Dsg1 expression in sun-exposed and non-sun-exposed skin; transcriptomic analysis reveals increased activation of keratinocyte Slug and reduced keratinocyte differentiation signaling by melanoma cells. (A) GTEx (Genotype-Tissue Expression) data showing Dsg1 mRNA levels were not altered in chronically sun-exposed skin. FPKM, bars represent minimum and maximum values. (B and C) Gene set enrichment analysis (GSEA) of RNA Seq run 2 comparing differentially expressed gene sets to published signatures of primary human keratinocyte differentiation expression patterns show a decrease in the enrichment of granular (GRN) and spinous II (SPNII) layer genes. (D–G) mRNA sequencing was performed on primary human keratinocytes (KC) treated with conditioned media from melanocytes or melanoma cells. Volcano plots depict significantly changed genes in keratinocytes treated with melanoma-conditioned media compared with those treated with melanocyte-conditioned media. Highlighted genes are those involved in pathways of differentiation and the identified upstream regulators for keratinocytes treated with 1341D media (run 1, D; run 2, E) or 501mel conditioned media (run 1, F; run 2, G). (H) Heatmap showing upstream regulators in keratinocytes predicted to be activated by melanoma conditioned media (run 2) using Ingenuity Pathway Analysis (IPA) including RAC1, Snai2, and MAPK family signaling members.