PO-302 Deconvolution of the tumour microenvironment of primary human pancreatic ductal adenocarcinoma and normal pancreas reveals specific deregulated signalling nodes

Introduction Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive disease with dismal prognosis. Despite promising results using in vitro systems or genetically engineered mouse models, new drug candidates have not yet made significant impact on PDAC patients. This highlights the urgent need for a better understanding of the complex signalling cascades taking place within human tumours in situ . However, due to the extensive presence of desmoplastic stroma within PDAC tumour mass, expression analyses of bulk tumour samples are difficult to interpret and remain uninformative with respect to the complex cellular and molecular architecture of these tumours. Thus, the detailed analysis of the tumor-stroma interactions occurring in primary human PDACs seems a critical missing link for a better understanding of this complex disease, what is critically important to develop novel innovative therapies. Material and methods We have isolated all major cell types present within primary human PDAC tumours (cancer associated fibroblasts (CAFs), immune, endothelial and epithelial cancer cells) by FACS sorting more than 20 fresh PDACs and supplemented these with the same cell populations isolated from 7 tumor-free adjacent (normal) pancreas samples. From these we have generated transcriptomic data by RNA-Seq and performed whole genome bisulfite sequencing (epithelial cancer/normal cells only) to determine their methylome. We have analysed and integrated these data using various computational analysis tools. Results and discussions Comparison of PDAC and normal pancreas datasets allowed the identification of a number of genes and pathways deregulated during PDAC tumorigenesis in all cellular compartments as well as specific reprogramming events happening in stromal cells. As example, our analysis revealed specific interferon mediated inflammatory signatures in a subset of patients. This generates a complex interactome between cancer cells and their environment to which various cell types contribute and which is associated with poor outcome. We will report on the influence of differential DNA methylation and how it affects specific signalling pathways relevant for PDAC prognosis and stratification. Conclusion The deconvolution of the cellular components within human PDAC and analyses of their associated molecular signatures compared to the corresponding normal pancreas components sheds new light into the signalling networks operational within PDAC masses. Our data identify novel pathways to potentially target the most aggressive PDAC tumours.