Immune evasion through mitochondrial transfer in the tumour microenvironment

Area of Science:

• Immunology
• Molecular Biology
• Cancer Research

Background:

• Tumor cells evade immune attack via complex mechanisms within the tumor microenvironment.
• Metabolic reprogramming and mitochondrial dysfunction in tumor-infiltrating lymphocytes (TILs) hinder anti-tumor immunity.
• The precise mechanisms underlying these immune evasion strategies remain incompletely understood.

Purpose of the Study:

• To elucidate the mechanisms by which cancer cells evade T cell-mediated attack.
• To investigate the role of mitochondrial transfer in cancer immune evasion.
• To determine the functional consequences of mitochondrial DNA (mtDNA) mutations in TILs.

Main Methods:

• Analysis of clinical tumor specimens.
• Identification of shared mtDNA mutations between cancer cells and TILs.
• In vitro and in vivo studies to assess mitochondrial transfer and its effects on T cell function.

Main Results:

• Shared mtDNA mutations were identified in TILs and cancer cells.
• Mitochondria with mtDNA mutations transfer from cancer cells to TILs.
• Transferred mitochondria resist mitophagy due to inhibitory molecules, leading to homoplasmic replacement and T cell dysfunction.
• mtDNA mutations in TILs impair effector functions and memory formation, reducing anti-tumor immunity.
• mtDNA mutations in tumor tissue predict poor response to immune checkpoint inhibitors in melanoma and non-small-cell lung cancer.

Conclusions:

• Mitochondrial transfer from cancer cells to TILs is a novel mechanism of immune evasion.
• Acquired mtDNA mutations disrupt TIL function and promote tumor immune escape.
• This pathway offers potential targets for developing new cancer immunotherapies.