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Oncogenic GNAS drives a gastric phenotype in Intraductal Papillary Mucinous Neoplasms of the pancreas

ABSTRACT: Intraductal Papillary Mucinous Neoplasms (IPMNs) of the pancreas are cyst-like precursor lesions that give rise to 25% of pancreatic ductal adenocarcinomas (PDAC). While ~90% of cases are diagnosed before cancer forms, metrics and markers by which to determine if an IPMN will progress are currently lacking. Overall, 96% of IPMNs harbor KRAS (~80%) and/or GNAS (~66%) driver mutations and IPMN may be classified as either gastric, intestinal, or pancreatobiliary type. Recently, we identified a shared program of pyloric type metaplasia between pancreatic and gastric injury. Here, we combined immunostaining, RNA-sequencing, molecular biology, and analysis of patient samples to identify major drivers of this program in IPMN. Methods Single cell RNA-sequencing datasets of human IPMN were assayed for markers of pyloric-type metaplasia. 37 IPMN patient samples were immunostained using MxIHC for MUC5AC, CD44v9, and AQP5. KrasG12D and GnasR201C expression was modified in IPMN cell lines to identify transcriptomic programs driven by each oncogene, and in combination. Gene sets were compared to murine and human gastric cell types. Transcriptomic drivers were identified and manipulated in vitro. Candidate driver expression was evaluated by immunostaining of patient IPMN and graded. Results Analysis of published bulk and scRNA-seq IPMN datasets revealed expression of previously described markers of pyloric type metaplasia. Marker expression was confirmed in patient samples. Manipulation of KrasG12D and GnasR201C expression in IPMN cell lines identified the relative contributions of each oncogene to this gastric phenotype. Regulon analysis suggests that transcription factors SPDEF, CREB3L1, and CREB3L4 amplify this program in response to GnasR201C expression. All transcription factors were expressed in patient IPMN samples. Conclusions In response to oncogenic mutation(s), IPMN form in the pancreas and express markers of pyloric type metaplasia. KrasG12D and GnasR201C expression drive this program through independent and synergistic mechanisms that result in amplified expression of mucins and gastrokines, consistent with the phenotype identified in vivo.

ORGANISM(S): Mus musculus

PROVIDER: GSE244280 | GEO | 2023/10/02

REPOSITORIES: GEO

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Project description:Background & Aims: Metaplasia and dysplasia in the corpus are reportedly derived from dedifferentiation of chief cells. However, the cellular origin of metaplasia and cancer remained uncertain. Therefore, we investigated whether pepsinogen Ctranscript expressing cells (PGC-transcript expressing cells) represent the cellular origin of metaplasia and cancer using a novel Pgc-specific CreERT2 recombinase mouse model. Methods: We generated a Pgc-mCherry-IRES-CreERT2 (Pgc-CreERT2) knock-in mouse model. Pgc-CreERT2/+ and Rosa-EYFP mice were crossed to generate PgcCreERT2/Rosa-EYFP (Pgc-CreERT2/YFP) mice. Gastric tissues were collected, followed by lineage-tracing experiments, histological and immunofluorescence staining. We further established Pgc-CreERT2;Kras G12D/+ mice and investigated whether PGCtranscript expressing cells are responsible for the precancerous state in gastric glands. To investigate cancer development from PGC-transcript expressing cells with activated Kras, inactivated Apc and Trp53 signaling pathways, we crossed Pgc-CreERT2/+ mice with conditional KrasG12D , Apcflox , Trp53 flox mice. Results: Expectedly, mCherry mainly labeled chief cells in the Pgc-CreERT2 mice. However, mCherry was also detected throughout the neck cell and isthmal stem/progenitor regions, albeit at lower levels. In the Pgc-CreERT2;Kras G12D/+ mice, PGC-transcript expressing cells with Kras G12D/+ mutation presented pseudopyloric metaplasia. The early induction of proliferation at the isthmus may reflect the ability of isthmal progenitors to react rapidly to Pgc-driven Kras G12D/+ oncogenic mutation. Furthermore, Pgc-CreERT2;KrasG12D/+ ;Apc flox/flox mice presented intramucosal dysplasia/carcinoma, while Pgc-CreERT2;KrasG12D/+ ;Apcflox/flox ;Trp53 flox/flox mice presented invasive and metastatic gastric carcinoma. Conclusions: The Pgc-CreERT2 knock-in mouse is an invaluable tool to study the effects of successive oncogenic activation in the mouse corpus. Time-course observations can be made regarding the responses of isthmal and chief cells to oncogenic insults. We can observe stomach-specific tumorigenesis from the beginning to metastatic development.

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Oncogenic GNAS drives a gastric phenotype in Intraductal Papillary Mucinous Neoplasms of the pancreas

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