KRAS mutation and epithelial–macrophage interplay in pancreatic neoplastic transformation

Abstract

Pancreatic ductal adenocarcinoma (PDA) is characterized by epithelial mutations in KRAS and prominent tumor-associated inflammation, including macrophage infiltration. But knowledge of early interactions between neoplastic epithelium and macrophages in PDA carcinogenesis is limited. Using a pancreatic organoid model, we found that the expression of mutant KRAS in organoids increased (i) ductal to acinar gene expression ratios, (ii) epithelial cells proliferation and (iii) colony formation capacity in vitro, and endowed pancreatic cells with the ability to generate neoplastic tumors in vivo. KRAS mutations induced a protumorigenic phenotype in macrophages. Altered macrophages decreased epithelial pigment epithelial derived factor (PEDF) expression and induced a cancerous phenotype. We validated our findings using annotated patient samples from The Cancer Genome Atlas (TCGA) and in our human PDA specimens. Epithelium-macrophage cross-talk occurs early in pancreatic carcinogenesis where KRAS directly induces cancer-related phenotypes in epithelium, and also promotes a protumorigenic phenotype in macrophages, in turn augmenting neoplastic growth.

Alcohol Effects on Colon Epithelium are Time‐Dependent

“…pMD2.G is a VSVG‐expressing lentiviral envelope plasmid (Addgene 12259). Lentiviral particles were prepared as previously described (Bishehsari et al., ). Caco‐2 cells were plated in a 6‐well plate to be least 40% confluent on the day of the infection.…”

An Organotypic Microcosm for the Pancreatic Tumor Microenvironment

“…Kras-mutated organoids began to develop defining features of early PDAC compared to wild-type organoids. In culture with macrophages, Kras-mutated organoids induced a shift in macrophages to a pro-tumorigenic phenotype and the organoids exhibited acinar to ductal differentiation [14]. These data further emphasize the detrimental impact of PDAC cells on the body's innate immunity and this relationship is portrayed in organoid cultures.…”

“…The stromal component of the tumor microenvironment presents a great challenge to the delivery of effective chemotherapies to the tumor. There are a few mechanisms of this blocking, including a physical barrier against drugs and secretion of intercellular signals to promote tumor survival [14]. Organoids cocultured with stromal cells have been used to study drug effects against PDAC cells.…”

“…Recent studies modeled macrophage transformation in the presence of PDAC organoids. Bishehsari et al developed a platform using a transwell insert to coculture murine macrophages with either Kras-mutated or wild-type murine pancreatic organoids [14]. Kras-mutated organoids began to develop defining features of early PDAC compared to wild-type organoids.…”

“…Compared to normal pancreatic organoids, tumor organoids contain nuclear irregularity, nucleolar prominence, and cell-cell adhesions as seen by hematoxylin and eosin staining [12,13]. Additionally, normal murine pancreatic organoids induced with a Kras mutation, which occurs in 94% of PDACs, displayed typical features of early PDAC, including multilayering epithelial cells, disorganized cells, and overlapping nuclei [14][15][16]. PDAC organoids also harbor pancreatic cancer markers CK7, CK19, P53, and lack of CK20, consistent with paired tumor tissues [12,13].…”