Downregulation of a human colonic sialyltransferase by a secondary bile acid and a phorbol ester

Ming Li, Ravi Vemulapalli, Asad Ullah, Leighton Izu, Michael E. Duffey, Peter Lance

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Fecal constituents such as bile acids and increased sialylation of membrane glycoproteins by α-2,6-sialyltransferase (HST6N-1) may contribute to colorectal tumorigenesis. We hypothesized that bile acids and phorbol ester [12-O-tetradecanoylphorbol-13-acetate (TPA)] would upregulate HST6N-1 in colonic cells. However, deoxycholate (DOC) (300 μmol/l), a secondary bile acid, and TPA (20 ng/ml) decreased expression of an ~100-kDa glycoprotein bearing α-2,6-linked sialic acid in a colon cancer cell line (T84) in vitro. HST6N-1 mRNA levels were reduced ~80% by treatment (≤24 h) with DOC or TPA but not by cholate, a primary bile acid. Treatment (24 h) with DOC or TPA decreased activity of this enzyme to 30% and 13% of control, respectively. These effects of DOC and TPA were transcriptional and were mediated by Ca2+ and protein kinase C, respectively. Thus DOC and TPA both downregulated, and did not upregulate, α-2,6-sialyltransferase expression in vitro, but by different transduction pathways. As colorectal tumors grow, their progressive removal from the fecal milieu that normally downregulates this enzyme may favor invasion and metastasis.

Original languageEnglish (US)
Pages (from-to)G599-G606
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Issue number3 37-3
StatePublished - Mar 1998


  • Colorectal neoplasia
  • Gene expression regulation
  • Glycosyltransferase expression

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)


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