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.

Malignant cell glycoproteins and glycolipids.

Preclinical and clinical studies with latex from ficus glabrata hbk, a traditional intestinal anthelminthic in the amazonian area

The European fanworm Sabella spallanzanii (Gmelin, 1791) was recently introduced to Port Phillip Bay and is now a conspicuous component of most benthic communities. Reproduction of the worm was investigated in a population at Queenscliff over a 2 yr period (October 1995 to October 1997) using gonadal histology. The worms are dioecious (sex ratio 1:1, n=250), and attained sexual maturity at ∼50 mm body length. Reproductive periodicity followed a distinct annual cycle, and spawning proceeded through an extended autumn/winter period. Spawning was broadly synchronous between sexes, and coincided with falling seawater temperatures and shorter day-lengths. The females were highly fecund, and >50 000 eggs were probably shed from large females (>300 mm body length) during the annual spawning period. Breeding cycles of S. spallanzanii in Port Phillip Bay are ∼6 mo out of phase with endemic populations located at similar latitudes in the northern hemisphere. The spread of S. spallanzanii within Port Phillip Bay has been monitored by divers on an annual basis since 1994. The most recent dive survey (1998) indicates that S. spallanzanii has extended its range through out the entire 2000 km2 embayment, and has invaded most subtidal habitats. Quantitative estimates of S. spallanzanii abundances were highest on pier pylons (12.5 individuals m−2, 0.5 to 7 m depths). On sediments, estimates were highest at shallow sites (0.3 m−2, 7 m depth), but numbers declined significantly with depth (0.1 m−2, 17 to 22 m depth). Mean worm lengths and biomass were, by contrast, significantly higher at intermediate depths (12 to 17 m) than in shallower (7 m) or deeper (22 m) locations. S. spallanzanii demonstrates a clear preference for growth in sheltered, nutrient-enriched waters, so it may not spread from Port Phillip Bay into the adjacent oceanic waters of Bass Strait; however, in view of S. spallanzanii's current high abundance, fecundity and extended spawning periodicity, there is a high risk of future range expansions, mediated by shipping, into other temperate-water ports.

Reproduction and distribution of the invasive European fanworm Sabella spallanzanii (Polychaeta: Sabellidae) in Port Phillip Bay, Victoria, Australia

beta-N-Acetylhexosaminidase (HEX, E.C. 3.2.1.52) from larvae of the ixodid tick Boophilus microplus was purified to capillary zone electrophoresis homogeneity, and characterized. Enzyme purification was carried out by sequential liquid chromatography on Sephadex G-200, p-aminobenzyl-N-acetyl-beta-D-thioglucosamine affinity, and Mono-Q FPLC columns. Purification was about 1600-fold, with a yield of 10%, as determined with p-nitrophenyl-N-acetylglucosaminide as substrate. The enzyme presented optimum pH 4.7, and optimum temperature 65 degrees C. The molecular weight of non-denatured enzyme was estimated as 127,000 by gel filtration chromatography, and 60,000 in SDS-PAGE. The tick hexosaminidase presented glycosyl residues, as evidenced by binding to Concanavalin-A. Among several p-nitrophenyl glycosides tested as substrate, HEX was active only on p-nitrophenyl-N-acetylglucosaminide and p-nitrophenyl-N-acetylgalactosaminide. The purified enzyme presented immunogenicity in rabbit, and the correspondent antibodies inhibited about 90% of its original, in vitro activity.

Purification and characterization of beta-N-acetylhexosaminidase from bovine tick Boophilus microplus (Ixodide) larvae.

Purification and characterization of β-N-acetylhexosaminidase from maize seedlings

A distinct β-hexosaminidase isoenzyme separated from human leukemic lymphocytes and myelocytes

On the active site of β-hexosaminidase from latex of Ficus glabrata

alpha-L-Fucosidase (EC 3.2.1.51) activity and isoenzyme characteristics were analyzed in normal lymphocyte subpopulations, chronic lymphocytic leukemia subpopulations, and acute lymphoblastic leukemia blasts. Similar pH activity profiles revealed that pH 5.0 was optimal in normal and leukemic cells. Unfractionated CLL lymphocytes had a lower specific activity than normal unfractionated lymphocytes (2.5 +/- 1.0 u/10(6) cells v. 4.0 +/- 1.1). CLL B cells and T-cells had lower specific activity than their respective normal counterparts (1.8 +/- 0.2 v. 5.9 +/- 2.0) (B-cells); (2.2 +/- 0.5 v. 3.7 +/- 1.0) (T-cells) suggesting T and B cells in CLL are abnormal. ALL blasts had a higher specific activity compared to unfractionated normal lymphocytes (9.7 +/- 3.0 v. 4.0 +/- 1.1; p less than 0.001). The isoenzyme pattern of normal, CLL and ALL lymphocytes were obtained by automated chromatofocusing on PBE 94 microcolumns using 0.025 M histidine and polybuffer 74. Two major isoenzyme components (B and A) were isolated. The activity ratio of B/A was different in normal, ALL, and CLL cells.

alpha-L-Fucosidase activity and isoenzyme characteristics analyzed by chromatofocusing in normal and leukemic lymphocytes.

1. 1. Two forms of β-hexosaminidase (A and B) were isolated from Annelida (Spirographis spallanzanii, Allolobophora caliginosa, Hirudo medicinalis) and their kinetic properties studied. 2. 2. The final sp. act. of hexosaminidase A and B increased 300–800-fold by purification scheme, which included ammonium sulphate fractionation, Sephadex G-200 column chromatography, concanavalin A-Sepharose affinity chromatography and chromatofocusing. β-N- Acetyl- d -glucosaminidase and β-N- acetyl- d -galactosaminidase , activity remain in a constant ratio throughout the purification procedure. 3. 3. Km values using both substrates, p- nitrophenyl -N- acetyl -β- d -glucosaminide and p- nitrophenyl -N- acetyl-β- d -galactosaminide , of each isoenzyme were similar in the three annelids. Data derived from the use of a mixture of substrates were consistent with the model, which proposes a common active site for either substrate in the case of hexosaminidase A and B. 4. 4. The reaction products, N-acetylglucosamine and N-acetylgalactosamine, are competitive inhibitors, but N-acetylgalactosamine was the strongest inhibitor in spite of the similar Km in accordance with the hexosaminidase covalent catalysis mechanism.

Isoenzymes separation by chromatofocusing and kinetic properties of β-hexosaminidase from Spirographis Spallanzanii, Allolobophora Caliginosa and Hirudo medicinalis

Good separations of the two major beta-hexosaminidase forms from human leukocytes were achieved by chromatofocusing, a technique which separates proteins on the basis of their isoelectric points. The use of an automated and reliable method is described for the identification of homozygotes and carriers of the GM2 gangliosidosis.

C. Maffei

Papers

A distinct β-hexosaminidase isoenzyme separated from human leukemic lymphocytes and myelocytes

On the active site of β-hexosaminidase from latex of Ficus glabrata

alpha-L-Fucosidase activity and isoenzyme characteristics analyzed by chromatofocusing in normal and leukemic lymphocytes.

Isoenzymes separation by chromatofocusing and kinetic properties of β-hexosaminidase from Spirographis Spallanzanii, Allolobophora Caliginosa and Hirudo medicinalis

Chromatofocusing coupled with automated assay for beta-hexosaminidase isoenzymes in GM2 gangliosidosis.