Hypoxia promotes tumor immune evasion by suppressing MHC-I expression and antigen presentation

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Hypoxia, low oxygen, is prevalent in solid tumors.
• Hypoxia is linked to resistance to cancer therapies, including immunotherapy.
• Hypoxic tumors can evade T-cell recognition and killing.

Purpose of the Study:

• To elucidate the molecular mechanisms by which hypoxia promotes tumor immune evasion.
• To investigate the impact of hypoxia on MHC class I expression and antigen presentation.
• To explore therapeutic strategies targeting hypoxia-induced immune suppression.

Main Methods:

• Analysis of hypoxic tumors to assess MHC class I expression and the immunopeptidome.
• Investigating the role of autophagy and the unfolded protein response (UPR) in hypoxia-induced immune evasion.
• Utilizing immunopeptidomics-based liquid chromatography-mass spectrometry (LC-MS).
• Employing a respiratory complex-I inhibitor in experimental tumors.

Main Results:

• Hypoxia downregulates MHC class I expression and reduces the presentation of antigens (immunopeptidome) in an oxygen-dependent manner.
• Hypoxia activates autophagy via the PERK arm of the UPR, contributing to decreased antigen presentation.
• Inhibition of autophagy under hypoxic conditions enhances antigen presentation.
• Reducing mitochondrial metabolism with a complex-I inhibitor increases tumor oxygenation, MHC class I levels, and the immunopeptidome.

Conclusions:

• Hypoxia drives tumor immune evasion by downregulating MHC class I and antigen presentation through autophagy activation.
• Targeting hypoxia-induced autophagy or mitochondrial metabolism may represent novel therapeutic strategies to enhance anti-tumor immunity.