Periodic Reporting for period 1 - BreaKer (Dissecting how breast cancer-associated inflammation shapes invariant natural killer T cell activity during metastatic progression)
Reporting period: 2022-09-01 to 2024-08-31
Breast cancer is a major health challenge, and when it spreads to other parts of the body (metastatic breast cancer), it becomes much harder to treat. Despite medical advances, survival rates for metastatic breast cancer remain low. Immunotherapy, which uses the body's own immune system to fight cancer, has shown promise, but only a small number of patients benefit from it. This means we need a better understanding of how the immune system interacts with breast cancer, especially in its advanced stages.
The immune system has different types of cells that work together to fight infections and diseases, including cancer. However, in cancer patients, this system often becomes unbalanced, allowing the disease to progress. One important type of immune cell, called invariant Natural Killer T (iNKT) cells, has the potential to fight tumors. These cells can quickly release substances that attack cancer and help other immune cells respond. However, iNKT cells do not always work effectively in breast cancer, and scientists do not yet fully understand why. Research suggests that changes in the environment around the tumor may weaken these cells, reducing their ability to fight the disease. This project aimed to investigate how inflammation associated with breast cancer affects iNKT cells and how these cells could be activated to improve cancer treatment.
The immune system has different types of cells that work together to fight infections and diseases, including cancer. However, in cancer patients, this system often becomes unbalanced, allowing the disease to progress. One important type of immune cell, called invariant Natural Killer T (iNKT) cells, has the potential to fight tumors. These cells can quickly release substances that attack cancer and help other immune cells respond. However, iNKT cells do not always work effectively in breast cancer, and scientists do not yet fully understand why. Research suggests that changes in the environment around the tumor may weaken these cells, reducing their ability to fight the disease. This project aimed to investigate how inflammation associated with breast cancer affects iNKT cells and how these cells could be activated to improve cancer treatment.
This cutting-edge translational research project seamlessly combined in-depth characterization of patient samples with mechanistic studies in state-of-the-art transgenic mouse models of breast cancer, utilizing advanced cell biology techniques to investigate the regulation and function of invariant Natural Killer T (iNKT) cells.
Human iNKT cells were isolated and expanded from the blood of breast cancer patients and healthy donors. Extensive immunophenotypic analysis revealed disease-driven alterations in circulating iNKT cells from breast cancer patients, mirroring observations in genetically engineered breast cancer mouse models developed in my host lab. To explore iNKT cell function, an iNKT-deficient mouse model (Jα18-/-) was generated in the FVB background. This model, which lacks iNKT cells due to a targeted deletion of the TRAJ18 gene encoding the TCR α-chain joining region 18, provides a valuable tool for studying iNKT cells in cancer. The FVB background ensures compatibility with most genetically engineered cancer mouse models, allowing me to examine tumor progression in iNKT cell-deficient and proficient settings. Surprisingly, the absence of iNKT cells did not affect tumor growth or metastasis, suggesting their function is either limited or profoundly suppressed in breast cancer. Further investigation identified neutrophils, macrophages, and Tregs as key contributors to iNKT cell suppression. Notably, targeting these suppressive mechanisms in combination with iNKT cell activation triggered a strong anti-metastatic response, significantly reshaping the immune landscape of breast cancer.
This project advanced our understanding of iNKT cells in metastatic breast cancer and their suppression by the tumor microenvironment, revealing their remarkable capacity to orchestrate immune responses. By uncovering novel mechanisms involving iNKT cells in tumor immunity, these findings open promising avenues for therapeutic intervention.
Human iNKT cells were isolated and expanded from the blood of breast cancer patients and healthy donors. Extensive immunophenotypic analysis revealed disease-driven alterations in circulating iNKT cells from breast cancer patients, mirroring observations in genetically engineered breast cancer mouse models developed in my host lab. To explore iNKT cell function, an iNKT-deficient mouse model (Jα18-/-) was generated in the FVB background. This model, which lacks iNKT cells due to a targeted deletion of the TRAJ18 gene encoding the TCR α-chain joining region 18, provides a valuable tool for studying iNKT cells in cancer. The FVB background ensures compatibility with most genetically engineered cancer mouse models, allowing me to examine tumor progression in iNKT cell-deficient and proficient settings. Surprisingly, the absence of iNKT cells did not affect tumor growth or metastasis, suggesting their function is either limited or profoundly suppressed in breast cancer. Further investigation identified neutrophils, macrophages, and Tregs as key contributors to iNKT cell suppression. Notably, targeting these suppressive mechanisms in combination with iNKT cell activation triggered a strong anti-metastatic response, significantly reshaping the immune landscape of breast cancer.
This project advanced our understanding of iNKT cells in metastatic breast cancer and their suppression by the tumor microenvironment, revealing their remarkable capacity to orchestrate immune responses. By uncovering novel mechanisms involving iNKT cells in tumor immunity, these findings open promising avenues for therapeutic intervention.
The key innovation of this project lies in the combination of mechanistic studies using state-of-the-art mouse models with validation studies on iNKT cells isolated from metastatic breast cancer patients. Unlike previous research, which primarily investigated iNKT cells in mice—often using cell-line-induced cancer models—this project leveraged genetically engineered mouse models that more accurately reflect the complexity of the tumor microenvironment and cancer-associated inflammation seen in patients. Additionally, many earlier studies lacked the appropriate tools to specifically target this rare cell subset. For instance, CD1d-/- mice were initially used instead of Jα18-/- mice, despite also lacking other lipid-specific T cells such as NKT2. Similarly, iNKT cells were often identified based on Vα24 expression, which can also be found on conventional T cells, rather than by their specific recognition of antigen-loaded CD1d tetramers. This project generated an unprecedented dataset detailing the immunophenotype of iNKT cells in breast cancer patients, coupled with strong mechanistic evidence from murine models. Through this comprehensive approach, I uncovered the role of iNKT cells in metastatic breast cancer progression and provided crucial insights into their network of cellular interactions. Ultimately, these findings support the development of novel combinatorial therapies aimed at restoring iNKT cell anti-tumor function by targeting the mechanisms driving their tumor-associated suppression.