Enzymatic basis of sugar structures of alpha-fetoprotein in hepatoma and hepatoblastoma cell lines: correlation with activities of alpha 1-6 fucosyltransferase and N-acetylglucosaminyltransferases III and V.
alpha-Fetoproteins (AFPs) were purified from 2 hepatoma cell lines (Hep G2 and HuH-7) and a hepatoblastoma cell line (HuH-6), and the structures of pyridylaminated (PA) derivatives of their sugar chains were analyzed by HPLC. Simultaneously, the activities of alpha 1-6 fucosyltransferase (alpha 1-6FT) and N-acetylglucosaminyltransferase III (GnT-III), IV (GnT-IV) and V (GnT-V) were assayed in these cell lines. For all 3 cell lines the major sugar chain detected was a fucosylated biantennary structure. Hep G2 cells contained a high level of GnT-V, which catalyzes the formation of a tri'-antennary structure, and in fact a substantial percentage of the AFP sugar chains in these cells had the tri'-antennary structure. alpha 1-6FT was also high, and fucosylated tri' structures were detected, which suggests that high activities of transferases affect the AFP sugar chains. In HuH-6 cells, GnT-III, which catalyzes the formation of bisecting GlcNAc, was elevated. Correspondingly, a fucosylated, bisected biantennary structure was found as a major sugar chain. In the HuH-7 cell line, the contents of bisecting GlcNAc and tri' structure were low and neither GnT-III nor GnT-V was elevated. These data indicate that the sugar structures of AFP in these cell lines correlate well with the activities of alpha 1-6 FT, GnT-III and GnT-V.
Ohno
M
M
Department of Biochemistry, Osaka University Medical School, Japan.
Nishikawa
A
A
Koketsu
M
M
Taga
H
H
Endo
Y
Y
Hada
T
T
Higashino
K
K
Taniguchi
N
N
D002241:Carbohydrates / Q000737:chemistry*; D006528:Carcinoma, Hepatocellular / Q000737:chemistry* / Q000201:enzymology; D005964:Glucosyltransferases / Q000032:analysis*; D006801:Humans; D008113:Liver Neoplasms / Q000737:chemistry* / Q000201:enzymology; D017351:N-Acetylglucosaminyltransferases; D014407:Tumor Cells, Cultured; D000509:alpha-Fetoproteins / Q000737:chemistry*
D002241:Carbohydrates; D000509:alpha-Fetoproteins; D005964:Glucosyltransferases; D017351:N-Acetylglucosaminyltransferases; C054599:beta-1,4-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase; C038111:alpha-1,3-mannosylglycoprotein beta-1,4-N-acetylglucosaminyltransferase; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase