ABSTRACT: To investigate the mRNA expression of purified tumour-infiltrating M-MDSCs from the NSD or HSD group, we employed Agilent Whole Genome Oligo Microarrays (one-color) as a discovery platform to identify differentially expressed genes (DEGs) between NSD and HSD group. We identified 5391 differentially expressed genes (DEGs) comprising 2586 upregulated and 2805 downregulated genes with a fold change greater than 1.5 between M-MDSCs from the NSD and HSD groups. Subsequently, the results demonstrated a significant shift towards an antitumour pro-inflammatory phenotype in HSD-fed mice with a dominant increase in NOS2, TNF, IL-12a, Toll-like receptor 4 (TLR4) and chemokine (C-C motif) ligand 19 (CCL19) expression and a decrease in lymphocyte antigen 6 complex, locus C1 (Ly6C1), C-C-C motif chemokine ligand 12 (CXCL12), indoleamine 2,3-dioxygenase 1 (IDO1) and CCL2 expression. Among these differences, the difference in the expression of IL-12, TNF-α, NOS2, IL-10 and arginase 1 (Arg1) was confirmed by ELISA or qRT-PCR . Meanwhile, the 2,586 DEGs upregulated (fold change >1.5) in M-MDSCs from the HSD group were markedly enriched in processes involving cytokine production, cell chemotaxis, INF-γ production, cell maturation, osmotic stress responses, acute inflammatory responses, etc. In addition, Analysis of the microarray dataset indicated that the expression of 2 key TFs (activating transcription factor 2 [ATF2] and NFAT5) responsible for osmotic stress was enhanced in the M-MDSCs from the HSD group . We further found that NFAT5 expression was significantly upregulated in M-MDSCs from the HSD group but that there was no difference in ATF2 expression between the two groups in both tumour models.
