Hypoxic transcriptomes predict survival and tumor-infiltrating immune cell composition in cutaneous melanoma.

Hypoxia has established associations with aggressive tumor phenotypes in many cancers. However, it is not currently understood whether tumor hypoxia levels map to distinct immune infiltrates in cutaneous melanoma, potentially unveiling novel therapeutic targets. To this end, we leveraged a previously identified seven-gene hypoxia signature to grade hypoxia levels of 460 cutaneous melanomas obtained from the Broad Institute GDAC Firehose portal. CIBERSORTx ( https://cibersortx.stanford.edu/ ) was employed to calculate the relative abundance of 22 mature human hematopoietic populations. Clinical outcomes and immune cell associations were assessed by computational means. Results indicated that patients with high-hypoxia tumors reported significantly worse overall survival and correlated with greater Breslow depth, validating the in-silico methodology. High-hypoxia tumors demonstrated increased infiltration of activated and resting dendritic cells, resting mast cells, neutrophils, and resting NK cells, but lower infiltration of gamma-delta T cells. These data suggest that high tumor hypoxia correlates with lower survival probability and distinct population differences of several tumor-infiltrating leukocytes in cutaneous melanomas.

Genomic subtypes of cutaneous melanoma have distinct metabolic profiles: A single-cell transcriptomic analysis.

OBJECTIVE: Genomic profiling previously classified melanoma into distinct subtypes based on the presence or absence of mutations in driver genes, but metabolic differences between and within these groups have yet to be thoroughly analyzed. Thus, the objective of the present study is to provide the first effort to holistically characterize the metabolic landscape of qualified melanoma genomic subtypes at single-cell resolution. METHODS: Expression data for a total of 1145 malignant cells sourced from NRAS(Q61L), BRAF(V600E), and NRAS/BRAF WT melanomas were retrieved from the Broad Single Cell Portal. Metabolic activity was interrogated by pathway scoring and gene set enrichment analysis. RESULTS: A total of 53 metabolic pathways were differentially regulated in at least one melanoma genomic subtype. Some notable findings include: BRAF/NRAS WT cells were enriched for fatty acid biosynthesis and depleted for metabolism of alanine, aspartate, and glutamate; BRAF(V600E) melanoma cells were enriched for beta-alanine metabolism and depleted for phenylalanine metabolism; NRAS(Q61L) melanoma cells were enriched for steroid biosynthesis and depleted for linoleic acid metabolism. CONCLUSION: Primary limitations include the total quantity of single cells and breadth of available genomic subtypes plus inherent noisiness of the applied methodologies. Nonetheless, these findings nominate novel, testable therapeutic targets.