Clinical significance of fucosidase
The definition and origin of fucosidase
Fucosidase Definition: A class of enzymes that catalyze the hydrolysis of glycosidic bonds include alpha-L-fucosidase (EC 3.2.1.51), β-D-fucosidase (EC 3.2.1.38), 1,2 -alpha-L-fucosidase (SEQ ID NO: EC 3.2.1.63), respectively, hydrolyzing the non-reducing terminal L-fucose residues of different forms of glycosidic linkages, wherein 1,2-α-L-fucosidase With a high degree of specificity. Applied science: biochemistry and molecular biology (a subject); enzyme (two subjects).
Α-L-fucosidase (AFU) is a lysosomal acid hydrolase, In 1980 the French scholar Deugnier other study found that AFU in the diagnosis of hepatocellular carcinoma in the sensitivity, and positive rate is AFP-positive rate More than three times, AFP-negative cases and small cell carcinoma of the diagnosis of great value, early diagnosis of primary liver cancer is a useful indicator. And was confirmed by many research institutes.
The biochemical characteristics of fucosidase
Α-L-fucosidase (AFU), mainly involved in fucosyl-containing various glycolipids, glycoproteins, mucopolysaccharides and other macromolecules catabolism. Widely present in the human body tissue lysosomes and body fluids. Specimens of serum, urine, saliva, tears and other specimens can be. Specimens should be clarified, stored at 4℃ for 3 days, -20℃ for 3 months, to avoid repeated freeze-thaw. Hemolysis, jaundice, high blood lipids, polluted specimens seriously affect the results.
Methods for the determination of fucosidase
Fluorescence method: AFU hydrolysis of 4-methyl umbelliferone α-L-fucopyranoside, the release of 4-methyl umbrella ketone, with alkaline buffer to terminate the reaction, and the product showed fluorescence, with 360nm or 365nm Excitation wavelength and emission wavelength of 400nm or 448nm to detect the fluorescence intensity, control the different concentration of 4-methyl umbrella ketone prepared by the standard curve for enzyme activity. This method is highly sensitive, the minimum detection limit of 0.06U/L.
Colorimetric method: 4-nitrophenyl α-L-fucopyranoside as substrate by Α-L-fucosidase (AFU) hydrolysis of 4-nitrophenol release, the same buffer with alkaline to terminate the reaction, the 4-NP was significant yellow, Absorbance A is read at the specified wavelength. The AFU activity was calculated using a standard curve or 4-NP molar absorbance using pure 4-NP as the standard. This method is simple, equipment requirements are not high, widely used at home and abroad.
Clinical significance of fucosidase
Hepatocellular carcinoma (HCC): AFU activity in serum of patients with primary hepatocellular carcinoma was significantly higher than that of normal controls, but also significantly higher than that of metastatic liver cancer, cholangiocarcinoma, malignant mesothelioma, malignant hemangioendothelioma, cirrhosis, congenital hepatic cyst and other Benign liver lesions. The diagnosis of primary liver cancer was 64% -84%, specificity of about 90%. Α-L-fucosidase (AFU) and AFP in primary liver cancer and liver cirrhosis patients showed that AFU and AFP were increased in patients with primary liver cancer and liver cirrhosis, and AFP 500ng/mL was the critical value for diagnosing liver cancer, the false positive rate was 43 %, Α-L-fucosidase (AFU)740nmol/(ml.h) as the critical value, the sensitivity of 84%, specificity of 94%. Therefore, serum AFU for the diagnosis of primary liver cancer have a high sensitivity and specificity. The sensitivity of AFU was 87% and the specificity was 78%, while that of AFP was 65% and 89% (the diagnostic limit was 20μg/L) for Α-L-fucosidase (AFU) and AFP in 24 patients with hepatocellular carcinoma. . Suggesting that the sensitivity of Α-L-fucosidase (AFU) diagnosis is good, and specificity is lower than AFP. Serum Α-L-fucosidase (AFU) activity and positive rate of liver cancer diameter and no significant correlation. The positive rate of serum AFU in small hepatocellular carcinoma group was significantly higher than that in AFP group (70.8% vs 37.5%). AFP negative and elevated AFP and not enough to diagnose primary liver cancer, the serum Α-L-fucosidase (AFU) positive rate of 80.8%. Liver biopsy confirmed primary liver cancer, serum Α-L-fucosidase (AFU) positive rate of AFP-positive rate of more than 3 times. Detecting AFU in cirrhotic patients, as increased activity, is more valuable in finding smaller tumors, where AFP can not diagnose smaller tumors. Therefore, the application and promotion of Α-L-fucosidase (AFU) as a new diagnostic indicator of primary liver cancer is of great significance, especially AFP-negative and small cell carcinoma of the diagnosis of greater value. Because there is no significant correlation with AFP can be initial diagnosis, combined detection can improve the detection rate of liver cancer.
Pregnancy and ovarian tumors: Studies have shown that with the increase in the number of weeks of pregnancy plasma Α-L-fucosidase (AFU) increments in natural childbirth or artificial termination of pregnancy, the rapid decline in 5 days to normal. The serum AFU activity in patients with ovarian cancer was lower than that in patients with ovarian cancer, and had no correlation with disease stage, tumor burden, histological type and tumor differentiation. The reduction of serum Α-L-fucosidase (AFU) activity in patients with benign and malignant ovarian cancer may be related to genetic factors
Other: Fucosidase storage in patients with congenital tissue and body fluids due to lack of Α-L-fucosidase (AFU) or decreased activity, leading to glycoprotein or glycolipid metabolic disorders. Serum AFU increased in patients with gastric cancer, acute pancreatitis does not increase cystic fibrosis associated with pancreatitis decreased, progressive pyramidal dystrophy serum AFU activity decreased.
81.2% of patients with primary liver cancer serum Α-L-fucosidase (AFU) levels increased, and AFP combined detection can improve the diagnosis of primary liver cancer positive rate of 93.1%.
Dynamic observation of liver cancer to determine the efficacy, prognosis, recurrence of great significance.
Serum AFP in metastatic liver cancer, lung cancer, breast cancer, ovarian cancer, uterine cancer can also be increased; in cirrhosis, chronic hepatitis, gastrointestinal bleeding also slightly increased.