Immunoglobulin Repertoire Analysis of Tumor Infiltrating B cells in a Metastatic HER2 Positive Breast Cancer Mouse Model - Breast cancer (BC) is the most commonly diagnosed cancer and one of the leading causes of cancer-related death worldwide. HER2 positive (HER2+) BC, present in approximately 30% of BC cases, is characterized by its aggressive progression and high likelihood of metastasis. Patient survival significantly declines once the cancer becomes resistant to standard treatments or spreads. Mutations in the tumor suppressor gene p53 are observed in 50% to 90% of HER2-positive BCs and are strongly correlated with poorer survival outcomes. Meanwhile, emerging evidence suggests that immunoglobulins (Igs) produced by tumor-infiltrating B cells (TIL-Bs) recognize and respond to tumor antigens and may play a tumor-suppressive role. Our preliminary data indicate that HER2+ BC patients with higher levels of Igs from the TIL-Bs experience longer survival compared to those with fewer Igs. Additionally, in a HER2+ BC mouse model, the number of Igs within tumors is significantly lower than in the precancerous mammary gland, and this number decreases further when the cancer metastasizes. The comprehensive study of the Ig repertoire in The Cancer Genome Atlas datasets led to the discovery of public Igs, which share identical CDR3 sequences and V/J gene usage across multiple patients and may possess potential anti-tumor activity. The goal of this proposed study is to investigate the Ig repertoires from the TIL-Bs and the function of the public Igs in a metastatic HER2+ BC mouse model. We hypothesize that nonmetastatic HER2+ BC contains distinct public Igs produced by the TIL-Bs, which possess antimetastatic function. Both metastatic and nonmetastatic primary tumors from the HER2+ mouse model harboring wild-type or mutant p53 will be subjected to Ig repertoire analysis. The public Igs will be synthesized, screened for potential antigens, and assessed for their tumor-binding activities. Lastly, selected public Igs will be tested for tumor suppressive efficacy both in vitro and in vivo. This project has the potential to significantly advance our understanding of HER2+ BC biology and contribute to the development of novel therapeutic strategies. Additionally, the project incorporates a comprehensive strategy to involve both graduate and undergraduate students in biomedical research, providing them with practical research experience and professional growth opportunities. Students will undergo thorough training in experimental methods, interdisciplinary teamwork, and critical thinking, equipping them for future studies and careers in cancer research. This initiative aims to nurture a new generation of biomedical researchers, empowering them with the expertise to make meaningful contributions to the field of cancer research.
