En masse organoid phenotyping informs metabolic-associated genetic susceptibility to NASH.

Genotype-phenotype associations for common diseases are often compounded by pleiotropy and metabolic state. Here, we devised a pooled human organoid-panel of steatohepatitis to investigate the impact of metabolic status on genotype-phenotype association. En masse population-based phenotypic analysis under insulin insensitive conditions predicted key non-alcoholic steatohepatitis (NASH)-genetic factors including the glucokinase regulatory protein (GCKR)-rs1260326:C>T. Analysis of NASH clinical cohorts revealed that GCKR-rs1260326-T allele elevates disease severity only under diabetic state but protects from fibrosis under non-diabetic states. Transcriptomic, metabolomic, and pharmacological analyses indicate significant mitochondrial dysfunction incurred by GCKR-rs1260326, which was not reversed with metformin. Uncoupling oxidative mechanisms mitigated mitochondrial dysfunction and permitted adaptation to increased fatty acid supply while protecting against oxidant stress, forming a basis for future therapeutic approaches for diabetic NASH. Thus, "in-a-dish" genotype-phenotype association strategies disentangle the opposing roles of metabolic-associated gene variant functions and offer a rich mechanistic, diagnostic, and therapeutic inference toolbox toward precision hepatology. VIDEO ABSTRACT.

Identification and Therapeutic Targeting of GPR20, Selectively Expressed in Gastrointestinal Stromal Tumors, with DS-6157a, a First-in-Class Antibody-Drug Conjugate.

Currently, the only approved treatments for gastrointestinal stromal tumor (GIST) are tyrosine kinase inhibitors (TKI), which eventually lead to the development of secondary resistance mutations in KIT or PDGFRA and disease progression. Herein, we identified G protein-coupled receptor 20 (GPR20) as a novel non-tyrosine kinase target in GIST, developed new GPR20 IHC, and assessed GPR20 expression in cell lines, patient-derived xenografts, and clinical samples from two institutes (United States and Japan). We studied GPR20 expression stratified by treatment line, KIT expression, GIST molecular subtype, and primary tumor location. We produced DS-6157a, an anti-GPR20 antibody-drug conjugate with a novel tetrapeptide-based linker and DNA topoisomerase I inhibitor exatecan derivative (DXd). DS-6157a exhibited GPR20 expression-dependent antitumor activity in GIST xenograft models including a GIST model resistant to imatinib, sunitinib, and regorafenib. Preclinical pharmacokinetics and safety profile of DS-6157a support its clinical development as a potential novel GIST therapy in patients who are refractory or have resistance or intolerance to approved TKIs. SIGNIFICANCE: GPR20 is selectively expressed in GIST across all treatment lines, regardless of KIT/PDGFRA genotypes. We generated DS-6157a, a DXd-based antibody-drug conjugate that exhibited antitumor activity in GIST models by a different mode of action than currently approved TKIs, showing favorable pharmacokinetics and safety profiles.This article is highlighted in the In This Issue feature, p. 1307.

Identification of the dog orthologue of human MAS-related G protein coupled receptor X2 (MRGPRX2) essential for drug-induced pseudo-allergic reactions.

MAS-related G protein coupled receptor-X2 (MRGPRX2), expressed in human mast cells, is associated with drug-induced pseudo-allergic reactions. Dogs are highly susceptible to drug-induced anaphylactoid reactions caused by various drugs; however, the distribution and physiological function of canine MRGPR family genes, including MRGPRX2, remain largely unknown. In the present study, we clarified the distribution of dog MRGPR family genes by real-time quantitative PCR and in situ hybridisation. We also investigated the stimulatory effects of various histamine-releasing agents, including fluoroquinolones, on HEK293 cells transiently transfected with dog MRGPR family genes to identify their physiological function. Dog MRGPRX2 and MRGPRG were distributed in a limited number of tissues, including the skin (from the eyelid, abdomen, and cheek), whereas MRGPRD and MRGPRF were extensively expressed in almost all tissues examined. Histochemical and in situ hybridisation analyses revealed that MRGPRX2 was expressed in dog connective tissue-type mast cells in the skin. Intracellular Ca2+ mobilisation assay revealed that HEK293 cells, expressing dog MRGPRX2 or human MRGPRX2, but not dog MRGPRD, MRGPRF, and MRGPRG, responded to histamine-releasing agents. Our results suggest that dog MRGPRX2 is the functional orthologue of human MRGPRX2 and plays an essential role in drug-induced anaphylactoid reactions in dogs.

Comprehensive analysis of cardiac function, blood biomarkers and histopathology for milrinone-induced cardiotoxicity in cynomolgus monkeys.

The objective of this study was to elucidate the underlying cardiotoxic mechanism of milrinone, a cAMP phosphodiesterase 3 inhibitor, by evaluating cardiac functions, blood biomarkers including cardiac troponin I (cTnI), microRNAs (miR-1, miR-133a and miR-499a) and various endogenous metabolites, and histopathology in conscious cynomolgus monkeys. Milrinone at doses of 0, 3 and 30 mg/kg were orally administered to monkeys (n = 3-4/group), and the endpoints were evaluated 1 to 24 h post-dosing. Milrinone caused myocardial injuries characterized by myocardial degeneration/necrosis, cell infiltration and hemorrhage 24 h after drug administration. Cardiac functional analysis revealed that milrinone dose-dependently increased the maximum upstroke velocity of the left ventricular pressure and heart rate, and decreased the QA interval and systemic blood pressure 1-4 h post-dosing, being associated with pharmacological action of the drug. In the blood biomarker analysis, only plasma cTnI was dose-dependently increased 4-7 h after drug administration, suggesting that cTnI is the most sensitive biomarker for early detection of milrinone-induced myocardial injuries. In the metabolomics analysis, high dose of milrinone induced transient changes in lipid metabolism, amino acid utilization and oxidative stress, together with the pharmacological action of increased cAMP and lipolysis 1 h post-dosing before the myocardial injuries were manifested by increased cTnI levels. Taken together, milrinone showed acute positive inotropic and multiple metabolic changes including excessive pharmacological actions, resulting in myocardial injuries. Furthermore, a comprehensive analysis of cardiac functions, blood biomarkers and histopathology can provide more appropriate information for overall assessment of preclinical cardiovascular safety.

Outer retinal involvement in N-methyl-D-aspartate-induced inner retinal injury in rabbits assessed by optical coherence tomography.

This study was aimed to investigate morphological alteration of the retina with N-methyl-D-aspartate (NMDA)-induced injury in rabbits by optical coherence tomography (OCT). The right and left eyes of a total of 12 rabbits received single-intravitreal injection of vehicle and NMDA, respectively. Four out of the 12 animals underwent OCT and quantification of plasma microRNA repeatedly (4, 48, and 168 hr after dosing), followed by ocular histopathology at the end of the study. Ocular histopathology was also conducted in the eyes collected 4 or 48 hr after dosing from 4 animals at each time period. OCT revealed hyper-reflective ganglion cell complex and thickened inner retina in NMDA-treated eyes 4 hr after dosing; the inner retina shifted to thinning at later time points. The eyes given NMDA also exhibited greater thickness of the outer retina, which contains photoreceptors, after treatment, and thickened and obscured ellipsoid zone 168 hr after dosing. The plasma levels of miR-182 and miR-183, which are known to be highly expressed in photoreceptors, were higher 4 hr after dosing than pre-dosing values. Histopathologically, NMDA-induced inner retinal damage was confirmed: single-cell necrosis was observed in the ganglion cell layer and the inner nuclear layer 4 hr after dosing, the incidence of which decreased thereafter. At 168 hr after dosing, reduced number of ganglion cells was noted. No change was histopathologically observed in the outer retina. In conclusion, our results suggest involvement of photoreceptors in NMDA-induced inner retinal injury. Additionally, OCT revealed acute inner retinal findings suggestive of temporary edema.

Fluoroquinolones suppress gluconeogenesis by inhibiting fructose 1,6-bisphosphatase in primary monkey hepatocytes.

Dysglycemia is one of the most serious adverse events associated with the clinical use of certain fluoroquinolones. The purpose of this study was to investigate the effects of the representative fluoroquinolones moxifloxacin and gatifloxacin on hepatic gluconeogenesis using primary monkey hepatocytes. Glucose production was induced after the cells were incubated for 4 h with 10 mM sodium lactate and 1 mM sodium pyruvate as gluconeogenic substrates. Under these conditions, moxifloxacin and gatifloxacin dose-dependently suppressed gluconeogenesis at concentrations of 100 µM or higher. Transcriptome analysis of rate-limiting enzymes involved in hepatic gluconeogenesis revealed that moxifloxacin and gatifloxacin at a concentration of 1000 µM did not affect the expression of key gluconeogenic enzymes such as phosphoenolpyruvate carboxykinase, glucose 6-phosphatase, and fructose 1,6-bisphosphatase. Furthermore, metabolome analysis, in vitro glucose production assay using additional gluconeogenic substrates, and fructose 1,6-bisphosphatase assay using the cell extracts showed that fluoroquinolones enzymatically suppressed hepatic gluconeogenesis by inhibiting fructose 1,6-bisphosphatase. These inhibitory effects may involve in the clinically relevant dysglycemia associated with fluoroquinolones in human.

A Novel HER3-Targeting Antibody-Drug Conjugate, U3-1402, Exhibits Potent Therapeutic Efficacy through the Delivery of Cytotoxic Payload by Efficient Internalization.

PURPOSE: HER3 is a compelling target for cancer treatment; however, no HER3-targeted therapy is currently clinically available. Here, we produced U3-1402, an anti-HER3 antibody-drug conjugate with a topoisomerase I inhibitor exatecan derivative (DXd), and systematically investigated its targeted drug delivery potential and antitumor activity in preclinical models. EXPERIMENTAL DESIGN: In vitro pharmacologic activities and the mechanisms of action of U3-1402 were assessed in several human cancer cell lines. Antitumor activity of U3-1402 was evaluated in xenograft mouse models, including patient-derived xenograft (PDX) models. Safety assessments were also conducted in rats and monkeys. RESULTS: U3-1402 showed HER3-specific binding followed by highly efficient cancer cell internalization. Subsequently, U3-1402 was translocated to the lysosome and released its payload DXd. While U3-1402 was able to inhibit HER3-activated signaling similar to its naked antibody patritumab, the cytotoxic activity of U3-1402 in HER3-expressing cells was predominantly mediated by released DXd through DNA damage and apoptosis induction. In xenograft mouse models, U3-1402 exhibited dose-dependent and HER3-dependent antitumor activity. Furthermore, U3-1402 exerted potent antitumor activity against PDX tumors with HER3 expression. Acceptable toxicity was noted in both rats and monkeys. CONCLUSIONS: U3-1402 demonstrated promising antitumor activity against HER3-expressing tumors with tolerable safety profiles. The activity of U3-1402 was driven by HER3-mediated payload delivery via high internalization into tumor cells.

Establishment of an in vitro cytotoxicity assay platform using primary monkey cardiomyocytes.

To establish an in vitro cytotoxicity assay platform using monkey cardiomyocytes, we isolated primary cardiomyocytes from fetal cynomolgus monkeys at different gestation days (from day 39 to 90) using the trypsin and collagenase digestion method, which was identical to the standard procedure for rat cardiomyocytes. Under these conditions, the primary cells obtained from monkeys at gestation day 63 or earlier showed spontaneous beating, with >80% cells being viable from all fetuses. Transcriptome analysis of the monkey cardiomyocytes indicated that the cells have essential components of cardiac functions, such as myosins, α-actin, cardiac troponins, and calcium-related molecules. The susceptibility to doxorubicin-induced cytotoxicity in monkey cardiomyocytes was comparable to that in rat cardiomyocytes, as evaluated based on intracellular ATP levels. Microarray analysis with Ingenuity Pathway Analysis revealed that doxorubicin predominantly increased the expression of several key genes involved in the endoplasmic reticulum stress pathway in monkey cardiomyocytes than in rat cardiomyocytes. In conclusion, we isolated primary monkey cardiomyocytes that showed similar sensitivity to doxorubicin as compared with rat cardiomyocytes. This in vitro monkey cardiomyocyte assay platform would serve as a powerful tool for the investigation of the interspecies differences in drug-induced cardiotoxicity and its underlying mechanism.

Plasma citrulline is a sensitive safety biomarker for small intestinal injury in rats.

Plasma citrulline is decreased in cases of severe intestinal injury with apparent villus and cellular atrophy. However, the fluctuation of plasma citrulline in slight intestinal injury remains to be investigated. To clarify this, irinotecan at 30 mg/kg or 60 mg/kg was administered intravenously to rats. Irinotecan reduced plasma citrulline concentrations compared to those in the pair-fed control, being concurrent with slight single cell necrosis and mucosal epithelium regeneration in the small intestine without apparent villus and cellular atrophy. Gene expression of enzymes converting glutamine to citrulline was decreased in the small intestine of the injury model. Moreover, citrulline and arginine levels in the ileum were decreased without alterations to glutamine and glutamate levels, indicating that citrulline synthesis from glutamine was impaired. Metabolome analysis revealed that plasma citrulline and arginine levels were decreased, while there were no marked alterations in other amino acids, metabolites of glycolysis, ketone bodies, or fatty acids. These results suggested that a decreased plasma citrulline level was unlikely to result from amino acid catabolism in response to malnutrition. In conclusion, plasma citrulline concentration reflects slight intestinal injury without apparent villus and cellular atrophy, and thus, it would be a sensitive biomarker for the small intestinal injury.

Absolute Quantification of Plasma MicroRNA Levels in Cynomolgus Monkeys, Using Quantitative Real-time Reverse Transcription PCR.

RT-qPCR is one of the most common methods to assess individual target miRNAs. MiRNAs levels are generally measured relative to a reference sample. This approach is appropriate for examining physiological changes in target gene expression levels. However, absolute quantification using better statistical analysis is preferable for a comprehensive assessment of gene expression levels. Absolute quantification is still not in common use. This report describes a protocol for measuring the absolute levels of plasma miRNA, using RT-qPCR with or without pre-amplification. A fixed volume (200 µL) of EDTA-plasma was prepared from the blood collected from the femoral vein of conscious cynomolgus monkeys (n = 50). Total RNA was extracted using commercially available system. Plasma miRNAs were quantified by probe-based RT-qPCR assays which contains miRNA-specific forward/reverse PCR primer and probe. Standard curves for absolute quantification were generated using commercially available synthetic RNA oligonucleotides. A synthetic cel-miR-238 was used as an external control for normalization and quality assessment. The miRNAs that showed quantification cycle (Cq) values above 35 were pre-amplified prior to the qPCR step. Among the 8 miRNAs examined, miR-122, miR-133a, and miR-192 were detectable without pre-amplification, whereas miR-1, miR-206, and miR-499a required pre-amplification because of their low expression levels. MiR-208a and miR-208b were not detectable even after pre-amplification. Sample processing efficiency was evaluated by the Cq values of the spiked cel-miR-238. In this assay method, technical variation was estimated to be less than 3-fold and the lower limit of quantification (LLOQ) was 102 copy/µL, for most of the examined miRNAs. This protocol provides a better estimate of the quantity of plasma miRNAs, and allows quality assessment of corresponding data from different studies. Considering the low number of miRNAs in body fluids, pre-amplification is useful to enhance detection of poorly expressed miRNAs.

DS-7250, a Diacylglycerol Acyltransferase 1 Inhibitor, Enhances Hepatic Steatosis in Zucker Fatty Rats via Upregulation of Fatty Acid Synthesis.

Diacylglycerol acyltransferase 1 (DGAT1) catalyzes the final step in triglyceride synthesis. Since Dgat1-/- mice fed a high-fat diet (HFD) are resistant to hepatic steatosis, DGAT1 inhibitors are expected to have antifatty liver effects. To evaluate the hepatic effects of DS-7250, a selective DGAT1 inhibitor, vehicle or 10 mg/kg of DS-7250 was administered orally to male Fisher 344 (F344) and Zucker fatty (ZF) rats fed a standard diet or HFD for 14 or 28 days. ZF rats showed slight hepatic steatosis regardless of feeding conditions. DS-7250 exacerbated hepatic steatosis in ZF rats fed an HFD compared with the vehicle control. Hepatic steatosis did not occur in F344 rats fed an HFD, in which systemic exposures of DS-7250 were comparable to those in ZF rats. There was a higher expression of genes involved in lipid uptake and fatty acid synthesis in ZF rats compared to F344 rats under HFD conditions. DS-7250 upregulated key genes involved in de novo lipogenesis, which causes hepatic steatosis independently of DGAT1, in ZF rats fed an HFD compared with the vehicle control. These data suggest that ZF rats were more susceptible to hepatic steatosis due to their genetic characteristics and DS-7250 exacerbated hepatic steatosis independently of DGAT1.

Circulating liver-specific microRNAs in cynomolgus monkeys.

Circulating microRNAs (miRNAs) can potentially be used as sensitive and specific biomarkers for tissue injury. However, the usefulness of circulating miRNAs as safety biomarkers in nonclinical toxicological studies using nonhuman primates is debatable owing to the limited information on organ-specific miRNAs. Therefore, a systematic investigation was performed to address this point. We identified organ-specific miRNAs from cynomolgus monkeys by next-generation sequencing analysis, which revealed that miR-122 was only abundant in the liver, whereas miR-192 was abundant in the liver, stomach, intestines, and kidney. The sequences of these miRNAs were identical to their human counterparts. Next, the absolute miR-122 and miR-192 levels were qualified by quantitative reverse transcription polymerase chain reaction (RT-qPCR) to determine the circulating levels of the miRNAs. No significant differences in the levels of circulating miRNAs between sexes were noted, and there was greater interindividual variation in miR-122 (20-fold variation) than in miR-192 (8-fold variation), based on their dynamic ranges. Finally, we evaluated the fluctuation in circulating liver-specific miRNAs in a monkey model of acetaminophen-induced hepatotoxicity. Acetaminophen with L-buthionine-(S,R)-sulfoximine induced hepatotoxicity in all the animals, which was characterized histopathologically by centrilobular necrosis and vacuolation of hepatocytes. Circulating miR-122 and miR-192 levels increased more than ALT levels after 24 h, indicating that circulating miR-122 and miR-192 may serve as sensitive biomarkers for the detection of hepatotoxicity in cynomolgus monkeys. This review describes the fundamental profiles of circulating liver-specific miRNAs in cynomolgus monkeys and focusses on their organ specificity, circulating levels, and fluctuations in drug-induced hepatotoxicity.

UNC569-induced Morphological Changes in Pigment Epithelia and Photoreceptor Cells in the Retina through MerTK Inhibition in Mice.

Mer proto-oncogene tyrosine kinase (MerTK), which is expressed in the retinal pigment epithelium (RPE), regulates phagocytosis of shed photoreceptor outer segments (POS). To investigate the effects of drug-induced MerTK inhibition on the retina, UNC569, a specific MerTK inhibitor, was orally administered to male mice at a concentration of 60, 100, or 150 mg/kg for up to 14 days. Furthermore, MerTK inhibition in the retinal tissue sample was examined using a phosphorylation assay following a single dose of UNC569 at 100 mg/kg. In electron microscopic examination, UNC569 at 100 mg/kg or more increased phagosomes and phagolysosomes in the RPE. In addition, UNC569 at 150 mg/kg increased chromatin-condensed nuclei in the outer nuclear layer, indicating the early phase of apoptosis of photoreceptor cells. MiR-183, miR-96, and miR-124, which are enriched in photoreceptor cells, were elevated in the plasma of mice following treatment of 150-mg/kg UNC569, in conjunction with the photoreceptor lesion. Additionally, 100-mg/kg UNC569 inhibited MerTK phosphorylation in the retina. These results suggest that MerTK inhibition impaired phagocytic function of the retina, leading to accumulation of shed POS within the POS layer and increasing phagosomes and phagolysosomes in the RPE to delay POS renewal, resulting in apoptosis of photoreceptor cells.

Gene expression analysis of Arc mRNA as a neuronal cell activity marker in the hippocampus and amygdala in two-way active avoidance test in rats.

INTRODUCTION: Immediate early genes are widely used as neuronal cell activity markers in neuroscience. The present study investigated the relationship between their expression and abnormality in context fear conditioning. METHODS: The learning test (two-way active avoidance test) was conducted in male rats administered with nonselective muscarinic antagonist scopolamine or selective dopamine D1-like receptor antagonist SCH 23390 at a dose level of 2.0 or 0.1mg/kg, respectively, for 4days. Expression levels of Arc and Fos mRNA in the hippocampus and amygdala were also evaluated on the second day of dosing by fluorescent in situ hybridization (FISH) and reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR). RESULTS: Scopolamine had no effect on avoidance rate, but decreased freezing in the two-way active avoidance test. SCH 23390 decreased avoidance rate and increased freezing. In FISH and RT-qPCR assays, scopolamine decreased Arc mRNA in the hippocampus and amygdala, whereas SCH 23390 increased Arc mRNA in the hippocampus. By contrast, scopolamine and SCH 23390 did not change Fos mRNA expression compared to Arc mRNA expression. DISCUSSION: The results of the learning test indicated that scopolamine or SCH 23390 respectively inhibited fear or context conditioning in rats. Furthermore, alteration of the expression of Arc mRNA but not of Fos mRNA in the hippocampus and amygdala of the brain was suggested to be a sensitive neuronal cell activity marker to detect behavioral abnormality in the two-way active avoidance test.

Comprehensive Analysis of Circulating microRNA Specific to the Liver, Heart, and Skeletal Muscle of Cynomolgus Monkeys.

Circulating microRNAs (miRNAs) could represent sensitive and specific biomarkers for tissue injury. However, their utility as biomarkers in nonclinical toxicological studies using nonhuman primates is limited by a lack of information on their organ specificity and circulating levels under resting condition of the animals. Herein, liver, heart, and skeletal muscle-specific expression patterns of miRNAs were determined in 27 tissues/organs from male and female monkeys (n =2/sex) by next-generation sequencing (NGS) analysis. This analysis revealed organ-specific miRNAs in the liver (miR-122), heart (miR-208a and miR-499a), and skeletal muscle (miR-206). Next, plasma was collected from conscious-naive male and female cynomolgus monkeys (n = 25/sex) to better understand the expressions of organ-specific circulating miRNAs. The absolute values of circulating miRNAs were quantified using a Taqman microRNA assay. MiR-1, miR-133a, and miR-208b showed preferential expression in the heart and skeletal muscles, whereas miR-192 was abundant in the liver, stomach, small intestine, and kidney. These miRNAs had identical sequences to their human counterparts. Six organ-specific miRNAs (miR-1, miR-122, miR-133a, miR-192, miR-206, and miR-499a) could be evaluated quantitatively by quantitative real-time reverse transcription polymerase chain reaction with or without preamplification. No significant sex differences were noted for these circulating miRNAs. For their circulation levels, miR-133a showed more than 900-fold interindividual variation, whereas miR-122 showed only a 20-fold variation. In conclusion, we profiled circulating organ-specific miRNAs for the liver, heart, and skeletal muscle of cynomolgus monkeys.

A monkey model of acetaminophen-induced hepatotoxicity; phenotypic similarity to human.

Species-specific differences in the hepatotoxicity of acetaminophen (APAP) have been shown. To establish a monkey model of APAP-induced hepatotoxicity, which has not been previously reported, APAP at doses up to 2,000 mg/kg was administered orally to fasting male and female cynomolgus monkeys (n = 3-5/group) pretreated intravenously with or without 300 mg/kg of the glutathione biosynthesis inhibitor, L-buthionine-(S,R)-sulfoximine (BSO). In all the animals, APAP at 2,000 mg/kg with BSO but not without BSO induced hepatotoxicity, which was characterized histopathologically by centrilobular necrosis and vacuolation of hepatocytes. Plasma levels of APAP and its reactive metabolite N-acethyl-p-benzoquinone imine (NAPQI) increased 4 to 7 hr after the APAP treatment. The mean Cmax level of APAP at 2,000 mg/kg with BSO was approximately 200 µg/mL, which was comparable to high-risk cutoff value of the Rumack-Matthew nomogram. Interestingly, plasma alanine aminotransferase (ALT) did not change until 7 hr and increased 24 hr or later after the APAP treatment, indicating that this phenotypic outcome was similar to that in humans. In addition, circulating liver-specific miR-122 and miR-192 levels also increased 24 hr or later compared with ALT, suggesting that circulating miR-122 and miR-192 may serve as potential biomarkers to detect hepatotoxicity in cynomolgus monkeys. These results suggest that the hepatotoxicity induced by APAP in the monkey model shown here was translatable to humans in terms of toxicokinetics and its toxic nature, and this model would be useful to investigate mechanisms of drug-induced liver injury and also potential translational biomarkers in humans.

Wide application of a novel topoisomerase I inhibitor-based drug conjugation technology.

To establish a novel and widely applicable payload-linker technology for antibody-drug conjugates (ADCs), we have focused our research on applying exatecan mesylate (DX-8951f), a potent topoisomerase I inhibitor, which exhibits extensive antitumor activity as well as significant myelotoxicity, as the payload part. Through this study, we discovered a promising exatecan derivative (DX-8951 derivative, DXd), that has the characteristics of low membrane permeability and shows considerably less myelotoxicity than that shown by exatecan mesylate in an in vitro human colony forming unit-granulocyte macrophage assay. DXd was further used for drug conjugation by using commercially or clinically useful monoclonal antibodies to evaluate the potency of the ADC. The result revealed that the DXd-ADCs targeting CD30, CD33, and CD70 were effective against each of their respective target-expressing tumor cell lines. Moreover, a novel DXd-ADC targeting B7-H3, which is a new target for ADCs, also showed potent antitumor efficacy both in vitro and in vivo. In conclusion, this study showed that this novel topoisomerase I inhibitor-based ADC technology is widely applicable to a diverse number of antibodies and is expected to mitigate myelotoxicity, thereby possibly resulting in better safety profiles than that of existing ADC technologies.

MicroRNA profiles in a monkey testicular injury model induced by testicular hyperthermia.

To characterize microRNAs (miRNAs) involved in testicular toxicity in cynomolgus monkeys, miRNA profiles were investigated using next-generation sequencing (NGS), microarray and reverse transcription-quantitative real-time-PCR (RT-qPCR) methods. First, to identify organ-specific miRNAs, we compared the expression levels of miRNAs in the testes to those in representative organs (liver, heart, kidney, lung, spleen and small intestine) obtained from naïve mature male and female monkeys (n = 2/sex) using NGS analysis. Consequently, miR-34c-5p, miR-202-5p, miR-449a and miR-508-3p were identified to be testicular-specific miRNAs in cynomolgus monkeys. Next, we investigated miRNA profiles after testicular-hyperthermia (TH) treatment to determine which miRNAs are involved in testicular injury. In this experiment, mature male monkeys were divided into groups with or without TH-treatment (n = 3/group) by immersion of the testes in a water bath at 43 °C for 30 min for 5 consecutive days. As a result, TH treatment induced testicular injury in all animals, which was characterized by decreased numbers of spermatocytes and spermatids. In a microarray analysis of the testis, 11 up-regulated (>2.0 fold) and 13 down-regulated (<0.5 fold) miRNAs were detected compared with those in the control animals. Interestingly, down-regulated miRNAs included two testicular-specific miRNAs, miR-34c-5p and miR-449a, indicating their potential use as biomarkers for testicular toxicity. Furthermore, RT-qPCR analysis revealed decreased expression levels of testicular miR-34b-5p and miR-34c-5p, which are enriched in meiotic cells, reflecting the decrease in pachytene spermatocytes and spermatids after TH treatment. These results provide valuable insights into the mechanism of testicular toxicity and potential translational biomarkers for testicular toxicity. Copyright © 2016 The Authors. Journal of Applied Toxicology published by John Wiley & Sons Ltd.

MicroRNA profiling in ethylene glycol monomethyl ether-induced monkey testicular toxicity model.

To establish and characterize ethylene glycol monomethyl ether (EGME)-induced testicular toxicity model in cynomolgus monkeys, EGME at 0 or 300 mg/kg was administered orally to sexually mature male cynomolgus monkeys (n = 3/group) for 4 consecutive days. Circulating and testicular microRNA (miRNA) profiles in this model were investigated using miRNA microarray or real-time quantitative reverse transcription-PCR methods. EGME at 300 mg/kg induced testicular toxicity in all the monkeys, which was characterized histopathologically by decreases in pachytene spermatocytes and round spermatids, without any severe changes in general conditions or clinical pathology. In microarray analysis, 16 down-regulated and 347 up-regulated miRNAs were detected in the testis, and 326 down-regulated but no up-regulated miRNAs were detected in plasma. Interestingly, miR-1228 and miR-2861 were identified as abundant miRNAs in plasma and the testis of control animals, associated presumably with apoptosis and cell differentiation, respectively, and were prominently increased in the testis of EGME-treated animals, reflecting the recovery from EGME-induced testicular damages via stimulating cell proliferation and differentiation of sperm. Furthermore, down-regulation of miR-34b-5p and miR-449a, which are enriched in meiotic cells like pachytene spermatocytes, was obvious in the testis, suggesting that these spermatogenic cells were damaged by the EGME treatment. In conclusion, EGME-induced testicular toxicity in cynomolgus monkeys was shown, and this model would be useful for investigating the mechanism of EGME-induced testicular toxicity and identifying testicular biomarkers. Additionally, testicular miR-34b-5p and miR-449a were suggested to be involved in damage of pachytene spermatocytes.

Hedgehog signaling through GLI1 and GLI2 is required for epithelial-mesenchymal transition in human trophoblasts.

BACKGROUND: Epithelial to mesenchymal transition (EMT) is critical for human placental development, trophoblastic differentiation, and pregnancy-associated diseases. Here, we investigated the effects of hedgehog (HH) signaling on EMT in human trophoblasts, and further explored the underlying mechanism. METHODS: Human primary cytotrophoblasts and trophoblast-like JEG-3 cells were used as in vitro models. Quantitative real-time RT-PCR and Western blot analysis were performed to examine mRNA and protein levels, respectively. Lentiviruses expressing short hairpin RNA were used to knock down the target genes. Reporter assays and chromatin immunoprecipitation were performed to determine the transactivity. Cell migration, invasion and colony formation were accessed by wound healing, Matrigel-coated transwell, and colony formation assays, respectively. RESULTS: Activation of HH signaling induced the transdifferentiation of cytotrophoblasts and trophoblast-like JEG-3 cells from epithelial to mesenchymal phenotypes, exhibiting the decreases in E-Cadherin expression as well as the increases in vimentin expression, invasion, migration and colony formation. Knockdown of GLI1 and GLI2 but not GLI3 attenuated HH-induced transdifferentiation, whereas GLI1 was responsible for the expression of HH-induced key EMT regulators including Snail1, Slug, and Twist, and both GLI1 and GLI2 acted directly as transcriptional repressor of CDH1 gene encoding E-Cadherin. CONCLUSION: HH through GLI1 and GLI2 acts as critical signals in supporting the physiological function of mature placenta. GENERAL SIGNIFICANCE: HH signaling through GLI1 and GLI2 could be required for the maintenance of human pregnancy.