Melanocyte PDL1 control of UVB-induced IFN-I

This new R01 proposal assembles a team with expertise in tumor immunology and immunotherapy, mouse cancer models, melanoma, IFN-I signals, tumor signaling, single cell spatial omics and novel statistical approaches. We developed an autochthonous melanoma model to generate tumors from melanoma cells of

origin (melanocytes) that are PDL1KO or CTRL and bear the NrasQ61R mutation. Our overarching hypothesis is that UVB elicits local and systemic melPDL1-dependent IFN-I production that promotes melanoma progression and treatment resistance through tumor inflammatory memory. General approaches. We compare outcomes of melanocyte PDL1 (melPDL1) expression on tumor immune

surveillance and TME composition and tumor progression in autochthonous melanomas induced ± UVB. Transplantable tumor lines from autochthonous tumors will be genetically engineered and used in distinct hosts to test tumor signal effects mediating relevant outcomes to confirm mechanisms. These outcomes will be

compared to data from human materials to validate human relevance. Aim 1 Test the hypothesis that UVB-induced IFN-I elicits melPDL1-dependent inflammatory memory. CTRL versus melPDL1KO mT/mG TNQ61R mice (with a melanocyte EGFP reporter) will be induced ± UVB. TME effects will be assessed by spectral flow cytometry, RPPA, bulk RNA-seq, scRNA-seq and spatial imaging

approaches. Cell-cell interactions are tested by COMMOT and confocal imaging. IFN-I effects are tested by αIFNAR and IFN-I quantification. Effects on tumor-specific immunity use pmel cells with gene reporters or IFNARKO for cell effector function and trafficking assays. Outcomes include tumor inflammatory memory, latency

and growth control. Detailed mechanisms are interrogated with transplantable lines from autochthonous tumors engineered to test specific molecules and pathways. Human relevance is confirmed in human tissues. Aim 2 Test the hypothesis that acute UVB affects later melanoma treatment responses. Effects of UVB

and IFN-I on treatment resistance (e.g., through tumor inflammatory memory versus alternatives) are assessed with immune checkpoint blockade and selected small molecule inhibitors. Mechanisms are defined using above approaches. Cutaneous UVB and IFN-I effects on metastatic sites (tumor draining lymph nodes, lungs) will be

elucidated and preliminary studies done, but logistics prevent full detailed mechanistic studies. Metastases are tracked by imaging and identified in RNA-seq data sets using mT/mG mice. Novel statistical analytic approaches are used for all outcomes, especially scRNAseq and spatial imaging.