Axin2+ Peribiliary Glands in the Periampullary Region Generate Biliary Epithelial Stem Cells That Give Rise to Ampullary Carcinoma

Gastroenterology. 2021 May;160(6):2133-2148.e6. doi: 10.1053/j.gastro.2021.01.028. Epub 2021 Jan 16.

Abstract

Background & aims: Peribiliary glands (PBGs), clusters of epithelial cells residing in the submucosal compartment of extrahepatic bile ducts, have been suggested as biliary epithelial stem/progenitor cell niche; however, evidence to support this claim is limited because of a lack of PBG-specific markers. We therefore sought to identify PBG-specific markers to investigate the potential role of PBGs as stem/progenitor cell niches, as well as an origin of cancer.

Methods: We examined the expression pattern of the Wnt target gene Axin2 in extrahepatic bile ducts. We then applied lineage tracing to investigate whether Axin2-expressing cells from PBGs contribute to biliary regeneration and carcinogenesis using Axin2-CreERT mice.

Results: Wnt signaling activation, marked by Axin2, was limited to PBGs located in the periampullary region. Lineage tracing showed that Axin2-expressing periampullary PBG cells are capable of self-renewal and supplying new biliary epithelial cells (BECs) to the luminal surface. Additionally, the expression pattern of Axin2 and the mature ductal cell marker CK19 were mutually exclusive in periampullary region, and fate tracing of CK19+ luminal surface BECs showed gradual replacement by CK19- cells, further supporting the continuous replenishment of new BECs from PBGs to the luminal surface. We also found that Wnt signal enhancer R-spondin3 secreted from Myh11-expressing stromal cells, corresponding to human sphincter of Oddi, maintained the periampullary Wnt signal-activating niche. Notably, introduction of PTEN deletion into Axin2+ PBG cells, but not CK19+ luminal surface BECs, induced ampullary carcinoma whose development was suppressed by Wnt inhibitor.

Conclusion: A specific cell population receiving Wnt-activating signal in periampullary PBGs functions as biliary epithelial stem/progenitor cells and also the cellular origin of ampullary carcinoma.

Keywords: Periampullary Region; R-Spondin3; Sphincter of Oddi; Wnt-Activating Niche.

MeSH terms

  • Ampulla of Vater* / pathology
  • Animals
  • Axin Protein / genetics
  • Axin Protein / metabolism*
  • Bile Ducts, Extrahepatic / metabolism
  • Bile Ducts, Extrahepatic / pathology
  • Carcinogenesis / genetics
  • Carcinoma / pathology*
  • Cell Lineage
  • Cell Proliferation
  • Common Bile Duct Neoplasms / pathology*
  • Epithelial Cells / metabolism
  • Epithelial Cells / pathology*
  • Keratin-19 / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Myosin Heavy Chains / genetics
  • Myosin Heavy Chains / metabolism
  • PTEN Phosphohydrolase / genetics
  • Sphincter of Oddi / metabolism
  • Stem Cells / metabolism
  • Stem Cells / pathology*
  • Thrombospondins / genetics
  • Thrombospondins / metabolism
  • Wnt Signaling Pathway*

Substances

  • Axin Protein
  • Axin2 protein, mouse
  • Keratin-19
  • R-spondin3 protein, mouse
  • Thrombospondins
  • myosin 11, mouse
  • PTEN Phosphohydrolase
  • Pten protein, mouse
  • Myosin Heavy Chains