Genes associated with epithelial-mesenchymal transition: possible therapeutic targets in ductal pancreatic adenocarcinoma?

Epithelial to mesenchymal transition (EMT) is a biological process that allows well-differentiated, polarized epithelial cells to undergo a conversion to motile, unpolarized mesenchymal cells. EMT plays crucial roles during implantation, embryogenesis, and organ development (Type 1 EMT), is associated with tissue regeneration and organ fibrosis (Type 2 EMT), and involved in cancer invasion, metastasis, and drug resistance (Type 3 EMT). Since aggressiveness and drug resistance are hallmarks of ductal pancreatic cancer, significant effort has been undertaken in recent years to elucidate molecular EMT mechanisms in this dismal malignancy. This represents a formidable challenge for several reasons: EMT is a dynamic process, both with regard to spatial and temporal heterogeneity. Moreover, EMT is induced and regulated by a complex network of traditional signaling pathways and new players like microRNAs. Interestingly, similar molecular characteristics link EMT-type cells also to the concept of cancer stem cells. This review tries to integrate the current knowledge regarding EMT and pancreatic cancer; furthermore to outline not only the perspective on novel EMT-associated therapeutic targets, but also on overcoming drug resistance by interfering with EMT.