Galectin-1 and Galectin-3 in B-Cell Precursor Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemias arising from the malignant transformation of B-cell precursors (BCP-ALLs) are protected against chemotherapy by both intrinsic factors as well as by interactions with bone marrow stromal cells. Galectin-1 and Galectin-3 are lectins with overlapping specificity for binding polyLacNAc glycans. Both are expressed by bone marrow stromal cells and by hematopoietic cells but show different patterns of expression, with Galectin-3 dynamically regulated by extrinsic factors such as chemotherapy. In a comparison of Galectin-1 x Galectin-3 double null mutant to wild-type murine BCP-ALL cells, we found reduced migration, inhibition of proliferation, and increased sensitivity to drug treatment in the double knockout cells. Plant-derived carbohydrates GM-CT-01 and GR-MD-02 were used to inhibit extracellular Galectin-1/-3 binding to BCP-ALL cells in co-culture with stromal cells. Treatment with these compounds attenuated migration of the BCP-ALL cells to stromal cells and sensitized human BCP-ALL cells to vincristine and the targeted tyrosine kinase inhibitor nilotinib. Because N-glycan sialylation catalyzed by the enzyme ST6Gal1 can regulate Galectin cell-surface binding, we also compared the ability of BCP-ALL wild-type and ST6Gal1 knockdown cells to resist vincristine treatment when they were co-cultured with Galectin-1 or Galectin-3 knockout stromal cells. Consistent with previous results, stromal Galectin-3 was important for maintaining BCP-ALL fitness during chemotherapy exposure. In contrast, stromal Galectin-1 did not significantly contribute to drug resistance, and there was no clear effect of ST6Gal1-catalysed N-glycan sialylation. Taken together, our results indicate a complicated joint contribution of Galectin-1 and Galectin-3 to BCP-ALL survival, with different roles for endogenous and stromal produced Galectins. These data indicate it will be important to efficiently block both extracellular and intracellular Galectin-1 and Galectin-3 with the goal of reducing BCP-ALL persistence in the protective bone marrow niche during chemotherapy.

Overcoming Microenvironment-Mediated Chemoprotection through Stromal Galectin-3 Inhibition in Acute Lymphoblastic Leukemia

Environmentally-mediated drug resistance in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) significantly contributes to relapse. Stromal cells in the bone marrow environment protect leukemia cells by secretion of chemokines as cues for BCP-ALL migration towards, and adhesion to, stroma. Stromal cells and BCP-ALL cells communicate through stromal galectin-3. Here, we investigated the significance of stromal galectin-3 to BCP-ALL cells. We used CRISPR/Cas9 genome editing to ablate galectin-3 in stromal cells and found that galectin-3 is dispensable for steady-state BCP-ALL proliferation and viability. However, efficient leukemia migration and adhesion to stromal cells are significantly dependent on stromal galectin-3. Importantly, the loss of stromal galectin-3 production sensitized BCP-ALL cells to conventional chemotherapy. We therefore tested novel carbohydrate-based small molecule compounds (Cpd14 and Cpd17) with high specificity for galectin-3. Consistent with results obtained using galectin-3-knockout stromal cells, treatment of stromal-BCP-ALL co-cultures inhibited BCP-ALL migration and adhesion. Moreover, these compounds induced anti-leukemic responses in BCP-ALL cells, including a dose-dependent reduction of viability and proliferation, the induction of apoptosis and, importantly, the inhibition of drug resistance. Collectively, these findings indicate galectin-3 regulates BCP-ALL cell responses to chemotherapy through the interactions between leukemia cells and the stroma, and show that a combination of galectin-3 inhibition with conventional drugs can sensitize the leukemia cells to chemotherapy.

Glycoproteome remodeling in MLL-rearranged B-cell precursor acute lymphoblastic leukemia

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) with mixed-lineage leukemia gene rearrangement (MLL-r) is a poor-prognosis subtype for which additional therapeutic targets are urgently needed. Currently no multi-omics data set for primary MLL r patient cells exists that integrates transcriptomics, proteomics and glycomics to gain an inclusive picture of theranostic targets. Methods: We have integrated transcriptomics, proteomics and glycomics to i) obtain the first inclusive picture of primary patient BCP-ALL cells and identify molecular signatures that distinguish leukemic from normal precursor B-cells and ii) better understand the benefits and limitations of the applied technologies to deliver deep molecular sequence data across major cellular biopolymers. Results: MLL-r cells feature an extensive remodeling of their glycocalyx, with increased levels of Core 2-type O-glycans and complex N-glycans as well as significant changes in sialylation and fucosylation. Notably, glycosaminoglycan remodeling from chondroitin sulfate to heparan sulfate was observed. A survival screen, to determine if glycan remodeling enzymes are redundant, identified MGAT1 and NGLY1, essential components of the N-glycosylation/degradation pathway, as highly relevant within this in vitro screening. OGT and OGA, unique enzymes that regulate intracellular O-GlcNAcylation, were also indispensable. Transcriptomics and proteomics further identified Fes and GALNT7-mediated glycosylation as possible therapeutic targets. While there is overall good correlation between transcriptomics and proteomics data, we demonstrate that a systematic combined multi-omics approach delivers important diagnostic information that is missed when applying a single omics technology. Conclusions: Apart from confirming well-known MLL-r BCP-ALL glycoprotein markers, our integrated multi-omics workflow discovered previously unidentified diagnostic/therapeutic protein targets.

Pre-B acute lymphoblastic leukemia expresses cell surface nucleolin as a 9-O-acetylated sialoglycoprotein

Precursor B acute lymphoblastic leukemias (pre-B ALLs) abnormally express a specific glycan structure, 9-O-acetylated sialic acid (9-O-Ac-Sia), on their cell surface, but glycoproteins that carry this modification have not been identified. Using three different lectins that specifically recognize this structure, we establish that nucleolin (NCL), a protein implicated in cancer, contains 9-O-Ac-Sia. Surprisingly, antibodies against the glycolipid 9-O-Ac-Sia GD3 also detected 9-O-Ac-Sia NCL. NCL is present on the surface of pre-B ALL cells as a sialoglycoprotein that is partly 9-O-acetylated and conversely, 9-O-Ac-Sia-containing structures other than NCL are present on these cells as well. Interestingly, NCL and the 9-O-Ac-Sia signal had less co-localization on normal pre-B cells. We also investigated regulation of NCL on the cell surface and found that sialidase treatment increased the percentage of cells positive for cell surface NCL, suggesting that sialylation of NCL promotes internalization. Treatment of pre-B ALL cells with the chemotherapy drug vincristine also increased the percentage of cells with surface NCL and correlated with increased 9-O-Ac-Sia expression. All tested leukemia cells including primary samples expressed NCL, suggesting it as a possible therapeutic target. We confirmed this by showing inhibition of cell proliferation in some pre-B ALLs by exposure to a NCL-specific aptamer AS1411.

Treatment of B-cell precursor acute lymphoblastic leukemia with the Galectin-1 inhibitor PTX008

Background

Drug resistance of B-cell precursor acute lymphoblastic leukemia (BP-ALL) cells is conferred by both intrinsic and extrinsic factors, which could be targeted to promote chemo-sensitization. Our previous studies showed that Galectin-3, a lectin that clusters galactose-modified glycoproteins and that has both an intracellular and extracellular location, protects different subtypes of BP-ALL cells against chemotherapy. Galectin-1 is related to Galectin-3 and its expression was previously reported to be restricted to the MLL subtype of BP-ALL.

Methods and results

Here, we report that Galectin-1 is expressed at different levels in and on different subclasses of BP-ALLs. Bone marrow plasma also contains high levels of Galectin-1. PTX008 is an allosteric inhibitor which inhibits Galectin-1 but not Galectin-3-mediated agglutination. The compound reduces migration of BP-ALL cells to CXCL12 and OP9 stromal cells and inhibits fibronectin-mediated adhesion. It also affects cell cycle progression of BCP-ALL cells. PTX008 is cytostatic for BP-ALL cells even when these are co-cultured with protective stroma, and can sensitize ALL cells to vincristine chemotherapy in vitro and in mice.

Conclusions

PTX008 inhibits multiple functions that contribute to BP-ALL survival. The effects of Galectin-1 inhibition on both BP-ALL cell proliferation and migration suggest both the leukemia cells as well as the microenvironment that protects these cells may be targeted.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0721-7) contains supplementary material, which is available to authorized users.

B-cell precursor acute lymphoblastic leukemia and stromal cells communicate through Galectin-3

The molecular interactions between B-cell precursor acute lymphoblastic leukemia (pre-B ALL) cells and stromal cells in the bone marrow that provide microenvironmentally-mediated protection against therapeutic drugs are not well-defined. Galectin-3 (Lgals3) is a multifunctional galactose-binding lectin with reported location in the nucleus, cytoplasm and extracellular space in different cell types. We previously reported that ALL cells co-cultured with stroma contain high levels of Galectin-3. We here establish that, in contrast to more mature B-lineage cancers, Galectin-3 detected in and on the ALL cells originates from stromal cells, which express it on their surface, secrete it as soluble protein and also in exosomes. Soluble and stromal-bound Galectin-3 is internalized by ALL cells, transported to the nucleus and stimulates transcription of endogenous LGALS3 mRNA. When human and mouse ALL cells develop tolerance to different drugs while in contact with protective stromal cells, Galectin-3 protein levels are consistently increased. This correlates with induction of Galectin-3 transcription in the ALL cells. Thus Galectin-3 sourced from stroma becomes supplemented by endogenous Galectin-3 production in the pre-B ALL cells that are under continuous stress from drug treatment. Our data suggest that stromal Galectin-3 may protect ALL cells through auto-induction of Galectin-3 mRNA and tonic NFκB pathway activation. Since endogenously synthesized Galectin-3 protects pre-B ALL cells against drug treatment, we identify Galectin-3 as one possible target to counteract the protective effects of stroma.

Novel roles of ginsenoside Rg3 in apoptosis through downregulation of epidermal growth factor receptor

Ginsenoside Rg3 (Rg3), a pharmacologically active compound from red ginseng, has been reported to induce cell death in various cancer cell lines, although the specific mechanisms have not been well established. In the present study, Rg3 treatment to A549 human lung adenocarcinoma led to cell death via not only apoptotic pathways but also the downregulation of epidermal growth factor receptor (EGFR). We used cross-linker and cell enzyme-linked immunosorbent assays to show that Rg3 inhibited EGFR dimerization by EGF stimulation and caused EGFR internalization from the cell membrane. Among several important phosphorylation sites in cytoplasmic EGFR, Rg3 increased the phosphorylation of tyrosine 1045 (pY1045) and serine 1046/1047 (pS1046/1047) for EGFR degradation and coincidently, attenuated pY1173 and pY1068 for mitogen-activated protein kinase activity. These effects were amplified under EGF-pretreated Rg3 stimulation. In vivo experiments showed that the average volume of the tumors treated with 30 mg/kg of Rg3 was significantly decreased by 40% compared with the control. Through immunohistochemistry, we detected the fragmentation of DNA, the accumulation of Rg3, and the reduction of EGFR expression in the Rg3-treated groups. Here, we provide the first description of the roles of Rg3 in the reduction of cell surface EGFR, the attenuation of EGFR signal transduction, and the eventual activation of apoptosis in A549 human lung adenocarcinoma.

Heavy chain transfer by tumor necrosis factor-stimulated gene 6 to the bikunin proteoglycan

We present data that hyaluronan (HA) polysaccharides, about 14-86 monosaccharides in length, are capable of accepting only a single heavy chain (HC) from inter-α-inhibitor via transfer by tumor necrosis factor-stimulated gene 6 (TSG-6) and that this transfer is irreversible. We propose that either the sulfate groups (or the sulfation pattern) at the reducing end of the chondroitin sulfate (CS) chain of bikunin, or the core protein itself, enables the bikunin proteoglycan (PG) to accept more than a single HC and permits TSG-6 to transfer these HCs from its relatively small CS chain to HA. To test these hypotheses, we investigated HC transfer to the intact CS chain of the bikunin PG, and to the free chain of bikunin. We observed that both the free CS chain and the intact bikunin PG were only able to accept a single HC from inter-α-inhibitor via transfer by TSG-6 and that HCs could be swapped from the bikunin PG and its free CS chain to HA. Furthermore, a significant portion of the bikunin PG was unable to accept a single heavy chain. We discuss explanations for these observations, including the intracellular assembly of inter-α-inhibitor. In summary, these data demonstrate that the sulfation of the CS chain of bikunin and/or its core protein promote HC transfer by TSG-6 to its relatively short CS chain, although they are insufficient to enable the CS chain of bikunin to accept more than one HC in the absence of other cofactors.

Carbohydrate-containing molecules as potential biomarkers in colon cancer

Glycans play a critical role in physiological and pathological processes through interaction with a variety of ligands. Altered expression and dysregulation of these molecules can cause aberrant cellular function such as malignancy. Glycomics provide information of the structure and function of glycans, glycolipids, and glycoproteins such as proteoglycans, and may help to predict cancer development and progression as biomarkers. In this report, we compared the expression of proteoglycans, the content and structure of glycosaminoglycans and glycolipids between patient-matched normal and cancer tissues obtained from colon cancer patients. Tumor-related proteoglycans, glypican-3, and syndecan-1 showed downregulation in cancer tissues compared to normal tissues. In cancer tissue, the total amount of chondroitin sulfate (CS)/dermatan sulfate and heparan sulfate were lower and, interestingly, the level of disaccharide units of both 4S6S (CS-E) and 6S (CS-C) were higher compared to normal tissue. Also, overall lipids including glycolipids, a major glycomics target, were analyzed by hydrophilic interaction liquid chromatography mass spectrometry. Increase of lyso-phosphatidylcholine (phospholipid), sphingomyelin (sphigolipid), and four types of glycolipids (glucosylceramide, lactosylceramide, monosialic acid ganglioside, and globoside 4) in cancer tissue showed the possibility as potential biomarkers in colon cancer. While requiring the need for careful interpretation, this type of broad investigation gives us a better understanding of pathophysiological roles on glycosaminoglycans and glycolipids and might be a powerful tool for colon cancer diagnosis.

Characterization of human placental glycosaminoglycans and regional binding to VAR2CSA in malaria infected erythrocytes

Placental malaria is a serious problem in sub-Saharan Africa. Young women are particular susceptible to contracting this form of malaria during their first or second pregnancy despite previously acquired immunity from past infections. Placental malaria is caused by Plasmodium falciparum parasites expressing VAR2CSA on the erythrocyte surface. This protein adheres to a low-sulfated chondroitin sulfate-A found in placental tissue causing great harm to both mother and developing fetus. In rare cases, the localization of infected erythrocytes to the placenta can even result in the vertical transmission of malaria. In an effort to better understand this infection, chondroitin sulfate was isolated from the cotyledon part of the placenta, which should be accessible for parasite adhesion, as well as two non-accessible parts of the placenta to serve as controls. The placental chondroitin sulfate structures and their VAR2CSA binding were characterized. All portions of human placenta contained sufficient amounts of the appropriate low-sulfated chondroitin sulfate-A to display high-affinity binding to a recombinant truncated VAR2CSA construct, as determined using surface plasmon resonance. The cotyledon is the only placental tissue accessible to parasites in the bloodstream, suggesting it is the primary receptor for parasite infected red blood cells.

Akebia saponin PA induces autophagic and apoptotic cell death in AGS human gastric cancer cells

In this study, we investigated the anticancer mechanism of akebia saponin PA (AS), a natural product isolated from Dipsacus asperoides in human gastric cancer cell lines. It was shown that AS-induced cell death is caused by autophagy and apoptosis in AGS cells. The apoptosis-inducing effect of AS was characterized by annexin V/propidium (PI) staining, increase of sub-G1 phase and caspase-3 activation, while the autophagy-inducing effect was indicated by the formation of cytoplasmic vacuoles and microtubule-associated protein 1 light chain-3 II (LC3-II) conversion. The autophagy inhibitor bafilomycin A1 (BaF1) decreased AS-induced cell death and caspase-3 activation, but caspase-3 inhibitor Ac-DEVD-CHO did not affect LC3-II accumulation or AS-induced cell viability, suggesting that AS induces autophagic cell death and autophagy contributes to caspase-3-dependent apoptosis. Furthermore, AS activated p38/c-Jun N-terminal kinase (JNK), which could be inhibited by BaF1, and caspase-3 activation was attenuated by both SB202190 and SP600125, indicating that AS-induced autophagy promotes mitogen-activated protein kinases (MAPKs)-mediated apoptosis. Taken together, these results demonstrate that AS induces autophagic and apoptotic cell death and autophagy plays the main role in akebia saponin PA-induced cell death.

Sequence analysis and domain motifs in the porcine skin decorin glycosaminoglycan chain

Decorin proteoglycan is comprised of a core protein containing a single O-linked dermatan sulfate/chondroitin sulfate glycosaminoglycan (GAG) chain. Although the sequence of the decorin core protein is determined by the gene encoding its structure, the structure of its GAG chain is determined in the Golgi. The recent application of modern MS to bikunin, a far simpler chondroitin sulfate proteoglycans, suggests that it has a single or small number of defined sequences. On this basis, a similar approach to sequence the decorin of porcine skin much larger and more structurally complex dermatan sulfate/chondroitin sulfate GAG chain was undertaken. This approach resulted in information on the consistency/variability of its linkage region at the reducing end of the GAG chain, its iduronic acid-rich domain, glucuronic acid-rich domain, and non-reducing end. A general motif for the porcine skin decorin GAG chain was established. A single small decorin GAG chain was sequenced using MS/MS analysis. The data obtained in the study suggest that the decorin GAG chain has a small or a limited number of sequences.

Induction of apoptosis by ginsenoside Rk1 in SK-MEL-2-human melanoma

Ginsenosides are active compounds isolated from Panax ginseng Meyer. Among these ginsenosides, less polar ginsenosides such as ginsenoside Rg3 and ginsenoside Rh2 have been demonstrated to have tumor inhibitory effects because of their cytotoxicity. In this study, we evaluated the apoptotic effects of ginsenoside Rk1 in SK-MEL-2 human melanoma. Ginsenoside Rk1 isolated from red ginseng is one of the novel ginsenosides that shows strong cytotoxicity compared to ginsenoside Rg3 in dose- and time-dependent manners. The results of DNA fragmentation, 4',6-diamidino-2-phenylindole staining, and flow cytometric analysis are corroborated that ginsenoside Rk1 induced apoptosis in SK-MEL-2 cells. Western blot analysis revealed up-regulation of Fas, FasL, and Bax protein expression and down-regulation of procaspase-8, procaspase-3, mutant p53 and Bcl-2 protein expression. These findings suggest that ginsenoside Rk1 might be a promising compound to induce apoptosis through both extrinsic and intrinsic pathways in SK-MEL-2 cells.

Induction of nucleolin translocation by acharan sulfate in A549 human lung adenocarcinoma

Acharan sulfate (AS), isolated from the giant African snail Achatina fulica, is a novel glycosaminoglycan, consisting primarily of the repeating disaccharide structure alpha-D-N-acetylglucosaminyl (1 --> 4) 2-sulfoiduronic acid. AS shows anti-tumor activity in vitro and in vivo. Despite this activity, AS is only weakly cytotoxic towards cancer cells. We examine the interactions between AS and cell-surface proteins in an effort to explain this anti-tumor activity. Using flow cytometry and affinity column chromatography, we confirm that AS has strong affinity to specific cell-surface proteins including nucleolin (NL) in A549 human lung adenocarcinomas. Surprisingly, we found the translocation of NL from nucleus to cytoplasm under the stimulation of AS (100 microg/ml) in vitro. Also, as NL exits the nucleus, the levels of growth factors such as bFGF and signaling cascade proteins, such as p38, p53, and pERK, are altered. These results suggest that the communication between AS and NL plays a critical role on signal transduction in tumor inhibition.

Generation and characterization of monoclonal antibody to ginsenoside rg3

While studying the mechanism of ginsenoside Rg3 (G-Rg3) on tumor inhibition, we produced monoclonal antibody to G-Rg3 for more specific investigation. We immunized Balb/c mice to G-Rg3 conjugated bovine serum albumin (BSA) by intraperitoneal injection and hybridized splenocytes from those immunized mice and myeloma cells. From those fusion cell lines, we selected productive monoclonal clones and obtained culture media containing monoclonal antibody to G-Rg3. After purification, we performed enzyme-linked immunosorbent assay (ELISA) to verify the sensitivity and specificity of the antibody. When compared with G-Rh2 having a very similar structure as a metabolite of G-Rg3, the antibody worked only with G-Rg3 in a concentration-dependent manner. We confirmed that the monoclonal antibody to G-Rg3 can be applied to immunocytochemistry for detection of the treated G-Rg3 inside A549 human lung adenocarcinomas. Thus, the monoclonal antibody to G-Rg3 would be a useful tool for measuring the bioactivity of G-Rg3 in various fields.

Circadian polymorphisms associated with affective disorders

BACKGROUND

Clinical symptoms of affective disorders, their response to light treatment, and sensitivity to other circadian interventions indicate that the circadian system has a role in mood disorders. Possibly the mechanisms involve circadian seasonal and photoperiodic mechanisms. Since genetic susceptibilities contribute a strong component to affective disorders, we explored whether circadian gene polymorphisms were associated with affective disorders in four complementary studies.

METHODS

Four groups of subjects were recruited from several sources: 1) bipolar proband-parent trios or sib-pair-parent nuclear families, 2) unrelated bipolar participants who had completed the BALM morningness-eveningness questionnaire, 3) sib pairs from the GenRed Project having at least one sib with early-onset recurrent unipolar depression, and 4) a sleep clinic patient group who frequently suffered from depression. Working mainly with the SNPlex assay system, from 2 to 198 polymorphisms in genes related to circadian function were genotyped in the participant groups. Associations with affective disorders were examined with TDT statistics for within-family comparisons. Quantitative trait associations were examined within the unrelated samples.

RESULTS

In NR1D1, rs2314339 was associated with bipolar disorder (P = 0.0005). Among the unrelated bipolar participants, 3 SNPs in PER3 and CSNK1E were associated with the BALM score. A PPARGC1B coding SNP, rs7732671, was associated with affective disorder with nominal significance in bipolar family groups and independently in unipolar sib pairs. In TEF, rs738499 was associated with unipolar depression; in a replication study, rs738499 was also associated with the QIDS-SR depression scale in the sleep clinic patient sample.

CONCLUSION

Along with anti-manic effects of lithium and the antidepressant effects of bright light, these findings suggest that perturbations of the circadian gene network at several levels may influence mood disorders, perhaps ultimately through regulation of MAOA and its modulation of dopamine transmission. Twenty-three associations of circadian polymorphisms with affective symptoms met nominal significance criteria (P < 0.05), whereas 15 would be expected by chance, indicating that many represented false discoveries (Type II errors). Some evidence of replication has been gathered, but more studies are needed to ascertain if circadian gene polymorphisms contribute to susceptibility to affective disorders.

Generation and characterization of a series of monoclonal antibodies that specifically recognize [HexA(+/-2S)-GlcNAc]n epitopes in heparan sulfate

Five monoclonal antibodies AS17, 22, 25, 38 and 48, a single monoclonal antibody ACH55, and three monoclonal antibodies NAH33, 43, 46, that recognize acharan sulfate (IdoA2S-GlcNAc)n, acharan (IdoA-GlcNAc)n and N-acetyl-heparosan (GlcA-GlcNAc)n, respectively, were generated by immunization of mice with keyhole limpet hemocyanin-conjugated polysaccharides. Specificity tests were performed using a panel of biotinylated GAGs that included chemically modified heparins. Each antibody bound avidly to the immunized polysaccharide, but did not bind to chondroitin sulfates, keratan sulfate, chondroitin nor hyaluronic acid. AS antibodies did not bind to heparan sulfate or heparin, but bound to 6-O-desulfated, N-desulfated and re-N-acetylated heparin to varying degrees. ACH55 bound to tri-desulfated and re-N-acetylated heparin but hardly bound to other modified heparins. NAH antibodies did not bind to heparin and modified heparins but bound to heparan sulfate to varying degrees. NAH43 and NAH46 also bound to partially N-de-acetylated N-acetyl-heparosan. Immunohistochemical analysis in rat cerebella was performed with the antibodies. While NAH46 stained endothelia, where heparan sulfate is typically present, neither ACH55 nor AS25 stained endothelia. On the contrary ACH55 and AS25 stained the molecular layer of the rat cerebella. Furthermore, ACH55 specifically stained Purkinje cells. These results suggest that there is unordinary expression of IdoA2S-GlcNAc and IdoA-GlcNAc in specific parts of the nervous system.

Dysbindin gene variants are associated with bipolar I disorder in a Korean population

The dysbindin gene (DTNBP1) has been associated with schizophrenia in several populations. Because the clinical characteristics of schizophrenia and bipolar disorder overlap in many respects and findings from genetic studies have suggested common genes between them, we conducted a case control association study of bipolar disorder in Korea to investigate the genetic association between DTNBP1 and bipolar disorder. In total, 163 patients with bipolar disorder and 350 controls were evaluated. We genotyped three single nucleotide polymorphisms of DTNBP1 (SNP A, P1763, and P1320) and analyzed the allele, genotype, and haplotype associations with bipolar disorder. We found significant genotypic associations with P1763 and P1320, but no association with SNP A in the bipolar I group. When we included bipolar II and schizoaffective disorder in the affected phenotype, the significance decreased. A positive association was observed between the SNP A-P1763 haplotype and the bipolar I phenotype. This haplotype association was lost when we either broadened our phenotype or included P1320 in a haplotype. The positive results of the present study lost significance after a Bonferroni correction for multiple testing. These findings are consistent with previous findings that showed a positive association of DTNBP1 with bipolar disorders. Moreover, our results suggest that DTNBP1 may contribute more to bipolar I disorder than bipolar II disorder or schizoaffective disorder. Further comprehensive studies will be required to clarify these association, however, it seems likely that DTNBP1 is a susceptibility gene for bipolar disorder.

Nucleolin: acharan sulfate-binding protein on the surface of cancer cells

Glycosaminoglycans (GAGs) are complex polysaccharides that participate in the regulation of physiological processes through the interactions with a wide variety of proteins. Acharan sulfate (AS), isolated from the giant African snail Achatina fulica, primarily consists of the repeating disaccharide structure alpha-D-N-acetylglucosaminyl (1-->4) 2-sulfoiduronic acid. Exogenous AS was injected subcutaneously near the tumor tissue in C57BL/6 mice that had been implanted with Lewis lung carcinoma cells (LLCs). The location of AS in the tumor was assessed by staining of sectioned tissues with alcian blue and periodic acid-Schiff (PAS) reagent. In vitro assays indicated binding of cells to 50 microg/ml AS (or heparin) after a 5-h incubation. Immunofluorescence assays, using anti-AS antibody, detected AS at the cell surface. The outer-surface of LLCs were next biotinylated to identify the AS-binding proteins. Biotinylated cells were lysed, and the lysates were fractionated on the AS affinity column using a stepwise salt gradient (0, 0.1, 0.3, 0.5, 0.7, 1.0, and 2.0 M). The fractions were analyzed by SDS-PAGE with silver staining and western blotting. We focused on the proteins with high affinity for AS (eluting at 1 M NaCl) and detected only two bands by western blotting. ESI Q-TOF MS analysis of one of these bands, molecular weight approximately 110 kDa, showed it to be nucleolin. A phosphorylated form of nucleolin on the surface of cells acts as a cell surface receptor for a variety of ligands, including growth factors (i.e., basic fibroblast growth factor) and chemokines (i.e., midkine). These results show that nucleolin is one of several AS-binding proteins and suggest that AS might demonstrate its tumor growth inhibitory activity by binding the nucleolin receptor protein on the surface of cancer cells.

Melanocortin 3 receptor (MC3R) gene variants in extremely obese women

OBJECTIVE

Following several reports of linkage of obesity related phenotypes to human chromosome 20q we sought to determine whether variations of the melanocortin 3 receptor (MC3R) gene are associated with obesity.

DESIGN

We screened the MC3R gene coding region and approximately 2 kb of 5' and 3' flanking sequences for DNA variants in unrelated extremely obese women and average weight controls using polymerase chain reaction (PCR) single strand conformation polymorphism (SSCP) analysis and DNA sequencing.

SUBJECTS

124 unrelated extremely obese women (body mass index, (BMI)>/=40 kg/m2) and 85 average weight controls (BMI<27 kg/m2).

MEASUREMENTS

Radiation hybrid (RH) mapping was performed to localize the MC3R gene. 5' and 3' flanking sequences of MC3R gene were cloned. PCR-SSCP and DNA sequencing were used to detect mutations in the MC3R gene coding region and flanking sequences.

RESULTS

RH mapping localized the MC3R gene to 20q13, between markers D20S100 and D20S149. 1083 bp 5' and 653 bp 3' flanking region of the MC3R gene were cloned. A missense mutation (+241, codon 81 ATT/GTT, Ile-->Val) was found in the MC3R coding region. Four more variants were detected in the 5' flanking sequence: -201(C-->G), -239 (A-->G), -762(A-->T) and -769(T-->C). Compared with controls, no significant allele frequency differences were found. Racial differences were found for the +241, -201, -239 and -762 polymorphisms.

CONCLUSIONS

Several sequence variants were found in the MC3R gene coding region and in 5' flanking sequences. However, none of the variants were associated with obesity phenotypes. The linkage of extreme human obesity on 20q13 is likely caused by genes other than MC3R. International Journal of Obesity (2000) 24, 206-210

Possible association between schizophrenia and a CAG repeat polymorphism in the spinocerebellar ataxia type 1 (SCA1) gene on human chromosome 6p23

The gene for spinocerebellar ataxia type 1 (SCA1) is a potential candidate gene for schizophrenia because of previous positive linkage findings in this region (6p22-24), and because the reported correlation between SCA1 onset and the number of CAG repeats suggests anticipation. To test the involvement of this gene in the development of schizophrenia, we examined genotypes of the SCA1 CAG repeat polymorphism for 49 Caucasian patients with schizophrenia, and 88 Caucasian controls. We found a significant association between the frequencies of alleles of this gene and schizophrenia (chi 2 = 18.40, df = 8, P = 0.018). Among 13 alleles, one allele (31 trinucleotide repeat) was significantly more frequent in patients with schizophrenia than in controls (chi 2 = 9.57, df = 1, P = 0.002). This association was sustained after applying a Bonferroni correction for multiple testing (P = 0.05/13 = 0.004), and the chi-square results were shown to be robust through Monte Carlo simulation. We observed no allelic association with three flanking microsatellite markers (D6S288, D6S1605, and D6S337), suggesting that our result was not due to population stratification. Further studies of this locus are needed to confirm this finding, and to determine a potential role for this gene in the development of schizophrenia.

Genome scan for human obesity and linkage to markers in 20q13

Obesity is a highly prevalent, multigenic trait that predicts increased morbidity and mortality. Here we report results from a genome scan based on 354 markers in 513 members of 92 nuclear families ascertained through extreme obesity and normal body weight. The average marker interval was approximately 10 cM. We examined four correlated obesity phenotypes, including the body-mass index (BMI) (both as a quantitative trait and as a discrete trait with a threshold of BMI > or /=30 kg/m2) and percentage of fat (both as a quantitative trait and as a discrete trait with a threshold of 40%) as assessed by bioelectrical impedance. In the initial stage of the genome scan, four markers in 20q gave positive evidence for linkage, which was consistent across most obesity phenotypes and analytic methods. After saturating 20q with additional markers (25 markers total) in an augmented sample of 713 members from 124 families, we found linkage to several markers in a region, 20q13, previously implicated in both human and animal studies. Three markers (D20S107, D20S211, and D20S149) in 20q13 had empirical P values (based on Monte Carlo simulations, which controlled for multiple testing) < or /=. 01 for single-point analysis. In addition, the parametric, affecteds-only analysis for D20S476 yielded a LOD score of 3.06 (P=. 00009), and the affected-sib-pair test yielded a LOD score of 3.17 (P=.000067). Multipoint analyses further strengthened and localized these findings. This region includes several plausible candidate genes for obesity. Our results suggest that one or more genes affecting obesity are located in 20q13.