Epigenetic control of antigen presentation failure in osteosarcoma: from single-cell chromatin maps to therapeutic...

Area of Science:

• Immunology
• Epigenetics
• Oncology

Background:

• Osteosarcoma exhibits heterogeneous tumor-immune ecosystems that limit immune surveillance and immunotherapy response.
• Impaired antigen visibility, driven by chromatin programs, is a key mechanism in osteosarcoma immune evasion.
• Epigenetic alterations like Polycomb-mediated repression and DNA hypermethylation affect the HLA class I/NLRC5/interferon pathway, reducing peptide display.

Purpose of the Study:

• To synthesize epigenetic mechanisms of antigen-presentation failure in osteosarcoma.
• To outline how single-cell chromatin profiling can guide strategies to reinstate tumor antigen visibility.
• To explore epigenetic reprogramming as a therapeutic avenue for osteosarcoma.

Main Methods:

• Utilized single-cell ATAC-seq integrated with single-cell and spatial transcriptomics.
• Analyzed promoter-enhancer accessibility at HLA, NLRC5, and antigen-processing genes.
• Examined epigenetic reprogramming strategies targeting Polycomb repressive complex 2 (PRC2) and DNA methyltransferases (DNMTs).

Main Results:

• Single-cell chromatin profiling resolves epigenetic constraints on antigen presentation, distinguishing reversible repression from fixed lesions.
• Identified context-dependent epigenetic variations across malignant clones and cellular niches.
• Demonstrated that epigenetic reprogramming offers potential biomarker-guided strategies to restore antigen presentation.

Conclusions:

• Epigenetic reprogramming targeting PRC2, DNMTs, and other regulators can restore antigen presentation in osteosarcoma.
• Therapeutic efficacy depends on clone selection, scheduling, and combination strategies.
• Single-cell chromatin profiling is crucial for guiding epigenetic therapies to improve osteosarcoma treatment outcomes.