Glycylproline dipeptidyl aminopeptidase isoenzyme in diagnosis of primary hepatocellular carcinoma.
OBJECTIVE
To investigate the role of glycylproline dipeptidyl aminopeptidase (GPDA) isoenzyme in the diagnosis of primary hepatocellular carcinoma (PHC), especially in patients with negative alpha-fetoprotein (AFP).


METHODS
A stage gradient polyacrylamide gel discontinuous electrophoresis system was developed to separate serum GPDA isoenzymes, which were determined in 102 patients with PHC, 45 cases with liver cirrhosis, 24 cases with chronic hepatitis, 35 cases with benign liver space-occupying lesions, 20 cases with metastatic liver cancer and 50 cases with extra-hepatic cancer, as well as 80 healthy subjects. The relationships between GPDA isoenzymes and AFP, the sizes of tumors, as well as alanine aminotransferase (ALT) were also analyzed.


RESULTS
Serum GPDA was separated into two isoenzymes, GPDA-S and GPDA-F. The former was positive in all subjects, while the latter was found mainly in majority of PHC (85.3 %) and a few cases with liver cirrhosis (11.1 %), chronic hepatitis (33.3 %), metastatic liver cancer (15.0 %) and non-hepatic cancer (16.0 %). GPDA-F was negative in all healthy subjects and patients with benign liver space-occupying lesions, including abscess, cysts and angioma. There was no correlation between GPDA-F and AFP concentration or tumor size. GPDA-F was consistently positive and not correlated with ALT in PHC, but GPDA-F often converted to negative as decline of ALT in benign liver diseases. The electrophoretic migration of GPDA-F became sluggish after the treatment of neuraminidase.


CONCLUSIONS
GPDA-F is a new useful serum marker for PHC. Measurement of serum GPDA-F is helpful in diagnosis of PHC, especially in patients with negative AFP. GPDA-F is one kind of glycoproteins rich in sialic acid.
Ni
Run-Zhou
RZ
Department of Gastroenterology, Affiliated Hospital of Nantong Medical College, Nantong 226001, Jiangsu Province, China. nirz@public.nt.js.cn
Huang
Jie-Fei
JF
Xiao
Ming-Bing
MB
Li
Mei
M
Meng
Xian-Yong
XY
D000626:Aminopeptidases / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood*; D006528:Carcinoma, Hepatocellular / Q000097:blood / Q000175:diagnosis* / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008107:Liver Diseases / Q000097:blood / Q000201:enzymology; D008113:Liver Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000201:enzymology; D009369:Neoplasms / Q000097:blood / Q000145:classification; D009439:Neuraminidase; D012016:Reference Values; D015203:Reproducibility of Results; D000509:alpha-Fetoproteins / Q000032:analysis
D014408:Biomarkers, Tumor; D007527:Isoenzymes; D000509:alpha-Fetoproteins; D009439:Neuraminidase; D000626:Aminopeptidases; C018085:glycylproline dipeptidyl aminopeptidase