Pancreatic ductal adenocarcinoma (PDAC) is an almost always deadly illness, and early identification is a crucial factor in enhancing survival. The tumour microenvironment (TME), a possible source of biomarkers in PDAC, has a significant impact in cell proliferation, metastasis, and treatment resistance, all of which contribute to a poorer clinical outcome. Metastatic PDAC (SW1990 cell line) and pancreatic stellate cells (PSCs), one of the major cell types that comprise the tumour microenvironment (TME) of pancreatic cancer, foster an immunosuppressive environment around the tumour. The purpose of this investigation was to examine the proteome profiles of conditioned media (CM) from PSCs, SW1990, and PSC+SW1990 co-culture. To establish the probable proteins responsible for the different immunosuppressive efficacy of PSCs, SW1990, and PSC+SW1990 co-culture, the CM containing the secreted proteins from all 3 cell line groups were analysed by Liquid Chromatography with tandem Mass Spectrometry (LC-MS/MS) and then subjected to bioinformatics analysis, including identification of differentially expressed proteins (DEPs), Gene Ontology (GO) terms analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment pathway. TGM2, KRT8, KRT18, KRT19, MYH9, NME1, NME1-NME2, and LDHA were the eight DEPs that were significantly elevated in all three cell line groups comparisons with a false discovery rate (FDR)  0.05 and fold change (FC) ≥ 2. Multiple signalling pathways, including oestrogen signalling, actin cytoskeleton, protein processing in endoplasmic reticulum, vascular smooth muscle contraction, the hypoxia-inducible factor 1 (HIF-1) and the central carbon metabolism, were enriched in the comparison study. The DEPs detected, their GO terns, and the signalling pathways were integrated and matched with literature and proteomic data from prior research in order to better comprehend their association with PSCs and metastatic PDAC. In conclusion, this comparative proteomic research extends 3 the evidence of protein alterations linked with PSCs and metastatic PDAC that should be studied further as possible biomarkers or therapeutic targets