Low mutation and neoantigen burden and fewer effector tumor infiltrating lymphocytes correlate with breast cancer metastasization to lymph nodes.

Lymph node metastasis is of major prognostic significance for breast cancer. Lymph node metastasis arises at a very early stage in some patients. Using the data downloaded from the TCGA database, we studied the differences between primary tumors with and without lymph node metastasis at the multi-omics level using bioinformatics approaches. Our study found that low mutation and neoantigen burdens correlated with lymph node metastazation of breast cancer. All three conserved domains in TP53 were mutated in lymph node-negative breast cancers, whereas only one domain was mutated in lymph node-positive samples. Mutations in microtubule-related proteins appear to help immune cells recognize tumors and inhibit their lymph node metastasis. Destroying microtubule-related proteins is a potential therapeutic strategy to inhibit lymph node metastasis of breast cancer. As the neoantigens specifically present in lymph node-positive breast cancers, MAPK10, BC9L, TRIM65, CD93, KITLG, CNPPD1, CPED1, CCDC146, TMEM185A, INO80D, and PSMD11 are potential targets for vaccine design. In the tumor microenvironment, reduced numbers of effector immune cells, especially activated memory CD4+ T cells and activated mast cells, facilitate breast cancer metastasis to the lymph nodes. According to transcriptome data, lymph node metastasis was mostly driven by gene mutation rather than by gene expression. Although differential gene expression analysis was based on lymph node metastasis status, many genes were shown to be differentially expressed based on estrogen receptor status.