A Human Antibody That Binds to the Sixth Ig-Like Domain of VCAM-1 Blocks Lung Cancer Cell Migration In Vitro

Vascular cell adhesion molecule-1 (VCAM-1) is closely associated with tumor progression and metastasis. However, the relevance and role of VCAM-1 in lung cancer have not been clearly elucidated. In this study, we found that VCAM-1 was highly overexpressed in lung cancer tissue compared with that of normal lung tissue, and high VCAM-1 expression correlated with poor survival in lung cancer patients. VCAM-1 knockdown reduced migration of A549 human lung cancer cells into Matrigel, and competitive blocking experiments targeting the Ig-like domain 6 of VCAM-1 (VCAM-1-D6) demonstrated that the VCAM-1-D6 domain was critical for VCAM-1 mediated A549 cell migration into Matrigel. Next, we developed a human monoclonal antibody specific to human and mouse VCAM-1-D6 (VCAM-1-D6 huMab), which was isolated from a human synthetic antibody library using phage display technology. Finally, we showed that VCAM-1-D6 huMab had a nanomolar affinity for VCAM-1-D6 and that it potently suppressed the migration of A549 and NCI-H1299 lung cancer cell lines into Matrigel. Taken together, these results suggest that VCAM-1-D6 is a key domain for regulating VCAM-1-mediated lung cancer invasion and that our newly developed VCAM-1-D6 huMab will be a useful tool for inhibiting VCAM-1-expressing lung cancer cell invasion.

28 IMPROVED HATCH RATE AFTER PARTIAL DISSECTION OF ZONA PELLUCIDA IN CLONED PIG EMBRYO

For last 20 years, the efficiency of animal cloning has remained extremely low, despite many attempts to improve it. Although nuclear transfer experiments have been almost optimized, artificial holes are inevitably made in the zona pellucida (ZP) during nuclear transfer experiments, such as enucleation of maternal genome or injection of nuclear donor. Hatching from the ZP is a prerequisite for mammalian embryo implantation, and the condition of the ZP has a lot of influence on hatching. The present studies were performed to investigate the effects of artificial holes in the ZP, because of the nuclear transfer procedure, on hatching of clone embryos in pigs. All experiments were done in triplicate. Statistical analysis was performed using SPSS statistical software (SPSS Inc., Chicago, IL, USA). First, we made a slit in the ZP of porcine parthenote that was identical to the artificial holes of nuclear transfer experiment and compared in vitro development of Day 7 embryos with control group with intact ZP. Of slit blastocysts, 89.9% (80/89) were trapped at a slit, which looked like typical figure-eight shape, and did not complete the hatching process until Day 8, though 68.8% (64/93) of control blastocysts completed the hatching at Day 7. Then, to solve these abnormal hatchings caused by a slit in the ZP, we applied partial zona dissection (PZD) to porcine clone embryos and compared the hatching process with that of conventional clone embryos. Contrary to conventional clone blastocysts that were trapped at slit in the ZP (91.4%; 43/47), 89.5% (60/67) of clone blastocysts in PZD group were preferentially hatched through dissected hole at Day 7. These results suggest that trapping of conventional clone blastocyst in a slit of the ZP could be avoided by PZD. Through this study, we demonstrated that a slit in the ZP would hinder a blastocyst from hatching from the ZP and that partial dissection at the ZP could help clone blastocyst to hatch without trapping at a slit in the ZP. This assisted hatching in clone embryos would be useful for the successful hatching of clone blastocysts with a capacity of full-term development, so that the efficiency of animal cloning might be improved.

199 EFFECTS OF REPROGRAMMING-CONDITIONED MEDIUM ON ULTRAVIOLET RAY A–DAMAGED HUMAN DERMAL FIBROBLASTS

Ultraviolet ray A (UVA) is an electromagnetic light with a long wavelength from the sun. The penetration of UVA deep into the human dermis causes changes in cells, such as DNA fragmentation, apoptosis, and senescence, eventually leading a decline of proliferation and wound-healing ability. These changes induced by UVA exposure are similar to those seen in the process of stem cell differentiation. We postulated that the condition that reverses cellular differentiation may alleviate the UVA-induced damage in skin cells. Human dermal fibroblasts (HDF) could be reprogrammed to induced pluripotent stem cells (iPSC). Conditioned medium (CM) was prepared during the process of iPSC reprogramming (referred to as Repro-CM). The UVA-irradiated HDF were cultured in Repro-CM for 24 h. In comparison with CM prepared from the culture of normal HDF and iPSC (referred to as HDF-CM and iPSC-CM, respectively), effects of Repro-CM on UVA-irradiated cells were investigated. Viability, wound-healing ability, apoptosis, and senescence of HDF were analysed by WST-1 assay, scratch assay, Annexin V assay, and senescence-associated β-galactosidase assay, respectively. Upon recovering from the UVA-induced damage, viability and wound-healing ability of HDF were significantly different (P < 0.05) among the treatments in the order of Repro-, HDF-, and iPSC-CM. In the same context, apoptosis and senescence were significantly different (P < 0.05) in the order of iPSC-, HDF-, and Repro-CM. Interestingly, iPSC-CM did not substantially ameliorate UVA-induced damage, suggesting that the conditions optimized to pluripotent stem cells may not be suitable for the recovery from damage in terminally differentiated cells, such as fibroblasts. The RNA-seq analysis was performed to assess the genome-wide transcriptional profile in the process of recovery. Repro- and HDF-CM were categorized more closely than iPSC-CM in hierarchical cluster analysis. In comparison with iPSC-CM, the up-regulated genes by Repro-CM treatment were related to regulation of cell proliferation and cell metabolism, whereas down-regulated genes were related to antiapoptosis and response to stimulation of chemical and organic substances. Overall, providing an environment of reprogramming, as shown by Repro-CM in the present study, may assist recovery of HDF from UVA-induced damage. The results of the study may be applicable in developing pharmaceuticals to treat aging and wrinkling of the skin caused by UVA irradiation.

Secreted tryptophanyl-tRNA synthetase as a primary defence system against infection

The N-terminal truncated form of a protein synthesis enzyme, tryptophanyl-tRNA synthetase (mini-WRS), is secreted as an angiostatic ligand. However, the secretion and function of the full-length WRS (FL-WRS) remain unknown. Here, we report that the FL-WRS, but not mini-WRS, is rapidly secreted upon pathogen infection to prime innate immunity. Blood levels of FL-WRS were increased in sepsis patients, but not in those with sterile inflammation. FL-WRS was secreted from monocytes and directly bound to macrophages via a toll-like receptor 4 (TLR4)-myeloid differentiation factor 2 (MD2) complex to induce phagocytosis and chemokine production. Administration of FL-WRS into Salmonella typhimurium-infected mice reduced the levels of bacteria and improved mouse survival, whereas its titration with the specific antibody aggravated the infection. The N-terminal 154-amino-acid eukaryote-specific peptide of WRS was sufficient to recapitulate FL-WRS activity and its interaction mode with TLR4-MD2 is now suggested. Based on these results, secretion of FL-WRS appears to work as a primary defence system against infection, acting before full activation of innate immunity.

Synthetic approach to the generation of antibody diversity

The in vitro antibody discovery technologies revolutionized the generation of target-specific antibodies that traditionally relied on the humoral response of immunized animals. An antibody library, a large collection of diverse, pre-constructed antibodies, can be rapidly screened using in vitro display technologies such as phage display. One of the keys to successful in vitro antibody discovery is the quality of the library diversity. Antibody diversity can be obtained either from natural B-cell sources or by the synthetic methods that combinatorially generate random nucleotide sequences. While the functionality of a natural antibody library depends largely upon the library size, various other factors can affect the quality of a synthetic antibody library, making the design and construction of synthetic antibody libraries complicated and challenging. In this review, we present various library designs and diversification methods for synthetic antibody library. From simple degenerate oligonucleotide synthesis to trinucleotide synthesis to physicochemically optimized library design, the synthetic approach is evolving beyond the simple emulation of natural antibodies, into a highly sophisticated method that is capable of producing high quality antibodies suitable for therapeutic, diagnostic, and other demanding applications. [BMB Reports 2015; 48(9): 489-494]

Discovery of novel peptides targeting pro-atherogenic endothelium in disturbed flow regions -Targeted siRNA delivery to pro-atherogenic endothelium in vivo

Atherosclerosis occurs preferentially in arterial regions exposed to disturbed blood flow. Targeting these pro-atherogenic regions is a potential anti-atherogenic therapeutic approach, but it has been extremely challenging. Here, using in vivo phage display approach and the partial carotid ligation model of flow-induced atherosclerosis in mouse, we identified novel peptides that specifically bind to endothelial cells (ECs) exposed to disturbed flow condition in pro-atherogenic regions. Two peptides, CLIRRTSIC and CPRRSHPIC, selectively bound to arterial ECs exposed to disturbed flow not only in the partially ligated carotids but also in the lesser curvature and branching point of the aortic arch in mice as well as human pulmonary artery branches. Peptides were conjugated to branched polyethylenimine-polyethylene glycol polymer to generate polyplexes carrying siRNA targeting intercellular adhesion molecule-1 (siICAM-1). In mouse model, CLIRRTSIC polyplexes carrying si-ICAM-1 specifically bound to endothelium in disturbed flow regions, reducing endothelial ICAM-1 expression. Mass spectrometry analysis revealed that non-muscle myosin heavy chain II A (NMHC IIA) is a protein targeted by CLIRRTSIC peptide. Further studies showed that shear stress regulates NMHC IIA expression and localization in ECs. The CLIRRTSIC is a novel peptide that could be used for targeted delivery of therapeutics such as siRNAs to pro-atherogenic endothelium.

221 DERIVATION OF INSULIN-PRODUCING CELLS FROM HUMAN DERMAL FIBROBLASTS AT INTERMEDIATE PHASE OF REPROGRAMMING

Process of somatic cell reprogramming into induced pluripotent stem (iPS) cells can broadly be divided into an early stochastic phase and a later, hierarchical and more deterministic phase of gene activation. Between the stochastic onset and the deterministic progression while approaching pluripotency, cells upon reprogramming undergo a transient activation or repression of developmental regulators. In these intermediate cells yet acquiring pluripotency, many somatic gene expressions are lost, while various lineage-specific factors are activated. In the present study, we produced pancreatic β cells by exposing human dermal fibroblasts (HDF) at the intermediate phase of reprogramming to pancreas-specific culture conditions. To obtain the intermediate cells, reprogramming factor Oct4, Sox2, Klf4, and c-Myc were transduced into HDF using retroviruses. By Day 9 after transduction, the expression of fibroblast-associated Thy1 was lost, while the early reprogramming marker CD49d was activated, suggesting that the cells are at the early stage of intermediate phase. These cells were capable of differentiating into 3 germ layers when cultured in tri-differentiation medium (including 100 ng mL–1 Activin A, 0.1 ng mL–1 Wnt3 for endodermal differentiation; 20 ng mL–1 BMP4, 20 ng mL–1 Activin A for mesodermal differentiation; 10 μM SB431542, 600 ng mL–1 Dorsomorphin, and 35 ng mL–1 Noggin for ectodermal differentiation) and expressing lineage-specific markers Sox17 (endoderm), Brachyury (mesoderm), and Otx2 (ectoderm). Further, the endodermal cells derived from HDF at intermediate phase of reprogramming were cultured in pancreas-induction medium (KO DMEM with 1% insulin-transferrin-selenium (ITS), 10 ng mL–1 BMP4, 10 mM nicotinamide, 10 μM forskolin, 10 μM dexamethasone, and 50 ng mL–1 exendin-4). After 5 days in culture, cells expressed pancreatic progenitor marker Pdx1, as examined by immunostaining and fluorescence-activated cell sorting (FACS) analysis. After culture for additional 10 days, the cells formed spherical clusters and expressed pancreatic islet-specific genes including insulin, somatostatin, glucagon, Nkx6.1, and MafA, as determined by RT-PCR. Moreover, the production of insulin and C-peptide from the derived β cells was confirmed by immunocytochemistry and FACS analysis. In response to glucose stimulation, these cells secreted insulin and C-peptide, as measured by ELISA. The present study demonstrates that fully differentiated functional cells could be converted from somatic cells at intermediate phase of reprogramming by exposing cells to specific culture conditions. The results shown in this study may provide a faster and potentially safer way to produce functional pancreatic cells without isolation and differentiation of iPS cells.

Generation of a human antibody that inhibits TSPAN8-mediated invasion of metastatic colorectal cancer cells

Tetraspanin 8 (TSPAN8) is a tumor-associated antigen implicated in tumor progression and metastasis. However, the validation of TSPAN8 as a potential therapeutic target in metastatic colorectal cancer (mCRC) has not yet been studied. In this study, through several in vitro methodologies, we identified a large extracellular loop of TSPAN8 (TSPAN8-LEL) as a key domain for regulating mCRC invasion. Using phage display technology, we developed a novel anti-TSPAN8-LEL human antibody with subnanomolar affinity that specifically recognizes amino acids 140-205 of TSPAN8-LEL in a conformation-dependent manner. Finally, we demonstrated that the antibody specifically reduces invasion in the HCT116 and LoVo mCRC cell lines more potently than in the HCT-8 and SW480 non-mCRC cell lines. Our data suggest that TSPAN8-LEL may play an important role in mCRC cell invasion, and that the antibody we have developed could be a useful tool for inhibiting the invasion of TSPAN8-expressing mCRCs.

Affinity Maturation of Monoclonal Antibody 1E11 by Targeted Randomization in CDR3 Regions Optimizes Therapeutic Antibody Targeting of HER2-Positive Gastric Cancer

Anti-HER2 murine monoclonal antibody 1E11 has strong and synergistic anti-tumor activity in HER2-overexpressing gastric cancer cells when used in combination with trastuzumab. We presently optimized this antibody for human therapeutics. First, the complementarity determining regions (CDRs) of the murine antibody were grafted onto human germline immunoglobulin variable genes. No difference in affinity and biological activity was observed between chimeric 1E11 (ch1E11) and humanized 1E11 (hz1E11). Next, affinity maturation of hz1E11 was performed by the randomization of CDR-L3 and H3 residues followed by stringent biopanning selection. Milder selection pressure favored the selection of more diverse clones, whereas higher selection stringency resulted in the convergence of the panning output to a smaller number of clones with improved affinity. Clone 1A12 had four amino acid substitutions in CDR-L3, and showed a 10-fold increase in affinity compared to the parental clone and increased potency in an in vitro anti-proliferative activity assay with HER2-overepxressing gastric cancer cells. Clone 1A12 inhibited tumor growth of NCI-N87 xenograft model with similar efficacy to trastuzumab alone, and the combination treatment of 1A12 and trastuzumab completely removed the established tumors. These results suggest that humanized and affinity matured monoclonal antibody 1A12 is a highly optimized molecule for future therapeutic development against HER2-positive tumors.

216 COMPLETE REDUCTION OF p53 EXPRESSION BY RNA INTERFERENCE FOLLOWING HETEROZYGOUS KNOCKOUT IN PORCINE FIBROBLASTS

Because p53 has a critical role in regulation of cell cycle and apoptosis in mammals, mutations of p53 often cause various cancers in mammals. Murine models have contributed to our understanding in cancer related to p53 mutations. Mice, however, have different characteristics from humans in many ways. For instance, the short lifespan of the mouse gives rise to limitations in clinical application of the data obtained from this species. Hence, it would be beneficial to establish a more suitable model in species other than the mouse. The porcine model could be an appropriate alternative because pigs share many anatomical and physiological similarities with humans. However, the production of pigs with homozygous knockout (KO) requires years of breeding heterozygous KO animals. Here, we completely reduced the expression level of p53 mRNA and protein in miniature pig fetal fibroblasts using a combination of gene targeting and RNA interference technique. These cells may be used for nuclear transfer to directly produce pigs without expression of the gene of interest. First, we disrupted the exon 2 region of p53 gene to produce p53 heterozygous KO cells. Miniature pig fetal fibroblasts were transfected with the p53 gene targeting vector. After Geneticin treatment for 2 weeks, a total of 48 surviving colonies were screened by PCR, and one was identified as a homologous recombinant (1/48, 2.08%). Second, the p53 shRNA expression vector was introduced into fibroblasts to isolate p53 knockdown (KD) cells. Transfected fibroblasts were treated with Zeocin for 3 weeks, and the shRNA integrations were confirmed by PCR. We obtained p53 KO, KD, and KOKD fibroblasts which involve p53 KO and KD either separately or simultaneously. In mRNA expression based on RT-PCR, p53 KO fibroblasts showed no difference with wild-type control (91.8 v. 100%). However, the expression levels of KD and KOKD cells significantly decreased (35.5 and 34.7%) compared with the control. In p53 protein levels analysed by Western blot, reduction of the protein was observed in p53 KD, whereas no reduction in p53 KO that might be due to heterozygous mutation. Interestingly, no p53 protein was detected in KOKD, suggesting complete reduction of the protein by synergistic effect of KO and KD. In this study, we demonstrated that various expression levels of p53 in porcine fibroblasts could be achieved by gene targeting and RNA interference technique. Moreover, complete abolishment of protein expression is feasible using combination of the 2 techniques. In further research, cloned miniature pigs with various levels of p53 expression or even lacking p53 expression may be produced using the fibroblasts isolated in the present study as nuclear donors. These pigs may provide new animal models and insights in cancer with respect to the effect of p53.

Human antibodies targeting the C-type lectin-like domain of the tumor endothelial cell marker clec14a regulate angiogenic properties in vitro

It has been suggested that clec14a may be involved in tumor angiogenesis. However, a molecular mechanism has not been clearly identified. In this study, we show for the first time that C-type lectin-like domain (CTLD) of clec14a may be important for regulating cell migration and filopodia formation. Using phage display technology, recombinant human antibodies specific to the CTLDs of human and mouse clec14a (clec14a-CTLD (immunoglobulin G) IgG) were selected. Functional assays using the antibodies showed that clec14a-CTLD IgGs specifically blocked endothelial cell migration and tube formation without affecting cell viability or activation. Further, clec14a-CTLD IgGs inhibited clec14a-mediated cell–cell contact by blocking interaction between CTLDs. Finally, clec14a cross-linking by the clec14a-CTLD IgGs significantly downregulated clec14a expression on the surface of endothelial cells. These results strongly suggest that the clec14a-CTLD may be a key domain in angiogenesis, and that clec14a-CTLD IgGs specifically inhibit angiogenesis by modulating CTLD-mediated cell interactions and clec14a expression on the surface of endothelial cells.