Differentiation-associated changes of glycolipid composition and metabolism in mouse myeloid leukemia cells. Induction of globotriaosylceramide and a galactosyltransferase

Glycosphingolipid expression in acute nonlymphocytic leukemia: common expression of shiga toxin and parvovirus B19 receptors on early myeloblasts

Glycosphingolipids (GSLs) are complex macromolecules on cell membranes that have been shown to play a role in neutrophil differentiation, activation, phagocytosis, and adhesion to both microorganisms and vascular endothelium. Because GSLs are often cryptic antigens on cell membranes, little is known regarding GSL expression in early myelopoiesis. To study the latter, myeloblasts were collected from patients with acute nonlymphocytic leukemia (ANLL) who required therapeutic leukocytopheresis for hyperleukocytosis. The neutral GSLs were isolated and identified by high-performance thin-layer chromatography (HPTLC), HPTLC immunostaining, gas chromatography, nuclear magnetic resonance, and fast atom bombardment-mass spectrometry. Like mature peripheral blood neutrophils, myeloblasts expressed glucosylceramide, lactosylceramide, and the neolacto-family GSLs, lactotriaosylceramide and neolactotetraosylceramide. Unlike neutrophils and chronic myeloid leukemia, most ANLL samples also expressed the globo-series GSLs, globotriaosylceramide and globotetraosylceramide. Globo GSL expression was strongly associated with a myeloblastic (ANLL M0-M2) and monoblastic phenotype (M5). A weak association was also noted with expression of either lymphoid (P <.10) or early hematopoietic markers (terminal deoxynucleotidyl transferase [TdT], CD34; P <.10). Globo-positive ANLL samples bound both shiga toxin and parvovirus B19 on HPTLC immunostaining. Based on these findings, we propose that neolacto and globo GSLs are expressed during early myeloid differentiation. Globotriaosylceramide expression on myeloblasts, and possibly myeloid stem cells, may have important implications for the use of shiga toxin as an ex vivo purging agent in autologous stem cell transplantation. Expression of globotetraosylceramide, the parvovirus B19 receptor, on myeloblasts may also explain the association between B19 infection, aplastic anemia, and chronic neutropenia of childhood.

GD1alpha-replica peptides functionally mimic GD1alpha, an adhesion molecule of metastatic tumor cells, and suppress the tumor metastasis

A novel peptide technology to produce mimicking peptides of carbohydrate moiety (which we propose to name glyco-replica peptides) is a useful tool to elucidate the functions of glycoconjugate. Carbohydrate moiety of ganglioside GD1alpha functions as a molecule involved in the adhesion between murine highly metastatic lymphoma RAW117-H10 cells and hepatic sinusoidal endothelial (HSE) cells. To prepare peptides which mimic the carbohydrate structure of GD1alpha, phage clones expressing peptides which bound to a monoclonal antibody against GD1alpha (KA17) were isolated from a phage-displayed random peptide library. Four phage clones having affinity to the monoclonal antibody KA17 were isolated, and these clones showed inhibitory effect on the binding of KA17 to GD1alpha. The amino acid sequences of the displayed pentadecamers were determined, and one of the phages displaying sequence WHWRHRIPLQLAAGR bound to HSE cells directly and showed the highest inhibitory effect on the adhesion between RAW117-H10 cells and HSE cells. The synthesized peptides having the same sequences to the displayed 15mers in the four isolated phage clones also showed the inhibitory effect on the adhesion of RAW117-H10 cells to HSE cells, and, again, the WHWRHRIPLQLAAGR peptide showed the highest inhibitory effect. Furthermore, intravenous injection of the peptide brought almost complete inhibition of the metastasis of RAW117-H10 cells to lung and spleen, and about 50% inhibition of the liver metastasis. These results indicate that GD1alpha plays an important role for metastasis of RAW117-H10 cells, and the peptides obtained by the present procedure are able to mimic the functional role of the glycoconjugate.

Microscale analysis of glycosphingolipids by TLC blotting/secondary ion mass spectrometry: a novel blood group A-active glycosphingolipid and changes in glycosphingolipid expression in rat mammary tumour cells with different metastatic potentials

The glycosphingolipid compositions of rat mammary tumour cell lines with different metastatic potentials for the lung [a parental tumour cell line (MTC) and its subclones MTLn2 (a non metastatic subclone) and MTLn3 (a subclone with high metastatic potential to the lung)] were studied using a newly developed TLC blotting/secondary ion mass spectrometry system and crude glycosphingolipids obtained from 0.5-1 x 10(7) cells of each cell line. GM3 and GM2 were the major components of the MTC cell line, but they were very minor components in the MTLn2 and MTLn3 cell lines, GDla being the major ganglioside HexNAc-fucosyl-GMla was found in the MTLn2 cells by the TLC blotting/SIMS method, and the terminal sugar linkage was shown to be a blood group A-type structure by immunostaining. These findings suggest that the ganglioside is a novel type of blood group A-active ganglioside, GalNAc alpha 1-3(fuc alpha 1 -2)GMla. No blood group A-active lipid was present in MTLn3 cells, whereas Hex-GMla and neutral glycosphingolipids with more than 5 sugar residues were.

Alterations of cell-surface carbohydrates during differentiation and development

Expression of many cell-surface carbohydrates is controlled temporally and spatially by developmental programs. This subject is reviewed from 5 viewpoints: structural changes revealed by chemical analysis, cell-surface markers useful for cell identification and separation, core proteins carrying the developmentally regulated carbohydrate chain, glycosyltransferases responsible for the change and the biological meaning of the phenomenon. The differentiation systems covered are mainly early mammalian embryogenesis and the differentiation of blood and nerve cells.

Structure of a new disialoganglioside GD1c from spontaneous murine thymoma

A major mono- and a di-sialoganglioside were isolated and purified to homogeneity from a spontaneous thymoma that occurs in AKR mice. Compositional and methylation analyses and the use of exoglycosidases established the monosialoganglioside to be alpha Neu(2----3)beta Gal(1----3)beta GalNAc(1----4)beta Gal(1----4)Glc(1----4)Cer and the disialoganglioside to be alpha NeuAc(2----8)alpha NeuAc(2----3)beta Gal(1----3)beta GalNAc(1----4)beta Gal(1----4)Glc(1----1)Cer (GD1c). A possible pathway for the biosynthesis of this disialoganglioside is presented.

Natural killer activity against cultured human neural tumor and fetal brain cells

Ten human neural tumor lines and three established from normal human brain were analyzed for sensitivities to natural killer (NK) cytolysis. Compared to MOLT-4, fetal brain cells were sensitive, but those from adult brain and eight of ten neural tumor cell lines demonstrated marked NK resistance. The frequencies of target-binding cells (TBC) and single-cell lysis of glioma cells bound within tumor cell conjugates demonstrated that the resistance of two lines was explained either by a decrease in the frequencies of TBC or reduced ability of bound NK cells to lyse the tumor cell conjugates. A third resistant line demonstrated decreases in both TBC and tumor cell conjugate lysis. Two glioma lines with less NK resistance had greater frequencies of TBC or conjugate lysis than the resistant lines. Thus, NK resistance can result from decreased recognition of targets, diminished NK lysis of bound targets, or a combination of both.

Carbohydrate structure in tumor immunity

Researchers have endeavored to define surface alterations associated with neoplasia for at least 25 years. In comparisons of normal tissues with animal and human tumors, cultured cells before and after transformation with oncogenic agents, tumorigenic and nontumorigenic transformed cells, metastatic and nonmetastatic tumor cells, high- and low-metastatic variants, and tumor cells before and after induction of differentiation to a less malignant phenotype, a consistent finding has been some form of alteration in surface carbohydrate structures. These changes in glycolipids, glycoproteins and glycosaminoglycans are reviewed, and their structures are illustrated. Both nucleotide sugar biosynthesis and glycosyltransferase changes have been associated with these alterations. In some cases, alterations in transformed cells were related to growth, rather than transformation. In others, the altered glycoconjugates are truly tumor-associated. There is evidence that cell surface glycoconjugates may function in growth control. Altered carbohydrate structures could also serve as receptors for growth promoting factors and be directly responsible for altered growth control. Recent studies with monoclonal antibodies indicate that the vast majority of antibodies recognizing tumor-associated antigens are detecting altered carbohydrate structures. Mechanisms by which the immune system can recognize these carbohydrate structures are considered, and immune recognition of tumor-associated carbohydrate structural alterations is explored. A number of these hypotheses relating to alterations in glycosylation, growth control, and tumor immunity deserve further investigation.