Cognate Nonlytic Interactions between CD8⁺ T Cells and Breast Cancer Cells Induce Cancer Stem Cell-like Properties

Area of Science:

• Immunology
• Cancer Biology
• Cellular Differentiation

Background:

• Immune checkpoint blockade (ICB) shows therapeutic promise but often fails, with some patients experiencing hyperprogression.
• Understanding cancer cell responses to ineffective T cells is crucial for improving immunotherapy outcomes.

Purpose of the Study:

• To investigate how breast cancer cells respond to antigen-specific CD8+ T cells lacking cytotoxic function.
• To identify molecular and cellular changes in cancer cells induced by non-lytic T cell interactions.

Main Methods:

• Co-culture of MCF-7 breast cancer cells with Concanamycin A-treated CD8+ T cells.
• Gene expression analysis to identify induced pathways.
• Assessment of stem cell-like properties and tumor-forming capacity in vivo.

Main Results:

• Non-lytic T cell interaction induced PD-L1, IDO1, and CEACAM1 in cancer cells.
• Observed gene signatures indicative of dedifferentiation and pluripotency (Yamanaka factors).
• Increased stem cell-like cancer cells, enhanced tumor growth, proliferation, and metastasis in mice.

Conclusions:

• Ineffective CD8+ T cell interactions can drive cancer cell dedifferentiation and stemness, representing a novel immune escape mechanism.
• This immune-mediated dedifferentiation enhances malignant potential and may explain immunotherapy-induced hyperprogression.
• Targeting this pathway could offer new strategies to overcome resistance to cancer immunotherapy.