✍🏼 Pengfei Liu, Wenjing Ma, Tao Wang, Jinhui Lü, Weizhong Wang, Yixing Wang, Qifan Tang, Jing Di, Evelyne Bischof, Qian Zhao & Zuoren Yu

🏠 Medical Innovation Center & State Key Laboratory of Cardiovascular Diseases, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China

📑 Cell Death Discovery (2025)

Abstract
Mental stress has been shown to negatively impact the development and progression of human cancer, including breast cancer. However, its effects on the tumor microenvironment (TME) remain unclear. In this study, we applied single-cell sequencing analysis to tumor tissues from MMTV-PyMT transgenic mice with mammary gland tumors with or without exposure to mental stress. In association with a significant promotion of the cell cycle and tumor growth induced by mental stress, we observed the dedifferentiation of luminal subtype of tumor cells into a subgroup of cancer stem cell-like basal cells, as well as enhanced cell proliferation in epithelial tumor cells, endothelial cells, and fibroblasts. In addition, stress stimulation led to an increase in tumor-associated neutrophils (TANs) and tumor-infiltrating dendritic cells (TIDCs), while suppressing immune cells such as cytotoxic T lymphocytes (CTLs), naïve T cells, B cells, and NK cells within the TME. We also observed a shift in macrophages from the M1 to the M2 phenotype. Furthermore, pathway enrichment analysis of differentially expressed genes, gene signature U score analysis, and immunofluorescence staining of the tumor tissue sections were conducted for further validation. The current study not only systematically elucidates the impact of mental stress on mammary gland tumors and the TME in vivo, but also provides insights into the mechanism underlying mental stress-induced tumor growth and progression in breast cancer.

How the WOLF was used in this study
In the Cell Death Discovery article (DOI: 10.1038/s41420-025-02619-1), the authors employed the WOLF Cell Sorter as part of their single-cell preparation workflow to isolate viable individual cells from dissociated tumor tissue prior to downstream single-cell RNA sequencing. Specifically, after enzymatically and mechanically dissociating the mammary tumors into a single-cell suspension, the WOLF Cell Sorter was used to enrich for live, intact tumor and microenvironment cells while removing dead cells and debris, ensuring that high-quality, viable cells entered the single-cell sequencing pipeline. This sorting step was critical for generating reliable transcriptomic profiles that accurately reflect the cellular heterogeneity and stress-induced alterations in both tumor cells and tumor-associated immune and stromal populations.