Immune profiling of melanoma tumors reflecting aggressiveness in a preclinical model

Melanoma, like most solid tumors, is highly heterogeneous in terms of invasive, proliferative, and tumor-initiating potential. This heterogeneity is the outcome of differential gene expression resulting from conditions in the tumor microenvironment and the selective pressure of the immune system. To investigate possible signatures combining immune-related gene expression and lymphocyte infiltration, we established a preclinical model using B16.F1-derived clones, in the context of melanoma aggressiveness. Combinatorial analyses revealed that tumors concomitantly expressing low levels of Tnf-a, Pd-1, Il-10, Il-1ra, Ccl5, Ido, high Il-9, and with low infiltration by CD45⁺, CD3⁺, CD4⁺ and CD8⁺ cells and a high CD4⁺:CD8⁺ T cell ratio exhibited the most aggressive growth characteristics. Overall, these results support the notion that the intratumoral immunologic network molds aggressive melanoma phenotypes.