The unfolded protein response links tumor aneuploidy to local immune dysregulation

Aneuploidy is a chromosomal abnormality associated with poor prognosis in many cancer types. Here we tested the hypothesis that the unfolded protein response (UPR) links mechanistically aneuploidy and local immune dysregulation. Using a single somatic copy-number alteration (SCNA) score inclusive of whole-chromosome, arm and focal chromosome alterations in a pan-cancer analysis of 9,375 samples in The Cancer Genome Atlas (TCGA) database, we found an inverse correlation with a cytotoxicity (CYT) score across disease stages. Co-expression patterns of UPR genes changed substantially between SCNAlow and SCNAhigh groups. Pathway activity scores showed increased activity by multiple branches of the UPR in response to aneuploidy. The PERK branch showed the strongest association with a reduced CYT score. The conditioned medium of aneuploid cells transmitted XBP1 splicing and caused IL-6 and Arginase1 transcription in receiver bone marrow-derived macrophages. We propose the UPR as a mechanistic link between aneuploidy and immune dysregulation in the tumor microenvironment. Statement of SignificanceAneuploidy accumulates over the life of a tumor and is associated with poor prognosis. Tumor progression is also associated with a progressive immune dysregulation. To explain these complex and concurrent disorders we tested the hypothesis that the unfolded protein could represent the link between aneuploidy and a dysregulation of local immunity favoring tumor progression.