Squamous trans-differentiation of pancreatic cancer cells promotes stromal inflammation (ChIP-seq)

A highly aggressive subset of pancreatic ductal adenocarcinomas undergo trans-differentiation into the squamous lineage during disease progression. While the tumorigenic consequences of this aberrant cell fate transition are poorly understood, recent studies have identified a role for the master regulator TP63 in this process. Here, we investigated whether squamous trans- differentiation of pancreatic cancer cells can influence the phenotype of non-neoplastic cells in the tumor microenvironment. Conditioned media experiments revealed that squamous-subtype pancreatic cancer cells secrete factors that convert quiescent pancreatic stellate cells into a specialized subtype of cancer-associated fibroblasts (CAFs) that express inflammatory genes at high levels. We use gain- and loss-of-function approaches in vivo to show that squamous-subtype pancreatic tumor models become enriched with inflammatory CAFs and neutrophils in a TP63- dependent manner. These non cell-autonomous effects occur, at least in part, through TP63- mediated activation of enhancers at pro-inflammatory cytokine loci, which includes IL1A as a key target. Taken together, our findings reveal enhanced tissue inflammation as a consequence of squamous trans-differentiation in pancreatic cancer, thus highlighting an instructive role of tumor cell lineage in reprogramming the stromal microenvironment. H3K27ac ChIP-seq was performed using antibody recognizing endogenous protein with input genomic DNA as control with/without transduction of sgNEG/sgTP63#2/sgTP63#4 (BxPC3 cells) or MTV/TP63ΔN (SUIT2 cells). TP63 ChIP-seq in BxPC3 cells was performed using antibody recognizing endogenous protein with input genomic DNA as control. FLAG-TP63 ChIP-seq in SUIT2 cells was performed in FLAG-TP63 expressing cells with input genomic DNA as control.