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Updated: Jan 14, 2026
Modeling Oral-Esophageal Squamous Cell Carcinoma in 3D Organoids
Published on: December 23, 2022
Multiomics identifies a cholesterol-TFEB-PLD3-TLR9 axis driving immunosuppressive tumor-associated macrophage
Licheng Tan1, Hongyu Zhou2, Baifeng Zhang1
1Department of Clinical Oncology, Centre for Cancer Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong 852, Special Administrative Region, China.
Abstract:
Tumor-associated macrophages (TAMs) reshape the tumor immune microenvironment and promote tumor progression, yet the underlying mechanisms remain largely unclear. Through integration of single-cell RNA (scRNA) sequencing datasets from esophageal squamous cell carcinoma (ESCC), we identified a distinct protumoral macrophage population with elevated expression of phospholipase D3 (PLD3). Multiomics investigations revealed that high infiltration of these PLD3-high macrophages was associated with poor clinical outcomes in ESCC patients. Mechanistically, tumor cells secreted cholesterol to modulate the microenvironment. Upon the uptake by TAMs, cholesterol triggered the nuclear translocation of transcription factor EB (TFEB), which directly bound to the PLD3 promoter region and activated its transcription. The overexpressed PLD3 localized to lysosomes, enzymatically degrading single-stranded nucleic acids, thereby suppressing the activation of the toll-like receptor 9 (TLR9) pathway. This cascade ultimately impaired effector T cell function and sustained an immunosuppressive tumor microenvironment (TME). Notably, therapeutic intervention using ODN2216-siPLD3 in murine models enhanced CD8 T cell infiltration and significantly inhibited tumor growth. Our findings highlight PLD3-high macrophages as a promising diagnostic biomarker and a therapeutic target for ESCC, paving the way for potential clinical translation.
Insights
Tumor-associated macrophages expressing high levels of phospholipase D3 (PLD3) promote esophageal cancer progression by suppressing T cell function. Targeting PLD3 offers a potential therapeutic strategy for esophageal squamous cell carcinoma (ESCC).
Area of Science:
- Immunology
- Oncology
- Molecular Biology
Background:
- Tumor-associated macrophages (TAMs) are key players in shaping the tumor immune microenvironment.
- The specific mechanisms by which TAMs promote tumor progression, particularly in esophageal squamous cell carcinoma (ESCC), are not fully understood.
Purpose of the Study:
- To identify and characterize protumoral macrophage populations in ESCC.
- To elucidate the molecular mechanisms by which these macrophages contribute to an immunosuppressive tumor microenvironment.
- To evaluate PLD3 as a potential diagnostic biomarker and therapeutic target in ESCC.
Main Methods:
- Integration of single-cell RNA sequencing datasets from ESCC patients.
- Multiomics investigations including cholesterol uptake, transcription factor EB (TFEB) nuclear translocation, and PLD3 expression analysis.
- Assessment of the role of PLD3 in nucleic acid degradation and Toll-like receptor 9 (TLR9) pathway activation.
- Therapeutic intervention using ODN2216-siPLD3 in murine models.
Main Results:
- A distinct protumoral macrophage population with elevated phospholipase D3 (PLD3) expression was identified in ESCC.
- High infiltration of PLD3-high macrophages correlated with poor clinical outcomes in ESCC patients.
- Cholesterol secreted by tumor cells induced TFEB-mediated PLD3 transcription in TAMs.
- PLD3 degrades single-stranded nucleic acids, suppressing TLR9 pathway activation, impairing effector T cell function, and creating an immunosuppressive TME.
- Therapeutic inhibition of PLD3 enhanced CD8 T cell infiltration and suppressed tumor growth in mouse models.
Conclusions:
- PLD3-high macrophages represent a critical protumoral cell type in ESCC.
- The cholesterol-TFEB-PLD3 axis is a key mechanism driving immunosuppression in the ESCC tumor microenvironment.
- PLD3 is a promising diagnostic biomarker and therapeutic target for ESCC, with potential for clinical translation.
