A Novel Total Drug Assay for Quantification of Anti-C5 Therapeutic Monoclonal Antibody in the Presence of Abundant Target.

SKY59 or RO7112689 is a humanized monoclonal antibody against complement protein C5 with pH-dependent C5-binding and neonatal Fc receptor-mediated recycling capabilities, which result in long-lasting neutralization of C5. We developed and validated a novel total drug assay for quantification of target-binding competent SKY59 in the presence of endogenous C5 in cynomolgus monkey plasma. The target-binding competent SKY59 was determined after complex formation by the addition of recombinant monkey C5 using goat anti-human IgG-heavy chain monkey-adsorbed polyclonal antibody as a capture antibody and rabbit anti-C5 monoclonal antibody (mAb) non-competing with SKY59 for detection. The total SKY59 assay was shown to be accurate and precise over the range of 0.05-3.2 µg/mL as well as be tolerant to more than 400 µg/mL of C5 (~ 3000-fold molar excess of target). We also developed and validated a total C5 assay, confirmed selectivity and parallelism, and verified the utility of recombinant monkey C5 for the total C5 assay as well as the total SKY59 assay. Furthermore, we used these validated methods to measure SKY59 and C5 concentrations in cynomolgus monkey plasma samples in a toxicology study. This total drug assay can be applied not only to other antibody therapeutics against shed/soluble targets when a non-competing reagent mAb is available but also for clinical studies when a reagent mAb specific for engineered Fc region on a therapeutic mAb is available.

Novel myostatin-specific antibody enhances muscle strength in muscle disease models.

Myostatin, a member of the transforming growth factor-ß superfamily, is an attractive target for muscle disease therapy because of its role as a negative regulator of muscle growth and strength. Here, we describe a novel antibody therapeutic approach that maximizes the potential of myostatin-targeted therapy. We generated an antibody, GYM329, that specifically binds the latent form of myostatin and inhibits its activation. Additionally, via "sweeping antibody technology", GYM329 reduces or "sweeps" myostatin in the muscle and plasma. Compared with conventional anti-myostatin agents, GYM329 and its surrogate antibody exhibit superior muscle strength-improvement effects in three different mouse disease models. We also demonstrate that the superior efficacy of GYM329 is due to its myostatin specificity and sweeping capability. Furthermore, we show that a GYM329 surrogate increases muscle mass in normal cynomolgus monkeys without any obvious toxicity. Our findings indicate the potential of GYM329 to improve muscle strength in patients with muscular disorders.

Antibody engineering to generate SKY59, a long-acting anti-C5 recycling antibody.

Modulating the complement system is a promising strategy in drug discovery for disorders with uncontrolled complement activation. Although some of these disorders can be effectively treated with an antibody that inhibits complement C5, the high plasma concentration of C5 requires a huge dosage and frequent intravenous administration. Moreover, a conventional anti-C5 antibody can cause C5 to accumulate in plasma by reducing C5 clearance when C5 forms an immune complex (IC) with the antibody, which can be salvaged from endosomal vesicles by neonatal Fc receptor (FcRn)-mediated recycling. In order to neutralize the increased C5, an even higher dosage of the antibody would be required. This antigen accumulation can be suppressed by giving the antibody a pH-dependent C5-binding property so that C5 is released from the antibody in the acidic endosome and then trafficked to the lysosome for degradation, while the C5-free antibody returns back to plasma. We recently demonstrated that a pH-dependent C5-binding antibody, SKY59, exhibited long-lasting neutralization of C5 in cynomolgus monkeys, showing potential for subcutaneous delivery or less frequent administration. Here we report the details of the antibody engineering involved in generating SKY59, from humanizing a rabbit antibody to improving the C5-binding property. Moreover, because the pH-dependent C5-binding antibodies that we first generated still accumulated C5, we hypothesized that the surface charges of the ICs partially contributed to a slow uptake rate of the C5-antibody ICs. This idea motivated us to engineer the surface charges of the antibody. Our surface-charge engineered antibody consequently exhibited a high capacity to sweep C5 and suppressed the C5 accumulation in vivo by accelerating the cycle of sweeping: uptake of ICs into cells, release of C5 from the antibody in endosomes, and salvage of the antigen-free antibody. Thus, our engineered anti-C5 antibody, SKY59, is expected to provide significant benefits for patients with complement-mediated disorders.

Long lasting neutralization of C5 by SKY59, a novel recycling antibody, is a potential therapy for complement-mediated diseases.

Dysregulation of the complement system is linked to the pathogenesis of a variety of hematological disorders. Eculizumab, an anti-complement C5 monoclonal antibody, is the current standard of care for paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS). However, because of high levels of C5 in plasma, eculizumab has to be administered biweekly by intravenous infusion. By applying recycling technology through pH-dependent binding to C5, we generated a novel humanized antibody against C5, SKY59, which has long-lasting neutralization of C5. In cynomolgus monkeys, SKY59 suppressed C5 function and complement activity for a significantly longer duration compared to a conventional antibody. Furthermore, epitope mapping by X-ray crystal structure analysis showed that a histidine cluster located on C5 is crucial for the pH-dependent interaction with SKY59. This indicates that the recycling effect of SKY59 is driven by a novel mechanism of interaction with its antigen and is distinct from other known pH-dependent antibodies. Finally, SKY59 showed neutralizing effect on C5 variant p.Arg885His, while eculizumab does not inhibit complement activity in patients carrying this mutation. Collectively, these results suggest that SKY59 is a promising new anti-C5 agent for patients with PNH and other complement-mediated disorders.

miRNAs and regulation of cell signaling.

MicroRNAs (miRNAs) regulate gene expression post-transcriptionally by binding to target mRNAs in a sequence-specific manner. A large number of genes appear to be the target of miRNAs, and an essential role for miRNAs in the regulation of various conserved cell signaling cascades, such as mitogen-activated protein kinase, Notch and Hedgehog, is emerging. Extensive studies have also revealed the spatial and temporal regulation of miRNA expression by various cell signaling cascades. The insights gained in such studies support the idea that miRNAs are involved in the highly complex network of cell signaling pathways. In this minireview, we present an overview of these complex networks by providing examples of recent findings.

The silkworm Green b locus encodes a quercetin 5-O-glucosyltransferase that produces green cocoons with UV-shielding properties.

In the silkworm Bombyx mori, dietary flavonoids are metabolized and accumulate in cocoons, thereby causing green coloration. Classical genetic studies suggest that more than seven independent loci are associated with this trait; however, because of the complex inheritance pattern, none of these loci have been characterized molecularly, and a plausible and comprehensive model for their action has not been proposed. Here, we report the identification of the gene responsible for the Green b (Gb) locus involving the green cocoon trait. In +(Gb) animals, glucosylation at the 5-O position of dietary quercetin did not occur, and the total amount of flavonoids in tissues and cocoons was dramatically reduced. We performed positional cloning of Gb and found a 38-kb deletion in a UDP-glucosyltransferase (UGT) gene cluster associated with the +(Gb) allele. RT-PCR and biochemical studies suggested that deletion of Bm-UGT10286 (UGT) is responsible for Gb and Bm-UGT10286 is virtually the sole source of UGT activity toward the 5-O position of quercetin. Our data show that the regiospecific glucosylation of flavonoids by the quercetin 5-O-glucosyltransferase can greatly affect the overall bioavailability of flavonoids in animals. Furthermore, we provide evidence that flavonoids increase the UV-shielding activity of cocoons and thus could confer an increased survival advantage to insects contained in these cocoons. This study will lead to greater understanding of mechanisms for metabolism, uptake, and transport of dietary flavonoids, which have a variety of biological activities in animals and beneficial effects on human health.

MicroRNA-34a inhibits cell proliferation by repressing mitogen-activated protein kinase kinase 1 during megakaryocytic differentiation of K562 cells.

Phorbol 12-myristate 13-acetate (PMA) induces megakaryocytic differentiation of the human chronic myelocytic leukemia cell line K562. We examined the potential regulatory role of microRNAs (miRNAs) in this process. Genome-wide expression profiling identified 21 miRNAs (miRs) that were induced by the treatment of K562 cells with PMA. Among them, the expression of miR-34a, miR-221, and miR-222 was induced in the early stages and maintained throughout the late stages of differentiation. Cell signaling analysis showed that the activation of extracellular signal-regulated protein kinase (ERK) in response to PMA strongly induced miR-34a expression by transactivation via the activator protein-1 binding site in the upstream region of the miR-34a gene. Reporter gene assays identified mitogen-activated protein kinase kinase 1 (MEK1) as a direct target of miR-34a and c-fos as a direct target of miR-221/222. Although overexpression of the three miRNAs had little effect on cell differentiation, overexpression of miR-34a significantly repressed the proliferation of K562 cells with a concomitant reduction in MEK1 protein expression. Conversely, a locked nucleic acid probe against miR-34a significantly enhanced the proliferation of PMA-treated K562 cells. Taken together, the results show that PMA activates the MEK-ERK pathway and strongly induces miRNA-34a expression, which in turn inhibits cell proliferation by repressing the expression of MEK1. Thus, the results highlight an important regulatory role for miR-34a in the process of megakaryocytic differentiation, especially in the arrest of cell growth, which is a prerequisite for cells to enter differentiation.

Genome-wide analysis of aberrant methylation in human breast cancer cells using methyl-DNA immunoprecipitation combined with high-throughput sequencing.

BACKGROUND: Cancer cells undergo massive alterations to their DNA methylation patterns that result in aberrant gene expression and malignant phenotypes. However, the mechanisms that underlie methylome changes are not well understood nor is the genomic distribution of DNA methylation changes well characterized. RESULTS: Here, we performed methylated DNA immunoprecipitation combined with high-throughput sequencing (MeDIP-seq) to obtain whole-genome DNA methylation profiles for eight human breast cancer cell (BCC) lines and for normal human mammary epithelial cells (HMEC). The MeDIP-seq analysis generated non-biased DNA methylation maps by covering almost the entire genome with sufficient depth and resolution. The most prominent feature of the BCC lines compared to HMEC was a massively reduced methylation level particularly in CpG-poor regions. While hypomethylation did not appear to be associated with particular genomic features, hypermethylation preferentially occurred at CpG-rich gene-related regions independently of the distance from transcription start sites. We also investigated methylome alterations during epithelial-to-mesenchymal transition (EMT) in MCF7 cells. EMT induction was associated with specific alterations to the methylation patterns of gene-related CpG-rich regions, although overall methylation levels were not significantly altered. Moreover, approximately 40% of the epithelial cell-specific methylation patterns in gene-related regions were altered to those typical of mesenchymal cells, suggesting a cell-type specific regulation of DNA methylation. CONCLUSIONS: This study provides the most comprehensive analysis to date of the methylome of human mammary cell lines and has produced novel insights into the mechanisms of methylome alteration during tumorigenesis and the interdependence between DNA methylome alterations and morphological changes.

Global correlation analysis for micro-RNA and mRNA expression profiles in human cell lines.

Microribonucleic acids (miRNAs) are small noncoding RNAs that negatively regulate gene expression at the posttranscriptional level. Although considerable progress has been made in studying the function of miRNAs, they still remain largely unclear, mainly because of the difficulty in identifying target genes for miRNA. We performed a global analysis of both miRNAs and mRNAs expression across 16 human cell lines and extracted negatively correlated pairs of miRNA and mRNA which indicate miRNA-target relationship. The many of known-target of miR-124a showed negative correlation, suggesting our analysis were valid. We further extracted physically relevant miRNA-target gene pairs, applying computational target prediction algorithm with inverse correlations of miRNA and messenger RNA (mRNA) expression. Furthermore, gene-ontology-based annotation and functional enrichment analysis of the extracted miRNA-target gene pairs made it possible to indicate putative functions of miRNAs. The data collected here will be of value for further studies into the function of miRNA.

Glucocorticoid-induced alternative promoter usage for a novel 5' variant of granzyme A.

Glucocorticoids exert diverse physiological functions through transcriptional regulation of genes including granzyme A (GZMA). GZMA is one of the apoptotic effectors localized in cytotoxic T lymphocytes and is considered to mediate glucocorticoid-induced apoptosis of human leukemia 697 cells. In the present study, we identified a novel 5' variant transcript of GZMA in dexamethasone (DEX)-treated 697 cells. We designated this novel transcript as GZMAbeta. The transcription of GZMAbeta starts at 290 bp downstream of the first intronic glucocorticoid response element (GRE). Chromatin immunoprecipitation assay showed that glucocorticoid receptor (GR) binds to the intronic GRE in a DEX-dependent manner. Luciferase assay and RT-PCR also showed that DEX induces GZMAbeta transcription mediated by GR binding to the intronic GRE. Our results show that there exist at least two transcripts in human GZMA, whose expression is differentially regulated by glucocorticoid.

Transcriptional regulation of connective tissue growth factor by sphingosine 1-phosphate in rat cultured mesangial cells.

Connective tissue growth factor (CTGF) is induced by transforming growth factor-beta (TGF-beta) via Smad activation in mesangial cells. We recently reported that sphingosine 1-phosphate (S1P) induces CTGF expression in rat cultured mesangial cells. However, the mechanism by which S1P induces CTGF expression is unknown. The present study revealed that S1P-induced CTGF expression is mediated via pertussis toxin-insensitive pathways, which are involved in the activation of small GTPases of the Rho family and protein kinase C. We also showed by luciferase reporter assays and chromatin immunoprecipitation that S1P induces CTGF expression via Smad activation as TGF-beta does.

Free fatty acids inhibit serum deprivation-induced apoptosis through GPR120 in a murine enteroendocrine cell line STC-1.

Free fatty acids (FFAs) provide an important energy source and also act as signaling molecules. FFAs are known to exert a variety of physiological responses via their G protein-coupled receptors (GPCRs), such as the GPR40 family. Recently, we identified a novel FFA receptor, GPR120, that promotes secretion of glucagon-like peptide-1 (Hirasawa, A., Tsumaya, K., Awaji, T., Katsuma, S., Adachi, T., Yamada, M., Sugimoto, Y., Miyazaki, S., and Tsujimoto, G. (2005) Nat. Med. 11, 90-94). Here we showed that FFAs inhibit serum deprivation-induced apoptosis of murine enteroendocrine STC-1 cells, which express two types of GPCRs, GPR120 and GPR40, for unsaturated long chain FFA. We first found that linolenic acid potently activated ERK and Akt/protein kinase B (Akt) in STC-1 cells. ERK kinase inhibitors significantly reduced the anti-apoptotic effects of linolenic acid. Inhibitors for phosphatidylinositol 3-kinase (PI3K), a major target of which is Akt, significantly reduced the anti-apoptotic effects. Transfection of STC-1 cells with the dominant-negative form of Akt also inhibited the anti-apoptotic effect. These results suggested that the activation of ERK and PI3K-Akt pathways is required for FFA-induced anti-apoptotic effects on STC-1 cells. Transient transfection of STC-1 cells with GPR120 cDNA, but not GPR40 cDNA, enhanced inhibition of caspase-3 activation. RNA interference experiments showed that reduced expression of GPR120, but not GPR40, resulted in reduced ERK activation and reduced effects of FFAs on caspase-3 inhibition. Collectively, these results demonstrated that FFAs promote the activation of ERK and PI3K-Akt pathways mainly via GPR120, leading to the anti-apoptotic effect of STC-1 cells.