Single-cell and Spatial Transcriptomic Analyses Implicate Formation of the Immunosuppressive Microenvironment during...

Area of Science:

• Oncology
• Immunology
• Genomics

Background:

• Ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) are key stages in breast cancer progression.
• Genomic instability, marked by increased mutation and copy number variation rates, is a hallmark of tumor development.
• Understanding cellular states and intercellular interactions during tumor progression is crucial for deciphering cancer evolution.

Purpose of the Study:

• To investigate the evolutionary trajectory of tumor cells during breast cancer progression.
• To elucidate the mechanisms establishing an immunosuppressive tumor microenvironment.
• To analyze cellular and molecular changes from ductal carcinoma in situ to invasive ductal carcinoma.

Main Methods:

• Exploratory analysis of single-cell sequencing data from 13 breast cancer samples (DCIS and IDC).
• Utilized spatial transcriptomics to confirm cellular colocalization and molecular interactions.
• Investigated gene expression patterns of tumor and immune cells.

Main Results:

• Tumor cells exhibited increased malignancy and aggressiveness during progression from DCIS to IDC.
• T cells transitioned to an exhausted phenotype, contributing to immune suppression.
• Tumor cells expressed coinhibitory ligands, interacting with immune cell receptors to foster an immunosuppressive microenvironment.
• Spatial transcriptomics validated the physical proximity of tumor and immune cells and the expression of key ligand-receptor pairs.

Conclusions:

• Breast cancer progression is associated with escalating tumor cell malignancy and immune evasion.
• The formation of an immunosuppressive tumor microenvironment is driven by specific tumor-immune cell interactions.
• These findings offer insights into the cellular and molecular basis of immune suppression in breast cancer progression.