Abstract B06: Impact of intratumoral microenvironment and epithelial cells crosstalk in pancreatic carcinogenesis

Pancreatic adenocarcinoma (PDAC) is a cancer particularly resistant to current therapies. One possible reason consists in its cellular composition that limits access to drugs. Indeed, non-tumor cells, mainly activated fibroblasts (stellate cells) and immune cells, display 80% of the tumor mass composing the microenvironment or stroma. The stellate cells have the ability to secrete a lot of protein and extensive amounts of extracellular matrix which contributes to the formation of a fibrotic shield around epithelial cells, making those tumors highly hypoxic. Despite these knowledge the precise role of stromal components, and specifically stellate cells, in PDAC is poorly understood. In order to develop a simultaneous therapy targeting both tumoral and stromal cells, we investigate specific molecules implicated in the dialogue between those compartments to analyze their impact on pancreatic carcinogenesis. In this study, we used a laser microdissection approach of human PDAC stromal and epithelial compartment, followed by mass spectrometry and bioinformatics analysis (statistics/interactome) to compare protein composition and networks within both compartments. We found the presence of a proteic complex composed of three proteins, expressed only in stromal compartment, related to lipid and intracellular trafficking. To validate such data, we confirmed the specific stromal expression of each protein, on human PDAC samples, and found that our three targets were expressed mainly in stellate cells. However before to investigate the dialogue between epithelial and stromal cells, we designed an in vitro model, based on co-culture of stromal cells: immune and stellate cells, which take into account the multi-cellular composition of such tumors and added PDAC relevant metabolic stresses: hypoxia and nutrient starvation. To improve our model, we used primary stellate cells that we extracted from freshly resected human PDAC tumor pieces. We added pancreatic tumoral cells in our model to investigate dialogue between stromal and tumoral cells. Our data show that under nutrient and hypoxic stresses, co-cultures from stellate and immune cells provide a proliferative and pro-migratory advantage to tumor cells. Moreover, and only in these same specific condition, the proteic complex identified is formed in stellate cells. So, we hypothesized that a specific “lipid related process” is developed by stellate cells in order to subvert the metabolically deprivated tumor cell. To