Inhibition of polypeptide N-acetyl-α-galactosaminyltransferases is an underlying mechanism of dietary polyphenols preventing colorectal tumorigenesis

Bioorg Med Chem. 2019 Aug 1;27(15):3372-3382. doi: 10.1016/j.bmc.2019.06.020. Epub 2019 Jun 11.

Abstract

Ellagitannin-derived ellagic acid (EA) and colonic metabolite urolithins are functional dietary ingredients for cancer prevention, but the underlying mechanism need elucidation. Mucin-type O-glycosylation, initiated by polypeptide N-acetyl-α-galactosaminyltransferases (ppGalNAc-Ts), fine-tunes multiple biological processes and is closely associated with cancer progression. Herein, we aim to explore how specific tannin-based polyphenols affect tumor behavior of colorectal cancer cells (CRC) by modulating O-glycosylation. Utilizing HPLC-based enzyme assay, we find urolithin D (UroD), EA and gallic acid (GA) potently inhibit ppGalNAc-Ts. In particular, UroD inhibits ppGalNAc-T2 through a peptide/protein-competitive manner with nanomolar affinity. Computational simulations combined with site-directed mutagenesis further support the inhibitors' mode of action. Moreover, lectin analysis and metabolic labelling reveal that UroD can reduce cell O-glycans but not N-glycans. Transwell experiments prove that UroD inhibits migration and invasion of CRC cells. Our work proves that specific tannin-based polyphenols can potently inhibit ppGalNAc-Ts activity to reduce cell O-glycosylation and lead to lowering the migration and invasion of CRC cells, suggesting that disturbance of mucin-type O-glycosylation is an important mechanism for the function of dietary polyphenols.

Keywords: Colorectal cancer; Dietary polyphenol; O-glycosylation; Urolithin D; ppGalNAc-T.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinogenesis / drug effects*
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Colorectal Neoplasms / pathology
  • Colorectal Neoplasms / prevention & control*
  • Dose-Response Relationship, Drug
  • Humans
  • Molecular Structure
  • N-Acetylgalactosaminyltransferases / antagonists & inhibitors*
  • N-Acetylgalactosaminyltransferases / metabolism
  • Peptides / antagonists & inhibitors*
  • Peptides / metabolism
  • Polyphenols / chemical synthesis
  • Polyphenols / chemistry
  • Polyphenols / pharmacology*
  • Structure-Activity Relationship

Substances

  • Peptides
  • Polyphenols
  • N-Acetylgalactosaminyltransferases