MAP3K1 mutations confer tumor immune heterogeneity in hormone receptor-positive HER2-negative breast cancer

Area of Science:

• Oncology
• Immunology
• Genetics

Background:

• Hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer, the most prevalent subtype, exhibits challenges like endocrine therapy resistance and distant relapse.
• While immunotherapy shows promise in triple-negative breast cancer, its application in HR+/HER2- breast cancer requires further immunological investigation.

Purpose of the Study:

• To investigate the immunological heterogeneity in HR+/HER2- breast cancer.
• To identify biomarkers associated with this heterogeneity and elucidate underlying mechanisms.
• To explore novel therapeutic strategies for enhancing immunotherapy efficacy in this subtype.

Main Methods:

• Multi-omics analysis of a cohort of 351 HR+/HER2- breast cancer patients.
• Experimental validation of the impact of MAP3K1 mutations on antitumor immunity.
• Investigation of the role of MAP3K1 mutations in MHC-I antigen presentation and TAP1/2 mRNA degradation.
• Preclinical testing of tyramine as a therapeutic intervention.

Main Results:

• HR+/HER2- breast cancer exhibits significant tumor immune microenvironment heterogeneity.
• Mitogen-activated protein kinase kinase kinase 1 (MAP3K1) mutations are linked to this immunological heterogeneity.
• MAP3K1 mutations attenuate CD8+ T cell-mediated immunity by suppressing MHC-I presentation via TAP1/2 mRNA degradation, promoting immune escape.
• The postbiotic tyramine reversed MAP3K1 mutation-induced MHC-I reduction in preclinical models, enhancing immunotherapy efficacy.

Conclusions:

• MAP3K1 mutation is a key driver of immunological heterogeneity in HR+/HER2- breast cancer.
• MAP3K1 mutations promote tumor immune escape through impaired antigen presentation.
• Tyramine presents a promising novel therapeutic strategy to overcome MAP3K1-driven immune evasion and augment immunotherapy.