The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor, regulating expression of a group of specific genes including cytochrome P450 1A1 (Cyp1a1). Stably transfected ...luciferase with dioxin responsive elements (DRE) in its promoter region has been commonly used as a reporter gene to study the mechanism of AhR signaling and compare potencies of TCDD and related compounds. However, how these two genes might respond to structurally diverse AhR ligands was unknown. This study investigates their expression in the same cells in response to TCDD, the most potent agonist, and 3
′M4
′NF, a reported potent antagonist. Our data suggest that these two compounds appear to play different roles in regulating these genes. While TCDD enhanced transcription of both genes, 3
′M4
′NF induced the endogenous Cyp1a1, but not the reporter gene. Mechanistic studies indicated that the increase in induction of CYP1A1 protein by 3
′M4
′NF was mediated by AhR-dependent transcriptional activation. Further analysis of the Cyp1a1 promoter sequence did not reveal any 3
′M4
′NF-specific responsive elements other than DREs. Rather, the interaction between the 3
′M4
′NF-bound receptor complex and DREs was confirmed by the observation that a single nucleotide mutation in DRE core sequences obliterated AhR enhancer activity in response to both TCDD and 3
′M4
′NF. Together these data suggest that 3
′M4
′NF, a weak AhR agonist, activates the AhR to recognize and interact with the same DREs as TCDD. However, depending on its concentration as well as the promoter context of a particular gene, the ability of 3
′M4
′NF to act as an AhR antagonist or agonist may appear different for various genes.
In this study, pumpkin seedlings were subjected to cadmium stress (100 mg/L cadmium ion solution, 10 days) without or with wheat straw biochar at different concentrations (0%, 0.5%, 1%, and 2% w/v). ...As the biochar concentration increased, the amount of cadmium accumulated in the root and stem of pumpkin seedlings decreased and the fresh weight of root, stem and leaf increased. The highest cadmium concentration was in the root, followed by the stem and then the leaf. 1% and 2% biochar treatments reduced the oxidative stress of cadmium to seedlings, and added the contents of fatty acid, carbohydrate, amino acid and indoleacetic acid in the root. With the increase of biochar concentration, the metabolites promoting root growth increased. These results provide new information about how biochar alleviates cadmium stress by affecting the metabolic response.
Allopolyploids undergo “genomic shock” leading to significant genetic and epigenetic modifications. Previous studies have mainly focused on nuclear changes, while little is known about the ...inheritance and changes of organelle genome in allopolyploidization. The synthetic allotetraploid Cucumis ×hytivus, which is generated via hybridization between C. hystrix and C. sativus, is a useful model system for studying cytonuclear variation. Here, we report the chloroplast genome of allotetraploid C. ×hytivus and its diploid parents via sequencing and comparative analysis. The size of the obtained chloroplast genomes ranged from 154 673 to 155 760 bp, while their gene contents, gene orders, and GC contents were similar to each other. Comparative genome analysis supports chloroplast maternal inheritance. However, we identified 51 indels and 292 SNP genetic variants in the chloroplast genome of the allopolyploid C. ×hytivus relative to its female parent C. hystrix. Nine intergenic regions with rich variation were identified through comparative analysis of the chloroplast genomes within the subgenus Cucumis. The phylogenetic network based on the chloroplast genome sequences clarified the evolution and taxonomic position of the synthetic allotetraploid C. ×hytivus. The results of this study provide us with an insight into the changes of organelle genome after allopolyploidization, and a new understanding of the cytonuclear evolution.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Antibody-drug conjugates (ADCs) have shown impressive clinical activity with approval of many agents in hematological and solid tumors. However, challenges remain with both efficacy and safety of ...ADCs. This study describes novel trastuzumab-auristatin conjugates with the hydrophilic MMAE prodrug MMAU, and optimization of a glycopeptide linker leading to a wider therapeutic window.
Trastuzumab was conjugated with auristatin payloads via a series of linkers using a stabilized maleimide handle. The ADCs were characterized in vitro and their relative in vivo anti-tumor efficacies were assessed in HER2+ xenograft models. Relative linker stabilities and the mechanism of linker cleavage were studied using in vitro assays. Toxicity and toxicokinetics of the best performing ADC were evaluated in cynomolgus monkey (cyno).
The trastuzumab-MMAU ADC with stabilized glycopeptide linker showed maleimide stabilization and higher resistance to cleavage by serum and lysosomal enzymes compared to a valine-citrulline conjugated trastuzumab ADC (trastuzumab-vc-MMAE). A single dose of 1 or 2 mg/kg of trastuzumab-MMAU at drug-to-antibody ratios (DAR) of 8 and 4 respectively resulted in xenograft tumor growth inhibition, with superior efficacy to trastuzumab-vc-MMAE. Trastuzumab-MMAU DAR4 was tolerated at doses up to 12 mg/kg in cyno, which represents 2- to 4-fold higher dose than that observed with vedotin ADCs, and had increased terminal half-life and exposure.
The optimized trastuzumab-MMAU ADC showed potent antitumor activity and was well tolerated with excellent pharmacokinetics in non-human primates, leading to a superior preclinical therapeutic window. The data supports potential utility of trastuzumab-MMAU for treatment of HER2+ tumors.
JNJ-10450232 (NTM-006) is a new molecular entity that is structurally related to acetaminophen. A comprehensive non-clinical safety program was conducted to support first-in-human and clinical ...efficacy studies based on preclinical data suggesting that the compound has comparable or enhanced antinociceptive and antipyretic efficacy without causing hepatotoxicity at supratherapeutic doses. No hepatic toxicity was noted in a mouse model sensitive to acetaminophen hepatotoxicity or in rats, dogs, and non-human primates in 28-day repeat dose toxicity studies at and above doses/exposures at which acetaminophen is known to cause hepatotoxicity. In the 28-day toxicity studies, all treatment-related findings were monitorable and reversible. Methemoglobinemia, which was observed in dogs and to a lesser extent in rats, is also observed with acetaminophen. This finding is considered not relevant to humans due to species differences in metabolism. Thyroid hypertrophy and hyperplasia were also observed in dogs and were shown to be a consequence of a species-specific UGT induction also demonstrated with increased thyroid hormone metabolism. Indirect bilirubin elevation was observed in rats as a result of UGT1A1 Inhibition. JNJ-10450232 (NTM-006) had no toxicologically relevant findings in safety pharmacology or genotoxicity studies. Together, these data supported progressing into safety and efficacy studies in humans.
•Novel non-opioid analgesic assessed in nonclinical safety studies.•No toxicologically relevant findings in safety pharmacology or genotoxicity studies.•Comparable pharmacology shown for novel analgesic and acetaminophen.•Novel analgesic shows reduced potential to cause hepatotoxicity on overdose.•Studies supported progressing to safety and efficacy studies in humans.
New crop varieties containing traits such as enhanced nutritional profiles, increased yield, and tolerance to drought are being developed. In some cases, these new traits are dependent on small RNAs ...or regulatory proteins such as transcription factors (TF) that modify the expression of endogenous plant genes. To date, the food and feed safety of genetically modified (GM) crops has been assessed by the application of a set of internationally accepted procedures for evaluating the safety of GM crops. The goal of this paper is to review the main aspects of the current safety assessment paradigm and to recommend scientifically sound principles for conducting a safety assessment for GM crops that are developed by technologies that modify endogenous plant gene expression. Key considerations for such a safety assessment include the following:(1)RNA and TF are generally recognized as safe (GRAS);(2)Genes encoding RNAi and regulatory proteins such as TFs are an important component of the plant genome;(3)Crops engineered using RNAi modifications are not expected to produce heterologous proteins;(4)The modulation of TFs may result in quantitative differences in endogenous plant components, which can be assessed through agronomic performance and compositional analysis on a case-by-case basis.
Abstract
Protein arginine methyltransferase 5 (PRMT5) is an epigenetic enzyme with oncogenic properties. JNJ-64619178 (JNJ178) is a potent, selective, structurally unique PRMT5 inhibitor with good ...preclinical efficacy in inhibiting the growth of hematologic and solid tumor cell lines. Toxicology studies showed that JNJ178 decreased reticulocytes and neutrophils in rats and dogs. The objectives of translational modeling and simulation were to understand the exposure-response relationship of both safety and efficacy and provide guidance to the first-in-human clinical development of JNJ178.
Experimental data for the PK/PD (Pharmacokinetics/Pharmacodynamics) modeling included: plasma concentration after single dose of JNJ178 in non-tumor bearing mice, plasma concentration and PD markers of dimethylation of arginine (%SDMA in plasma and %SMD1/3-Me2 in tumor, respectively) after multiple doses (1 to 10 mg/kg) QD (once daily) of JNJ178 in H1048 (human small cell lung carcinoma) xenografts, and tumor volume in four xenograft mouse models (A427, human lung carcinoma; H441, human lung adenocarcinoma; H520, human squamous cell lung carcinoma; and H1048). Plasma PK were first described by a standard two-compartment model and used as a driver of PD and tumor volume (efficacy). Plasma and tumor PD were modeled using an indirect response model. A hybrid tumor growth coupled with transit compartment mediated tumor killing model was used to fit the tumor volume data. To predict the safety profile of JNJ178, lifespan based indirect response model for erythropoiesis and Friberg myelosuppression model were used to simulate hemoglobin and neutrophil kinetics in human.
The PK/PD model described the data well and validated the hypothesis that PD is driven by trough concentration. Based on the exposure-response relationship from the four xenograft models, the trough concentration needed to achieve tumor stasis for mouse was determined. In addition, the level of inhibition in tumor and plasma PD marker that was associated with tumor stasis was identified. Together with human PK parameters scaled using allometry, the dose range needed to achieve target therapeutic exposure for a typical human subject was predicted. Simulation results from erythropoiesis and Friberg myelosuppression models informed the optimal doing schedules for certain dose levels that would allow hematological toxicity to be manageable with <40% reduction in hemoglobin and >1.0 x 109/L neutrophil counts at all times. Overall, a translational modeling and simulation approach that considers safety and efficacy has been instrumental in the design of the first-in-human clinical development of PRMT5 inhibitor JNJ178 regarding selection of dose and schedule.
Citation Format: Yue Guo, Nahor Haddish-Berhane, Hillary J. Millar, Tinne Verhulst, Tony Greway, Junguo Zhou, Loeckie DeZwart, Dana Gaffney, Joseph Portale, Dirk Brehmer, An Boeckx, Erika Van Heerde, Daniele Ouellet. Translational efficacy and safety modeling and simulation to support the clinical development of JNJ-64619178, a PRMT5 inhibitor abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3905.
