MYCN: from oncoprotein to tumor-associated antigen

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• The MYCN oncogene is frequently overexpressed in various human cancers, notably neuroblastoma (NB), where it serves as a poor-prognosis biomarker.
• MYCN belongs to a family of transcription factors, including C-MYC, and its downregulation has shown promise in tumor regression models, identifying MYC proteins as potential therapeutic targets.

Purpose of the Study:

• To evaluate the MYCN protein as a potential tumor-associated antigen (TAA) for immunotherapeutic strategies in neuroblastoma (NB).
• To discuss the challenges and strategies for targeting MYCN using cytotoxic T lymphocytes (CTLs) in the context of NB immune evasion mechanisms.

Main Methods:

• Assessed MYCN expression patterns in tumor cells versus adult tissues.
• Identified MYCN-derived peptides with high affinity for HLA-A1 and HLA-A2 molecules.
• Reviewed NB cell antigen-presenting capabilities, including HLA class I expression and co-stimulatory molecule presence.
• Examined immune evasion strategies employed by NB cells, such as soluble immunosuppressive molecules and immunosuppressive cells.

Main Results:

• MYCN protein is absent in normal adult tissues but upregulated in NB cells, fulfilling a key criterion for a TAA.
• Immunogenic MYCN peptides capable of binding to HLA-A1 and HLA-A2 have been identified.
• NB cells exhibit deficiencies in antigen presentation, including low HLA class I expression and defects in antigen processing machinery, alongside immune evasion mechanisms.

Conclusions:

• MYCN protein is a viable candidate TAA for NB immunotherapy due to its tumor-specific expression and processing into immunogenic peptides.
• Overcoming NB cell-intrinsic antigen-presenting cell deficiencies and tumor-mediated immune suppression is critical for developing effective CTL-based immunotherapies targeting MYCN.