Resident Stanford University Mountain View, California, United States
Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.
Participants should be aware of the following financial/non-financial relationships:
Carlos Ayala, MD, PhD: I do not have any relevant financial / non-financial relationships with any proprietary interests.
Introduction: Pseudomyxoma peritonei (PMP) follows rupture of an appendiceal mucinous neoplasm (AMN) with subsequent invasion of the abdominal cavity by mucinous epithelial cells (MECs) and the production of mucinous ascites. We have characterized and shown that MECs have a goblet cell signature. However, the biological characteristics of the epithelial cells in mucinous ascites and its composition in PMP patients remains poorly understood.
Methods: Patients were consented using IRB protocols for tissue collection. Ascites collected from patients was filtered and CD45 cell depleted (Miltenyi) to generate single cells suspensions (n=4). These were used to generate cDNA libraries (10X Genomics) that were sequenced followed by in-house pipeline processing of the data. Patient-derived malignant ascites from patients with PMP (n=4) and non-PMP (n=3, mesothelioma, pancreatic and cholangiocarcinoma) were used for mass-spectrometry analysis.
Results: Here we show the epithelial cell population of patient derived mucinous ascites represents less than 1% of the total of cells processed. Following bioinformatics analysis, we identified MECs in mucinous ascites have a goblet cell identity that recapitulates our previous findings from primary and metastatic tumors of PMP patients. Using mass-spectrometry analysis, we have detected a protein profile consistent with goblet cell secretory products in PMP patient derived ascites, when compared to non-PMP patients. Importantly, we can trace these secretory products to MECs of PMP tumors and ascites in our single cell transcriptomic analysis. Last, we show differences in the protein compositions of PMP and non-PMP derived ascites of patients evaluated that may aid in diagnosis of these tumors in the future.
Conclusions: Using single cell transcriptomic analysis of mucinous ascites we are able to detect a small cell population of cells (MECs) with a goblet cell identity. The identification of MECs in patient derived ascites supports their role in the pathogenesis of PMP and mucinous ascites formation. In light of this, we propose MECs use ascites as a vehicle to colonize the intra-abdominal cavity.
Learning Objectives:
Upon completion the participant should be able to identify the lineage or signature of mucinous epithelial cell responsible for PMP
Upon completion the participant should be able to be able to know the signature of mucinous ascites as revealed by mass spectrometry analysis
Upon completion the participant should be able to identify the cell type responsible for the production of the components of mucinous ascites.
