Increased expression of N-acetylglucosaminyltransferase-V in human hepatoma cells by retinoic acid and 1alpha,25-dihydroxyvitamin D3.

Abstract

UDP-N-acetylglucosamine: alpha-6-D-mannoside beta-1,6N-acetylglucosaminyltransferase-V activities were determined in human hepatoma cell lines of Hep3B and HepG2, and also compared with those of normal liver tissues and primary hepatocytes. When GlcNAcbeta1-2Manalpha1-3(GlcNAcbeta1-2Manalpha1-4)(Manbeta1-4GlcNAc-2-amino pyridine (GlcN,GlcN-biant-PA) and UDP-GlcNAc were used as substrates, the enzymes displayed optimum temperatures of 50 degrees C, optimum pHs of 6.5 in each case, K(m) values for UDP-GlcNAc to be 5.8 (Hep3B) and 4.5 mM (HepG2) and K(m) values for GlcN,GlcN-biant-PA (mM) to be 1.28 (Hep3B) and 2.4 (HepG2). This indicates that values of Hep3B GlcNAc-transferase-V were distinguishable with HepG2 enzyme. Furthermore, Hep3B enzyme in membrane fraction showed about 1.5-fold higher specific activity (1.423 pmol/(h mg) than that (1.066 pmol/(h mg)) of HepG2. Normal hepatocytes are characterized by very low level of GlcNAc-transferase-V activity whereas hepatoma cells contained high activities. Treatment of hepatoma cells with retinoic acid and 1alpha,2,5-dihydroxyvitamin D(3) (Vit-D(3)) resulted in an increase in GlcNAc-transferase-V activity, while treatment with dimethyl sulfoxide and cytosine-arabinoside resulted in decrease in the enzyme activity. Although retinoic acid (RA) treated cells shows a changed GlcNAc-transferase-V mRNA expression, expression of marker proteins such as alpha-fetoprotein and albumin was not changed. This is the first demonstration of GlcNAc-transferase-V activity in RA and Vit-D(3)-treated hepatoma cell lines.

• Authors: Cheorl-Ho Kim
• Journal: The international journal of biochemistry & cell biology (Int J Biochem Cell Biol) Vol. 36 Issue 11 Pg. 2307-19 (Nov 2004) ISSN: 1357-2725 [Print] Netherlands
• PMID: 15313475 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Albumins
• Pyridines
• Cytarabine
• Tretinoin
• N-Acetylglucosaminyltransferases
• alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase
• Calcitriol
• Dimethyl Sulfoxide

Topics

• Albumins (metabolism)
• Calcitriol (pharmacology)
• Carcinoma, Hepatocellular (enzymology)
• Cytarabine (pharmacology)
• Dimethyl Sulfoxide (pharmacology)
• Enzyme Activation (drug effects)
• Humans
• Liver Neoplasms (enzymology)
• N-Acetylglucosaminyltransferases (metabolism)
• Pyridines (metabolism)
• Tretinoin (pharmacology)