Carcinoembryonic antigen as a specific glycoprotein ligand of rBC2LCN lectin on pancreatic ductal adenocarcinoma cells

Cancer Sci. 2021 Sep;112(9):3722-3731. doi: 10.1111/cas.15023. Epub 2021 Jun 29.

Abstract

The rBC2LCN lectin, known as a stem cell marker probe that binds to an H type 3 fucosylated trisaccharide motif, was recently revealed to also bind to pancreatic ductal adenocarcinoma (PDAC) cells. A lectin-drug conjugate was generated by fusing rBC2LCN with a cytocidal toxin, and it showed a strong anticancer effect in in vitro and in vivo PDAC models. However, it is unclear which molecules are carrier proteins of rBC2LCN on PDAC cells. In this study, we identified a rBC2LCN-positive glycoprotein expressed in PDAC. Tumor lysates of PDAC patient-derived xenografts (PDXs) were coprecipitated with rBC2LCN lectin and analyzed by liquid chromatography-mass spectrometry. A total of 343 proteins were initially identified. We used a web-based database to select five glycoproteins and independently evaluated their expression in PDAC by immunohistochemistry (IHC). Among them, we focused on carcinoembryonic antigen 5 (CEA) as the most cancer-specific carrier protein in PDAC, as it showed the most prominent difference in expression rate between PDAC cells (74%) and normal pancreatic duct cells (0%, P > .0001). rBC2LCN lectin and CEA colocalization in PDAC samples was confirmed by double-staining analysis. Furthermore, rBC2LCN-precipitated fractions were blotted with an anti-CEA polyclonal antibody (pAb), and CEA pAb-precipitated fractions were blotted with rBC2LCN lectin. The results demonstrate that CEA is in fact a ligand of rBC2LCN lectin.

Keywords: CEA; glycoprotein; lectin; pancreatic ductal adenocarcinoma; rBC2LCN.

MeSH terms

  • Animals
  • Antibodies / immunology
  • Carcinoembryonic Antigen / immunology
  • Carcinoembryonic Antigen / metabolism*
  • Carcinoma, Pancreatic Ductal / metabolism*
  • Carcinoma, Pancreatic Ductal / pathology
  • Carrier Proteins / metabolism*
  • Cell Line, Tumor
  • Female
  • GPI-Linked Proteins / immunology
  • GPI-Linked Proteins / metabolism
  • Heterografts
  • Humans
  • Immunohistochemistry / methods
  • Immunoprecipitation / methods
  • Lectins / metabolism*
  • Ligands
  • Mice
  • Mice, Inbred ICR
  • Mice, SCID
  • Neoplasm Transplantation
  • Pancreatic Neoplasms / metabolism*
  • Pancreatic Neoplasms / pathology

Substances

  • Antibodies
  • CEACAM5 protein, human
  • Carcinoembryonic Antigen
  • Carrier Proteins
  • GPI-Linked Proteins
  • Lectins
  • Ligands
  • rBC2LCN lectin