ID #671 Single Cell Resolution Spatial Transcriptomic Analysis of Adamantinomatous Craniopharyngioma Reveals Whorls and Infiltrating Dendritic Cells as Hubs of EGFR Ligand Production.
Andrew Donson, John DeSisto, Aaron Knox, Eric Prince, Stephen Medlin, Nicholas Foreman, Siddhartha Mitra, Todd HankinsonAbstract
Background
Adamantinomatous craniopharyngioma (ACP) is a pituitary tumor that driven by CTNNB1 mutations that result in b-catenin accumulation in the nuclei of whorls within ACP epithelial zones. ACP whorls are signaling hubs within the tumor microenvironment (TME), releasing ligands such as SHH that act in a paracrine fashion to slowly drive growth in the surrounding stellate reticulum and palisading epithelium. To better understand the interactions between these heterogenous cell types we applied recently developed Xenium in situ Spatial transcriptomics to ACP patient samples.
Results
A panel of 480 Xenium gene probes was designed based on pediatric brain tumor subpopulation scRNAseq marker genes and hybridized to ACP patient samples. Through integration of transcript and morphological markers, we were able to distinguish major ACP TME subpopulations – whorls, stellate reticulum, palisading epithelium and infiltrating immune cells – and subcategories within these cell types. Importantly, we identified highly restricted expression of EGFR ligand transforming growth factor-A (TGFA) in a subpopulation within whorls. EGFR was largely expressed in the proliferative palisading epithelial cell layer and to a lesser extent in stellate reticulum. In addition, a second EGFR ligand, amphiregulin (AREG), that had previously been shown to be highly expressed in ACP versus other pediatric brain tumors, was highly expressed by infiltrating dendritic cells (CDs) in non-epithelial zones adjacent to palisading epithelium. Thus, both ACP whorls and DCs send growth signals to palisading epithelium in a paracrine manner.
Conclusion
The identification of converging paracrine EGFR ligand signaling in the ACP TME fits the theory that ACP recapitulates the normal human skin repair process, where heterogenous cellular subtypes support wound re-epithelialization. This theory is also consistent with the inflammatory and extracellular matrix remodeling processes that have also been identified in ACP.