Serum activities of lysosomal enzymes in patients with liver cell carcinoma

Hereditary fructose intolerance mimicking a biochemical phenotype of mucolipidosis: A review of the literature of secondary causes of lysosomal enzyme activity elevation in serum

We describe a patient with failure to thrive, hepatomegaly, liver dysfunction, and elevation of multiple plasma lysosomal enzyme activities mimicking mucolipidosis II or III, in whom a diagnosis of hereditary fructose intolerance (HFI) was ultimately obtained. She presented before introduction of solid foods, given her consumption of a fructose-containing infant formula. We present the most extensive panel of lysosomal enzyme activities reported to date in a patient with HFI, and propose that multiple enzyme elevations in plasma, especially when in conjunction with a normal plasma α-mannosidase activity, should elicit a differential diagnosis of HFI. We also performed a review of the literature on the different etiologies of elevated lysosomal enzyme activities in serum or plasma. © 2016 Wiley Periodicals, Inc.

Variations in serum alpha-L-fucosidase activity during childhood and pregnancy

Variations in serum alpha-L-fucosidase activity (AFU) have been studied during childhood and pregnancy. 994 children, ages 1 day to 15 yr, were examined; no sex-linked difference was found, but significant variations according to age were demonstrated. AFU activity rose during the first 10-15 days after birth, remained high during the second month then decreased till the end of the first year, thereafter no significant changes were observed. In pregnancy, AFU activity rose and dropped quickly after delivery; neither hypertension nor fetal distress led to AFU activity changes during pregnancy. Thus, in addition to the great variability of AFU linked to the genetic polymorphism, the physiological factors such as age or pregnancy have to be taken into account to establish the significance of AFU variations in pathological situations.

Malignant cell glycoproteins and glycolipids

The cell surface is involved in cell growth and division, cell-cell interaction, communication, differentiation and migration, and other processes likely to be involved in malignant transformation and/or the metastatic spread of cancer. Although there are many alterations of glycoproteins and glycolipids on the malignant cell surface, it is unclear whether these alterations are epiphenomena or an integral part of the malignancy process. This article reviews the recent literature and some earlier studies relevant for understanding emerging concepts and trends with respect to malignant cell glycoconjugates. Emphasis is on structural alterations of the carbohydrate portions of malignant cell glycoproteins and glycolipids and on the enzymes (glycosyltransferases and glycosidases) involved in their metabolism. Practical applications derived from malignant cell glycoconjugate studies are discussed briefly with respect to the diagnosis, staging, monitoring, and treatment of malignant disease. The review concludes by indicating which research areas on malignant cell glycoconjugates are likely to be fruitful in increasing our basic understanding of, and ability to deal effectively with, malignant disease.

Glycosidases in cancer and invasion

Glycosidases have been demonstrated to be elevated in the interstitial fluid of tumors, sera of animals and patients with tumors, and in some tumor tissue as compared to normal adjacent tissue. Elevations of serum beta-N-acetylglucosaminidase and beta-glucuronidase most commonly have been found to occur and these enzymes have been shown to be secreted into the extracellular medium by many different tumor cell types in vitro. The mechanism of cellular release of these hydrolytic enzymes probably involves tumor lysosomal exocytosis. Increased tumor glycosidase levels may promote increased tumor cell shedding from primary tumors, local invasion and perhaps be responsible directly, or indirectly for structural changes in tumor cell surface glycoconjugates. These cell surface changes could facilitate tumor cell thrombus formation, secondary site implantation and attachment in the microcirculation to endothelial cells and/or subendothelial basement membrane components. Other studies have demonstrated a correlation between metastatic cell potential and increased endoglycosidase and polysaccharide lyase activity. Generally, metastatic tumor cell variants have been found to be more invasive and capable of degrading proteoglycan basement membrane components, in part due to these increased levels of degradative enzymes. Hence, it is of considerable interest to develop inhibitors against these enzymes. Initial studies with glucuronidase inhibitors in the therapy of bladder tumors have been promising and with the advent of better agents and the use of appropriate in vitro metastatic models it may be possible to design and develop agents which interfere in various metastatic events and limit tumor progression.

Serum alpha-L-fucosidase: a new marker for the diagnosis of primary hepatic carcinoma?

alpha-L-fucosidase, a lysosomal enzyme which catabolizes fucoproteins, was studied in sera from 30 controls, 32 patients with primary hepatic carcinomas, 24 patients with secondary metastatic liver carcinomas and 36 patients with cirrhosis. Serum alpha-L-fucosidase was increased in primary hepatic carcinomas (145.5 +/- 12 nkat per liter) with a high statistical significance versus controls (51.4 +/- 4.5 - p less than 10(-7], secondary metastatic liver carcinomas (58.9 +/- 6.4 - p less than 10(-5] and cirrhotics (71.3 +/- 6 - p less than 10(-5). A level exceeding 110 was a useful marker for the diagnosis of primary hepatic carcinoma with 75% sensitivity and 90% specificity.

A comparison of lysosomal acid hydrolase activities in human gastric antrum and in different regions of the porcine stomach

Lysosomes are known to be implicated in many disease states in both humans and animals. In order to assess the possible role of lysosomes in the aetiology of human gastric ulceration, lysosomal enzyme levels and some of their properties were determined in human gastric antrum and in three discrete porcine gastric regions. Of the four regions investigated, the strongest similarity emerged between the enzymes of the porcine pyloric gland area and those of the human antrum. These data suggest that the pyloric gland is an appropriate model tissue for a comparative in vitro study of lysosomal involvement in human gastric ulceration.