deletion of SusD/RagB or blockade of Notch1 signaling abrogated B. fragilis-mediated chemoresistance. Finally, B. fragilis-targeting phage VA7 selectively suppressed B. fragilis and restored chemosensitivity in preclinical CRC mouse models. Our findings have offered insights into the potential of precise gut microbiota manipulation for the clinical management of CRC.

How the WOLF was used in this study
The WOLF Cell Sorter was used during preparation of samples for single-cell RNA sequencing to isolate specific, viable immune cell populations from mouse colorectal tumor tissues. Following enzymatic dissociation of AOM/DSS-induced tumor samples into single-cell suspensions, cells were stained with FITC-conjugated anti-mouse CD45 to identify hematopoietic immune cells and propidium iodide to exclude nonviable cells. The WOLF cell sorter was then used to gently enrich live CD45⁺, PI⁻ cells, ensuring high cell viability and purity prior to downstream single-cell transcriptomic analysis. This sorting step enabled accurate profiling of tumor-infiltrating immune cells while minimizing cellular stress and preserving RNA integrity, which is critical for high-quality single-cell RNA-seq data.