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We have identified eight genes whose expression in human melanoma metastases and ovarian cancers is associated with a lack of Th1 immune signatures. They encode molecules with mechanical barrier function in the skin and other normal tissues and include filaggrin (FLG), tumor-associated calcium signal transducer 2 (TACSTD2), and six desmosomal proteins (DST, DSC3, DSP, PPL, PKP3, and JUP). This association has been validated in an independent series of 114 melanoma metastases. In these, DST expression alone is sufficient to identify melanomas without immune signatures, while FLG and the other six putative barrier molecules are overexpressed in a different subset of melanomas lacking immune signatures. Similar associations have been identified in a set of 186 ovarian cancers. RNA-seq data from 471 melanomas and 307 ovarian cancers in the TCGA database further support these findings and also reveal that overexpression of barrier molecules is strongly associated with early patient mortality for melanoma (p= 0.0002) and for ovarian cancer (p< 0.01). Interestingly, this association persists for FLG for melanoma (p= 0.012) and ovarian cancer (p= 0.006), whereas DST overexpression is negatively associated with CD8+gene expression, but not with patient survival. Thus, overexpression of FLG or DST identifies two distinct patient populations with low immune cell infiltration in these cancers, but with different prognostic implications for each. These data raise the possibility that molecules with mechanical barrier function in skin and other tissues may be used by cancer cells to protect them from immune cell infiltration and immune-mediated destruction. [ABSTRACT FROM AUTHOR]

Melanoma is known to be under latent immunosurveillance. Here, we studied four biomarkers of immunogenic cell stress and death (microtubule-associated proteins 1A/1B light chain 3B (MAP-LC3B, best known as LC3B)-positive puncta in the cytoplasm as a sign of autophagy; presence of nuclear HMGB1; phosphorylation of eIF2α; increase in ploidy) in melanoma cells, in tissue microarrays (TMA) from metastases from 147 melanoma patients. These biomarkers of immunogenicity were correlated with the density of immune cells infiltrating the metastases and expressing CD3, CD4+, CD8+, CD20, CD45, CD56, CD138, CD163, DC-LAMP or FOXP3. LC3B puncta positively correlated with the infiltration of metastases by CD163+macrophages, while expression of HMGB1 correlated with infiltration by FOXP3+regulatory T cells and CD56+lymphocytes. eIF2α phosphorylation was associated with an augmentation of nuclear diameters, reflecting an increase in ploidy. Interestingly, therapeutic vaccination led to a reduction of eIF2α phosphorylation suggestive of immunoselection against cells bearing this sign of endoplasmic reticulum (ER) stress. None of the stress/death-related biomarkers had a significant prognostic impact, contrasting with the major prognostic effect of the ratio of cytotoxic T lymphocytes (CTL) over immunosuppressive FOXP3+and CD163+cells. Altogether, these results support the idea of a mutual dialog between, on one hand, melanoma cells with their cell-intrinsic stress pathways and, on the other hand, immune effectors. Future work is required to understand the detailed mechanisms of this interaction. [ABSTRACT FROM AUTHOR]