Construction and characterization of TCR repertoires in diverse mouse breast cancer models

SPF-grade 4-week-old female BALB/c and C57BL/6 mice were used to establish three breast cancer mouse models: 7 BALB/c mice inoculated with EMT6 cells, 8 BALB/c mice inoculated with 4T1 cells, and 7 C57BL/6 mice inoculated with E0771 cells, along with healthy control groups (5 BALB/c and 3 C57BL/6 mice). After euthanasia of model mice, tumor tissues, spleens, and lung tissues were collected: CD4+CD25+ regulatory T cells (Tregs) were sorted from tumor tissues and spleens, while total T cells were sorted from lung tumor-infiltrating tissues; for healthy control mice, only spleens were collected and CD4+CD25+ Tregs were sorted. Total DNA was extracted from all sorted cell samples, and TCR beta CDR3 repertoires were constructed by multiplex PCR and characterized by high-throughput sequencing.