Trophoblast cell surface antigen-2 phosphorylation triggered by binding of galectin-3 drives metastasis through down-regulation of E-cadherin.

The expression of trophoblast cell surface antigen-2 (Trop-2) is enhanced in many tumor tissues and is correlated with increased malignancy and poor survival of patients with cancer. Previously, we demonstrated that the Ser-322 residue of Trop-2 is phosphorylated by protein kinase Cα (PKCα) and PKCδ. Here, we demonstrate that phosphomimetic Trop-2 expressing cells have markedly decreased E-cadherin mRNA and protein levels. Consistently, mRNA and protein of the E-cadherin-repressing transcription factors zinc finger E-Box binding homeobox 1 (ZEB1) were elevated, suggesting transcriptional regulation of E-cadherin expression. The binding of galectin-3 to Trop-2 enhanced the phosphorylation and subsequent cleavage of Trop-2, followed by intracellular signaling by the resultant C-terminal fragment. Binding of ß-catenin/transcription factor 4 (TCF4) along with the C-terminal fragment of Trop-2 to the ZEB1 promoter upregulated ZEB1 expression. Of note, siRNA-mediated knockdown of ß-catenin and TCF4 increased the expression of E-cadherin through ZEB1 downregulation. Knockdown of Trop-2 in MCF-7 cells and DU145 cells resulted in downregulation of ZEB1 and subsequent upregulation of E-cadherin. Furthermore, wild-type and phosphomimetic Trop-2 but not phosphorylation-blocked Trop-2 were detected in the liver and/or lung of some nude mice bearing primary tumors inoculated intraperitoneally or subcutaneously with wild-type or mutated Trop-2 expressing cells, suggesting that Trop-2 phosphorylation, plays an important role in tumor cell mobility in vivo, too. Together with our previous finding of Trop-2 dependent regulation of claudin-7, we suggest that the Trop-2-mediated cascade involves concurrent derangement of both tight and adherence junctions, which may drive metastasis of epithelial tumor cells.

Characterization of novel antibodies that recognize sialylated keratan sulfate and lacto-N-fucopentaose I on human induced pluripotent cells: comparison with existing antibodies.

This report describes the isolation and characterization of two new antibodies, R-6C (IgM) and R-13E (IgM), which were generated in C57BL/6 mice (Mus musculus) using the Tic (JCRB1331) human induced pluripotent cell (hiPSC) line as an antigen, and their comparisons with two existing antibodies, R-10G (IgG1) and R-17F (IgG1). Their epitopes were studied by western blotting after various glycosidase digestions, binding analyses using enzyme-linked immunosorbent assays (ELISAs) and microarrays with various synthetic oligosaccharides. The minimum epitope structures identified were: Siaα2-3Galß1-3GlcNAc(6S)ß1-3Galß1-4GlcNAc(6S)ß1 (R-6C), Fucα1-2Galß1-3GlcNAcß1-3Galß1 (R-13E), Galß1-4GlcNAc(6S)ß1-3Galß1-4GlcNAc(6S)ß1 (R-10G), and Fucα1-2Galß1-3GlcNAß1-3Galß1-4Glc (lacto-N-fucopentaose I) (R-17F). Most glycoprotein epitopes are expressed as O-glycans. The common feature of these epitopes is the presence of an N-acetyllactosamine type 1 structure (Galß1-3GlcNAc) at their nonreducing termini, followed by a type 2 structure (Galß1-4GlcNAc); this arrangement comprises a type 1-type 2 motif. This motif is also shared by TRA-1-60, a traditional onco-fetal antigen. In contrast, the R-10G epitope has a type 2-type 2 motif. Among these antibodies, R-17F and R-13E exhibit cytotoxic activity toward hiPSCs. R-17F and R-13E exhibit extremely high similarity in the amino acid sequences in their complementarity-determining regions (CDRs), which is consistent with their highly similar glycan recognition. These antibodies are excellent tools for investigating the biological functions of glycoconjugates in hiPSCs/hESCs; they could be useful for the selection, isolation and selective killing of such undifferentiated pluripotent stem cells.

Transient ETV2 Expression Promotes the Generation of Mature Endothelial Cells from Human Pluripotent Stem Cells.

Differentiation protocols are used for induced pluripotent stem cells (iPSCs) in in vitro disease modeling and clinical applications. Transplantation of endothelial cells (ECs) is an important treatment strategy for ischemic diseases. For example, in vitro generated ECs can be used to provide the vascular plexus to regenerate organs such as the liver. Here, we demonstrate that the E-twenty-six (ETS) transcription factor ETV2 alone can directly convert iPSCs into vascular endothelial cells (iPS-ETV2-ECs) with an efficiency of over 90% within 5 d. Although the stable overexpression of ETV2 induced the expression of multiple key factors for endothelial development, the induced ECs were less mature. Furthermore, doxycycline-inducible transient ETV2 expression could upregulate the expression of von Willebrand factor (vWF) in iPS-ETV2-ECs, leading to a mature phenotype. The findings of this study on generation of mature iPS-ETV2-ECs provide further insights into the exploration of cell reprogramming from iPSCs. Here, we provide a new protocol for differentiation of iPSCs, thus providing a new source of ECs for in vitro disease modeling and clinical applications.

Inhibition of Glycogen Synthase Kinase 3ß Enhances Functions of Induced Pluripotent Stem Cell-Derived Brain Microvascular Endothelial Cells in the Blood-Brain Barrier.

Brain microvascular endothelial cells (BMECs) are essential component of the blood-brain barrier (BBB). BMECs strictly regulate the entry of various molecules into the central nervous system from the peripheral circulation by forming tight junctions and expressing various influx/efflux transporters and receptors. In vitro BBB models have been widely reported with primary BMECs isolated from animals, although it is known that the expression patterns and levels of transporters and receptors in BMECs differ between humans and animals. Recently, several methods to differentiate BMECs from human induced pluripotent stem (hiPS) cell have been developed. However, the expression of P-glycoprotein (P-gp), which is a key efflux transporter, in hiPS cell-derived BMECs was detected at a relatively low level compared with primary human BMECs. In this study, we examined the involvement of the canonical Wnt signaling pathway, which contributes to the development of BBB formation, in the regulation of P-gp expression in hiPS cell-derived BMECs. We found that the barrier integrity was significantly enhanced in hiPS cell-derived BMECs treated with glycogen synthase kinase-3ß (GSK-3ß) inhibitors, which are known to positively regulate the canonical Wnt signaling pathway. In addition, our data also showed P-gp expression level was increased by treatment with GSK-3ß inhibitors. In conclusion, physiological barrier function and P-gp expression in BMECs can be enhanced by the canonical Wnt signaling pathway. Our results may be useful for promoting the development of drugs for central nervous system diseases using in vitro BBB model.

The role of galanin in the differentiation of mucosal mast cells in mice.

Mast cells are generally classified into two phenotypically distinct populations: mucosal-type mast cells (MMCs) and connective tissue-type mast cells (CTMCs). However, the molecular basis determining the different characteristics of the mast cell subclasses still remains unclear. Unfortunately, the number of mast cells that can be obtained from tissues is limited, which makes it difficult to study the function of each mast cell subclass. Here, we report the generation and characterization of MMCs and CTMCs derived from mouse BM mast cells (BMMCs). We found that the expression of galanin receptor 3 was elevated in MMCs when compared to the expression in CTMCs. Moreover, intraperitoneal injection of a galanin antagonist reduced MMCs and inhibited the inflammation of dextran sodium sulfate-induced colitis in mice. Therefore, these results suggest that galanin promotes MMC differentiation in vivo, and provide important insights into the molecular mechanisms underlying the differentiation of mast cell subclasses.

Functional Investigation of Solute Carrier Family 35, Member F2, in Three Cellular Models of the Primate Blood-Brain Barrier.

Understanding the mechanisms of drug transport across the blood-brain barrier (BBB) is an important issue for regulating the pharmacokinetics of drugs in the central nervous system. In this study, we focused on solute carrier family 35, member F2 (SLC35F2), whose mRNA is highly expressed in the BBB. SLC35F2 protein was enriched in isolated mouse and monkey brain capillaries relative to brain homogenates and was localized exclusively on the apical membrane of MDCKII cells and brain microvascular endothelial cells (BMECs) differentiated from human induced pluripotent stem cells (hiPS-BMECs). SLC35F2 activity was assessed using its substrate, YM155, and pharmacological experiments revealed SLC35F2 inhibitors, such as famotidine (half-maximal inhibitory concentration, 160 µM). Uptake of YM155 was decreased by famotidine or SLC35F2 knockdown in immortalized human BMECs (human cerebral microvascular endothelial cell/D3 cells). Furthermore, famotidine significantly inhibited the apical (A)-to-basal (B) transport of YM155 in primary cultured monkey BMECs and hiPS-BMECs. Crucially, SLC35F2 knockout diminished the A-to-B transport and intracellular accumulation of YM155 in hiPS-BMECs. By contrast, in studies using an in situ brain perfusion technique, neither deletion of Slc35f2 nor famotidine reduced brain uptake of YM155, even though YM155 is a substrate of mouse SLC35F2. YM155 uptake was decreased significantly by losartan and naringin, inhibitors for the organic anion transporting polypeptide (OATP) 1A4. These findings suggest SLC35F2 is a functional transporter in various cellular models of the primate BBB that delivers its substrates to the brain and that its relative importance in the BBB is modified by differences in the expression of OATPs between primates and rodents. SIGNIFICANCE STATEMENT: This study demonstrated that SLC35F2 is a functional drug influx transporter in three different cellular models of the primate blood-brain barrier (i.e., human cerebral microvascular endothelial cell/D3 cells, primary cultured monkey BMECs, and human induced pluripotent stem-BMECs) but has limited roles in mouse brain. SLC35F2 facilitates apical-to-basal transport across the tight cell monolayer. These findings will contribute to the development of improved strategies for targeting drugs to the central nervous system.

Silver-Promoted Fluorination Reactions of α-Bromoamides.

Silver-promoted C-F bond formation in α-bromoamides by using AgF under mild conditions is reported. This simple method enables access to tertiary, secondary, and primary alkyl fluorides involving biomolecular scaffolds. This transformation is applicable to primary and secondary amides and shows broad functional-group tolerance. Kinetics experiments revealed that the reaction rate increased in the order of 3°>2°>1° α-carbon atom. In addition, it was found that the acidic amide proton plays an important role in accelerating the reaction. Mechanistic studies suggested generation of an aziridinone intermediate that undergoes subsequent nucleophilic addition to form the C-F bond with stereospecificity (i.e., retention of configuration). The synthesis of sterically hindered alcohols and ethers by using AgI is also demonstrated. Examples of reactions of α-bromoamides with O nucleophiles are presented.

Trifluoromethylthiolation of Hindered α-Bromoamides with Nucleophilic Trifluoromethylthiolating Reagents.

General methods have not been previously developed for the synthesis of sterically hindered α-SCF3-substituted carbonyl compounds using nucleophilic trifluoromethylthiolating reagents. Thus, we herein report sp3C-SCF3 bond formation in hindered α-bromoamides containing 3-bromo-oxindoles and linear α-bromoamides using CuSCF3 or AgSCF3 under mild conditions to access sterically hindered α-SCF3-substituted amides. This transformation is applicable to not only 3-SCF3-substituted oxindoles but also primary and secondary amides and reveals a broad functional group tolerance. This method will benefit the fields of medicinal and agricultural chemistry.

Human Induced Pluripotent Stem Cell-Based Skin for Assessing Transdermal Drug Permeability and Irritancy.

To establish a system for assessing drug permeation and irritation of the skin, the permeation of benzoic acid and isosorbide dinitrate, which are listed in the Pharmacopoeia, and the chemical irritation were evaluated using skin generated from human induced pluripotent stem cells (iPSCs). Multilayer structures and cellular markers (keratin 14 and 10, which are in basal and suprabasal epidermal layers) were clearly detected in our iPSC-based skin. Transepidermal water loss (TEWL) decreased after iPSC-derived keratinocytes were cultured on collagen gels from human primary fibroblasts. These results indicate that the barrier function was partly increased by formation of the living epidermis. The cumulative amount of benzoic acid and isosorbide dinitrate across human iPSC-based skin gradually increased after an initial lag time. Moreover, the irritancy of various chemicals (non-irritants: ultrapure water, allyl phenoxy-acetate, isopropanol, and hexyl salicylate and irritants: 5% sodium dodecyl sulfate (SDS), heptanal, potassium hydroxide (5% aq.) and cyclamen aldehyde) to iPSC-based skin was almost met the irritation criteria of the Organisation for Economic Co-operation and Development (OECD) guideline. The results of our iPSC-based skin evaluation provide useful basic information for developing an assessment system to predict the permeation and safety of new transdermal drugs in human skin.

Monitoring of glutamate-induced excitotoxicity by mitochondrial oxygen consumption.

Dysfunction of mitochondrial activity is often associated with the onset and progress of neurodegenerative diseases. Membrane depolarization induced by Na+ influx increases intracellular Ca2+ levels in neurons, which upregulates mitochondrial activity. However, overlimit of Na+ influx and its prolonged retention ultimately cause excitotoxicity leading to neuronal cell death. To return the membrane potential to the normal level, Na+ /K+ -ATPase exchanges intracellular Na+ with extracellular K+ by consuming a large amount of ATP. This is a reason why mitochondria are important for maintaining neurons. In addition, astrocytes are thought to be important for supporting neighboring neurons by acting as energy providers and eliminators of excessive neurotransmitters. In this study, we examined the meaning of changes in the mitochondrial oxygen consumption rate (OCR) in primary mouse neuronal populations. By varying the medium constituents and using channel modulators, we found that pyruvate rather than lactate supported OCR levels and conferred on neurons resistance to glutamate-mediated excitotoxicity. Under a pyruvate-restricted condition, our OCR monitoring could detect excitotoxicity induced by glutamate at only 10 µM. The OCR monitoring also revealed the contribution of the N-methyl-D-aspartate receptor and Na+ /K+ -ATPase to the toxicity, which allowed evaluating spontaneous excitation. In addition, the OCR monitoring showed that astrocytes preferentially used glutamate, not glutamine, for a substrate of the tricarboxylic acid cycle. This mechanism may be coupled with astrocyte-dependent protection of neurons from glutamate-mediated excitotoxicity. These results suggest that OCR monitoring would provide a new powerful tool to analyze the mechanisms underlying neurotoxicity and protection against it.

Competing Interactions in Hierarchical Porphyrin Self-Assembly Introduce Robustness in Pathway Complexity.

Pathway complexity in supramolecular polymerization has recently sparked interest as a method to generate complex material behavior. The response of these systems relies on the existence of a metastable, kinetically trapped state. In this work, we show that strong switch-like behavior in supramolecular polymers can also be achieved through the introduction of competing aggregation pathways. This behavior is illustrated with the supramolecular polymerization of a porphyrin-based monomer at various concentrations, solvent compositions, and temperatures. It is found that the monomers aggregate via an isodesmic mechanism in weakly coupled J-type aggregates at intermediate solvent quality and temperature, followed by nucleated H-aggregates at lower solvent qualities and temperatures. At further increased thermodynamic driving forces, such as high concentration and low temperature, the H-aggregates can form hierarchical superhelices. Our mathematical models show that, contrary to a single-pathway polymerization, the existence of the isodesmic aggregation pathway buffers the free monomer pool and renders the nucleation of the H-aggregates insensitive to concentration changes in the limit of high concentrations. We also show that, at a given temperature or solvent quality, the thermodynamically stable aggregate morphology can be selected by controlling the remaining free external parameter. As a result, the judicious application of pathway complexity allows us to synthesize a diverse set of materials from only a single monomer. We envision that the engineering of competing pathways can increase the robustness in a wide variety of supramolecular polymer materials and lead to increasingly versatile applications.

Expression and Functional Characterization of Drug Transporters in Brain Microvascular Endothelial Cells Derived from Human Induced Pluripotent Stem Cells.

Brain microvascular endothelial cells derived from human induced pluripotent stem cells (hiPS-BMECs) have been proposed as a new blood-brain barrier model, but their transport function has not been fully clarified. Therefore, in this study, we investigated the gene expression and function of transporters in hiPS-BMECs by means of quantitative reverse transcription-PCR, in vitro transcellular transport studies, and uptake experiments. mRNAs encoding ABC and SLC transporters, such as BCRP, MCT1, CAT1, and GLAST, were highly expressed in hiPS-BMECs. Transcellular transport studies showed that prazosin, [14C]l-lactate, [3H]l-arginine, and [3H]l-glutamate (substrates of BCRP, MCT1, CAT1, and GLAST, respectively) were transported asymmetrically across the hiPS-BMEC monolayer. Substrates of LAT1, OCTN2, CAT1, GLAST, MCT1, and proton-coupled organic cation (H+/OC) antiporter were taken up by hiPS-BMECs in a time-, temperature-, and concentration-dependent manner, and the uptakes were markedly decreased by inhibitors of the corresponding transporter. These results indicate that hiPS-BMECs express multiple nutrient and drug transporters.

Prenatal diagnosis of premature chromatid separation/mosaic variegated aneuploidy (PCS/MVA) syndrome.

Premature chromatid separation/mosaic variegated aneuploidy (PCS/MVA) syndrome is a rare genetic disorder. In this case report, we describe the prenatal diagnosis of PCS/MVA syndrome in a 24-year-old, gravida 1, para 1, woman who was referred to us in her second trimester due to fetal growth restriction and extreme microcephaly (-5.0 standard deviations). Amniocentesis and chromosomal analysis confirmed PCS in 80% of cultured fetal cells. PCS findings were positive in 9% of paternal cells and 11% of maternal cells, indicative that both were PCS carriers. Genetic analysis confirmed that the fetus carried a combined heterozygote of maternal G > A point mutation of the promoter area of the BUB1B gene and a paternal Alu sequence insertion between intron 8 and exon 9 of the BUB1B gene. As PCS/MVA syndrome is associated with the development of various malignancies in early life, prenatal diagnosis is important for effective planning of post-natal care.

In vitro model of cerebral ischemia by using brain microvascular endothelial cells derived from human induced pluripotent stem cells.

Brain-derived microvascular endothelial cells (BMECs), which play a central role in blood brain barrier (BBB), can be used for the evaluation of drug transport into the brain. Although human BMEC cell lines have already been reported, they lack original properties such as barrier integrity. Pluripotent stem cells (PSCs) can be used for various applications such as regenerative therapy, drug screening, and pathological study. In the recent study, an induction method of BMECs from PSCs has been established, making it possible to more precisely study the in vitro human BBB function. Here, using induced pluripotent stem (iPS) cell-derived BMECs, we examined the effects of oxygen-glucose deprivation (OGD) and OGD/reoxygenation (OGD/R) on BBB permeability. OGD disrupted the barrier function, and the dysfunction was rapidly restored by re-supply of the oxygen and glucose. Interestingly, TNF-α, which is known to be secreted from astrocytes and microglia in the cerebral ischemia, prevented the restoration of OGD-induced barrier dysfunction in an apoptosis-independent manner. Thus, we could establish the in vitro BBB disease model that mimics the cerebral ischemia by using iPS cell-derived BMECs.

CCAAT/enhancer binding protein-mediated regulation of TGFß receptor 2 expression determines the hepatoblast fate decision.

Human embryonic stem cells (hESCs) and their derivatives are expected to be used in drug discovery, regenerative medicine and the study of human embryogenesis. Because hepatocyte differentiation from hESCs has the potential to recapitulate human liver development in vivo, we employed this differentiation method to investigate the molecular mechanisms underlying human hepatocyte differentiation. A previous study has shown that a gradient of transforming growth factor beta (TGFß) signaling is required to segregate hepatocyte and cholangiocyte lineages from hepatoblasts. Although CCAAT/enhancer binding proteins (c/EBPs) are known to be important transcription factors in liver development, the relationship between TGFß signaling and c/EBP-mediated transcriptional regulation in the hepatoblast fate decision is not well known. To clarify this relationship, we examined whether c/EBPs could determine the hepatoblast fate decision via regulation of TGFß receptor 2 (TGFBR2) expression in the hepatoblast-like cells differentiated from hESCs. We found that TGFBR2 promoter activity was negatively regulated by c/EBPα and positively regulated by c/EBPß. Moreover, c/EBPα overexpression could promote hepatocyte differentiation by suppressing TGFBR2 expression, whereas c/EBPß overexpression could promote cholangiocyte differentiation by enhancing TGFBR2 expression. Our findings demonstrated that c/EBPα and c/EBPß determine the lineage commitment of hepatoblasts by negatively and positively regulating the expression of a common target gene, TGFBR2, respectively.

TANK-binding kinase 1-dependent or -independent signaling elicits the cell-type-specific innate immune responses induced by the adenovirus vector.

Adenovirus vectors (Adv) elicit innate immune responses via several pattern-recognition receptors. Although it has been suggested that various Adv-induced mechanisms play important roles in the induction of innate immunity in vitro, the impacts of these mechanisms in vivo remain unclear. Viral nucleic acids elicit innate immune responses through the recognition of cytosolic nucleic acid sensors and transduce intracellular signals to TANK-binding kinase (TBK) 1. In this study, to determine the impacts of viral nucleic acids on innate immune responses in vivo, we administered transgene-expressing Adv to Tbk1-deficient mice. The systemic Adv administration failed to induce type I interferons (type I IFNs) in the spleen, but not the liver, of Tbk1-deficient mice, resulting in the increase of transgene-expressing cells in the spleen, but not the liver. Moreover, Adv failed to induce type I IFNs in the bone-marrow-derived dendritic cells, but not the mouse embryonic fibroblasts, from Tbk1-deficient mice in vitro. These results support the idea that Adv elicit innate immunity in immune cells and non-immune cells in a TBK1-dependent and TBK1-independent manner, respectively.

Characterization of glycoproteins expressing the blood group H type 1 epitope on human induced pluripotent stem (hiPS) cells.

Recently, we established two mouse monoclonal antibodies (R-10G and R-17F). The R-17F antibody (IgG1 subtype) exhibited a strong cytotoxic effect on hiPS/ES cells. The R-17F antigen isolated from a total lipid extract of hiPS (Tic) cells was identified as LNFP I (Fucα1-2Galß1-3GlcNAcß1-3Galß1-4Glc). In the present study, R-17F binding proteins were isolated from hiPS (Tic) cell lysates with an affinity column of R-17F. They gave one major R-17F positive band around 250 kDa, and several minor bands between 150 kDa and 25 kDa. The former band was identified as podocalyxin by LC/MS/MS after SDS-PAGE. Hapten inhibition studies on R-17F binding to R-17F column-purified proteins with various synthetic oligosaccharides revealed that the blood group H type 1 triaose structure (Fucα1-2Galß1-3GlcNAc) was the predominant epitope on all the R-17F binding proteins. These bands disappeared completely on digestion with α1-2 fucosidase, but not with α1-3/4 fucosidase. Upon PNGase F digestion, the R-17F positive band around and above 250 kDa did not show any change, while the minor bands between 150 kDa and 25 kDa disappeared completely, suggesting that the epitope is expressed on N-glycans in the latter and probably on O-glycans in the former. These results, together with those obtained in our previous studies on R-10G (Kawabe et al. Glycobiology, 23, 322-336 (2013)), indicated that both R-10G and R-17F epitopes are carried on the same podocalyxin molecule. The R-17F epitopes on these glycoproteins expressed on hiPS cells could be associated with the molecular mechanism underlying the carbohydrate-mediated cytotoxic activity of R-17F.

Induction of amphiregulin by p53 promotes apoptosis via control of microRNA biogenesis in response to DNA damage.

Upon DNA damage, tumor suppressor p53 determines cell fate by repairing DNA lesions to survive or by inducing apoptosis to eliminate damaged cells. The decision is based on its posttranslational modifications. Especially, p53 phosphorylation at Ser46 exerts apoptotic cell death. However, little is known about the precise mechanism of p53 phosphorylation on the induction of apoptosis. Here, we show that amphiregulin (AREG) is identified for a direct target of Ser46 phosphorylation via the comprehensive expression analyses. Ser46-phosphorylated p53 selectively binds to the promoter region of AREG gene, indicating that the p53 modification changes target genes by altering its binding affinity to the promoter. Although AREG belongs to a family of the epidermal growth factor, it also emerges in the nucleus under DNA damage. To clarify nuclear function of AREG, we analyze AREG-binding proteins by mass spectrometry. AREG interacts with DEAD-box RNA helicase p68 (DDX5). Intriguingly, AREG regulates precursor microRNA processing (i.e., miR-15a) with DDX5 to reduce the expression of antiapoptotic protein Bcl-2. These findings collectively support a mechanism in which the induction of AREG by Ser46-phosphorylated p53 is required for the microRNA biogenesis in the apoptotic response to DNA damage.

A Cytotoxic Antibody Recognizing Lacto-N-fucopentaose I (LNFP I) on Human Induced Pluripotent Stem (hiPS) Cells.

We have generated a mouse monoclonal antibody (R-17F, IgG1 subtype) specific to human induced pluripotent stem (hiPS)/embryonic stem (ES) cells by using a hiPS cell line as an antigen. Triple-color confocal immunostaining images of hiPS cells with R-17F indicated that the R-17F epitope was expressed exclusively and intensively on the cell membranes of hiPS cells and co-localized partially with those of SSEA-4 and SSEA-3. Lines of evidence suggested that the predominant part of the R-17F epitope was a glycolipid. Upon TLC blot of total lipid extracts from hiPS cells with R-17F, one major R-17F-positive band was observed at a slow migration position close to that of anti-blood group H1(O) antigen. MALDI-TOF-MS and MS(n) analyses of the purified antigen indicated that the presumptive structure of the R-17F antigen was Fuc-Hex-HexNAc-Hex-Hex-Cer. Glycan microarray analysis involving 13 different synthetic oligosaccharides indicated that R-17F bound selectively to LNFP I (Fucα1-2Galß1-3GlcNAcß1-3Galß1-4Glc). A critical role of the terminal Fucα1-2 residue was confirmed by the selective disappearance of R-17F binding to the purified antigen upon α1-2 fucosidase digestion. Most interestingly, R-17F, when added to hiPS/ES cell suspensions, exhibited potent dose-dependent cytotoxicity. The cytotoxic effect was augmented markedly upon the addition of the secondary antibody (goat anti-mouse IgG1 antibody). R-17F may be beneficial for safer regenerative medicine by eliminating residual undifferentiated hiPS cells in hiPS-derived regenerative tissues, which are considered to be a strong risk factor for carcinogenesis.