Yang, Y. H. | Search bioRxiv

bioRxiv2025

Deciphering Tumor Microenvironment Dynamics in Tumorigenesis and Lymph Node Metastasis of Esophageal Squamous Cell Carcinoma using Single-Cell RNA Sequencing

Esophageal squamous cell carcinoma (ESCC) exhibits profound inter-tissue heterogeneity, yet how immune and stromal ecosystems diverge between primary tumors and metastatic lymph nodes remains poorly understood. Here, we generated a single-cell atlas of 344,790 cells and paired T cell receptor profiles from primary tumor mucosa, adjacent mucosa, non-metastatic lymph nodes, and metastatic lymph nodes from 18 patients with treatment-naive ESCC. We identify compartment-specific immune and stromal architectures that shape distinct antitumor responses and suppressive programs. Primary tumors were characterized by marked enrichment of regulatory T cells (TREG) and activated dendritic cells coordinated through CTLA4-associated circuits, accompanied by accelerated CD8+ T cell differentiation toward intermediate and terminal exhaustion with loss of cytotoxicity. In contrast, metastatic lymph nodes preserved substantial pools of pre-exhausted CD8+ T cells with retained effector potential and strong clonal connectivity to the primary tumor, suggesting sustained antigen-driven trafficking. However, these reinvigoration-competent populations were embedded within a niche dominated by TREM2high macrophages that delivered SPP1-dependent suppressive signals to exhausted and regulatory T cells. Stromal lineages also displayed niche-specific specialization: tumor mucosa contained chemokine-rich inflammatory fibroblasts, whereas metastatic lymph nodes upregulated extracellular matrix remodeling programs. Together, our findings demonstrate that ESCC progression is governed by anatomically distinct exhaustion trajectories, clonal behaviors, stromal states, and suppressive circuits. This framework provides mechanistic insight into why lymph node response is a key determinant of clinical outcome and highlights the need for site-tailored immunomodulation strategies that target TREG-mediated suppression in primary tumors and TREM2high macrophage programs in metastatic nodes.

cancer biology↗

bioRxiv2019

Bax and Bak jointly control survival and dampen the early unfolded protein response in pancreatic β-cells under glucolipotoxic stress

ER stress and apoptosis contribute to the loss of pancreatic {beta}-cells under the pro-diabetic conditions of glucolipotoxicity. Although activation of the canonical pathway of intrinsic apoptosis is known to require Bax and Bak, their individual and combined involvement in glucolipotoxic {beta}-cell death have not been demonstrated. It has also remained an open question if Bax and Bak in {beta}-cells have non-apoptotic roles in mitochondrial function and ER stress signaling, as suggested in other cell types. Using mice with individual or combined {beta}-cell deletion of Bax and Bak, we demonstrated that glucolipotoxic {beta}-cell death in vitro happens in sequential stages; first via non-apoptotic mechanisms and later by apoptosis, which Bax and Bak were redundant in triggering. In contrast, they had non-redundant roles in mediating staurosporine-induced {beta}-cell apoptosis. We further established that Bax and Bak do not affect normal glucose-stimulated {beta}-cell Ca2+ responses, insulin secretion, or in vivo glucose tolerance. Finally, our experiments revealed that Bax and Bak together dampen the unfolded protein response in {beta}-cells during the early stages of chemical- or glucolipotoxicity-induced ER stress. These findings identify novel roles of the canonical apoptosis machinery in modulating stress signals that are important for the pathobiology of {beta}-cells in diabetes.

cell biology↗