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S Hakomori

Publications and source records attributed to S Hakomori.

At least 19 recordsLinked to original sources
PubMed2001

Binding specificity of siglec7 to disialogangliosides of renal cell carcinoma: possible role of disialogangliosides in tumor progression.

Previous studies indicate that expression of higher gangliosides in renal cell carcinoma (RCC) is correlated with metastatic potential, particularly in the lung. Out of five major gangliosides in RCC, three disialogangliosides (disialogalactosylgloboside, IV(3)NeuAcIII(6)NeuAcLc(4), and IV(4)GalNAcIV(3)NeuAcIII(6)NeuAcLc(4)) bind strongly to siglec7, which is expressed highly in monocytes and natural killer cells. Out of other gangliosides tested, 2-->6 sialylparagloboside, GD3, GD2, and GT1b, but not other lacto- or ganglio-series gangliosides, showed clear binding to siglec7. In view of preferential metastasis of RCC to the lung, and binding of RCC cell line TOS-1 to lung tissue sections as shown in our previous study, we examined expression of siglec7 in the lung. siglec7 is expressed highly in resident blood cells, but not in parenchymatous cells. TOS-1 cells aggregate together strongly through adhesion with peripheral blood mononuclear cells to form large clumps. This suggests the possibility that such aggregates may form embolisms of microvasculature, particularly in the lung, which initiate metastasis. Other possible roles of higher gangliosides in RCC in promoting metastasis and tumor progression are discussed.

Animals↗
PubMed2001

Binding specificity of siglec7 to disialogangliosides of renal cell carcinoma: possible role of disialogangliosides in tumor progression.

Previous studies indicate that expression of higher gangliosides in renal cell carcinoma (RCC) is correlated with metastatic potential, particularly in the lung. Out of five major gangliosides in RCC, three disialogangliosides (disialogalactosylgloboside, IV(3)NeuAcIII(6)NeuAcLc(4), and IV(4)GalNAcIV(3)NeuAcIII(6)NeuAcLc(4)) bind strongly to siglec7, which is expressed highly in monocytes and natural killer cells. Out of other gangliosides tested, 2-->6 sialylparagloboside, GD3, GD2, and GT1b, but not other lacto- or ganglio-series gangliosides, showed clear binding to siglec7. In view of preferential metastasis of RCC to the lung, and binding of RCC cell line TOS-1 to lung tissue sections as shown in our previous study, we examined expression of siglec7 in the lung. siglec7 is expressed highly in resident blood cells, but not in parenchymatous cells. TOS-1 cells aggregate together strongly through adhesion with peripheral blood mononuclear cells to form large clumps. This suggests the possibility that such aggregates may form embolisms of microvasculature, particularly in the lung, which initiate metastasis. Other possible roles of higher gangliosides in RCC in promoting metastasis and tumor progression are discussed.

Animals↗
PubMed2001

GM3 ganglioside inhibits CD9-facilitated haptotactic cell motility: coexpression of GM3 and CD9 is essential in the downregulation of tumor cell motility and malignancy.

A cooperative inhibitory effect of GM3, together with CD9, on haptotactic cell motility was demonstrated by a few lines of study as described below. (i) Haptotactic motility of colorectal carcinoma cell lines SW480, SW620, and HRT18, which express CD9 at a high level, is inhibited by exogenous GM3, but not by GM1. (ii) Motility of gastric cancer cell line MKN74, which expresses CD9 at a low level, was not affected by exogenous GM3. Its motility became susceptible to and inhibited by exogenous GM3, but not GM1, when the CD9 level of MKN74 cells was converted to a high level by transfection with CD9 cDNA. Findings i and ii suggest that haptotactic tumor cell motility is cooperatively inhibited by coexpression of CD9 and GM3. (iii) This possibility was further demonstrated using cell line ldlD 14, and its derivative expressing CD9 through transfection of its gene (termed ldlD/CD9). Both of these cell lines are defective in UDP-Gal 4-epimerase and cannot synthesize GM3 unless cultured in the presence of galactose (Gal(+)), whereas GM3 synthesis does not occur when cells are cultured in the absence of Gal (Gal(-)). Haptotactic motility of parental ldlD cells is low, and shows no difference in the presence and absence of Gal. In contrast, the motility of ldlD/CD9 cells is very high in Gal(-) whereby endogenous GM3 synthesis does not occur, and is very reduced in Gal(+) whereby endogenous GM3 synthesis occurs. (iv) Photoactivatable (3)H-labeled GM3 added to HRT18 cells, followed by UV irradiation, causes cross-linking of GM3 to CD9, as evidenced by (3)H labeling of CD9, which is immunoprecipitated with anti-CD9 antibody. These findings suggest that CD9 is a target molecule interacting with GM3, and that CD9 and GM3 cooperatively downregulate tumor cell motility.

Animals↗
PubMed2001

A novel ganglioside isolated from renal cell carcinoma.

In renal cell carcinoma (RCC), the level of higher gangliosides is correlated with degree of metastatic potential, and cell lines derived from metastatic deposits of RCC are characterized by high expression of disialogangliosides (Saito, S., Orikasa, S., Ohyama, C., Satoh, M., and Fukushi, Y. (1991) Int. J. Cancer 49, 329-334 and Saito, S., Orikasa, S., Satoh, M., Ohyama, C., Ito, A., and Takahashi, T. (1997) Jpn. J. Cancer Res. (Gann) 88, 652-659). We now report two disialogangliosides, G1 and G2, found in the RCC cell line TOS-1. G1 from TOS-1 cells was characterized as having a novel hybrid structure between ganglio-series (region I as in Structure; same as the terminal structure of ganglioside GM2), and the lacto-series type 1 (region II). The characterization was based on reactivity with various monoclonal antibodies (mAbs) with defined epitope specificity, as well as monosaccharide and fatty acid component analysis, (1)H NMR spectroscopy, and electrospray ionization mass spectrometry of the intact compound. G1 showed strong reactivity with mAb RM2, raised originally against TOS-1 cells, and weak cross-reactivity with anti-GM2 mAb MK-1-8. The antigen is hereby termed GalNAc disialosyl Lc4Cer (IV4GalNAcIV3NeuAcIII6NeuAcLc4; abbreviated GalNAcDSLc4). G2 was identified by 1H NMR and mass spectrometry as having a structure similar to Structure but without the GalNAcbeta1-->4 substitution and showed strong reactivity with mAb FH9 reported previously to be specific for disialosyl lacto-series type 1 (disialosyl Lc(4)) having vicinal alpha2-->3 and alpha2-->6 sialosyl residues, an antigen associated with human colonic cancer. Clinicopathological studies indicate that expression of these disialoganglioside antigens in RCC tissue is correlated with the metastatic potential of RCC.

Antibodies, Monoclonal↗
PubMed2001

Tumor-associated carbohydrate antigens defining tumor malignancy: basis for development of anti-cancer vaccines.

Tumors expressing a high level of certain types of tumor-associated carbohydrate antigens (TACAs) exhibit greater metastasis and progression than those expressing low level of TACAs, as reflected in decreased patient survival rate. Well-documented examples of such TACAs are: (i) H/Le(y)/Le(a) in primary non-small cell lung carcinoma; (ii) sialyl-Le(x) (SLe(x)) and sialyl-Le(a) (SLe(a)) in various types of cancer; (iii) Tn and sialyl-Tn in colorectal, lung, breast, and many other cancers; (iv) GM2, GD2, and GD3 gangliosides in neuroectodermal tumors (melanoma and neuroblastoma); (v) globo-H in breast, ovarian, and prostate cancer; (vi) disialylgalactosylgloboside in renal cell carcinoma. Some glycosylations and TACAs suppress invasiveness and metastatic potential. Well-documented examples are: (i) blood group A antigen in primary lung carcinoma; (ii) bisecting beta1 --> 4GlcNAc of N-linked structure in melanoma and other cancers; (iii) galactosylgloboside (GalGb4) in seminoma. The biochemical mechanisms by which the above glycosylation changes promote or suppress tumor metastasis and invasion are mostly unknown. A few exceptional cases in which we have some knowledge are: (i) SLe(x) and SLe(a) function as E-selectin epitopes promoting tumor cell interaction with endothelial cells; (ii) some tumor cells interact through binding of TACA to specific proteins other than selectin, or to specific carbohydrate expressed on endothelial cells or other target cells (carbohydrate-carbohydrate interaction); (iii) functional modification of adhesive receptor (integrin, cadherin, CD44) by glycosylation. So far, a few successful cases of anti-cancer vaccine in clinical trials have been reported, employing TACAs whose expression enhances malignancy. Examples are STn for suppression of breast cancer, GM2 and GD3 for melanoma, and globo-H for prostate cancer. Vaccine development canbe extended using other TACAs, with the following criteria for success: (i) the antigen is expressed highly on tumor cells; (ii) high antibody production depending on two factors: (a) clustering of antigen used in vaccine; (b) choice of appropriate carrier protein or lipid; (iii) high T cell response depending on choice of appropriate carrier protein or lipid; (iv) expression of the same antigen in normal epithelial tissues (e.g., renal, intestinal, colorectal) may not pose a major obstacle, i.e., these tissues are not damaged during immune response. Idiotypic anti-carbohydrate antibodies that mimic the surface profile of carbohydrate antigens, when administered to patients, elicit anti-carbohydrate antibody response, thus providing an effect similar to that of TACAs for suppression of tumor progression. An extension of this idea is the use of peptide mimetics of TACAs, based on phage display random peptide library. Although examples are so far highly limited, use of such "mimotopes" as immunogens may overcome the weak immunogenicity of TACAs in general.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed2000

Glycosylation effect on membrane domain (GEM) involved in cell adhesion and motility: a preliminary note on functional alpha3, alpha5-CD82 glycosylation complex in ldlD 14 cells.

Laminin (LN)- or fibronectin (FN)-dependent adhesion in Krieger's ldlD 14 (D14) cells is enhanced significantly in the presence vs absence, of galactose (Gal), whereas LN- or FN-induced haptotactic cell motility is barely affected unless cells express CD82 by its gene transfection (cells termed D14/CD82). The effect of CD82 on LN- or FN-induced motility is based on its ability to associate with alpha3 or alpha5 integrin to form a complex associated with a low-density lipid membrane domain (termed GEM or GSD). Complex formation is greatly affected by N-glycosylation of both integrin and CD82, as well as by concurrent GM3 ganglioside synthesis. The effect of glycosylation on alpha5-CD82 complex was also studied in D14 cells expressing mutant CD82, defective in all three N-glycosylation sites. LN-induced motility was greatly inhibited, whereas FN-induced motility was enhanced, with complete N-glycosylation in D14/CD82 cells in Gal-added medium, whereby alpha5-CD82 complex formation did not occur or occurred at a minimal level. Both LN- and FN-induced motility were inhibited when N-glycosylation was impaired, or N-glycosylation of CD82 was deleted, whereby alpha5-CD82 complex formation occurred strongly. Thus, glycosylation profoundly affects interaction of integrin with CD82, leading to significant inhibition or promotion of cell motility.

Animals↗
PubMed2000

Glycosylation affects translocation of integrin, Src, and caveolin into or out of GEM.

Endogenous GM3 synthesis and full N-glycosylation in membrane receptors occurred in "4-epimerase-less" ldlD (Krieger's CHO mutant) cells cultured in Gal-containing medium, whereby components of detergent-insoluble, low-density, buoyant membrane fraction, termed "glycolipid-enriched microdomain (GEM)," varied significantly by translocation into or out of GEM. Integrins alpha3 and alpha5 were translocated into GEM in the presence of 0.5 or 0.25% Triton X-100, particularly in the absence of Gal, whereby integrins are underglycosylated and GlcCer is the major glycolipid component in GEM. Src family kinase was translocated into and enriched in GEM fractions when prepared in 0.5 or 0.25% Triton X-100 from cells grown in Gal-containing medium, whereby GM3 synthesis is induced. In contrast, caveolin is highly enriched in GEM when GM3 synthesis does not occur, and is translocated into high-density membrane fraction when GM3 synthesis occurs. The results suggest that levels of key molecules controlling cell adhesion and signaling are defined by translocation into or out of GEM, which depends on glycosylation state.

Animals↗
PubMed2000

Reconstitution of membranes simulating "glycosignaling domain" and their susceptibility to lyso-GM3.

GM3 ganglioside at the surface of mouse melanoma B16 cells is clustered and organized with signal transducer molecules c-Src, Rho A, and focal adhesion kinase (FAK) to form a membrane unit separable from caveolae, which are enriched in cholesterol and caveolin but do not contain GM3 or the above three signal transducers. The GM3-enriched membrane units are involved in GM3-dependent cell adhesion coupled with activation of c-Src, Rho A, and FAK and are termed the "glycosphingolipid signaling domain" or the "glycosignaling domain" (GSD). In order to assess the essential components that display GSD function, membranes with properties similar to those of GSD were reconstituted using GM3, sphingomyelin, and c-Src, with or without other lipid components. The reconstituted membrane thus prepared displayed GM3-dependent adhesion to plates coated with Gg3 or anti-GM3 antibody, resulting in enhanced c-Src phosphorylation (c-Src phosphorylation response). This response in reconstituted membrane depends on GM3 concentration and was not observed when GM3 was absent or replaced with other gangliosides GM1 or GD1a, or with LacCer. The GM3-dependent c-Src phosphorylation response was enhanced when cholesterol and phosphatidylcholine were added. Although GM3, sphingomyelin, and c-Src are essential for GSD function, a small quantity of cholesterol and phosphatidylcholine may act as an auxiliary factor to stabilize membrane. GSD function in terms of GM3-dependent adhesion and signaling was blocked in the presence of lyso-GM3 or its analogue but not psychosine, lactosyl-sphingosine, or lyso-phosphatidylcholine. Such susceptibility of reconstituted GSD to lyso-GM3 and other lyso compounds is the same as GSD of original B16 cells. Thus, functional organization of the reconstituted membrane closely simulates that of GSD in B16 cells, which is based on clustered GM3 organized with c-Src as the essential components.

Animals↗
PubMed2000

Effect of synthetic sialyl 2-->1 sphingosine and other glycosylsphingosines on the structure and function of the "glycosphingolipid signaling domain (GSD)" in mouse melanoma B16 cells.

Mouse melanoma B16 cells are characterized by a high concentration of GM3 ganglioside, which has been identified as a melanoma-associated antigen and is present as a clustered microdomain organized with major signal transducers, c-Src, small G-protein (Rho A), and focal adhesion kinase (FAK), to form a "glycosphingolipid signaling domain" or "glycosignaling domain" (GSD) separable from cholesterol- and caveolin-enriched microdomain, "caveolae." Cholesterol-binding reagents, filipin and nystatin, disrupt the structure and function of caveolae, but have no effect on GSD function [Iwabuchi, K., et al. (1998) J. Biol. Chem. 273, 33766-33773]. In this study, we searched for compounds which disrupt the structure and function of GSD in B16 cells. Such compounds should have structural features analogous to those of GM3, destroy or reduce clustering of GM3 in GSD, and inhibit GM3-dependent adhesion and signaling. The simplest compound so far found with these properties is sialyl alpha2-->1 sphingosine (Sph). We describe the synthesis of this compound and its analogues, and their effects on GM3 expression pattern and GSD function, in comparison with effects of lyso-GM3 and other lyso compounds, in B16 cells. Incubation of B16 cells with 0.5-10 microM sialyl alpha2-->1 Sph or 1-5 microM lyso-GM3 reduced GM3 clustering and GM3-dependent adhesion, and inhibited adhesion-dependent cellular FAK activity. The c-Src activation response of GSD isolated from B16 cells was inhibited strongly by sialyl alpha2-->1 Sph. Substitution of the Sph amino group with a chloroacetyl or N,N-dimethyl group strongly reduced the inhibitory effect of sialyl alpha2-->1 Sph on GM3-dependent adhesion, FAK, and c-Src response. Other lyso compounds such as lyso-phosphatidylcholine, galactosyl-Sph (psychosine), and lactosyl-Sph at 0.5-10 microM did not show the same effect as sialyl alpha2-->1 Sph. Thus, adhesion coupled with signal transduction, initiated by clusters of GM3 in GSD, is blocked by sialyl alpha2-->1 Sph or lyso-GM3. Analogues with N-substitution of Sph in sialyl alpha2-->1 Sph, other lyso-phospholipids, and galactosyl- or lactosyl-Sph did not block such adhesion, coupled with activation of c-Src and FAK.

Animals↗
PubMed2000

Molecular detection of disseminated cancer cells in the peripheral blood and expression of sialylated antigens in colon cancers.

BACKGROUND AND OBJECTIVES: To improve the survival rate of patients with colon cancer, liver metastases must be eradicated in a clinically occult state. This study was designed to find a predictor for potential liver metastases or micrometastases in colon cancer. METHODS: Peripheral blood samples and tumor specimens were obtained from 36 patients with colon cancers. The blood samples were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, and the expression of sialylated carbohydrates was also investigated in the tumors immunohistochemically. RESULTS: A carcinoembryonic antigen (CEA)-specific signal in the blood was detected in 9 of 12 (75%) patients with liver metastasis and in 8 of 24 (33%) patients without liver metastasis, respectively (P < 0.05). The positive rates of sialyl Lewis A (sLeA) and sialyl Lewis X (sLeX) were 36.3% and 40% in tumors without liver metastasis vs. 58.3% and 100% with liver metastasis, respectively. Within a year after surgery, liver metastases became clinically evident in three of the four patients without liver metastasis who showed a CEA-positive signal in their blood preoperatively and who had tumors with a strong expression of sLeX. CONCLUSIONS: A combination of both markers may provide prognostic information for liver metastases in colon cancer.

Colonic Neoplasms↗
PubMed2000

Sphingosine-1-phosphate inhibits haptotactic motility by overproduction of focal adhesion sites in B16 melanoma cells through EDG-induced activation of Rho.

We investigated the molecular mechanism by which Sph-1-P affects the FN-dependent haptotactic motility of serum-starved mouse melanoma B16/F10 cells. We found that EDG-5-induced Rho activation followed by enhanced tyrosine phosphorylation of FAK and paxillin, and beta 1-integrin activation leading to overexpression of focal adhesion sites, as well as increment of stress fiber formation, must be the molecular basis of inhibition of haptotactic cell motility by Sph-1-P.

3T3 Cells↗
PubMed2000

Sialyl-Tn- and neuron-specific enolase-positive minimally differentiated erythroleukemia.

Flow cytometric, immunochemical and molecular studies were performed on leukemic blasts from a patient with minimally differentiated erythroleukemia (AML-M6v). The blasts expressed CD36 and CD71 but not lymphoid antigens, myeloid antigens, CD41 or glycophorin A. Analysis of carbohydrate antigens showed that the blasts expressed the sialyl-Tn antigen. Immunochemistry revealed that the blasts had neuron-specific enolase (NSE). Serum sialyl-Tn and NSE levels were markedly increased. Finally, an erythroid lineage was confirmed in the presence of alpha-globin messages in the blasts. Sialyl-Tn and NSE expression in leukemic blasts may be useful to identify AML-M6v.

Antigens, CD↗
PubMed2000

Association of renal cell carcinoma antigen, disialylgalactosylgloboside, with c-Src and Rho A in clustered domains at the surface membrane.

Disialylgalactosylgloboside (DSGG), defined by monoclonal antibody RM2, is a renal cell carcinoma (RCC)-associated antigen which mediates adhesion of RCC TOS-1 cells to certain lung tissue target cells. This adhesion process may initiate preferential lung metastasis of RCC. Ganglioside GM3 is a B16 melanoma-associated antigen which similarly adheres to target cells and promotes consequent metastasis. In view of the close association of GM3-enriched microdomain with transducer molecules c-Src, Rho A, and FAK in B16 cells, we investigated the organizational status of DSGG in RCC cell line TOS-1, with the following results: i) DSGG, but not monosialylgalactosylgloboside, showed extensive clustering at the TOS-1 cell surface; ii) a low-density membrane fraction isolated from TOS-1 cells contained >95% of cellular DSGG, although protein content in this fraction was <1% of total cellular protein; iii) this fraction contained c-Src, Rho A, and FAK, but not H-Ras; iv) c-Src and Rho A were co-immunoprecipitated with DSGG through anti-DSGG mAb RM2 (IgM) affixed to a column. These observations indicate that DSGG is clustered in RCC, as typified by TOS-1 cells, to form a microdomain in which it is closely associated with c-Src, Rho A, and FAK, and may constitute a functional unit as has been observed for GM3 with transducer molecules in B16 cells. The functional organization of such units may be essential in determining malignant properties of RCC cells.

Carcinoma, Renal Cell↗
PubMed1999

Antigen structure and genetic basis of histo-blood groups A, B and O: their changes associated with human cancer.

Three areas of research involved in blood group (or histo-blood group) ABO antigens and their genes, developed by our research group, are reviewed: (1) Antigen structures. The structural basis of A and H, A(1) and A(2), i and I antigens expressed in erythrocyte membranes. Major carriers of A and H determinants in erythrocytes are type 2 chain poly-LacNAc, short vs. long and unbranched vs. branched structures termed A(a), A(b), A(c), A(d) and H(1), H(2), H(3), H(4). Regular A (A(1)) and weak A (A(2)) were identified respectively as repetitive A (type 3 chain A) and A-associated H. A(1)- and A(2)-specific type 3 chain A and H, type 1 chain (representing Lewis blood group antigens), and type 4 chain (globo-series antigen; an extremely minor component in erythrocytes) are all glycosphingolipids. A and H determinants in fetal and newborn erythrocytes are carried by unbranched poly-LacNAc, whereas these determinants in adult erythrocytes are carried by branched poly-LacNAc. (2) ABO genes. A few cDNAs encoding A enzyme (UDP-GalNAc: H-a-GalNAc transferase) were cloned based on the amino acid sequence of purified A enzyme and their structures were compared with those of homologous cDNA from blood cells of B and O individuals (genotype BB, OO). Four nucleotide substitutions and four corresponding amino acid sequences essential for expression of A(1) allele and B allele, and differences between A and B enzymes, were identified. Amino acids 266 and 268, i.e. Leu and Gly for A enzyme vs. Met and Ala for B enzyme, were dominant in determining A vs. B activity (presumably recognizing UDP-GalNAc vs. UDP-Gal). The A(2) allele was characterized by deletion of the termination codon, extending nucleotides up to 1128 and thus encoding 21 extra amino acids at the C terminus, which may affect (diminish) the dominant function of amino acids 266 and 268. Typical O allele (O(1)) is characterized by deletion of nucleotide 261 G, causing frame shift and encoding of an entirely different, short polypeptide, due to appearance of early termination codon at nucleotide 354. Structures of other O alleles (O(1 v), O(2)) and other weak A alleles (A(3), A(el)) are also described. The genomic structure of ABO genes consists of seven exons which span approximately 19 kb of genomic DNA on chromosome 9, band q34. Most of the coding sequence is located in exon 7. Analysis of the 5' upstream region revealed the presence of the binding site for transcription factors and enhancer element. (3) Antigens and genes in cancer. A and B phenotypes aberrantly expressed in various types of human cancer, and their genetic basis, have been studied. One widely-occurring change observed in a large variety of human cancers is deletion of A or B epitope, associated with accumulation of their precursor H (Le(y), Le(b)), which causes enhanced malignancy. A less-commonly observed change is expression of incompatible A, identified as real type 1 chain A, in tumors of O or B individuals. A possible molecular genetic mechanism leading to such phenotypic changes is discussed.

ABO Blood-Group System↗