Novel targets identified by integrated cancer-stromal interactome analysis of pancreatic adenocarcinoma.

The pancreatic cancer microenvironment is crucial in cancer development, progression and drug resistance. Cancer-stromal interactions have been recognized as important targets for cancer therapy. However, identifying relevant and druggable cancer-stromal interactions is challenging due to the lack of quantitative methods to analyze the whole cancer-stromal interactome. Here we studied 14 resected pancreatic cancer specimens (8 pancreatic adenocarcinoma (PDAC) patients as a cancer group and 6 intraductal papillary-mucinous adenoma (IPMA) patients as a control). Shotgun proteomics of the stromal lesion dissected with laser captured microdissection (LCM) was performed, and identified 102 differentially expressed proteins in pancreatic cancer stroma. Next, we obtained gene expression data in human pancreatic cancer and normal pancreatic tissue from The Cancer Genome Atlas database (n = 169) and The Genotype-Tissue Expression database (n = 197), and identified 1435 genes, which were differentially expressed in pancreatic cancer cells. To identify relevant and druggable cancer-stromal-interaction targets, we applied these datasets to our in-house ligand-receptor database. Finally, we identified 9 key genes and 8 key cancer-stromal-interaction targets for PDAC patients. Furthermore, we examined FN1 and ITGA3 protein expression in pancreatic cancer tissues using tissue microarrays (TMAs) of 271 PDAC cases, and demonstrated that FN1-ITGA3 had unfavorable prognostic impact for PDAC patients.