Inducing Lipid Peroxidation in Lymph Node Cancer Cells to Promote an Immunogenic Response

PROJECT SUMMARY Melanoma progression requires evading a host immune response, and T cell activation plays a critical role in initiating an adaptive immune response for widespread anti-tumor clearance. While there is existing evidence that glutathione peroxidase 4 (Gpx4) inhibition in cancer cells can lead to the secretion of damage-associated molecular patterns (DAMPs), there is limited understanding of how lipid oxidation in cancer cells specifically in the lymph nodes, a context in which Gpx4-deficiency has demonstrated to have minimal effect on overall cancer cell survival, impacts the adaptive immune response. The abundance of antigen-presenting cells and immune cell populations in the lymph node comprise an ideal microenvironment for dendritic cell/T cell cross-presentation and activation in the context of anti-cancer immunogenicity, yet melanoma cells frequently metastasize to and form tumors in lymph nodes, suggesting a hospitable microenvironment for metastasizing cells. Prior research from our laboratory indicates that melanoma cells experience lower levels of lipid peroxidation in the lymph node, increasing ferroptosis resistance. In this work, I hypothesize that inducing lipid peroxidation in cancer cells in lymph nodes, but not in orthotopic tumors, enhances systemic anti-cancer immunity by promoting antigen cross- presentation and T cell activation. To test this, I will use a syngeneic B16F10 melanoma spontaneous metastasis model with genetic deletion of Gpx4, a crucial reducing enzyme preventing lipid peroxidation. I have established an ex vivo co-culture system to assess the systemic immune activity resulting from Gpx4-mediated lipid peroxidation in lymph node cancer cells. Using this system, I will: Aim 1. assess the capacity of sublethal lipid peroxidation in cancer cells in lymph nodes to evoke an anti-cancer immune response. Aim 2. determine the extent to which sublethal lipid peroxidation in cancer cells in lymph nodes modulates the development of distant metastasis. These findings have the potential to suggest a novel mechanism for provoking systemic anti-cancer adaptive immunity—by inhibiting Gpx4 locally in melanoma and breast cancer cells within lymph nodes, thus triggering the release of DAMPs and inducing cytokine production to initiate immune-mediated tumor clearance both locally in the lymph nodes, and systemically at distant metastatic sites.