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.