GSE159967
Dichotomous roles of Arid5a augment the immunosuppressive microenvironment of mesenchymal malignant tumors
Although mesenchymal subtypes of pancreatic ductal adenocarcinoma (PDAC) and colorectal cancer (CRC) are known as “immunologically cold” tumors, the molecular link between tumor immune evasiveness and mesenchymal phenotype remains largely unknown. Here, we show that AT-rich interaction domain-containing protein 5a (Arid5a), an RNA-binding protein, is involved in immune evasion in PDAC and CRC mouse models. Mass cytometry demonstrated that in tumors from Arid5a-deficient cells, the infiltration of granulocytic myeloid-derived suppressor cells and regulatory T cells is suppressed, but cytotoxic T-lymphocyte recruitment is enhanced. Mechanistically, Arid5a augmented Ido1 and Ccl2 expression by stabilizing these mRNAs in the PDAC model, but not Ido1 in the CRC model. Furthermore, Arid5a expression was substantially increased in mesenchymal subtypes of PDAC and CRC, mediated by ZEB1, and Arid5a promoted TGF-b-induced and IL6-induced epithelial-mesenchymal transition and acquisition of invasiveness in PDAC model cells. Thus, our findings demonstrate that Arid5a is a promising target for immunotolerant malignant tumors. Overall design: Comparison of gene expression profiles between WT and Arid5a knockout (KO) in KPC and MC38 cells by RNA sequencing