CD8+MTs+ Effector T Cells from Enlarged Tumor-Draining Lymph Nodes Drive Enhanced Tumor Immunogenicity and Improved Prognosis in Colorectal Cancer Patients

Tumor-draining lymph nodes (TDLNs) play a crucial role in anti-tumor immunity. However, the heterogeneity of TDLNs significantly impacts their immune function. We employed single-cell RNA sequencing to dissect the immune landscape of TDLNs of colorectal cancer (CRC), revealing that enlarged non-metastatic TDLNs (L-TDLNs) are enriched with CD8+ effector T cells (Teff) exhibiting a distinct metallothionein (MT)-positive signature. These CD8+MTs+ Teff cells, characterized by heightened cytotoxicity and a stress-adapted phenotype, are critical mediators of anti-tumor immunity. Our data indicate that these cells migrate from L-TDLNs to tumor sites, enhancing tumor immunogenicity. Moreover, CRC patients with a high level of CD8+MTs+ Teff in tumor site showed a significant survival advantage, particularly when treated with adjuvant chemotherapy. These findings underscore the importance of L-TDLNs in shaping effective antitumor immune responses in CRC, suggesting that the CD8+MTs+ Teff cell population may serve as a novel prognostic biomarker and therapeutic target. Our study provides a comprehensive framework for understanding the cellular dynamics within TDLNs and their impact on CRC progression and treatment response. To elucidate the ecosystem of primary CRC and especially the different TDLNs, we first used droplet-based scRNA-seq to profile the transcriptomes of 57,427 cells from 8 fresh CRC samples, including 2 CRC, 2 metastatic TDLNs (M-TDLNs), 4 non-metastatic TDLNs (N-TDLNs) tissues.