Keiko Furukawa

Chubu University, Касугай, Aichi, Japan

Are you Keiko Furukawa?

Claim your profile

Publications (199)840.88 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Mass spectrometry analysis of immunoprecipitates from serum-treated GD3-expressing melanoma cells with PY20 (anti-phosphotyrosine antibody) revealed that focal adhesion kinase (FAK) is more strongly activated in GD3-expressing cells than in GD3-negative cells. Involvement of FAK in the increased proliferation and invasion in GD3-expressing melanomas was demonstrated by siRNA-mediated knockdown. Also, it was shown that FAK is located up-stream of p130Cas and paxillin in the enhanced signaling pathway. GD3 expression enhanced the association of FAK with p130Cas after treatment with fetal calf serum. Thus, focal adhesion kinase as well as p130Cas and paxillin should be a crucial molecule undergoing stronger tyrosine phosphorylation in GD3-expressing melanoma cells. Molecules linking GD3 and FAK such as integrins in the enhanced signaling pathway remain to be investigated.
    Biochimica et Biophysica Acta 04/2008; 1780(3):513-9. DOI:10.1016/j.bbagen.2007.11.002 · 4.66 Impact Factor
  • Koichi Furukawa · Masahiko Okada · Keiko Furukawa ·
    [Show abstract] [Hide abstract]
    ABSTRACT: Gangliosides have been considered to play important roles in the development and differentiation of nervous systems in vertebrates. In particular, b-series gangliosides were reported to be effective as a neurotrophic factor, e.g. as inducer of neurite extension. In order to directly address these functions, we generated knockout mice of α-2,8-sialyltransferase gene (Haraguchi et al. 1994) that is responsible for the synthesis of GD3 (and GT3), and clearly showed that this enzyme is really critical for the synthesis of b-series gangliosides (Okada et al. 2002). The null mutant mice showed no apparent neurological disorders, and their brain and nervous tissues were almost normally generated. They showed no defects in spermatogenesis and immunological examination. However, the null mutants demonstrated reduced neuroregeneration in the hypoglossal resection experiments, suggesting that b-series gangliosides are important in the repair of lesioned nerves (Okada et al. 2002).
    12/2007: pages 394-395;
  • Koichi Furukawa · Koichi Iwamura · Keiko Furukawa ·
    [Show abstract] [Hide abstract]
    ABSTRACT: The most popular blood group antigen system, ABO antigens had been known to consist of alpha1,2-fucosylated galactose substituted with alpha1,3-N-acetylgalactosamine (A) or galactose (B). These biochemical results were clearly confirmed and further investigated by the molecular cloning of blood group A synthase cDNA (Yamamoto et al. 1990a, 1990b). It was demonstrated that blood group A synthase gene is located at the human 9th chromosome ABO locus with blood group B synthase as an allelic gene having 7 nucleotides mutation in the coding region (Fig. 1). Blood group O gene is also present at the same locus with no enzymatic activity due to one nucleotide deletion. As for P1/P/pk/p blood group system, P/pk/p blood group system has been clarified to be based on globo-series glycosphingolipids, i.e., P is globoside (Gb4, globotetraosylceramide) (Okajima et al. 2000), pk is Gb3 (globotriaosylceramide) that is accumulated in the deficiency of Gb4 synthase, and p means individuals lacking the activity of Gb3 synthesis (Furukawa et al. 2000; Table 1). P1 is, in turn, alpha4Gal- structure substituted on a neolacto-series core structure. There has been a long-time controversy on the identity between P1 synthase and Gb3 synthase (Kojima et al. 2000; Table 2). Iwamura et al. (2003) demonstrated P1 is synthesized by Gb3 synthase, suggesting that there should be differences in the transcription efficiency of Gb3 synthase gene between P1 and P2 individuals.
    12/2007: pages 363-365;
  • Koichi Furukawa · Akiko Tsuchida · Keiko Furukawa ·
    [Show abstract] [Hide abstract]
    ABSTRACT: Of the glycosyltransferases involved in the synthesis of glycosphingolipids, those involved in the common steps, those responsible for the synthesis of globo-series glycolipids, and those for the synthesis of lacto/neolacto-series glycolipids were summarized here. The common and fundamental steps consist of reactions catalyzed by Glc-Cer synthase (Ichikawa et al. 1996), lactosylceramide synthase (Nomura et al. 1997), or GalCer synthase (Schulte and Stoffel 1993). Globo-series includes the reactions catalyzed by Gb3/CD77 synthase (Furukawa et al. 2007), Gb4 synthase (Furukawa et al. 2007), Gb5 synthase (Zhou et al. 2000), or sialyl-Gb5 synthase (monosialyl-galactosylgloboside, MSGG) (Saito et al. 2003). Furthermore, DSGG (disialyl-galactosylgloboside) (Furukawa et al. 2007) is synthesized from MSGG by ST6GalNAcVI. Lacto/neolactoseries are generated by various enzymes consisting of amino-CTH synthase (β3GlcNAcTV) (Togayachi et al. 2001), core 1 precursor synthase (β3GalTV) (Isshiki et al. 1999) β4-galactosyltransferase, α2,3/6-sialyltransferase, α1,3/4-fucosyl transferase, ST6GalNAc-VI (α2,6-sialyltransferase) (Furukawa et al. 2007), etc.
    12/2007: pages 53-55;
  • Koichi Furukawa · Orie Tajima · Yusuke Ohmi · Keiko Furukawa ·
    [Show abstract] [Hide abstract]
    ABSTRACT: Gangliosides have been considered to play important roles in the development and differentiation of nervous systems in vertebrates. They have been also considered to have neurotrophic activity. In order to directly address these biological functions, we generated knockout mice of β-1,4-N-acetylgalactosaminyltransferase gene (Takamiya et al. 1996) that is responsible for the synthesis of GM2 and GD2 (and GA2), and those of α-2,8-sialyltransferase gene (Okada et al. 2000) that is responsible for the synthesis of GD3. These KO mice showed relatively mild abnormal phenotypes than expected. This seemed due to the compensatory effects of the remaining glycolipids in the individual KO mice (Furukawa et al. 2004). Therefore, we mated these two KO mice in order to generate double KO mice in which only GM3 should remain. Now we can largely eliminate the compensatory effects of remaining glycolipids and correctly observe the effects of ganglioside deficiency. DKO mutants were born with almost normal appearance, and grew up for a while after birth. However, they demonstrated marked neurodegeneration from early stages of life, and various abnormal phenotypes probably caused by neurodegeneration (Inoue et al. 2002).
    12/2007: pages 396-398;
  • Koichi Furukawa · Keiko Furukawa ·
    [Show abstract] [Hide abstract]
    ABSTRACT: The sialyltransferases involved in the biosynthesis of gangliosides were summarized in Table 1. The simplest sialosylglycolipid is GM3 except for GM4 (sialylgalactosyl ceramide). GM3 is located at the starting point of all ganglio-series glycolipids, extending to a-series, b-series and c-series gangliosides. GM3 synthase is called ST3Gal-V (Tsuji et al. 1996; Furukawa et al. 2007). GD3 synthase is the key enzyme for the synthesis of b-series and c-series gangliosides (GT3 synthase, Nakayama et al. 1996). GD3 synthase is called ST8Sia-I (Tsuji et al. 1996; Furukawa et al. 2007). After extending ganglio-core chain by GM2/GD2/GA2 synthase (Furukawa et al. 2007) and GM1/GD1b/GA1 synthase (Furukawa et al. 2007), GD1a/GT1b/GM1b synthase adds NeuAc to Gal at the nonreducing end (Tsuji et al. 1996). Then GT1a/GQ1b/GD1c synthase catalyzes biosynthesis of GT1a, GQ1b, or GD1c from GD1a, GT1b, or GM1b, respectively (Tsuji et al. 1996).
    12/2007: pages 56-58;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Paranodal axo-glial junctions are important for ion channel clustering and rapid action potential propagation in myelinated nerve fibers. Paranode formation depends on the cell adhesion molecules neurofascin (NF) 155 in glia, and a Caspr and contactin heterodimer in axons. We found that antibody to ganglioside GM1 labels paranodal regions. Autoantibodies to the gangliosides GM1 and GD1a are thought to disrupt nodes of Ranvier in peripheral motor nerves and cause Guillain-Barré syndrome, an autoimmune neuropathy characterized by acute limb weakness. To elucidate ganglioside function at and near nodes of Ranvier, we examined nodes in mice lacking gangliosides including GM1 and GD1a. In both peripheral and central nervous systems, some paranodal loops failed to attach to the axolemma, and immunostaining of Caspr and NF155 was attenuated. K(+) channels at juxtaparanodes were mislocalized to paranodes, and nodal Na(+) channel clusters were broadened. Abnormal immunostaining at paranodes became more prominent with age. Moreover, the defects were more prevalent in ventral than dorsal roots, and less frequent in mutant mice lacking the b-series gangliosides but with excess GM1 and GD1a. Electrophysiological studies revealed nerve conduction slowing and reduced nodal Na(+) current in mutant peripheral motor nerves. The amounts of Caspr and NF155 in low density, detergent insoluble membrane fractions were reduced in mutant brains. These results indicate that gangliosides are lipid raft components that contribute to stability and maintenance of neuron-glia interactions at paranodes.
    Glia 05/2007; 55(7):746-57. DOI:10.1002/glia.20503 · 6.03 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Caveolin-1 is a component of lipid rafts, and is considered to be a tumor suppressor molecule. However, the mechanisms by which caveolin-1 functions in cancer cells are not well understood. We generated caveolin-1 transfectant cells (Cav-1(+) cells) using a human melanoma cell line (SK-MEL-28) and investigated the effects of caveolin-1 overexpression on the GD3-mediated malignant properties of melanomas. Cav-1(+) cells had decreased cell growth and motility, and reduced phosphorylation levels of p130Cas and paxillin relative to controls. In floatation analysis, although GD3 was mainly localized in glycolipid-enriched microdomain (GEM)/rafts in control cells, it was dispersed from GEM/rafts in Cav-1(+) cells. Correspondingly, GD3 in Cav-1(+) cells stained uniformly throughout the membrane, whereas control cells showed partial staining of the membrane, probably at the leading edge. p130Cas and paxillin were stained in the leading edges and colocalized with GD3 in the control cells. In contrast, these molecules were diffusely stained and no definite leading edges were detected in Cav-1(+) cells. These results suggest that caveolin-1 regulates GD3-mediated malignant signals by altering GD3 distribution and leading edge formation. These results reveal one of the mechanisms by which caveolin-1 curtails the malignant properties of tumor cells.
    Cancer Science 05/2007; 98(4):512-20. DOI:10.1111/j.1349-7006.2007.00419.x · 3.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although disialyl glycosphingolipids such as GD3 and GD2 have been considered to be associated with malignant tumours, whether branched-type disialyl glycosphingolipids show such an association is not well understood. We investigated the sialyltransferases responsible for the biosynthesis of DSGG (disialylgalactosylgloboside) from MSGG (monosialylgalactosylgloboside). Among six GalNAc:alpha2,6-sialyltransferases cloned to date, we focused on ST6GalNAc III, V and VI, which utilize sialylglycolipids as substrates. In vitro enzyme analyses revealed that ST6GalNAc III and VI generated DSGG from MSGG with V(max)/K(m) values of 1.91 and 4.16 respectively. Transfection of the cDNA expression vectors for these enzymes resulted in DSGG expression in a renal cancer cell line. Although both ST6GalNAc III and VI genes were expressed in normal kidney cells, the expression profiles of ST6GalNAc VI among 20 renal cancer cell lines correlated clearly with those of DSGG, suggesting that the sialyltransferase involved in the synthesis of DSGG in the kidney is ST6GalNAc-VI. ST6GalNAc-VI and DSGG were found in proximal tubule epithelial cells in normal kidney tissues, while they were downregulated in renal cancer cell lines and cancer tissues. All these findings indicated that DSGG was suppressed during the malignant transformation of the proximal tubules as a maturation arrest of glycosylation.
    Biochemical Journal 04/2007; 402(3):459-70. DOI:10.1042/BJ20061118 · 4.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Based on the remodeling of glycosphingolipids on the human tumor cell lines with manipulation of glycosyltransferase genes, roles of sugar moieties in tumor-associated carbohydrate antigens have been analyzed. Two main topics, that is, the roles of ganglioside GD3 in human malignant melanomas and those of GD2 in small cell lung cancer (SCLC) were reported. GD3 enhances tyrosine phosphorylation of two adaptor molecules, p130Cas and paxillin, resulting in the increased cell growth and invasion in melanoma cells. GD2 also enhances the proliferation and invasion of SCLC cells. GD2 also mediates apoptosis with anti-GD2 monoclonal antibodies (mAbs) via dephosphorylation of the focal adhesion kinase. These approaches have promoted further understanding of mechanisms by which gangliosides modulate malignant properties of human cancer, and the results obtained here propose novel targets for cancer therapy.
    Annals of the New York Academy of Sciences 12/2006; 1086(1):185-98. DOI:10.1196/annals.1377.017 · 4.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Fucosyl GM1 has been reported to be specifically expressed in small cell lung cancer (SCLC) cells. However, the genetic basis for the synthesis of fucosyl GM1 has not been investigated. We analyzed the glycosyltransferases responsible for the synthesis of fucosyl GM1 in SCLC cell lines. In four SCLC cell lines expressing fucosyl GM1, both FUT1 and FUT2 mRNAs were detected, indicating that either one or both of alpha1,2-fucosyltransferases may be involved in the expression of fucosyl GM1. However, three of these four lines contained function-loss mutations in the FUT2 coding region, suggesting that FUT1 is mainly involved in the alpha1,2-fucosylation of GM1. The expression levels of the GM1 synthase gene showed no correlation with those of fucosyl GM1, whereas the co-transfection of GM1 synthase cDNA with FUT1 or FUT2 into SK-LC-17 clearly enhanced the neo-expression of fucosyl GM1, indicating its essential role. In contrast, the co-transfection of GD3 synthase cDNA reduced the expression levels of fucosyl GM1 with FUT1 or FUT2. Consequently, FUT1 seems to mainly contribute to the expression of fucosyl GM1, although both FUT1 and FUT2 are capable of generating the antigen. These results should promote the functional analysis of fucosyl GM1 leading to the development of novel therapies for SCLC.
    Glycobiology 11/2006; 16(10):916-25. DOI:10.1093/glycob/cwl022 · 3.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to analyze molecular mechanisms for cancer metastasis, we established a high-metastatic subline H7-Lu from a subline H7 of mouse Lewis lung cancer (P29) by repeated injection into tail veins. H7-Lu exhibited increased proliferation and invasion activity. Analysis of gene expression profiles between the parent H7 and H7-Lu revealed that several genes were down-regulated in H7-Lu. One of them, caveolin-1, was a component of lipid/rafts. After confirming the down-regulation of caveolin-1 mRNA by real-time RT-PCR and reduction of the protein by immunoblotting, respectively, H7 was transfected with siRNA for caveolin-1 to examine the role of caveolin-1 in H7-Lu. mRNA of the caveolin-1 gene was suppressed to approximately one third of the original level in H7 cells transfected with siRNA. The transfectant cells showed significantly increased cell proliferation and motility when analyzed by MTT assay and scratching wound healing assay, respectively. In the siRNA-transfectant cells, both ERK1/2 and Akt showed stronger phosphorylation than the mock-transfectant cells indicating that both of these signaling pathways were activated in caveolin-1-suppressed cells. These situations seem to reflect some aspects of the cellular changes in the high metastatic subline H7-Lu. Thus, down-regulation of caveolin-1 in a high-metastatic subline of Lewis lung cancer as defined by DNA array is really a causal factor for the increased malignant properties.
    Oncology Reports 09/2006; 16(2):289-94. DOI:10.3892/or.16.2.289 · 2.30 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To analyze mechanisms for cancer metastasis, we established high metastatic sublines from mouse Lewis lung cancer (P29) by repeated injection. Sublines established from the two subclones H7 and C4 commonly exhibited increased proliferation and invasion activity and reduced expression of ganglioside GM1, although they showed different preferences in their target organs of metastasis. The high metastatic sublines secreted higher levels of activated matrix metalloprotease (MMP)-9 as well as pro-MMP-9 in the culture medium than the parent lines. Furthermore, they contained MMP-9 at the glycolipid-enriched microdomain (GEM)/rafts fractionated by the sucrose density gradient ultracentrifugation of Triton X-100 extracts, whereas the parent cells showed faint bands at the fraction. When high metastatic sublines were treated with methyl-beta-cyclodextrin, their invasion activities were dramatically suppressed, and the MMP-9 secretion was also suppressed. All these results indicated that GEM/rafts play crucial roles in the increased invasion and high metastatic potential. To clarify the implication of reduced GM1 expression, low GM1-expressing cell lines were established using an RNA interference-expression vector of the GM1 synthase. Low GM1-expressing cell lines showed increased proliferation and invasion, enrichment in the GEM/rafts, and increased secretion of MMP-9. Among adhesion molecules, only integrin beta1 was detected in GEM/rafts with stronger intensity in high metastatic lines and low GM1-expressing cells. Taken together, integrins seemed to be enriched in the GEM/rafts by reduced GM1 levels, and subsequently MMP-9 was recruited to the GEM/rafts, resulting in its efficient secretion and activation, and eventually in the increased invasion and metastatic potentials.
    Journal of Biological Chemistry 07/2006; 281(26):18145-55. DOI:10.1074/jbc.M512566200 · 4.57 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To examine whether globotriaosylceramide (Gb3/CD77) is a receptor for verotoxins (VTs) in vivo, sensitivity of Gb3/CD77 synthase null mutant mice to VT-2 and VT-1 was analyzed. Although wild-type mice died after administration of 0.02 microg of VT-2 or 1.0 microg of VT-1, the mutant mice showed no reaction to doses as much as 100 times that administered to wild types. Expression analysis of Gb3/CD77 in mouse tissues with antibody revealed that low, but definite, levels of Gb3/CD77 were expressed in the microvascular endothelial cells of the brain cortex and pia mater and in renal tubular capillaries. Corresponding to the Gb3/CD77 expression, tissue damage with edema, congestion, and cytopathic changes was observed, indicating that Gb3/CD77 (and its derivatives) exclusively function as a receptor for VTs in vivo. The lethal kinetics were similar regardless of lipopolysaccharide elimination in VT preparation, suggesting that basal Gb3/CD77 levels are sufficient for lethal effects of VTs.
    Journal of Biological Chemistry 05/2006; 281(15):10230-5. DOI:10.1074/jbc.M600057200 · 4.57 Impact Factor
  • Koichi Furukawa · Tetsuya Okuda · Keiko Furukawa ·
    [Show abstract] [Hide abstract]
    ABSTRACT: Glycoshingolipids are involved in a wide variety of biological events, including cell proliferation, differentiation, development, regeneration, and apoptosis in vertebrates. Expression profiles of glycolipids during the development and cell differentiation or transformation suggest that glycolipids are largely implicated in the determination of cell fates by directly transducing biosignals as receptors and/or modulating receptors' function. Despite of a number of efforts to clarify the molecular functions of glycolipids, no unambiguous results have been obtained until genetic modification of glycolipids became possible. Recent progress in the isolation of cDNAs of glycosphingolipid synthase genes has enabled us to examine roles of glycosphingolipids and strongly promoted further understanding of significances of glycosphingolipids. In particular, knock-out mice of glycosyltransferases showed quite novel aspects of glycolipid function and also redundancy among similar enzymes and glycolipid structures. Here, we summarize analytical methods with which roles of glycolipids in the development and maintenance of nervous tissues, including techniques to establish transgenic mice and gene knock-out mice, to survey fundamental behavior abnormalities, and to examine fine morphological changes lying under abnormal phenotypes of the glycolipids-modified cells and glycolipid-lacking mutant mice.
    Methods in Enzymology 02/2006; 417:37-52. DOI:10.1016/S0076-6879(06)17004-4 · 2.09 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Biological functions of globo-series glycosphingolipids are not well understood. In this study, murine cDNAs of two glycosyltransferases responsible for the synthesis of globo-series glycolipids and mRNA expression of those genes were analyzed. Distribution of their products was also analyzed. Murine cDNAs for Gb3/CD77 synthase and Gb4 synthase predicted that both of them are type II membrane proteins with 348 and 331 amino acids, respectively. In northern blotting, Gb3/CD77 synthase gene was mainly expressed in kidney and lung but also detected in many other tissues. Gb4 synthase was expressed in brain, heart, kidney, liver, skin, and testis. In the immunohistological analysis, Gb3/CD77 was mainly expressed in the proximal tubules as revealed with coincidental expression with angiotensin-converting enzyme (ACE). In spleen, it was detected in pre-B cells in the peripheral region of the white pulp, as suggested with coincidental expression with CD10. It was also expressed on the endothelia of the alveolar capillaries in lung and on the sebaceous ducts aside of the hair follicles. Gb4 was also detected mainly on the proximal tubules in kidney and on the endothelia of the alveolar capillaries in lung as Gb3/CD77. But it was also detected on the epithelium of the bronchus, seminiferous tubules and tails of spermatozoa in testis, blood vessels of choroids plexus and endothelial cells in brain, and central and hepatoportal veins in liver. The expression patterns of two genes and their products almost corresponded with some exception. The results would provide essential information for the functional studies of globo-series glycolipids.
    Glycobiology 01/2006; 15(12):1257-67. DOI:10.1093/glycob/cwj015 · 3.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Gangliosides are a family of sialic acid-containing glycosphingolipids that are highly enriched in the mammalian nervous system. In particular, b- and c-series gangliosides, all of which contain alpha-2,8 sialic acids, have been considered to play important roles in adhesion, toxin-binding, neurite extension, cell growth and apoptosis. However, the neurobiological functions of these series of gangliosides remain largely unknown. To clarify the function of b- and c-series gangliosides in pain sensation in vivo, we generated mice in whom the gene for the alpha-2,8-sialyltransferase (GD3 synthase), which is responsible for the generation of all b-series gangliosides as well as c-series gangliosides, was disrupted. Compared to the wild-type mice, the mutant mice exhibited increased sensory responses to thermal and mechanical stimuli as measured by a hot plate test and von Frey test. In contrast, the mutant mice showed decreased responses during the late phase of the formalin test. Paw edema and Fos expression in the spinal cord after formalin injection were significantly decreased in the mutant mice compared to the wild-type mice. No significant differences in the conduction velocity of the sciatic nerve, and no apparent morphologic differences in the spinal cord and the sciatic nerve were detected between the wild-type and the mutant mice. These results suggested that b- and c-series gangliosides are critical in the development and/or maintenance of the sensory nervous system responsible for the transmission of acute pain sensation and pain modulation. Moreover, they play an important role in the development of hyperalgesia induced by inflammation.
    Pain 11/2005; 117(3):271-9. DOI:10.1016/j.pain.2005.06.016 · 5.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We isolated human ST6GalNAc III cDNA clones. The typical cDNA clones predicted a type II membrane protein of 305 amino acids with a short cytoplasmic transmembrane domain of sixteen amino acids and a catalytic domain of 280 amino acids. A short form clone predicted a protein of 240 amino acids lacking 65 amino acids including the transmembrane portion. The alternative usage of the second exon seemed to generate these two transcripts. Both had two common regions found among sialyltransferases cloned so far, i.e. sialyl motif L and sialyl motif S. Alignments of human, mouse and rat orthologs indicated that high homologies, i.e. 85-95% identity among these species at amino acid levels. We analyzed the expression pattern and substrate specificity of the product, demonstrating a very restricted expression pattern and a high substrate specificity. Northern blotting revealed that hST6GalNAc III is expressed in kidney and brain as a single band at 3.2 kb. In enzyme assay of the long form, the transfer of sialic acid onto alpha2,3-sialylated acceptor substrates, i.e. GM1b and sialyl lactotetraosylceramide, was observed. hST6GalNAc III also showed sialyltransferase activity toward O-glycans (but not N-glycans) in fetuin.
    Journal of Biochemistry 10/2005; 138(3):237-43. DOI:10.1093/jb/mvi124 · 2.58 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although ganglioside GD3 levels are highly elevated in malignant melanomas, the role of GD3 in melanomas' malignant properties has not been clearly shown. To investigate this problem, we genetically generated GD3-positive (GD3+) transfectant cells from a GD3-negative (GD3-) mutant line SK-MEL-28-N1 and analyzed the phenotypic changes in the transfected cells. GD3+ cells showed markedly increased cell growth and invasive characteristics. Two bands that underwent stronger tyrosine phosphorylation in GD3+ cell lines than in controls after treatment with FCS were found with molecular masses of 130 and 68 kDa. They were identified as p130Cas and paxillin by sequential immunoprecipitation. Their roles in cell growth and invasion were analyzed with a small interfering RNA (siRNA) approach. Cell growth, as analyzed by BrdUrd uptake, was strongly suppressed in GD3+ cells to near the levels of GD3- cells when treated with siRNA for p130Cas but not when treated with siRNA for paxillin. However, treatment with siRNAs of either p130Cas or paxillin resulted in the marked suppression of the invasive activity of GD3+ cells almost to the levels of control cells. These results suggested that these two molecules function as effectors of GD3-mediated signaling, leading to such malignant properties as rapid cell growth and invasion.
    Proceedings of the National Academy of Sciences 09/2005; 102(31):11041-6. DOI:10.1073/pnas.0503658102 · 9.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Anti-GD2 ganglioside antibodies could be a promising, novel therapeutic approach to the eradication of human small cell lung cancers, as anti-GD2 monoclonal antibodies (mAbs) induced apoptosis of small cell lung cancer cells in culture. In this study, we analyzed the mechanisms for the apoptosis of these cells by anti-GD2 mAbs and elucidated the mechanisms by which apoptosis signals were transduced via reduction in the phosphorylation levels of focal adhesion kinase (FAK) and the activation of a MAPK family member, p38, upon the antibody binding. Knock down of FAK resulted in apoptosis and p38 activation. The inhibition of p38 activity blocked antibody-induced apoptosis, indicating that p38 is involved in this process. Immunoprecipitation-immunoblotting analysis of immune precipitates with anti-FAK or anti-integrin antibodies using an anti-GD2 mAb revealed that GD2 could be precipitated with integrin and/or FAK. These results suggested that GD2, integrin, and FAK form a huge molecular complex across the plasma membrane. Taken together with the fact that GD2+ cells showed marked detachment from the plate during apoptosis, GD2+ small cell lung cancer cells seemed to undergo anoikis through the conformational changes of integrin molecules and subsequent FAK dephosphorylation.
    Journal of Biological Chemistry 09/2005; 280(33):29828-36. DOI:10.1074/jbc.M414041200 · 4.57 Impact Factor

Publication Stats

5k Citations
840.88 Total Impact Points


  • 2008-2015
    • Chubu University
      • • Department of Biomedical Sciences
      • • College of Life and Health Sciences
      Касугай, Aichi, Japan
  • 1997-2014
    • Nagoya University
      • • Graduate School of Medicine
      • • Division of General Medicine
      Nagoya, Aichi, Japan
  • 2009
    • Pacific Northwest Diabetes Research Institute
      Seattle, Washington, United States
    • University of Glasgow
      • BHF Glasgow Cardiovascular Research Centre
      Glasgow, SCT, United Kingdom
  • 2005
    • Leiden University
      Leyden, South Holland, Netherlands
  • 1995-2000
    • Nagasaki University Hospital
      Nagasaki, Nagasaki, Japan
  • 1998
    • Mie University
      • School of Medicine
      Tu, Mie, Japan
  • 1996
    • Tarleton State University
      SEP, Texas, United States
  • 1992-1995
    • Nagasaki University
      • School of Medicine
      Nagasaki, Nagasaki, Japan
  • 1986-1995
    • Memorial Sloan-Kettering Cancer Center
      • Department of Medicine
      New York City, New York, United States
  • 1994
    • Kyoto University
      Kioto, Kyōto, Japan